content: /*
   * Copyright (C) 2006 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package android.view;
  
  import static android.os.Build.VERSION_CODES.JELLY_BEAN_MR1;
  
  import android.animation.LayoutTransition;
  import android.annotation.CallSuper;
  import android.annotation.IdRes;
  import android.annotation.NonNull;
  import android.annotation.TestApi;
  import android.annotation.UiThread;
  import android.annotation.UnsupportedAppUsage;
  import android.content.ClipData;
  import android.content.Context;
  import android.content.Intent;
  import android.content.pm.PackageManager;
  import android.content.res.Configuration;
  import android.content.res.TypedArray;
  import android.graphics.Bitmap;
  import android.graphics.Canvas;
  import android.graphics.Color;
  import android.graphics.Insets;
  import android.graphics.Matrix;
  import android.graphics.Paint;
  import android.graphics.PointF;
  import android.graphics.Rect;
  import android.graphics.RectF;
  import android.graphics.Region;
  import android.os.Build;
  import android.os.Bundle;
  import android.os.Parcelable;
  import android.os.SystemClock;
  import android.util.AttributeSet;
  import android.util.Log;
  import android.util.Pools;
  import android.util.Pools.SynchronizedPool;
  import android.util.SparseArray;
  import android.util.SparseBooleanArray;
  import android.view.WindowInsetsAnimationListener.InsetsAnimation;
  import android.view.accessibility.AccessibilityEvent;
  import android.view.accessibility.AccessibilityManager;
  import android.view.accessibility.AccessibilityNodeInfo;
  import android.view.animation.Animation;
  import android.view.animation.AnimationUtils;
  import android.view.animation.LayoutAnimationController;
  import android.view.animation.Transformation;
  import android.view.autofill.Helper;
  import android.view.inspector.InspectableProperty;
  import android.view.inspector.InspectableProperty.EnumEntry;
  
  import com.android.internal.R;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.function.Predicate;
  
  /**
   * <p>
   * A <code>ViewGroup</code> is a special view that can contain other views
   * (called children.) The view group is the base class for layouts and views
   * containers. This class also defines the
   * {@link android.view.ViewGroup.LayoutParams} class which serves as the base
   * class for layouts parameters.
   * </p>
   *
   * <p>
   * Also see {@link LayoutParams} for layout attributes.
   * </p>
   *
   * <div class="special reference">
   * <h3>Developer Guides</h3>
   * <p>For more information about creating user interface layouts, read the
   * <a href="{@docRoot}guide/topics/ui/declaring-layout.html">XML Layouts</a> developer
   * guide.</p></div>
   *
   * <p>Here is a complete implementation of a custom ViewGroup that implements
   * a simple {@link android.widget.FrameLayout} along with the ability to stack
   * children in left and right gutters.</p>
   *
   * {@sample development/samples/ApiDemos/src/com/example/android/apis/view/CustomLayout.java
   *      Complete}
   *
   * <p>If you are implementing XML layout attributes as shown in the example, this is the
   * corresponding definition for them that would go in <code>res/values/attrs.xml</code>:</p>
   *
   * {@sample development/samples/ApiDemos/res/values/attrs.xml CustomLayout}
   *
   * <p>Finally the layout manager can be used in an XML layout like so:</p>
   *
   * {@sample development/samples/ApiDemos/res/layout/custom_layout.xml Complete}
   *
   * @attr ref android.R.styleable#ViewGroup_clipChildren
   * @attr ref android.R.styleable#ViewGroup_clipToPadding
   * @attr ref android.R.styleable#ViewGroup_layoutAnimation
   * @attr ref android.R.styleable#ViewGroup_animationCache
   * @attr ref android.R.styleable#ViewGroup_persistentDrawingCache
   * @attr ref android.R.styleable#ViewGroup_alwaysDrawnWithCache
   * @attr ref android.R.styleable#ViewGroup_addStatesFromChildren
   * @attr ref android.R.styleable#ViewGroup_descendantFocusability
   * @attr ref android.R.styleable#ViewGroup_animateLayoutChanges
   * @attr ref android.R.styleable#ViewGroup_splitMotionEvents
   * @attr ref android.R.styleable#ViewGroup_layoutMode
   */
  @UiThread
  public abstract class ViewGroup extends View implements ViewParent, ViewManager {
      private static final String TAG = "ViewGroup";
  
      @UnsupportedAppUsage
      private static final boolean DBG = false;
  
      /**
       * Views which have been hidden or removed which need to be animated on
       * their way out.
       * This field should be made private, so it is hidden from the SDK.
       * {@hide}
       */
      @UnsupportedAppUsage
      protected ArrayList<View> mDisappearingChildren;
  
      /**
       * Listener used to propagate events indicating when children are added
       * and/or removed from a view group.
       * This field should be made private, so it is hidden from the SDK.
       * {@hide}
       */
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 123768704)
      protected OnHierarchyChangeListener mOnHierarchyChangeListener;
  
      // The view contained within this ViewGroup that has or contains focus.
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
      private View mFocused;
      // The view contained within this ViewGroup (excluding nested keyboard navigation clusters)
      // that is or contains a default-focus view.
      private View mDefaultFocus;
      // The last child of this ViewGroup which held focus within the current cluster
      View mFocusedInCluster;
  
      /**
       * A Transformation used when drawing children, to
       * apply on the child being drawn.
       */
      private Transformation mChildTransformation;
  
      /**
       * Used to track the current invalidation region.
       */
      RectF mInvalidateRegion;
  
      /**
       * A Transformation used to calculate a correct
       * invalidation area when the application is autoscaled.
       */
      Transformation mInvalidationTransformation;
  
      // Current frontmost child that can accept drag and lies under the drag location.
      // Used only to generate ENTER/EXIT events for pre-Nougat aps.
      private View mCurrentDragChild;
  
      // Metadata about the ongoing drag
      private DragEvent mCurrentDragStartEvent;
      private boolean mIsInterestedInDrag;
      private HashSet<View> mChildrenInterestedInDrag;
  
      // Used during drag dispatch
      private PointF mLocalPoint;
  
      // Lazily-created holder for point computations.
      private float[] mTempPoint;
  
      // Layout animation
      private LayoutAnimationController mLayoutAnimationController;
      private Animation.AnimationListener mAnimationListener;
  
      // First touch target in the linked list of touch targets.
      @UnsupportedAppUsage
      private TouchTarget mFirstTouchTarget;
  
      // For debugging only.  You can see these in hierarchyviewer.
      @SuppressWarnings({"FieldCanBeLocal", "UnusedDeclaration"})
      @ViewDebug.ExportedProperty(category = "events")
      private long mLastTouchDownTime;
      @ViewDebug.ExportedProperty(category = "events")
      private int mLastTouchDownIndex = -1;
      @SuppressWarnings({"FieldCanBeLocal", "UnusedDeclaration"})
      @ViewDebug.ExportedProperty(category = "events")
      private float mLastTouchDownX;
      @SuppressWarnings({"FieldCanBeLocal", "UnusedDeclaration"})
      @ViewDebug.ExportedProperty(category = "events")
      private float mLastTouchDownY;
  
      // First hover target in the linked list of hover targets.
      // The hover targets are children which have received ACTION_HOVER_ENTER.
      // They might not have actually handled the hover event, but we will
      // continue sending hover events to them as long as the pointer remains over
      // their bounds and the view group does not intercept hover.
      private HoverTarget mFirstHoverTarget;
  
      // True if the view group itself received a hover event.
      // It might not have actually handled the hover event.
      private boolean mHoveredSelf;
  
      // The child capable of showing a tooltip and currently under the pointer.
      private View mTooltipHoverTarget;
  
      // True if the view group is capable of showing a tooltip and the pointer is directly
      // over the view group but not one of its child views.
      private boolean mTooltipHoveredSelf;
  
      /**
       * Internal flags.
       *
       * This field should be made private, so it is hidden from the SDK.
       * {@hide}
       */
      @ViewDebug.ExportedProperty(flagMapping = {
              @ViewDebug.FlagToString(mask = FLAG_CLIP_CHILDREN, equals = FLAG_CLIP_CHILDREN,
                      name = "CLIP_CHILDREN"),
              @ViewDebug.FlagToString(mask = FLAG_CLIP_TO_PADDING, equals = FLAG_CLIP_TO_PADDING,
                      name = "CLIP_TO_PADDING"),
              @ViewDebug.FlagToString(mask = FLAG_PADDING_NOT_NULL, equals = FLAG_PADDING_NOT_NULL,
                      name = "PADDING_NOT_NULL")
      }, formatToHexString = true)
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 123769411)
      protected int mGroupFlags;
  
      /**
       * Either {@link #LAYOUT_MODE_CLIP_BOUNDS} or {@link #LAYOUT_MODE_OPTICAL_BOUNDS}.
       */
      private int mLayoutMode = LAYOUT_MODE_UNDEFINED;
  
      /**
       * NOTE: If you change the flags below make sure to reflect the changes
       *       the DisplayList class
       */
  
      // When set, ViewGroup invalidates only the child's rectangle
      // Set by default
      static final int FLAG_CLIP_CHILDREN = 0x1;
  
      // When set, ViewGroup excludes the padding area from the invalidate rectangle
      // Set by default
      private static final int FLAG_CLIP_TO_PADDING = 0x2;
  
      // When set, dispatchDraw() will invoke invalidate(); this is set by drawChild() when
      // a child needs to be invalidated and FLAG_OPTIMIZE_INVALIDATE is set
      static final int FLAG_INVALIDATE_REQUIRED  = 0x4;
  
      // When set, dispatchDraw() will run the layout animation and unset the flag
      private static final int FLAG_RUN_ANIMATION = 0x8;
  
      // When set, there is either no layout animation on the ViewGroup or the layout
      // animation is over
      // Set by default
      static final int FLAG_ANIMATION_DONE = 0x10;
  
      // If set, this ViewGroup has padding; if unset there is no padding and we don't need
      // to clip it, even if FLAG_CLIP_TO_PADDING is set
      private static final int FLAG_PADDING_NOT_NULL = 0x20;
  
      /** @deprecated - functionality removed */
      @Deprecated
      private static final int FLAG_ANIMATION_CACHE = 0x40;
  
      // When set, this ViewGroup converts calls to invalidate(Rect) to invalidate() during a
      // layout animation; this avoid clobbering the hierarchy
      // Automatically set when the layout animation starts, depending on the animation's
      // characteristics
      static final int FLAG_OPTIMIZE_INVALIDATE = 0x80;
  
      // When set, the next call to drawChild() will clear mChildTransformation's matrix
      static final int FLAG_CLEAR_TRANSFORMATION = 0x100;
  
      // When set, this ViewGroup invokes mAnimationListener.onAnimationEnd() and removes
      // the children's Bitmap caches if necessary
      // This flag is set when the layout animation is over (after FLAG_ANIMATION_DONE is set)
      private static final int FLAG_NOTIFY_ANIMATION_LISTENER = 0x200;
  
      /**
       * When set, the drawing method will call {@link #getChildDrawingOrder(int, int)}
       * to get the index of the child to draw for that iteration.
       *
       * @hide
       */
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 123769377)
      protected static final int FLAG_USE_CHILD_DRAWING_ORDER = 0x400;
  
      /**
       * When set, this ViewGroup supports static transformations on children; this causes
       * {@link #getChildStaticTransformation(View, android.view.animation.Transformation)} to be
       * invoked when a child is drawn.
       *
       * Any subclass overriding
       * {@link #getChildStaticTransformation(View, android.view.animation.Transformation)} should
       * set this flags in {@link #mGroupFlags}.
       *
       * {@hide}
       */
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 123769647)
      protected static final int FLAG_SUPPORT_STATIC_TRANSFORMATIONS = 0x800;
  
      // UNUSED FLAG VALUE: 0x1000;
  
      /**
       * When set, this ViewGroup's drawable states also include those
       * of its children.
       */
      private static final int FLAG_ADD_STATES_FROM_CHILDREN = 0x2000;
  
      /** @deprecated functionality removed */
      @Deprecated
      private static final int FLAG_ALWAYS_DRAWN_WITH_CACHE = 0x4000;
  
      /** @deprecated functionality removed */
      @Deprecated
      private static final int FLAG_CHILDREN_DRAWN_WITH_CACHE = 0x8000;
  
      /**
       * When set, this group will go through its list of children to notify them of
       * any drawable state change.
       */
      private static final int FLAG_NOTIFY_CHILDREN_ON_DRAWABLE_STATE_CHANGE = 0x10000;
  
      private static final int FLAG_MASK_FOCUSABILITY = 0x60000;
  
      /**
       * This view will get focus before any of its descendants.
       */
      public static final int FOCUS_BEFORE_DESCENDANTS = 0x20000;
  
      /**
       * This view will get focus only if none of its descendants want it.
       */
      public static final int FOCUS_AFTER_DESCENDANTS = 0x40000;
  
      /**
       * This view will block any of its descendants from getting focus, even
       * if they are focusable.
       */
      public static final int FOCUS_BLOCK_DESCENDANTS = 0x60000;
  
      /**
       * Used to map between enum in attrubutes and flag values.
       */
      private static final int[] DESCENDANT_FOCUSABILITY_FLAGS =
              {FOCUS_BEFORE_DESCENDANTS, FOCUS_AFTER_DESCENDANTS,
                      FOCUS_BLOCK_DESCENDANTS};
  
      /**
       * When set, this ViewGroup should not intercept touch events.
       * {@hide}
       */
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 123983692)
      protected static final int FLAG_DISALLOW_INTERCEPT = 0x80000;
  
      /**
       * When set, this ViewGroup will split MotionEvents to multiple child Views when appropriate.
       */
      private static final int FLAG_SPLIT_MOTION_EVENTS = 0x200000;
  
      /**
       * When set, this ViewGroup will not dispatch onAttachedToWindow calls
       * to children when adding new views. This is used to prevent multiple
       * onAttached calls when a ViewGroup adds children in its own onAttached method.
       */
      private static final int FLAG_PREVENT_DISPATCH_ATTACHED_TO_WINDOW = 0x400000;
  
      /**
       * When true, indicates that a layoutMode has been explicitly set, either with
       * an explicit call to {@link #setLayoutMode(int)} in code or from an XML resource.
       * This distinguishes the situation in which a layout mode was inherited from
       * one of the ViewGroup's ancestors and cached locally.
       */
      private static final int FLAG_LAYOUT_MODE_WAS_EXPLICITLY_SET = 0x800000;
  
      static final int FLAG_IS_TRANSITION_GROUP = 0x1000000;
  
      static final int FLAG_IS_TRANSITION_GROUP_SET = 0x2000000;
  
      /**
       * When set, focus will not be permitted to enter this group if a touchscreen is present.
       */
      static final int FLAG_TOUCHSCREEN_BLOCKS_FOCUS = 0x4000000;
  
      /**
       * When true, indicates that a call to startActionModeForChild was made with the type parameter
       * and should not be ignored. This helps in backwards compatibility with the existing method
       * without a type.
       *
       * @see #startActionModeForChild(View, android.view.ActionMode.Callback)
       * @see #startActionModeForChild(View, android.view.ActionMode.Callback, int)
       */
      private static final int FLAG_START_ACTION_MODE_FOR_CHILD_IS_TYPED = 0x8000000;
  
      /**
       * When true, indicates that a call to startActionModeForChild was made without the type
       * parameter. This helps in backwards compatibility with the existing method
       * without a type.
       *
       * @see #startActionModeForChild(View, android.view.ActionMode.Callback)
       * @see #startActionModeForChild(View, android.view.ActionMode.Callback, int)
       */
      private static final int FLAG_START_ACTION_MODE_FOR_CHILD_IS_NOT_TYPED = 0x10000000;
  
      /**
       * When set, indicates that a call to showContextMenuForChild was made with explicit
       * coordinates within the initiating child view.
       */
      private static final int FLAG_SHOW_CONTEXT_MENU_WITH_COORDS = 0x20000000;
  
      /**
       * Indicates which types of drawing caches are to be kept in memory.
       * This field should be made private, so it is hidden from the SDK.
       * {@hide}
       */
      @UnsupportedAppUsage
      protected int mPersistentDrawingCache;
  
      /**
       * Used to indicate that no drawing cache should be kept in memory.
       *
       * @deprecated The view drawing cache was largely made obsolete with the introduction of
       * hardware-accelerated rendering in API 11. With hardware-acceleration, intermediate cache
       * layers are largely unnecessary and can easily result in a net loss in performance due to the
       * cost of creating and updating the layer. In the rare cases where caching layers are useful,
       * such as for alpha animations, {@link #setLayerType(int, Paint)} handles this with hardware
       * rendering. For software-rendered snapshots of a small part of the View hierarchy or
       * individual Views it is recommended to create a {@link Canvas} from either a {@link Bitmap} or
       * {@link android.graphics.Picture} and call {@link #draw(Canvas)} on the View. However these
       * software-rendered usages are discouraged and have compatibility issues with hardware-only
       * rendering features such as {@link android.graphics.Bitmap.Config#HARDWARE Config.HARDWARE}
       * bitmaps, real-time shadows, and outline clipping. For screenshots of the UI for feedback
       * reports or unit testing the {@link PixelCopy} API is recommended.
       */
      @Deprecated
      public static final int PERSISTENT_NO_CACHE = 0x0;
  
      /**
       * Used to indicate that the animation drawing cache should be kept in memory.
       *
       * @deprecated The view drawing cache was largely made obsolete with the introduction of
       * hardware-accelerated rendering in API 11. With hardware-acceleration, intermediate cache
       * layers are largely unnecessary and can easily result in a net loss in performance due to the
       * cost of creating and updating the layer. In the rare cases where caching layers are useful,
       * such as for alpha animations, {@link #setLayerType(int, Paint)} handles this with hardware
       * rendering. For software-rendered snapshots of a small part of the View hierarchy or
       * individual Views it is recommended to create a {@link Canvas} from either a {@link Bitmap} or
       * {@link android.graphics.Picture} and call {@link #draw(Canvas)} on the View. However these
       * software-rendered usages are discouraged and have compatibility issues with hardware-only
       * rendering features such as {@link android.graphics.Bitmap.Config#HARDWARE Config.HARDWARE}
       * bitmaps, real-time shadows, and outline clipping. For screenshots of the UI for feedback
       * reports or unit testing the {@link PixelCopy} API is recommended.
       */
      @Deprecated
      public static final int PERSISTENT_ANIMATION_CACHE = 0x1;
  
      /**
       * Used to indicate that the scrolling drawing cache should be kept in memory.
       *
       * @deprecated The view drawing cache was largely made obsolete with the introduction of
       * hardware-accelerated rendering in API 11. With hardware-acceleration, intermediate cache
       * layers are largely unnecessary and can easily result in a net loss in performance due to the
       * cost of creating and updating the layer. In the rare cases where caching layers are useful,
       * such as for alpha animations, {@link #setLayerType(int, Paint)} handles this with hardware
       * rendering. For software-rendered snapshots of a small part of the View hierarchy or
       * individual Views it is recommended to create a {@link Canvas} from either a {@link Bitmap} or
       * {@link android.graphics.Picture} and call {@link #draw(Canvas)} on the View. However these
       * software-rendered usages are discouraged and have compatibility issues with hardware-only
       * rendering features such as {@link android.graphics.Bitmap.Config#HARDWARE Config.HARDWARE}
       * bitmaps, real-time shadows, and outline clipping. For screenshots of the UI for feedback
       * reports or unit testing the {@link PixelCopy} API is recommended.
       */
      @Deprecated
      public static final int PERSISTENT_SCROLLING_CACHE = 0x2;
  
      /**
       * Used to indicate that all drawing caches should be kept in memory.
       *
       * @deprecated The view drawing cache was largely made obsolete with the introduction of
       * hardware-accelerated rendering in API 11. With hardware-acceleration, intermediate cache
       * layers are largely unnecessary and can easily result in a net loss in performance due to the
       * cost of creating and updating the layer. In the rare cases where caching layers are useful,
       * such as for alpha animations, {@link #setLayerType(int, Paint)} handles this with hardware
       * rendering. For software-rendered snapshots of a small part of the View hierarchy or
       * individual Views it is recommended to create a {@link Canvas} from either a {@link Bitmap} or
       * {@link android.graphics.Picture} and call {@link #draw(Canvas)} on the View. However these
       * software-rendered usages are discouraged and have compatibility issues with hardware-only
       * rendering features such as {@link android.graphics.Bitmap.Config#HARDWARE Config.HARDWARE}
       * bitmaps, real-time shadows, and outline clipping. For screenshots of the UI for feedback
       * reports or unit testing the {@link PixelCopy} API is recommended.
       */
      @Deprecated
      public static final int PERSISTENT_ALL_CACHES = 0x3;
  
      // Layout Modes
  
      private static final int LAYOUT_MODE_UNDEFINED = -1;
  
      /**
       * This constant is a {@link #setLayoutMode(int) layoutMode}.
       * Clip bounds are the raw values of {@link #getLeft() left}, {@link #getTop() top},
       * {@link #getRight() right} and {@link #getBottom() bottom}.
       */
      public static final int LAYOUT_MODE_CLIP_BOUNDS = 0;
  
      /**
       * This constant is a {@link #setLayoutMode(int) layoutMode}.
       * Optical bounds describe where a widget appears to be. They sit inside the clip
       * bounds which need to cover a larger area to allow other effects,
       * such as shadows and glows, to be drawn.
       */
      public static final int LAYOUT_MODE_OPTICAL_BOUNDS = 1;
  
      /** @hide */
      public static int LAYOUT_MODE_DEFAULT = LAYOUT_MODE_CLIP_BOUNDS;
  
      /**
       * We clip to padding when FLAG_CLIP_TO_PADDING and FLAG_PADDING_NOT_NULL
       * are set at the same time.
       */
      protected static final int CLIP_TO_PADDING_MASK = FLAG_CLIP_TO_PADDING | FLAG_PADDING_NOT_NULL;
  
      // Index of the child's left position in the mLocation array
      private static final int CHILD_LEFT_INDEX = 0;
      // Index of the child's top position in the mLocation array
      private static final int CHILD_TOP_INDEX = 1;
  
      // Child views of this ViewGroup
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P)
      private View[] mChildren;
      // Number of valid children in the mChildren array, the rest should be null or not
      // considered as children
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P)
      private int mChildrenCount;
  
      // Whether layout calls are currently being suppressed, controlled by calls to
      // suppressLayout()
      boolean mSuppressLayout = false;
  
      // Whether any layout calls have actually been suppressed while mSuppressLayout
      // has been true. This tracks whether we need to issue a requestLayout() when
      // layout is later re-enabled.
      private boolean mLayoutCalledWhileSuppressed = false;
  
      private static final int ARRAY_INITIAL_CAPACITY = 12;
      private static final int ARRAY_CAPACITY_INCREMENT = 12;
  
      private static float[] sDebugLines;
  
      // Used to draw cached views
      Paint mCachePaint;
  
      // Used to animate add/remove changes in layout
      private LayoutTransition mTransition;
  
      // The set of views that are currently being transitioned. This list is used to track views
      // being removed that should not actually be removed from the parent yet because they are
      // being animated.
      private ArrayList<View> mTransitioningViews;
  
      // List of children changing visibility. This is used to potentially keep rendering
      // views during a transition when they otherwise would have become gone/invisible
      private ArrayList<View> mVisibilityChangingChildren;
  
      // Temporary holder of presorted children, only used for
      // input/software draw dispatch for correctly Z ordering.
      private ArrayList<View> mPreSortedChildren;
  
      // Indicates how many of this container's child subtrees contain transient state
      @ViewDebug.ExportedProperty(category = "layout")
      private int mChildCountWithTransientState = 0;
  
      /**
       * Currently registered axes for nested scrolling. Flag set consisting of
       * {@link #SCROLL_AXIS_HORIZONTAL} {@link #SCROLL_AXIS_VERTICAL} or {@link #SCROLL_AXIS_NONE}
       * for null.
       */
      private int mNestedScrollAxes;
  
      // Used to manage the list of transient views, added by addTransientView()
      private List<Integer> mTransientIndices = null;
      private List<View> mTransientViews = null;
  
      /**
       * Keeps track of how many child views have UnhandledKeyEventListeners. This should only be
       * updated on the UI thread so shouldn't require explicit synchronization.
       */
      int mChildUnhandledKeyListeners = 0;
  
      /**
       * Empty ActionMode used as a sentinel in recursive entries to startActionModeForChild.
       *
       * @see #startActionModeForChild(View, android.view.ActionMode.Callback)
       * @see #startActionModeForChild(View, android.view.ActionMode.Callback, int)
       */
      private static final ActionMode SENTINEL_ACTION_MODE = new ActionMode() {
          @Override
          public void setTitle(CharSequence title) {}
  
          @Override
          public void setTitle(int resId) {}
  
          @Override
          public void setSubtitle(CharSequence subtitle) {}
  
          @Override
          public void setSubtitle(int resId) {}
  
          @Override
          public void setCustomView(View view) {}
  
          @Override
          public void invalidate() {}
  
          @Override
          public void finish() {}
  
          @Override
          public Menu getMenu() {
              return null;
          }
  
          @Override
          public CharSequence getTitle() {
              return null;
          }
  
          @Override
          public CharSequence getSubtitle() {
              return null;
          }
  
          @Override
          public View getCustomView() {
              return null;
          }
  
          @Override
          public MenuInflater getMenuInflater() {
              return null;
          }
      };
  
      public ViewGroup(Context context) {
          this(context, null);
      }
  
      public ViewGroup(Context context, AttributeSet attrs) {
          this(context, attrs, 0);
      }
  
      public ViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
          this(context, attrs, defStyleAttr, 0);
      }
  
      public ViewGroup(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
          super(context, attrs, defStyleAttr, defStyleRes);
  
          initViewGroup();
          initFromAttributes(context, attrs, defStyleAttr, defStyleRes);
      }
  
      private void initViewGroup() {
          // ViewGroup doesn't draw by default
          if (!debugDraw()) {
              setFlags(WILL_NOT_DRAW, DRAW_MASK);
          }
          mGroupFlags |= FLAG_CLIP_CHILDREN;
          mGroupFlags |= FLAG_CLIP_TO_PADDING;
          mGroupFlags |= FLAG_ANIMATION_DONE;
          mGroupFlags |= FLAG_ANIMATION_CACHE;
          mGroupFlags |= FLAG_ALWAYS_DRAWN_WITH_CACHE;
  
          if (mContext.getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.HONEYCOMB) {
              mGroupFlags |= FLAG_SPLIT_MOTION_EVENTS;
          }
  
          setDescendantFocusability(FOCUS_BEFORE_DESCENDANTS);
  
          mChildren = new View[ARRAY_INITIAL_CAPACITY];
          mChildrenCount = 0;
  
          mPersistentDrawingCache = PERSISTENT_SCROLLING_CACHE;
      }
  
      private void initFromAttributes(
              Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
          final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ViewGroup,
                  defStyleAttr, defStyleRes);
          saveAttributeDataForStyleable(context, R.styleable.ViewGroup, attrs, a, defStyleAttr,
                  defStyleRes);
  
          final int N = a.getIndexCount();
          for (int i = 0; i < N; i++) {
              int attr = a.getIndex(i);
              switch (attr) {
                  case R.styleable.ViewGroup_clipChildren:
                      setClipChildren(a.getBoolean(attr, true));
                      break;
                  case R.styleable.ViewGroup_clipToPadding:
                      setClipToPadding(a.getBoolean(attr, true));
                      break;
                  case R.styleable.ViewGroup_animationCache:
                      setAnimationCacheEnabled(a.getBoolean(attr, true));
                      break;
                  case R.styleable.ViewGroup_persistentDrawingCache:
                      setPersistentDrawingCache(a.getInt(attr, PERSISTENT_SCROLLING_CACHE));
                      break;
                  case R.styleable.ViewGroup_addStatesFromChildren:
                      setAddStatesFromChildren(a.getBoolean(attr, false));
                      break;
                  case R.styleable.ViewGroup_alwaysDrawnWithCache:
                      setAlwaysDrawnWithCacheEnabled(a.getBoolean(attr, true));
                      break;
                  case R.styleable.ViewGroup_layoutAnimation:
                      int id = a.getResourceId(attr, -1);
                      if (id > 0) {
                          setLayoutAnimation(AnimationUtils.loadLayoutAnimation(mContext, id));
                      }
                      break;
                  case R.styleable.ViewGroup_descendantFocusability:
                      setDescendantFocusability(DESCENDANT_FOCUSABILITY_FLAGS[a.getInt(attr, 0)]);
                      break;
                  case R.styleable.ViewGroup_splitMotionEvents:
                      setMotionEventSplittingEnabled(a.getBoolean(attr, false));
                      break;
                  case R.styleable.ViewGroup_animateLayoutChanges:
                      boolean animateLayoutChanges = a.getBoolean(attr, false);
                      if (animateLayoutChanges) {
                          setLayoutTransition(new LayoutTransition());
                      }
                      break;
                  case R.styleable.ViewGroup_layoutMode:
                      setLayoutMode(a.getInt(attr, LAYOUT_MODE_UNDEFINED));
                      break;
                  case R.styleable.ViewGroup_transitionGroup:
                      setTransitionGroup(a.getBoolean(attr, false));
                      break;
                  case R.styleable.ViewGroup_touchscreenBlocksFocus:
                      setTouchscreenBlocksFocus(a.getBoolean(attr, false));
                      break;
              }
          }
  
          a.recycle();
      }
  
      /**
       * Gets the descendant focusability of this view group.  The descendant
       * focusability defines the relationship between this view group and its
       * descendants when looking for a view to take focus in
       * {@link #requestFocus(int, android.graphics.Rect)}.
       *
       * @return one of {@link #FOCUS_BEFORE_DESCENDANTS}, {@link #FOCUS_AFTER_DESCENDANTS},
       *   {@link #FOCUS_BLOCK_DESCENDANTS}.
       */
      @ViewDebug.ExportedProperty(category = "focus", mapping = {
          @ViewDebug.IntToString(from = FOCUS_BEFORE_DESCENDANTS, to = "FOCUS_BEFORE_DESCENDANTS"),
          @ViewDebug.IntToString(from = FOCUS_AFTER_DESCENDANTS, to = "FOCUS_AFTER_DESCENDANTS"),
          @ViewDebug.IntToString(from = FOCUS_BLOCK_DESCENDANTS, to = "FOCUS_BLOCK_DESCENDANTS")
      })
      @InspectableProperty(enumMapping = {
              @EnumEntry(value = FOCUS_BEFORE_DESCENDANTS, name = "beforeDescendants"),
              @EnumEntry(value = FOCUS_AFTER_DESCENDANTS, name = "afterDescendants"),
              @EnumEntry(value = FOCUS_BLOCK_DESCENDANTS, name = "blocksDescendants")
      })
      public int getDescendantFocusability() {
          return mGroupFlags & FLAG_MASK_FOCUSABILITY;
      }
  
      /**
       * Set the descendant focusability of this view group. This defines the relationship
       * between this view group and its descendants when looking for a view to
       * take focus in {@link #requestFocus(int, android.graphics.Rect)}.
       *
       * @param focusability one of {@link #FOCUS_BEFORE_DESCENDANTS}, {@link #FOCUS_AFTER_DESCENDANTS},
       *   {@link #FOCUS_BLOCK_DESCENDANTS}.
       */
      public void setDescendantFocusability(int focusability) {
          switch (focusability) {
              case FOCUS_BEFORE_DESCENDANTS:
              case FOCUS_AFTER_DESCENDANTS:
              case FOCUS_BLOCK_DESCENDANTS:
                  break;
              default:
                  throw new IllegalArgumentException("must be one of FOCUS_BEFORE_DESCENDANTS, "
                          + "FOCUS_AFTER_DESCENDANTS, FOCUS_BLOCK_DESCENDANTS");
          }
          mGroupFlags &= ~FLAG_MASK_FOCUSABILITY;
          mGroupFlags |= (focusability & FLAG_MASK_FOCUSABILITY);
      }
  
      @Override
      void handleFocusGainInternal(int direction, Rect previouslyFocusedRect) {
          if (mFocused != null) {
              mFocused.unFocus(this);
              mFocused = null;
              mFocusedInCluster = null;
          }
          super.handleFocusGainInternal(direction, previouslyFocusedRect);
      }
  
      @Override
      public void requestChildFocus(View child, View focused) {
          if (DBG) {
              System.out.println(this + " requestChildFocus()");
          }
          if (getDescendantFocusability() == FOCUS_BLOCK_DESCENDANTS) {
              return;
          }
  
          // Unfocus us, if necessary
          super.unFocus(focused);
  
          // We had a previous notion of who had focus. Clear it.
          if (mFocused != child) {
              if (mFocused != null) {
                  mFocused.unFocus(focused);
              }
  
              mFocused = child;
          }
          if (mParent != null) {
              mParent.requestChildFocus(this, focused);
          }
      }
  
      void setDefaultFocus(View child) {
          // Stop at any higher view which is explicitly focused-by-default
          if (mDefaultFocus != null && mDefaultFocus.isFocusedByDefault()) {
              return;
          }
  
          mDefaultFocus = child;
  
          if (mParent instanceof ViewGroup) {
              ((ViewGroup) mParent).setDefaultFocus(this);
          }
      }
  
      /**
       * Clears the default-focus chain from {@param child} up to the first parent which has another
       * default-focusable branch below it or until there is no default-focus chain.
       *
       * @param child
       */
      void clearDefaultFocus(View child) {
          // Stop at any higher view which is explicitly focused-by-default
          if (mDefaultFocus != child && mDefaultFocus != null
                  && mDefaultFocus.isFocusedByDefault()) {
              return;
          }
  
          mDefaultFocus = null;
  
          // Search child siblings for default focusables.
          for (int i = 0; i < mChildrenCount; ++i) {
              View sibling = mChildren[i];
              if (sibling.isFocusedByDefault()) {
                  mDefaultFocus = sibling;
                  return;
              } else if (mDefaultFocus == null && sibling.hasDefaultFocus()) {
                  mDefaultFocus = sibling;
              }
          }
  
          if (mParent instanceof ViewGroup) {
              ((ViewGroup) mParent).clearDefaultFocus(this);
          }
      }
  
      @Override
      boolean hasDefaultFocus() {
          return mDefaultFocus != null || super.hasDefaultFocus();
      }
  
      /**
       * Removes {@code child} (and associated focusedInCluster chain) from the cluster containing
       * it.
       * <br>
       * This is intended to be run on {@code child}'s immediate parent. This is necessary because
       * the chain is sometimes cleared after {@code child} has been detached.
       */
      void clearFocusedInCluster(View child) {
          if (mFocusedInCluster != child) {
              return;
          }
          clearFocusedInCluster();
      }
  
      /**
       * Removes the focusedInCluster chain from this up to the cluster containing it.
       */
      void clearFocusedInCluster() {
          View top = findKeyboardNavigationCluster();
          ViewParent parent = this;
          do {
              ((ViewGroup) parent).mFocusedInCluster = null;
              if (parent == top) {
                  break;
              }
              parent = parent.getParent();
          } while (parent instanceof ViewGroup);
      }
  
      @Override
      public void focusableViewAvailable(View v) {
          if (mParent != null
                  // shortcut: don't report a new focusable view if we block our descendants from
                  // getting focus or if we're not visible
                  && (getDescendantFocusability() != FOCUS_BLOCK_DESCENDANTS)
                  && ((mViewFlags & VISIBILITY_MASK) == VISIBLE)
                  && (isFocusableInTouchMode() || !shouldBlockFocusForTouchscreen())
                  // shortcut: don't report a new focusable view if we already are focused
                  // (and we don't prefer our descendants)
                  //
                  // note: knowing that mFocused is non-null is not a good enough reason
                  // to break the traversal since in that case we'd actually have to find
                  // the focused view and make sure it wasn't FOCUS_AFTER_DESCENDANTS and
                  // an ancestor of v; this will get checked for at ViewAncestor
                  && !(isFocused() && getDescendantFocusability() != FOCUS_AFTER_DESCENDANTS)) {
              mParent.focusableViewAvailable(v);
          }
      }
  
      @Override
      public boolean showContextMenuForChild(View originalView) {
          if (isShowingContextMenuWithCoords()) {
              // We're being called for compatibility. Return false and let the version
              // with coordinates recurse up.
              return false;
          }
          return mParent != null && mParent.showContextMenuForChild(originalView);
      }
  
      /**
       * @hide used internally for compatibility with existing app code only
       */
      public final boolean isShowingContextMenuWithCoords() {
          return (mGroupFlags & FLAG_SHOW_CONTEXT_MENU_WITH_COORDS) != 0;
      }
  
      @Override
      public boolean showContextMenuForChild(View originalView, float x, float y) {
          try {
              mGroupFlags |= FLAG_SHOW_CONTEXT_MENU_WITH_COORDS;
              if (showContextMenuForChild(originalView)) {
                  return true;
              }
          } finally {
              mGroupFlags &= ~FLAG_SHOW_CONTEXT_MENU_WITH_COORDS;
          }
          return mParent != null && mParent.showContextMenuForChild(originalView, x, y);
      }
  
      @Override
      public ActionMode startActionModeForChild(View originalView, ActionMode.Callback callback) {
          if ((mGroupFlags & FLAG_START_ACTION_MODE_FOR_CHILD_IS_TYPED) == 0) {
              // This is the original call.
              try {
                  mGroupFlags |= FLAG_START_ACTION_MODE_FOR_CHILD_IS_NOT_TYPED;
                  return startActionModeForChild(originalView, callback, ActionMode.TYPE_PRIMARY);
              } finally {
                  mGroupFlags &= ~FLAG_START_ACTION_MODE_FOR_CHILD_IS_NOT_TYPED;
              }
          } else {
              // We are being called from the new method with type.
              return SENTINEL_ACTION_MODE;
          }
      }
  
      @Override
      public ActionMode startActionModeForChild(
              View originalView, ActionMode.Callback callback, int type) {
          if ((mGroupFlags & FLAG_START_ACTION_MODE_FOR_CHILD_IS_NOT_TYPED) == 0
                  && type == ActionMode.TYPE_PRIMARY) {
              ActionMode mode;
              try {
                  mGroupFlags |= FLAG_START_ACTION_MODE_FOR_CHILD_IS_TYPED;
                  mode = startActionModeForChild(originalView, callback);
              } finally {
                  mGroupFlags &= ~FLAG_START_ACTION_MODE_FOR_CHILD_IS_TYPED;
              }
              if (mode != SENTINEL_ACTION_MODE) {
                  return mode;
              }
          }
          if (mParent != null) {
              try {
                  return mParent.startActionModeForChild(originalView, callback, type);
              } catch (AbstractMethodError ame) {
                  // Custom view parents might not implement this method.
                  return mParent.startActionModeForChild(originalView, callback);
              }
          }
          return null;
      }
  
      /**
       * @hide
       */
      @Override
      public boolean dispatchActivityResult(
              String who, int requestCode, int resultCode, Intent data) {
          if (super.dispatchActivityResult(who, requestCode, resultCode, data)) {
              return true;
          }
          int childCount = getChildCount();
          for (int i = 0; i < childCount; i++) {
              View child = getChildAt(i);
              if (child.dispatchActivityResult(who, requestCode, resultCode, data)) {
                  return true;
              }
          }
          return false;
      }
  
      /**
       * Find the nearest view in the specified direction that wants to take
       * focus.
       *
       * @param focused The view that currently has focus
       * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and
       *        FOCUS_RIGHT, or 0 for not applicable.
       */
      @Override
      public View focusSearch(View focused, int direction) {
          if (isRootNamespace()) {
              // root namespace means we should consider ourselves the top of the
              // tree for focus searching; otherwise we could be focus searching
              // into other tabs.  see LocalActivityManager and TabHost for more info.
              return FocusFinder.getInstance().findNextFocus(this, focused, direction);
          } else if (mParent != null) {
              return mParent.focusSearch(focused, direction);
          }
          return null;
      }
  
      @Override
      public boolean requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate) {
          return false;
      }
  
      @Override
      public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event) {
          ViewParent parent = mParent;
          if (parent == null) {
              return false;
          }
          final boolean propagate = onRequestSendAccessibilityEvent(child, event);
          if (!propagate) {
              return false;
          }
          return parent.requestSendAccessibilityEvent(this, event);
      }
  
      /**
       * Called when a child has requested sending an {@link AccessibilityEvent} and
       * gives an opportunity to its parent to augment the event.
       * <p>
       * If an {@link android.view.View.AccessibilityDelegate} has been specified via calling
       * {@link android.view.View#setAccessibilityDelegate(android.view.View.AccessibilityDelegate)} its
       * {@link android.view.View.AccessibilityDelegate#onRequestSendAccessibilityEvent(ViewGroup, View, AccessibilityEvent)}
       * is responsible for handling this call.
       * </p>
       *
       * @param child The child which requests sending the event.
       * @param event The event to be sent.
       * @return True if the event should be sent.
       *
       * @see #requestSendAccessibilityEvent(View, AccessibilityEvent)
       */
      public boolean onRequestSendAccessibilityEvent(View child, AccessibilityEvent event) {
          if (mAccessibilityDelegate != null) {
              return mAccessibilityDelegate.onRequestSendAccessibilityEvent(this, child, event);
          } else {
              return onRequestSendAccessibilityEventInternal(child, event);
          }
      }
  
      /**
       * @see #onRequestSendAccessibilityEvent(View, AccessibilityEvent)
       *
       * Note: Called from the default {@link View.AccessibilityDelegate}.
       *
       * @hide
       */
      public boolean onRequestSendAccessibilityEventInternal(View child, AccessibilityEvent event) {
          return true;
      }
  
      /**
       * Called when a child view has changed whether or not it is tracking transient state.
       */
      @Override
      public void childHasTransientStateChanged(View child, boolean childHasTransientState) {
          final boolean oldHasTransientState = hasTransientState();
          if (childHasTransientState) {
              mChildCountWithTransientState++;
          } else {
              mChildCountWithTransientState--;
          }
  
          final boolean newHasTransientState = hasTransientState();
          if (mParent != null && oldHasTransientState != newHasTransientState) {
              try {
                  mParent.childHasTransientStateChanged(this, newHasTransientState);
              } catch (AbstractMethodError e) {
                  Log.e(TAG, mParent.getClass().getSimpleName() +
                          " does not fully implement ViewParent", e);
              }
          }
      }
  
      @Override
      public boolean hasTransientState() {
          return mChildCountWithTransientState > 0 || super.hasTransientState();
      }
  
      @Override
      public boolean dispatchUnhandledMove(View focused, int direction) {
          return mFocused != null &&
                  mFocused.dispatchUnhandledMove(focused, direction);
      }
  
      @Override
      public void clearChildFocus(View child) {
          if (DBG) {
              System.out.println(this + " clearChildFocus()");
          }
  
          mFocused = null;
          if (mParent != null) {
              mParent.clearChildFocus(this);
          }
      }
  
      @Override
      public void clearFocus() {
          if (DBG) {
              System.out.println(this + " clearFocus()");
          }
          if (mFocused == null) {
              super.clearFocus();
          } else {
              View focused = mFocused;
              mFocused = null;
              focused.clearFocus();
          }
      }
  
      @Override
      void unFocus(View focused) {
          if (DBG) {
              System.out.println(this + " unFocus()");
          }
          if (mFocused == null) {
              super.unFocus(focused);
          } else {
              mFocused.unFocus(focused);
              mFocused = null;
          }
      }
  
      /**
       * Returns the focused child of this view, if any. The child may have focus
       * or contain focus.
       *
       * @return the focused child or null.
       */
      public View getFocusedChild() {
          return mFocused;
      }
  
      View getDeepestFocusedChild() {
          View v = this;
          while (v != null) {
              if (v.isFocused()) {
                  return v;
              }
              v = v instanceof ViewGroup ? ((ViewGroup) v).getFocusedChild() : null;
          }
          return null;
      }
  
      /**
       * Returns true if this view has or contains focus
       *
       * @return true if this view has or contains focus
       */
      @Override
      public boolean hasFocus() {
          return (mPrivateFlags & PFLAG_FOCUSED) != 0 || mFocused != null;
      }
  
      /*
       * (non-Javadoc)
       *
       * @see android.view.View#findFocus()
       */
      @Override
      public View findFocus() {
          if (DBG) {
              System.out.println("Find focus in " + this + ": flags="
                      + isFocused() + ", child=" + mFocused);
          }
  
          if (isFocused()) {
              return this;
          }
  
          if (mFocused != null) {
              return mFocused.findFocus();
          }
          return null;
      }
  
      @Override
      boolean hasFocusable(boolean allowAutoFocus, boolean dispatchExplicit) {
          // This should probably be super.hasFocusable, but that would change
          // behavior. Historically, we have not checked the ancestor views for
          // shouldBlockFocusForTouchscreen() in ViewGroup.hasFocusable.
  
          // Invisible and gone views are never focusable.
          if ((mViewFlags & VISIBILITY_MASK) != VISIBLE) {
              return false;
          }
  
          // Only use effective focusable value when allowed.
          if ((allowAutoFocus || getFocusable() != FOCUSABLE_AUTO) && isFocusable()) {
              return true;
          }
  
          // Determine whether we have a focused descendant.
          final int descendantFocusability = getDescendantFocusability();
          if (descendantFocusability != FOCUS_BLOCK_DESCENDANTS) {
              return hasFocusableChild(dispatchExplicit);
          }
  
          return false;
      }
  
      boolean hasFocusableChild(boolean dispatchExplicit) {
          // Determine whether we have a focusable descendant.
          final int count = mChildrenCount;
          final View[] children = mChildren;
  
          for (int i = 0; i < count; i++) {
              final View child = children[i];
  
              // In case the subclass has overridden has[Explicit]Focusable, dispatch
              // to the expected one for each child even though we share logic here.
              if ((dispatchExplicit && child.hasExplicitFocusable())
                      || (!dispatchExplicit && child.hasFocusable())) {
                  return true;
              }
          }
  
          return false;
      }
  
      @Override
      public void addFocusables(ArrayList<View> views, int direction, int focusableMode) {
          final int focusableCount = views.size();
  
          final int descendantFocusability = getDescendantFocusability();
          final boolean blockFocusForTouchscreen = shouldBlockFocusForTouchscreen();
          final boolean focusSelf = (isFocusableInTouchMode() || !blockFocusForTouchscreen);
  
          if (descendantFocusability == FOCUS_BLOCK_DESCENDANTS) {
              if (focusSelf) {
                  super.addFocusables(views, direction, focusableMode);
              }
              return;
          }
  
          if (blockFocusForTouchscreen) {
              focusableMode |= FOCUSABLES_TOUCH_MODE;
          }
  
          if ((descendantFocusability == FOCUS_BEFORE_DESCENDANTS) && focusSelf) {
              super.addFocusables(views, direction, focusableMode);
          }
  
          int count = 0;
          final View[] children = new View[mChildrenCount];
          for (int i = 0; i < mChildrenCount; ++i) {
              View child = mChildren[i];
              if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                  children[count++] = child;
              }
          }
          FocusFinder.sort(children, 0, count, this, isLayoutRtl());
          for (int i = 0; i < count; ++i) {
              children[i].addFocusables(views, direction, focusableMode);
          }
  
          // When set to FOCUS_AFTER_DESCENDANTS, we only add ourselves if
          // there aren't any focusable descendants.  this is
          // to avoid the focus search finding layouts when a more precise search
          // among the focusable children would be more interesting.
          if ((descendantFocusability == FOCUS_AFTER_DESCENDANTS) && focusSelf
                  && focusableCount == views.size()) {
              super.addFocusables(views, direction, focusableMode);
          }
      }
  
      @Override
      public void addKeyboardNavigationClusters(Collection<View> views, int direction) {
          final int focusableCount = views.size();
  
          if (isKeyboardNavigationCluster()) {
              // Cluster-navigation can enter a touchscreenBlocksFocus cluster, so temporarily
              // disable touchscreenBlocksFocus to evaluate whether it contains focusables.
              final boolean blockedFocus = getTouchscreenBlocksFocus();
              try {
                  setTouchscreenBlocksFocusNoRefocus(false);
                  super.addKeyboardNavigationClusters(views, direction);
              } finally {
                  setTouchscreenBlocksFocusNoRefocus(blockedFocus);
              }
          } else {
              super.addKeyboardNavigationClusters(views, direction);
          }
  
          if (focusableCount != views.size()) {
              // No need to look for groups inside a group.
              return;
          }
  
          if (getDescendantFocusability() == FOCUS_BLOCK_DESCENDANTS) {
              return;
          }
  
          int count = 0;
          final View[] visibleChildren = new View[mChildrenCount];
          for (int i = 0; i < mChildrenCount; ++i) {
              final View child = mChildren[i];
              if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                  visibleChildren[count++] = child;
              }
          }
          FocusFinder.sort(visibleChildren, 0, count, this, isLayoutRtl());
          for (int i = 0; i < count; ++i) {
              visibleChildren[i].addKeyboardNavigationClusters(views, direction);
          }
      }
  
      /**
       * Set whether this ViewGroup should ignore focus requests for itself and its children.
       * If this option is enabled and the ViewGroup or a descendant currently has focus, focus
       * will proceed forward.
       *
       * @param touchscreenBlocksFocus true to enable blocking focus in the presence of a touchscreen
       */
      public void setTouchscreenBlocksFocus(boolean touchscreenBlocksFocus) {
          if (touchscreenBlocksFocus) {
              mGroupFlags |= FLAG_TOUCHSCREEN_BLOCKS_FOCUS;
              if (hasFocus() && !isKeyboardNavigationCluster()) {
                  final View focusedChild = getDeepestFocusedChild();
                  if (!focusedChild.isFocusableInTouchMode()) {
                      final View newFocus = focusSearch(FOCUS_FORWARD);
                      if (newFocus != null) {
                          newFocus.requestFocus();
                      }
                  }
              }
          } else {
              mGroupFlags &= ~FLAG_TOUCHSCREEN_BLOCKS_FOCUS;
          }
      }
  
      private void setTouchscreenBlocksFocusNoRefocus(boolean touchscreenBlocksFocus) {
          if (touchscreenBlocksFocus) {
              mGroupFlags |= FLAG_TOUCHSCREEN_BLOCKS_FOCUS;
          } else {
              mGroupFlags &= ~FLAG_TOUCHSCREEN_BLOCKS_FOCUS;
          }
      }
  
      /**
       * Check whether this ViewGroup should ignore focus requests for itself and its children.
       */
      @ViewDebug.ExportedProperty(category = "focus")
      @InspectableProperty
      public boolean getTouchscreenBlocksFocus() {
          return (mGroupFlags & FLAG_TOUCHSCREEN_BLOCKS_FOCUS) != 0;
      }
  
      boolean shouldBlockFocusForTouchscreen() {
          // There is a special case for keyboard-navigation clusters. We allow cluster navigation
          // to jump into blockFocusForTouchscreen ViewGroups which are clusters. Once in the
          // cluster, focus is free to move around within it.
          return getTouchscreenBlocksFocus() &&
                  mContext.getPackageManager().hasSystemFeature(PackageManager.FEATURE_TOUCHSCREEN)
                  && !(isKeyboardNavigationCluster()
                          && (hasFocus() || (findKeyboardNavigationCluster() != this)));
      }
  
      @Override
      public void findViewsWithText(ArrayList<View> outViews, CharSequence text, int flags) {
          super.findViewsWithText(outViews, text, flags);
          final int childrenCount = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < childrenCount; i++) {
              View child = children[i];
              if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE
                      && (child.mPrivateFlags & PFLAG_IS_ROOT_NAMESPACE) == 0) {
                  child.findViewsWithText(outViews, text, flags);
              }
          }
      }
  
      /** @hide */
      @Override
      public View findViewByAccessibilityIdTraversal(int accessibilityId) {
          View foundView = super.findViewByAccessibilityIdTraversal(accessibilityId);
          if (foundView != null) {
              return foundView;
          }
  
          if (getAccessibilityNodeProvider() != null) {
              return null;
          }
  
          final int childrenCount = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < childrenCount; i++) {
              View child = children[i];
              foundView = child.findViewByAccessibilityIdTraversal(accessibilityId);
              if (foundView != null) {
                  return foundView;
              }
          }
  
          return null;
      }
  
      /** @hide */
      @Override
      public View findViewByAutofillIdTraversal(int autofillId) {
          View foundView = super.findViewByAutofillIdTraversal(autofillId);
          if (foundView != null) {
              return foundView;
          }
  
          final int childrenCount = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < childrenCount; i++) {
              View child = children[i];
              foundView = child.findViewByAutofillIdTraversal(autofillId);
              if (foundView != null) {
                  return foundView;
              }
          }
  
          return null;
      }
  
      @Override
      public void dispatchWindowFocusChanged(boolean hasFocus) {
          super.dispatchWindowFocusChanged(hasFocus);
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchWindowFocusChanged(hasFocus);
          }
      }
  
      @Override
      public void addTouchables(ArrayList<View> views) {
          super.addTouchables(views);
  
          final int count = mChildrenCount;
          final View[] children = mChildren;
  
          for (int i = 0; i < count; i++) {
              final View child = children[i];
              if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                  child.addTouchables(views);
              }
          }
      }
  
      /**
       * @hide
       */
      @Override
      @UnsupportedAppUsage
      public void makeOptionalFitsSystemWindows() {
          super.makeOptionalFitsSystemWindows();
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].makeOptionalFitsSystemWindows();
          }
      }
  
      @Override
      public void dispatchDisplayHint(int hint) {
          super.dispatchDisplayHint(hint);
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchDisplayHint(hint);
          }
      }
  
      /**
       * Called when a view's visibility has changed. Notify the parent to take any appropriate
       * action.
       *
       * @param child The view whose visibility has changed
       * @param oldVisibility The previous visibility value (GONE, INVISIBLE, or VISIBLE).
       * @param newVisibility The new visibility value (GONE, INVISIBLE, or VISIBLE).
       * @hide
       */
      @UnsupportedAppUsage
      protected void onChildVisibilityChanged(View child, int oldVisibility, int newVisibility) {
          if (mTransition != null) {
              if (newVisibility == VISIBLE) {
                  mTransition.showChild(this, child, oldVisibility);
              } else {
                  mTransition.hideChild(this, child, newVisibility);
                  if (mTransitioningViews != null && mTransitioningViews.contains(child)) {
                      // Only track this on disappearing views - appearing views are already visible
                      // and don't need special handling during drawChild()
                      if (mVisibilityChangingChildren == null) {
                          mVisibilityChangingChildren = new ArrayList<View>();
                      }
                      mVisibilityChangingChildren.add(child);
                      addDisappearingView(child);
                  }
              }
          }
  
          // in all cases, for drags
          if (newVisibility == VISIBLE && mCurrentDragStartEvent != null) {
              if (!mChildrenInterestedInDrag.contains(child)) {
                  notifyChildOfDragStart(child);
              }
          }
      }
  
      @Override
      protected void dispatchVisibilityChanged(View changedView, int visibility) {
          super.dispatchVisibilityChanged(changedView, visibility);
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchVisibilityChanged(changedView, visibility);
          }
      }
  
      @Override
      public void dispatchWindowVisibilityChanged(int visibility) {
          super.dispatchWindowVisibilityChanged(visibility);
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchWindowVisibilityChanged(visibility);
          }
      }
  
      @Override
      boolean dispatchVisibilityAggregated(boolean isVisible) {
          isVisible = super.dispatchVisibilityAggregated(isVisible);
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              // Only dispatch to visible children. Not visible children and their subtrees already
              // know that they aren't visible and that's not going to change as a result of
              // whatever triggered this dispatch.
              if (children[i].getVisibility() == VISIBLE) {
                  children[i].dispatchVisibilityAggregated(isVisible);
              }
          }
          return isVisible;
      }
  
      @Override
      public void dispatchConfigurationChanged(Configuration newConfig) {
          super.dispatchConfigurationChanged(newConfig);
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchConfigurationChanged(newConfig);
          }
      }
  
      @Override
      public void recomputeViewAttributes(View child) {
          if (mAttachInfo != null && !mAttachInfo.mRecomputeGlobalAttributes) {
              ViewParent parent = mParent;
              if (parent != null) parent.recomputeViewAttributes(this);
          }
      }
  
      @Override
      void dispatchCollectViewAttributes(AttachInfo attachInfo, int visibility) {
          if ((visibility & VISIBILITY_MASK) == VISIBLE) {
              super.dispatchCollectViewAttributes(attachInfo, visibility);
              final int count = mChildrenCount;
              final View[] children = mChildren;
              for (int i = 0; i < count; i++) {
                  final View child = children[i];
                  child.dispatchCollectViewAttributes(attachInfo,
                          visibility | (child.mViewFlags&VISIBILITY_MASK));
              }
          }
      }
  
      @Override
      public void bringChildToFront(View child) {
          final int index = indexOfChild(child);
          if (index >= 0) {
              removeFromArray(index);
              addInArray(child, mChildrenCount);
              child.mParent = this;
              requestLayout();
              invalidate();
          }
      }
  
      private PointF getLocalPoint() {
          if (mLocalPoint == null) mLocalPoint = new PointF();
          return mLocalPoint;
      }
  
      @Override
      boolean dispatchDragEnterExitInPreN(DragEvent event) {
          if (event.mAction == DragEvent.ACTION_DRAG_EXITED && mCurrentDragChild != null) {
              // The drag exited a sub-tree of views; notify of the exit all descendants that are in
              // entered state.
              // We don't need this recursive delivery for ENTERED events because they get generated
              // from the recursive delivery of LOCATION/DROP events, and hence, don't need their own
              // recursion.
              mCurrentDragChild.dispatchDragEnterExitInPreN(event);
              mCurrentDragChild = null;
          }
          return mIsInterestedInDrag && super.dispatchDragEnterExitInPreN(event);
      }
  
      // TODO: Write real docs
      @Override
      public boolean dispatchDragEvent(DragEvent event) {
          boolean retval = false;
          final float tx = event.mX;
          final float ty = event.mY;
          final ClipData td = event.mClipData;
  
          // Dispatch down the view hierarchy
          final PointF localPoint = getLocalPoint();
  
          switch (event.mAction) {
          case DragEvent.ACTION_DRAG_STARTED: {
              // Clear the state to recalculate which views we drag over.
              mCurrentDragChild = null;
  
              // Set up our tracking of drag-started notifications
              mCurrentDragStartEvent = DragEvent.obtain(event);
              if (mChildrenInterestedInDrag == null) {
                  mChildrenInterestedInDrag = new HashSet<View>();
              } else {
                  mChildrenInterestedInDrag.clear();
              }
  
              // Now dispatch down to our children, caching the responses
              final int count = mChildrenCount;
              final View[] children = mChildren;
              for (int i = 0; i < count; i++) {
                  final View child = children[i];
                  child.mPrivateFlags2 &= ~View.DRAG_MASK;
                  if (child.getVisibility() == VISIBLE) {
                      if (notifyChildOfDragStart(children[i])) {
                          retval = true;
                      }
                  }
              }
  
              // Notify itself of the drag start.
              mIsInterestedInDrag = super.dispatchDragEvent(event);
              if (mIsInterestedInDrag) {
                  retval = true;
              }
  
              if (!retval) {
                  // Neither us nor any of our children are interested in this drag, so stop tracking
                  // the current drag event.
                  mCurrentDragStartEvent.recycle();
                  mCurrentDragStartEvent = null;
              }
          } break;
  
          case DragEvent.ACTION_DRAG_ENDED: {
              // Release the bookkeeping now that the drag lifecycle has ended
              final HashSet<View> childrenInterestedInDrag = mChildrenInterestedInDrag;
              if (childrenInterestedInDrag != null) {
                  for (View child : childrenInterestedInDrag) {
                      // If a child was interested in the ongoing drag, it's told that it's over
                      if (child.dispatchDragEvent(event)) {
                          retval = true;
                      }
                  }
                  childrenInterestedInDrag.clear();
              }
              if (mCurrentDragStartEvent != null) {
                  mCurrentDragStartEvent.recycle();
                  mCurrentDragStartEvent = null;
              }
  
              if (mIsInterestedInDrag) {
                  if (super.dispatchDragEvent(event)) {
                      retval = true;
                  }
                  mIsInterestedInDrag = false;
              }
          } break;
  
          case DragEvent.ACTION_DRAG_LOCATION:
          case DragEvent.ACTION_DROP: {
              // Find the [possibly new] drag target
              View target = findFrontmostDroppableChildAt(event.mX, event.mY, localPoint);
  
              if (target != mCurrentDragChild) {
                  if (sCascadedDragDrop) {
                      // For pre-Nougat apps, make sure that the whole hierarchy of views that contain
                      // the drag location is kept in the state between ENTERED and EXITED events.
                      // (Starting with N, only the innermost view will be in that state).
  
                      final int action = event.mAction;
                      // Position should not be available for ACTION_DRAG_ENTERED and
                      // ACTION_DRAG_EXITED.
                      event.mX = 0;
                      event.mY = 0;
                      event.mClipData = null;
  
                      if (mCurrentDragChild != null) {
                          event.mAction = DragEvent.ACTION_DRAG_EXITED;
                          mCurrentDragChild.dispatchDragEnterExitInPreN(event);
                      }
  
                      if (target != null) {
                          event.mAction = DragEvent.ACTION_DRAG_ENTERED;
                          target.dispatchDragEnterExitInPreN(event);
                      }
  
                      event.mAction = action;
                      event.mX = tx;
                      event.mY = ty;
                      event.mClipData = td;
                  }
                  mCurrentDragChild = target;
              }
  
              if (target == null && mIsInterestedInDrag) {
                  target = this;
              }
  
              // Dispatch the actual drag notice, localized into the target coordinates.
              if (target != null) {
                  if (target != this) {
                      event.mX = localPoint.x;
                      event.mY = localPoint.y;
  
                      retval = target.dispatchDragEvent(event);
  
                      event.mX = tx;
                      event.mY = ty;
  
                      if (mIsInterestedInDrag) {
                          final boolean eventWasConsumed;
                          if (sCascadedDragDrop) {
                              eventWasConsumed = retval;
                          } else {
                              eventWasConsumed = event.mEventHandlerWasCalled;
                          }
  
                          if (!eventWasConsumed) {
                              retval = super.dispatchDragEvent(event);
                          }
                      }
                  } else {
                      retval = super.dispatchDragEvent(event);
                  }
              }
          } break;
          }
  
          return retval;
      }
  
      // Find the frontmost child view that lies under the given point, and calculate
      // the position within its own local coordinate system.
      View findFrontmostDroppableChildAt(float x, float y, PointF outLocalPoint) {
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = count - 1; i >= 0; i--) {
              final View child = children[i];
              if (!child.canAcceptDrag()) {
                  continue;
              }
  
              if (isTransformedTouchPointInView(x, y, child, outLocalPoint)) {
                  return child;
              }
          }
          return null;
      }
  
      boolean notifyChildOfDragStart(View child) {
          // The caller guarantees that the child is not in mChildrenInterestedInDrag yet.
  
          if (ViewDebug.DEBUG_DRAG) {
              Log.d(View.VIEW_LOG_TAG, "Sending drag-started to view: " + child);
          }
  
          final float tx = mCurrentDragStartEvent.mX;
          final float ty = mCurrentDragStartEvent.mY;
  
          final float[] point = getTempPoint();
          point[0] = tx;
          point[1] = ty;
          transformPointToViewLocal(point, child);
  
          mCurrentDragStartEvent.mX = point[0];
          mCurrentDragStartEvent.mY = point[1];
          final boolean canAccept = child.dispatchDragEvent(mCurrentDragStartEvent);
          mCurrentDragStartEvent.mX = tx;
          mCurrentDragStartEvent.mY = ty;
          mCurrentDragStartEvent.mEventHandlerWasCalled = false;
          if (canAccept) {
              mChildrenInterestedInDrag.add(child);
              if (!child.canAcceptDrag()) {
                  child.mPrivateFlags2 |= View.PFLAG2_DRAG_CAN_ACCEPT;
                  child.refreshDrawableState();
              }
          }
          return canAccept;
      }
  
      @Override
      public void dispatchWindowSystemUiVisiblityChanged(int visible) {
          super.dispatchWindowSystemUiVisiblityChanged(visible);
  
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i=0; i <count; i++) {
              final View child = children[i];
              child.dispatchWindowSystemUiVisiblityChanged(visible);
          }
      }
  
      @Override
      public void dispatchSystemUiVisibilityChanged(int visible) {
          super.dispatchSystemUiVisibilityChanged(visible);
  
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i=0; i <count; i++) {
              final View child = children[i];
              child.dispatchSystemUiVisibilityChanged(visible);
          }
      }
  
      @Override
      boolean updateLocalSystemUiVisibility(int localValue, int localChanges) {
          boolean changed = super.updateLocalSystemUiVisibility(localValue, localChanges);
  
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i=0; i <count; i++) {
              final View child = children[i];
              changed |= child.updateLocalSystemUiVisibility(localValue, localChanges);
          }
          return changed;
      }
  
      @Override
      public boolean dispatchKeyEventPreIme(KeyEvent event) {
          if ((mPrivateFlags & (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS))
                  == (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS)) {
              return super.dispatchKeyEventPreIme(event);
          } else if (mFocused != null && (mFocused.mPrivateFlags & PFLAG_HAS_BOUNDS)
                  == PFLAG_HAS_BOUNDS) {
              return mFocused.dispatchKeyEventPreIme(event);
          }
          return false;
      }
  
      @Override
      public boolean dispatchKeyEvent(KeyEvent event) {
          if (mInputEventConsistencyVerifier != null) {
              mInputEventConsistencyVerifier.onKeyEvent(event, 1);
          }
  
          if ((mPrivateFlags & (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS))
                  == (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS)) {
              if (super.dispatchKeyEvent(event)) {
                  return true;
              }
          } else if (mFocused != null && (mFocused.mPrivateFlags & PFLAG_HAS_BOUNDS)
                  == PFLAG_HAS_BOUNDS) {
              if (mFocused.dispatchKeyEvent(event)) {
                  return true;
              }
          }
  
          if (mInputEventConsistencyVerifier != null) {
              mInputEventConsistencyVerifier.onUnhandledEvent(event, 1);
          }
          return false;
      }
  
      @Override
      public boolean dispatchKeyShortcutEvent(KeyEvent event) {
          if ((mPrivateFlags & (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS))
                  == (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS)) {
              return super.dispatchKeyShortcutEvent(event);
          } else if (mFocused != null && (mFocused.mPrivateFlags & PFLAG_HAS_BOUNDS)
                  == PFLAG_HAS_BOUNDS) {
              return mFocused.dispatchKeyShortcutEvent(event);
          }
          return false;
      }
  
      @Override
      public boolean dispatchTrackballEvent(MotionEvent event) {
          if (mInputEventConsistencyVerifier != null) {
              mInputEventConsistencyVerifier.onTrackballEvent(event, 1);
          }
  
          if ((mPrivateFlags & (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS))
                  == (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS)) {
              if (super.dispatchTrackballEvent(event)) {
                  return true;
              }
          } else if (mFocused != null && (mFocused.mPrivateFlags & PFLAG_HAS_BOUNDS)
                  == PFLAG_HAS_BOUNDS) {
              if (mFocused.dispatchTrackballEvent(event)) {
                  return true;
              }
          }
  
          if (mInputEventConsistencyVerifier != null) {
              mInputEventConsistencyVerifier.onUnhandledEvent(event, 1);
          }
          return false;
      }
  
      @Override
      public boolean dispatchCapturedPointerEvent(MotionEvent event) {
          if ((mPrivateFlags & (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS))
                  == (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS)) {
              if (super.dispatchCapturedPointerEvent(event)) {
                  return true;
              }
          } else if (mFocused != null && (mFocused.mPrivateFlags & PFLAG_HAS_BOUNDS)
                  == PFLAG_HAS_BOUNDS) {
              if (mFocused.dispatchCapturedPointerEvent(event)) {
                  return true;
              }
          }
          return false;
      }
  
      @Override
      public void dispatchPointerCaptureChanged(boolean hasCapture) {
          exitHoverTargets();
  
          super.dispatchPointerCaptureChanged(hasCapture);
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchPointerCaptureChanged(hasCapture);
          }
      }
  
      @Override
      public PointerIcon onResolvePointerIcon(MotionEvent event, int pointerIndex) {
          final float x = event.getX(pointerIndex);
          final float y = event.getY(pointerIndex);
          if (isOnScrollbarThumb(x, y) || isDraggingScrollBar()) {
              return PointerIcon.getSystemIcon(mContext, PointerIcon.TYPE_ARROW);
          }
          // Check what the child under the pointer says about the pointer.
          final int childrenCount = mChildrenCount;
          if (childrenCount != 0) {
              final ArrayList<View> preorderedList = buildOrderedChildList();
              final boolean customOrder = preorderedList == null
                      && isChildrenDrawingOrderEnabled();
              final View[] children = mChildren;
              for (int i = childrenCount - 1; i >= 0; i--) {
                  final int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
                  final View child = getAndVerifyPreorderedView(preorderedList, children, childIndex);
                  if (!child.canReceivePointerEvents()
                          || !isTransformedTouchPointInView(x, y, child, null)) {
                      continue;
                  }
                  final PointerIcon pointerIcon =
                          dispatchResolvePointerIcon(event, pointerIndex, child);
                  if (pointerIcon != null) {
                      if (preorderedList != null) preorderedList.clear();
                      return pointerIcon;
                  }
              }
              if (preorderedList != null) preorderedList.clear();
          }
  
          // The pointer is not a child or the child has no preferences, returning the default
          // implementation.
          return super.onResolvePointerIcon(event, pointerIndex);
      }
  
      private PointerIcon dispatchResolvePointerIcon(MotionEvent event, int pointerIndex,
              View child) {
          final PointerIcon pointerIcon;
          if (!child.hasIdentityMatrix()) {
              MotionEvent transformedEvent = getTransformedMotionEvent(event, child);
              pointerIcon = child.onResolvePointerIcon(transformedEvent, pointerIndex);
              transformedEvent.recycle();
          } else {
              final float offsetX = mScrollX - child.mLeft;
              final float offsetY = mScrollY - child.mTop;
              event.offsetLocation(offsetX, offsetY);
              pointerIcon = child.onResolvePointerIcon(event, pointerIndex);
              event.offsetLocation(-offsetX, -offsetY);
          }
          return pointerIcon;
      }
  
      private int getAndVerifyPreorderedIndex(int childrenCount, int i, boolean customOrder) {
          final int childIndex;
          if (customOrder) {
              final int childIndex1 = getChildDrawingOrder(childrenCount, i);
              if (childIndex1 >= childrenCount) {
                  throw new IndexOutOfBoundsException("getChildDrawingOrder() "
                          + "returned invalid index " + childIndex1
                          + " (child count is " + childrenCount + ")");
              }
              childIndex = childIndex1;
          } else {
              childIndex = i;
          }
          return childIndex;
      }
  
      @SuppressWarnings({"ConstantConditions"})
      @Override
      protected boolean dispatchHoverEvent(MotionEvent event) {
          final int action = event.getAction();
  
          // First check whether the view group wants to intercept the hover event.
          final boolean interceptHover = onInterceptHoverEvent(event);
          event.setAction(action); // restore action in case it was changed
  
          MotionEvent eventNoHistory = event;
          boolean handled = false;
  
          // Send events to the hovered children and build a new list of hover targets until
          // one is found that handles the event.
          HoverTarget firstOldHoverTarget = mFirstHoverTarget;
          mFirstHoverTarget = null;
          if (!interceptHover && action != MotionEvent.ACTION_HOVER_EXIT) {
              final float x = event.getX();
              final float y = event.getY();
              final int childrenCount = mChildrenCount;
              if (childrenCount != 0) {
                  final ArrayList<View> preorderedList = buildOrderedChildList();
                  final boolean customOrder = preorderedList == null
                          && isChildrenDrawingOrderEnabled();
                  final View[] children = mChildren;
                  HoverTarget lastHoverTarget = null;
                  for (int i = childrenCount - 1; i >= 0; i--) {
                      final int childIndex = getAndVerifyPreorderedIndex(
                              childrenCount, i, customOrder);
                      final View child = getAndVerifyPreorderedView(
                              preorderedList, children, childIndex);
                      if (!child.canReceivePointerEvents()
                              || !isTransformedTouchPointInView(x, y, child, null)) {
                          continue;
                      }
  
                      // Obtain a hover target for this child.  Dequeue it from the
                      // old hover target list if the child was previously hovered.
                      HoverTarget hoverTarget = firstOldHoverTarget;
                      final boolean wasHovered;
                      for (HoverTarget predecessor = null; ;) {
                          if (hoverTarget == null) {
                              hoverTarget = HoverTarget.obtain(child);
                              wasHovered = false;
                              break;
                          }
  
                          if (hoverTarget.child == child) {
                              if (predecessor != null) {
                                  predecessor.next = hoverTarget.next;
                              } else {
                                  firstOldHoverTarget = hoverTarget.next;
                              }
                              hoverTarget.next = null;
                              wasHovered = true;
                              break;
                          }
  
                          predecessor = hoverTarget;
                          hoverTarget = hoverTarget.next;
                      }
  
                      // Enqueue the hover target onto the new hover target list.
                      if (lastHoverTarget != null) {
                          lastHoverTarget.next = hoverTarget;
                      } else {
                          mFirstHoverTarget = hoverTarget;
                      }
                      lastHoverTarget = hoverTarget;
  
                      // Dispatch the event to the child.
                      if (action == MotionEvent.ACTION_HOVER_ENTER) {
                          if (!wasHovered) {
                              // Send the enter as is.
                              handled |= dispatchTransformedGenericPointerEvent(
                                      event, child); // enter
                          }
                      } else if (action == MotionEvent.ACTION_HOVER_MOVE) {
                          if (!wasHovered) {
                              // Synthesize an enter from a move.
                              eventNoHistory = obtainMotionEventNoHistoryOrSelf(eventNoHistory);
                              eventNoHistory.setAction(MotionEvent.ACTION_HOVER_ENTER);
                              handled |= dispatchTransformedGenericPointerEvent(
                                      eventNoHistory, child); // enter
                              eventNoHistory.setAction(action);
  
                              handled |= dispatchTransformedGenericPointerEvent(
                                      eventNoHistory, child); // move
                          } else {
                              // Send the move as is.
                              handled |= dispatchTransformedGenericPointerEvent(event, child);
                          }
                      }
                      if (handled) {
                          break;
                      }
                  }
                  if (preorderedList != null) preorderedList.clear();
              }
          }
  
          // Send exit events to all previously hovered children that are no longer hovered.
          while (firstOldHoverTarget != null) {
              final View child = firstOldHoverTarget.child;
  
              // Exit the old hovered child.
              if (action == MotionEvent.ACTION_HOVER_EXIT) {
                  // Send the exit as is.
                  handled |= dispatchTransformedGenericPointerEvent(
                          event, child); // exit
              } else {
                  // Synthesize an exit from a move or enter.
                  // Ignore the result because hover focus has moved to a different view.
                  if (action == MotionEvent.ACTION_HOVER_MOVE) {
                      final boolean hoverExitPending = event.isHoverExitPending();
                      event.setHoverExitPending(true);
                      dispatchTransformedGenericPointerEvent(
                              event, child); // move
                      event.setHoverExitPending(hoverExitPending);
                  }
                  eventNoHistory = obtainMotionEventNoHistoryOrSelf(eventNoHistory);
                  eventNoHistory.setAction(MotionEvent.ACTION_HOVER_EXIT);
                  dispatchTransformedGenericPointerEvent(
                          eventNoHistory, child); // exit
                  eventNoHistory.setAction(action);
              }
  
              final HoverTarget nextOldHoverTarget = firstOldHoverTarget.next;
              firstOldHoverTarget.recycle();
              firstOldHoverTarget = nextOldHoverTarget;
          }
  
          // Send events to the view group itself if no children have handled it and the view group
          // itself is not currently being hover-exited.
          boolean newHoveredSelf = !handled &&
                  (action != MotionEvent.ACTION_HOVER_EXIT) && !event.isHoverExitPending();
          if (newHoveredSelf == mHoveredSelf) {
              if (newHoveredSelf) {
                  // Send event to the view group as before.
                  handled |= super.dispatchHoverEvent(event);
              }
          } else {
              if (mHoveredSelf) {
                  // Exit the view group.
                  if (action == MotionEvent.ACTION_HOVER_EXIT) {
                      // Send the exit as is.
                      handled |= super.dispatchHoverEvent(event); // exit
                  } else {
                      // Synthesize an exit from a move or enter.
                      // Ignore the result because hover focus is moving to a different view.
                      if (action == MotionEvent.ACTION_HOVER_MOVE) {
                          super.dispatchHoverEvent(event); // move
                      }
                      eventNoHistory = obtainMotionEventNoHistoryOrSelf(eventNoHistory);
                      eventNoHistory.setAction(MotionEvent.ACTION_HOVER_EXIT);
                      super.dispatchHoverEvent(eventNoHistory); // exit
                      eventNoHistory.setAction(action);
                  }
                  mHoveredSelf = false;
              }
  
              if (newHoveredSelf) {
                  // Enter the view group.
                  if (action == MotionEvent.ACTION_HOVER_ENTER) {
                      // Send the enter as is.
                      handled |= super.dispatchHoverEvent(event); // enter
                      mHoveredSelf = true;
                  } else if (action == MotionEvent.ACTION_HOVER_MOVE) {
                      // Synthesize an enter from a move.
                      eventNoHistory = obtainMotionEventNoHistoryOrSelf(eventNoHistory);
                      eventNoHistory.setAction(MotionEvent.ACTION_HOVER_ENTER);
                      handled |= super.dispatchHoverEvent(eventNoHistory); // enter
                      eventNoHistory.setAction(action);
  
                      handled |= super.dispatchHoverEvent(eventNoHistory); // move
                      mHoveredSelf = true;
                  }
              }
          }
  
          // Recycle the copy of the event that we made.
          if (eventNoHistory != event) {
              eventNoHistory.recycle();
          }
  
          // Done.
          return handled;
      }
  
      private void exitHoverTargets() {
          if (mHoveredSelf || mFirstHoverTarget != null) {
              final long now = SystemClock.uptimeMillis();
              MotionEvent event = MotionEvent.obtain(now, now,
                      MotionEvent.ACTION_HOVER_EXIT, 0.0f, 0.0f, 0);
              event.setSource(InputDevice.SOURCE_TOUCHSCREEN);
              dispatchHoverEvent(event);
              event.recycle();
          }
      }
  
      private void cancelHoverTarget(View view) {
          HoverTarget predecessor = null;
          HoverTarget target = mFirstHoverTarget;
          while (target != null) {
              final HoverTarget next = target.next;
              if (target.child == view) {
                  if (predecessor == null) {
                      mFirstHoverTarget = next;
                  } else {
                      predecessor.next = next;
                  }
                  target.recycle();
  
                  final long now = SystemClock.uptimeMillis();
                  MotionEvent event = MotionEvent.obtain(now, now,
                          MotionEvent.ACTION_HOVER_EXIT, 0.0f, 0.0f, 0);
                  event.setSource(InputDevice.SOURCE_TOUCHSCREEN);
                  view.dispatchHoverEvent(event);
                  event.recycle();
                  return;
              }
              predecessor = target;
              target = next;
          }
      }
  
      @Override
      boolean dispatchTooltipHoverEvent(MotionEvent event) {
          final int action = event.getAction();
          switch (action) {
              case MotionEvent.ACTION_HOVER_ENTER:
                  break;
  
              case MotionEvent.ACTION_HOVER_MOVE:
                  View newTarget = null;
  
                  // Check what the child under the pointer says about the tooltip.
                  final int childrenCount = mChildrenCount;
                  if (childrenCount != 0) {
                      final float x = event.getX();
                      final float y = event.getY();
  
                      final ArrayList<View> preorderedList = buildOrderedChildList();
                      final boolean customOrder = preorderedList == null
                              && isChildrenDrawingOrderEnabled();
                      final View[] children = mChildren;
                      for (int i = childrenCount - 1; i >= 0; i--) {
                          final int childIndex =
                                  getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
                          final View child =
                                  getAndVerifyPreorderedView(preorderedList, children, childIndex);
                          if (!child.canReceivePointerEvents()
                                  || !isTransformedTouchPointInView(x, y, child, null)) {
                              continue;
                          }
                          if (dispatchTooltipHoverEvent(event, child)) {
                              newTarget = child;
                              break;
                          }
                      }
                      if (preorderedList != null) preorderedList.clear();
                  }
  
                  if (mTooltipHoverTarget != newTarget) {
                      if (mTooltipHoverTarget != null) {
                          event.setAction(MotionEvent.ACTION_HOVER_EXIT);
                          mTooltipHoverTarget.dispatchTooltipHoverEvent(event);
                          event.setAction(action);
                      }
                      mTooltipHoverTarget = newTarget;
                  }
  
                  if (mTooltipHoverTarget != null) {
                      if (mTooltipHoveredSelf) {
                          mTooltipHoveredSelf = false;
                          event.setAction(MotionEvent.ACTION_HOVER_EXIT);
                          super.dispatchTooltipHoverEvent(event);
                          event.setAction(action);
                      }
                      return true;
                  }
  
                  mTooltipHoveredSelf = super.dispatchTooltipHoverEvent(event);
                  return mTooltipHoveredSelf;
  
              case MotionEvent.ACTION_HOVER_EXIT:
                  if (mTooltipHoverTarget != null) {
                      mTooltipHoverTarget.dispatchTooltipHoverEvent(event);
                      mTooltipHoverTarget = null;
                  } else if (mTooltipHoveredSelf) {
                      super.dispatchTooltipHoverEvent(event);
                      mTooltipHoveredSelf = false;
                  }
                  break;
          }
          return false;
      }
  
      private boolean dispatchTooltipHoverEvent(MotionEvent event, View child) {
          final boolean result;
          if (!child.hasIdentityMatrix()) {
              MotionEvent transformedEvent = getTransformedMotionEvent(event, child);
              result = child.dispatchTooltipHoverEvent(transformedEvent);
              transformedEvent.recycle();
          } else {
              final float offsetX = mScrollX - child.mLeft;
              final float offsetY = mScrollY - child.mTop;
              event.offsetLocation(offsetX, offsetY);
              result = child.dispatchTooltipHoverEvent(event);
              event.offsetLocation(-offsetX, -offsetY);
          }
          return result;
      }
  
      private void exitTooltipHoverTargets() {
          if (mTooltipHoveredSelf || mTooltipHoverTarget != null) {
              final long now = SystemClock.uptimeMillis();
              MotionEvent event = MotionEvent.obtain(now, now,
                      MotionEvent.ACTION_HOVER_EXIT, 0.0f, 0.0f, 0);
              event.setSource(InputDevice.SOURCE_TOUCHSCREEN);
              dispatchTooltipHoverEvent(event);
              event.recycle();
          }
      }
  
      /** @hide */
      @Override
      protected boolean hasHoveredChild() {
          return mFirstHoverTarget != null;
      }
  
      /** @hide */
      @Override
      protected boolean pointInHoveredChild(MotionEvent event) {
          if (mFirstHoverTarget != null) {
              return isTransformedTouchPointInView(event.getX(), event.getY(),
                  mFirstHoverTarget.child, null);
          }
          return false;
      }
  
      @Override
      public void addChildrenForAccessibility(ArrayList<View> outChildren) {
          if (getAccessibilityNodeProvider() != null) {
              return;
          }
          ChildListForAccessibility children = ChildListForAccessibility.obtain(this, true);
          try {
              final int childrenCount = children.getChildCount();
              for (int i = 0; i < childrenCount; i++) {
                  View child = children.getChildAt(i);
                  if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                      if (child.includeForAccessibility()) {
                          outChildren.add(child);
                      } else {
                          child.addChildrenForAccessibility(outChildren);
                      }
                  }
              }
          } finally {
              children.recycle();
          }
      }
  
      /**
       * Implement this method to intercept hover events before they are handled
       * by child views.
       * <p>
       * This method is called before dispatching a hover event to a child of
       * the view group or to the view group's own {@link #onHoverEvent} to allow
       * the view group a chance to intercept the hover event.
       * This method can also be used to watch all pointer motions that occur within
       * the bounds of the view group even when the pointer is hovering over
       * a child of the view group rather than over the view group itself.
       * </p><p>
       * The view group can prevent its children from receiving hover events by
       * implementing this method and returning <code>true</code> to indicate
       * that it would like to intercept hover events.  The view group must
       * continuously return <code>true</code> from {@link #onInterceptHoverEvent}
       * for as long as it wishes to continue intercepting hover events from
       * its children.
       * </p><p>
       * Interception preserves the invariant that at most one view can be
       * hovered at a time by transferring hover focus from the currently hovered
       * child to the view group or vice-versa as needed.
       * </p><p>
       * If this method returns <code>true</code> and a child is already hovered, then the
       * child view will first receive a hover exit event and then the view group
       * itself will receive a hover enter event in {@link #onHoverEvent}.
       * Likewise, if this method had previously returned <code>true</code> to intercept hover
       * events and instead returns <code>false</code> while the pointer is hovering
       * within the bounds of one of a child, then the view group will first receive a
       * hover exit event in {@link #onHoverEvent} and then the hovered child will
       * receive a hover enter event.
       * </p><p>
       * The default implementation handles mouse hover on the scroll bars.
       * </p>
       *
       * @param event The motion event that describes the hover.
       * @return True if the view group would like to intercept the hover event
       * and prevent its children from receiving it.
       */
      public boolean onInterceptHoverEvent(MotionEvent event) {
          if (event.isFromSource(InputDevice.SOURCE_MOUSE)) {
              final int action = event.getAction();
              final float x = event.getX();
              final float y = event.getY();
              if ((action == MotionEvent.ACTION_HOVER_MOVE
                      || action == MotionEvent.ACTION_HOVER_ENTER) && isOnScrollbar(x, y)) {
                  return true;
              }
          }
          return false;
      }
  
      private static MotionEvent obtainMotionEventNoHistoryOrSelf(MotionEvent event) {
          if (event.getHistorySize() == 0) {
              return event;
          }
          return MotionEvent.obtainNoHistory(event);
      }
  
      @Override
      protected boolean dispatchGenericPointerEvent(MotionEvent event) {
          // Send the event to the child under the pointer.
          final int childrenCount = mChildrenCount;
          if (childrenCount != 0) {
              final float x = event.getX();
              final float y = event.getY();
  
              final ArrayList<View> preorderedList = buildOrderedChildList();
              final boolean customOrder = preorderedList == null
                      && isChildrenDrawingOrderEnabled();
              final View[] children = mChildren;
              for (int i = childrenCount - 1; i >= 0; i--) {
                  final int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
                  final View child = getAndVerifyPreorderedView(preorderedList, children, childIndex);
                  if (!child.canReceivePointerEvents()
                          || !isTransformedTouchPointInView(x, y, child, null)) {
                      continue;
                  }
  
                  if (dispatchTransformedGenericPointerEvent(event, child)) {
                      if (preorderedList != null) preorderedList.clear();
                      return true;
                  }
              }
              if (preorderedList != null) preorderedList.clear();
          }
  
          // No child handled the event.  Send it to this view group.
          return super.dispatchGenericPointerEvent(event);
      }
  
      @Override
      protected boolean dispatchGenericFocusedEvent(MotionEvent event) {
          // Send the event to the focused child or to this view group if it has focus.
          if ((mPrivateFlags & (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS))
                  == (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS)) {
              return super.dispatchGenericFocusedEvent(event);
          } else if (mFocused != null && (mFocused.mPrivateFlags & PFLAG_HAS_BOUNDS)
                  == PFLAG_HAS_BOUNDS) {
              return mFocused.dispatchGenericMotionEvent(event);
          }
          return false;
      }
  
      /**
       * Dispatches a generic pointer event to a child, taking into account
       * transformations that apply to the child.
       *
       * @param event The event to send.
       * @param child The view to send the event to.
       * @return {@code true} if the child handled the event.
       */
      private boolean dispatchTransformedGenericPointerEvent(MotionEvent event, View child) {
          boolean handled;
          if (!child.hasIdentityMatrix()) {
              MotionEvent transformedEvent = getTransformedMotionEvent(event, child);
              handled = child.dispatchGenericMotionEvent(transformedEvent);
              transformedEvent.recycle();
          } else {
              final float offsetX = mScrollX - child.mLeft;
              final float offsetY = mScrollY - child.mTop;
              event.offsetLocation(offsetX, offsetY);
              handled = child.dispatchGenericMotionEvent(event);
              event.offsetLocation(-offsetX, -offsetY);
          }
          return handled;
      }
  
      /**
       * Returns a MotionEvent that's been transformed into the child's local coordinates.
       *
       * It's the responsibility of the caller to recycle it once they're finished with it.
       * @param event The event to transform.
       * @param child The view whose coordinate space is to be used.
       * @return A copy of the the given MotionEvent, transformed into the given View's coordinate
       *         space.
       */
      private MotionEvent getTransformedMotionEvent(MotionEvent event, View child) {
          final float offsetX = mScrollX - child.mLeft;
          final float offsetY = mScrollY - child.mTop;
          final MotionEvent transformedEvent = MotionEvent.obtain(event);
          transformedEvent.offsetLocation(offsetX, offsetY);
          if (!child.hasIdentityMatrix()) {
              transformedEvent.transform(child.getInverseMatrix());
          }
          return transformedEvent;
      }
  
      @Override
      public boolean dispatchTouchEvent(MotionEvent ev) {
          if (mInputEventConsistencyVerifier != null) {
              mInputEventConsistencyVerifier.onTouchEvent(ev, 1);
          }
  
          // If the event targets the accessibility focused view and this is it, start
          // normal event dispatch. Maybe a descendant is what will handle the click.
          if (ev.isTargetAccessibilityFocus() && isAccessibilityFocusedViewOrHost()) {
              ev.setTargetAccessibilityFocus(false);
          }
  
          boolean handled = false;
          if (onFilterTouchEventForSecurity(ev)) {
              final int action = ev.getAction();
              final int actionMasked = action & MotionEvent.ACTION_MASK;
  
              // Handle an initial down.
              if (actionMasked == MotionEvent.ACTION_DOWN) {
                  // Throw away all previous state when starting a new touch gesture.
                  // The framework may have dropped the up or cancel event for the previous gesture
                  // due to an app switch, ANR, or some other state change.
                  cancelAndClearTouchTargets(ev);
                  resetTouchState();
              }
  
              // Check for interception.
              final boolean intercepted;
              if (actionMasked == MotionEvent.ACTION_DOWN
                      || mFirstTouchTarget != null) {
                  final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
                  if (!disallowIntercept) {
                      intercepted = onInterceptTouchEvent(ev);
                      ev.setAction(action); // restore action in case it was changed
                  } else {
                      intercepted = false;
                  }
              } else {
                  // There are no touch targets and this action is not an initial down
                  // so this view group continues to intercept touches.
                  intercepted = true;
              }
  
              // If intercepted, start normal event dispatch. Also if there is already
              // a view that is handling the gesture, do normal event dispatch.
              if (intercepted || mFirstTouchTarget != null) {
                  ev.setTargetAccessibilityFocus(false);
              }
  
              // Check for cancelation.
              final boolean canceled = resetCancelNextUpFlag(this)
                      || actionMasked == MotionEvent.ACTION_CANCEL;
  
              // Update list of touch targets for pointer down, if needed.
              final boolean split = (mGroupFlags & FLAG_SPLIT_MOTION_EVENTS) != 0;
              TouchTarget newTouchTarget = null;
              boolean alreadyDispatchedToNewTouchTarget = false;
              if (!canceled && !intercepted) {
  
                  // If the event is targeting accessibility focus we give it to the
                  // view that has accessibility focus and if it does not handle it
                  // we clear the flag and dispatch the event to all children as usual.
                  // We are looking up the accessibility focused host to avoid keeping
                  // state since these events are very rare.
                  View childWithAccessibilityFocus = ev.isTargetAccessibilityFocus()
                          ? findChildWithAccessibilityFocus() : null;
  
                  if (actionMasked == MotionEvent.ACTION_DOWN
                          || (split && actionMasked == MotionEvent.ACTION_POINTER_DOWN)
                          || actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
                      final int actionIndex = ev.getActionIndex(); // always 0 for down
                      final int idBitsToAssign = split ? 1 << ev.getPointerId(actionIndex)
                              : TouchTarget.ALL_POINTER_IDS;
  
                      // Clean up earlier touch targets for this pointer id in case they
                      // have become out of sync.
                      removePointersFromTouchTargets(idBitsToAssign);
  
                      final int childrenCount = mChildrenCount;
                      if (newTouchTarget == null && childrenCount != 0) {
                          final float x = ev.getX(actionIndex);
                          final float y = ev.getY(actionIndex);
                          // Find a child that can receive the event.
                          // Scan children from front to back.
                          final ArrayList<View> preorderedList = buildTouchDispatchChildList();
                          final boolean customOrder = preorderedList == null
                                  && isChildrenDrawingOrderEnabled();
                          final View[] children = mChildren;
                          for (int i = childrenCount - 1; i >= 0; i--) {
                              final int childIndex = getAndVerifyPreorderedIndex(
                                      childrenCount, i, customOrder);
                              final View child = getAndVerifyPreorderedView(
                                      preorderedList, children, childIndex);
  
                              // If there is a view that has accessibility focus we want it
                              // to get the event first and if not handled we will perform a
                              // normal dispatch. We may do a double iteration but this is
                              // safer given the timeframe.
                              if (childWithAccessibilityFocus != null) {
                                  if (childWithAccessibilityFocus != child) {
                                      continue;
                                  }
                                  childWithAccessibilityFocus = null;
                                  i = childrenCount - 1;
                              }
  
                              if (!child.canReceivePointerEvents()
                                      || !isTransformedTouchPointInView(x, y, child, null)) {
                                  ev.setTargetAccessibilityFocus(false);
                                  continue;
                              }
  
                              newTouchTarget = getTouchTarget(child);
                              if (newTouchTarget != null) {
                                  // Child is already receiving touch within its bounds.
                                  // Give it the new pointer in addition to the ones it is handling.
                                  newTouchTarget.pointerIdBits |= idBitsToAssign;
                                  break;
                              }
  
                              resetCancelNextUpFlag(child);
                              if (dispatchTransformedTouchEvent(ev, false, child, idBitsToAssign)) {
                                  // Child wants to receive touch within its bounds.
                                  mLastTouchDownTime = ev.getDownTime();
                                  if (preorderedList != null) {
                                      // childIndex points into presorted list, find original index
                                      for (int j = 0; j < childrenCount; j++) {
                                          if (children[childIndex] == mChildren[j]) {
                                              mLastTouchDownIndex = j;
                                              break;
                                          }
                                      }
                                  } else {
                                      mLastTouchDownIndex = childIndex;
                                  }
                                  mLastTouchDownX = ev.getX();
                                  mLastTouchDownY = ev.getY();
                                  newTouchTarget = addTouchTarget(child, idBitsToAssign);
                                  alreadyDispatchedToNewTouchTarget = true;
                                  break;
                              }
  
                              // The accessibility focus didn't handle the event, so clear
                              // the flag and do a normal dispatch to all children.
                              ev.setTargetAccessibilityFocus(false);
                          }
                          if (preorderedList != null) preorderedList.clear();
                      }
  
                      if (newTouchTarget == null && mFirstTouchTarget != null) {
                          // Did not find a child to receive the event.
                          // Assign the pointer to the least recently added target.
                          newTouchTarget = mFirstTouchTarget;
                          while (newTouchTarget.next != null) {
                              newTouchTarget = newTouchTarget.next;
                          }
                          newTouchTarget.pointerIdBits |= idBitsToAssign;
                      }
                  }
              }
  
              // Dispatch to touch targets.
              if (mFirstTouchTarget == null) {
                  // No touch targets so treat this as an ordinary view.
                  handled = dispatchTransformedTouchEvent(ev, canceled, null,
                          TouchTarget.ALL_POINTER_IDS);
              } else {
                  // Dispatch to touch targets, excluding the new touch target if we already
                  // dispatched to it.  Cancel touch targets if necessary.
                  TouchTarget predecessor = null;
                  TouchTarget target = mFirstTouchTarget;
                  while (target != null) {
                      final TouchTarget next = target.next;
                      if (alreadyDispatchedToNewTouchTarget && target == newTouchTarget) {
                          handled = true;
                      } else {
                          final boolean cancelChild = resetCancelNextUpFlag(target.child)
                                  || intercepted;
                          if (dispatchTransformedTouchEvent(ev, cancelChild,
                                  target.child, target.pointerIdBits)) {
                              handled = true;
                          }
                          if (cancelChild) {
                              if (predecessor == null) {
                                  mFirstTouchTarget = next;
                              } else {
                                  predecessor.next = next;
                              }
                              target.recycle();
                              target = next;
                              continue;
                          }
                      }
                      predecessor = target;
                      target = next;
                  }
              }
  
              // Update list of touch targets for pointer up or cancel, if needed.
              if (canceled
                      || actionMasked == MotionEvent.ACTION_UP
                      || actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
                  resetTouchState();
              } else if (split && actionMasked == MotionEvent.ACTION_POINTER_UP) {
                  final int actionIndex = ev.getActionIndex();
                  final int idBitsToRemove = 1 << ev.getPointerId(actionIndex);
                  removePointersFromTouchTargets(idBitsToRemove);
              }
          }
  
          if (!handled && mInputEventConsistencyVerifier != null) {
              mInputEventConsistencyVerifier.onUnhandledEvent(ev, 1);
          }
          return handled;
      }
  
      /**
       * Provide custom ordering of views in which the touch will be dispatched.
       *
       * This is called within a tight loop, so you are not allowed to allocate objects, including
       * the return array. Instead, you should return a pre-allocated list that will be cleared
       * after the dispatch is finished.
       * @hide
       */
      public ArrayList<View> buildTouchDispatchChildList() {
          return buildOrderedChildList();
      }
  
      /**
       * Finds the child which has accessibility focus.
       *
       * @return The child that has focus.
       */
      private View findChildWithAccessibilityFocus() {
          ViewRootImpl viewRoot = getViewRootImpl();
          if (viewRoot == null) {
              return null;
          }
  
          View current = viewRoot.getAccessibilityFocusedHost();
          if (current == null) {
              return null;
          }
  
          ViewParent parent = current.getParent();
          while (parent instanceof View) {
              if (parent == this) {
                  return current;
              }
              current = (View) parent;
              parent = current.getParent();
          }
  
          return null;
      }
  
      /**
       * Resets all touch state in preparation for a new cycle.
       */
      private void resetTouchState() {
          clearTouchTargets();
          resetCancelNextUpFlag(this);
          mGroupFlags &= ~FLAG_DISALLOW_INTERCEPT;
          mNestedScrollAxes = SCROLL_AXIS_NONE;
      }
  
      /**
       * Resets the cancel next up flag.
       * Returns true if the flag was previously set.
       */
      private static boolean resetCancelNextUpFlag(@NonNull View view) {
          if ((view.mPrivateFlags & PFLAG_CANCEL_NEXT_UP_EVENT) != 0) {
              view.mPrivateFlags &= ~PFLAG_CANCEL_NEXT_UP_EVENT;
              return true;
          }
          return false;
      }
  
      /**
       * Clears all touch targets.
       */
      private void clearTouchTargets() {
          TouchTarget target = mFirstTouchTarget;
          if (target != null) {
              do {
                  TouchTarget next = target.next;
                  target.recycle();
                  target = next;
              } while (target != null);
              mFirstTouchTarget = null;
          }
      }
  
      /**
       * Cancels and clears all touch targets.
       */
      private void cancelAndClearTouchTargets(MotionEvent event) {
          if (mFirstTouchTarget != null) {
              boolean syntheticEvent = false;
              if (event == null) {
                  final long now = SystemClock.uptimeMillis();
                  event = MotionEvent.obtain(now, now,
                          MotionEvent.ACTION_CANCEL, 0.0f, 0.0f, 0);
                  event.setSource(InputDevice.SOURCE_TOUCHSCREEN);
                  syntheticEvent = true;
              }
  
              for (TouchTarget target = mFirstTouchTarget; target != null; target = target.next) {
                  resetCancelNextUpFlag(target.child);
                  dispatchTransformedTouchEvent(event, true, target.child, target.pointerIdBits);
              }
              clearTouchTargets();
  
              if (syntheticEvent) {
                  event.recycle();
              }
          }
      }
  
      /**
       * Gets the touch target for specified child view.
       * Returns null if not found.
       */
      private TouchTarget getTouchTarget(@NonNull View child) {
          for (TouchTarget target = mFirstTouchTarget; target != null; target = target.next) {
              if (target.child == child) {
                  return target;
              }
          }
          return null;
      }
  
      /**
       * Adds a touch target for specified child to the beginning of the list.
       * Assumes the target child is not already present.
       */
      private TouchTarget addTouchTarget(@NonNull View child, int pointerIdBits) {
          final TouchTarget target = TouchTarget.obtain(child, pointerIdBits);
          target.next = mFirstTouchTarget;
          mFirstTouchTarget = target;
          return target;
      }
  
      /**
       * Removes the pointer ids from consideration.
       */
      private void removePointersFromTouchTargets(int pointerIdBits) {
          TouchTarget predecessor = null;
          TouchTarget target = mFirstTouchTarget;
          while (target != null) {
              final TouchTarget next = target.next;
              if ((target.pointerIdBits & pointerIdBits) != 0) {
                  target.pointerIdBits &= ~pointerIdBits;
                  if (target.pointerIdBits == 0) {
                      if (predecessor == null) {
                          mFirstTouchTarget = next;
                      } else {
                          predecessor.next = next;
                      }
                      target.recycle();
                      target = next;
                      continue;
                  }
              }
              predecessor = target;
              target = next;
          }
      }
  
      @UnsupportedAppUsage
      private void cancelTouchTarget(View view) {
          TouchTarget predecessor = null;
          TouchTarget target = mFirstTouchTarget;
          while (target != null) {
              final TouchTarget next = target.next;
              if (target.child == view) {
                  if (predecessor == null) {
                      mFirstTouchTarget = next;
                  } else {
                      predecessor.next = next;
                  }
                  target.recycle();
  
                  final long now = SystemClock.uptimeMillis();
                  MotionEvent event = MotionEvent.obtain(now, now,
                          MotionEvent.ACTION_CANCEL, 0.0f, 0.0f, 0);
                  event.setSource(InputDevice.SOURCE_TOUCHSCREEN);
                  view.dispatchTouchEvent(event);
                  event.recycle();
                  return;
              }
              predecessor = target;
              target = next;
          }
      }
  
      private float[] getTempPoint() {
          if (mTempPoint == null) {
              mTempPoint = new float[2];
          }
          return mTempPoint;
      }
  
      /**
       * Returns true if a child view contains the specified point when transformed
       * into its coordinate space.
       * Child must not be null.
       * @hide
       */
      @UnsupportedAppUsage
      protected boolean isTransformedTouchPointInView(float x, float y, View child,
              PointF outLocalPoint) {
          final float[] point = getTempPoint();
          point[0] = x;
          point[1] = y;
          transformPointToViewLocal(point, child);
          final boolean isInView = child.pointInView(point[0], point[1]);
          if (isInView && outLocalPoint != null) {
              outLocalPoint.set(point[0], point[1]);
          }
          return isInView;
      }
  
      /**
       * @hide
       */
      @UnsupportedAppUsage
      public void transformPointToViewLocal(float[] point, View child) {
          point[0] += mScrollX - child.mLeft;
          point[1] += mScrollY - child.mTop;
  
          if (!child.hasIdentityMatrix()) {
              child.getInverseMatrix().mapPoints(point);
          }
      }
  
      /**
       * Transforms a motion event into the coordinate space of a particular child view,
       * filters out irrelevant pointer ids, and overrides its action if necessary.
       * If child is null, assumes the MotionEvent will be sent to this ViewGroup instead.
       */
      private boolean dispatchTransformedTouchEvent(MotionEvent event, boolean cancel,
              View child, int desiredPointerIdBits) {
          final boolean handled;
  
          // Canceling motions is a special case.  We don't need to perform any transformations
          // or filtering.  The important part is the action, not the contents.
          final int oldAction = event.getAction();
          if (cancel || oldAction == MotionEvent.ACTION_CANCEL) {
              event.setAction(MotionEvent.ACTION_CANCEL);
              if (child == null) {
                  handled = super.dispatchTouchEvent(event);
              } else {
                  handled = child.dispatchTouchEvent(event);
              }
              event.setAction(oldAction);
              return handled;
          }
  
          // Calculate the number of pointers to deliver.
          final int oldPointerIdBits = event.getPointerIdBits();
          final int newPointerIdBits = oldPointerIdBits & desiredPointerIdBits;
  
          // If for some reason we ended up in an inconsistent state where it looks like we
          // might produce a motion event with no pointers in it, then drop the event.
          if (newPointerIdBits == 0) {
              return false;
          }
  
          // If the number of pointers is the same and we don't need to perform any fancy
          // irreversible transformations, then we can reuse the motion event for this
          // dispatch as long as we are careful to revert any changes we make.
          // Otherwise we need to make a copy.
          final MotionEvent transformedEvent;
          if (newPointerIdBits == oldPointerIdBits) {
              if (child == null || child.hasIdentityMatrix()) {
                  if (child == null) {
                      handled = super.dispatchTouchEvent(event);
                  } else {
                      final float offsetX = mScrollX - child.mLeft;
                      final float offsetY = mScrollY - child.mTop;
                      event.offsetLocation(offsetX, offsetY);
  
                      handled = child.dispatchTouchEvent(event);
  
                      event.offsetLocation(-offsetX, -offsetY);
                  }
                  return handled;
              }
              transformedEvent = MotionEvent.obtain(event);
          } else {
              transformedEvent = event.split(newPointerIdBits);
          }
  
          // Perform any necessary transformations and dispatch.
          if (child == null) {
              handled = super.dispatchTouchEvent(transformedEvent);
          } else {
              final float offsetX = mScrollX - child.mLeft;
              final float offsetY = mScrollY - child.mTop;
              transformedEvent.offsetLocation(offsetX, offsetY);
              if (! child.hasIdentityMatrix()) {
                  transformedEvent.transform(child.getInverseMatrix());
              }
  
              handled = child.dispatchTouchEvent(transformedEvent);
          }
  
          // Done.
          transformedEvent.recycle();
          return handled;
      }
  
      /**
       * Enable or disable the splitting of MotionEvents to multiple children during touch event
       * dispatch. This behavior is enabled by default for applications that target an
       * SDK version of {@link Build.VERSION_CODES#HONEYCOMB} or newer.
       *
       * <p>When this option is enabled MotionEvents may be split and dispatched to different child
       * views depending on where each pointer initially went down. This allows for user interactions
       * such as scrolling two panes of content independently, chording of buttons, and performing
       * independent gestures on different pieces of content.
       *
       * @param split <code>true</code> to allow MotionEvents to be split and dispatched to multiple
       *              child views. <code>false</code> to only allow one child view to be the target of
       *              any MotionEvent received by this ViewGroup.
       * @attr ref android.R.styleable#ViewGroup_splitMotionEvents
       */
      public void setMotionEventSplittingEnabled(boolean split) {
          // TODO Applications really shouldn't change this setting mid-touch event,
          // but perhaps this should handle that case and send ACTION_CANCELs to any child views
          // with gestures in progress when this is changed.
          if (split) {
              mGroupFlags |= FLAG_SPLIT_MOTION_EVENTS;
          } else {
              mGroupFlags &= ~FLAG_SPLIT_MOTION_EVENTS;
          }
      }
  
      /**
       * Returns true if MotionEvents dispatched to this ViewGroup can be split to multiple children.
       * @return true if MotionEvents dispatched to this ViewGroup can be split to multiple children.
       */
      @InspectableProperty(name = "splitMotionEvents")
      public boolean isMotionEventSplittingEnabled() {
          return (mGroupFlags & FLAG_SPLIT_MOTION_EVENTS) == FLAG_SPLIT_MOTION_EVENTS;
      }
  
      /**
       * Returns true if this ViewGroup should be considered as a single entity for removal
       * when executing an Activity transition. If this is false, child elements will move
       * individually during the transition.
       *
       * @return True if the ViewGroup should be acted on together during an Activity transition.
       * The default value is true when there is a non-null background or if
       * {@link #getTransitionName()} is not null or if a
       * non-null {@link android.view.ViewOutlineProvider} other than
       * {@link android.view.ViewOutlineProvider#BACKGROUND} was given to
       * {@link #setOutlineProvider(ViewOutlineProvider)} and false otherwise.
       */
      @InspectableProperty
      public boolean isTransitionGroup() {
          if ((mGroupFlags & FLAG_IS_TRANSITION_GROUP_SET) != 0) {
              return ((mGroupFlags & FLAG_IS_TRANSITION_GROUP) != 0);
          } else {
              final ViewOutlineProvider outlineProvider = getOutlineProvider();
              return getBackground() != null || getTransitionName() != null ||
                      (outlineProvider != null && outlineProvider != ViewOutlineProvider.BACKGROUND);
          }
      }
  
      /**
       * Changes whether or not this ViewGroup should be treated as a single entity during
       * Activity Transitions.
       * @param isTransitionGroup Whether or not the ViewGroup should be treated as a unit
       *                          in Activity transitions. If false, the ViewGroup won't transition,
       *                          only its children. If true, the entire ViewGroup will transition
       *                          together.
       * @see android.app.ActivityOptions#makeSceneTransitionAnimation(android.app.Activity,
       * android.util.Pair[])
       */
      public void setTransitionGroup(boolean isTransitionGroup) {
          mGroupFlags |= FLAG_IS_TRANSITION_GROUP_SET;
          if (isTransitionGroup) {
              mGroupFlags |= FLAG_IS_TRANSITION_GROUP;
          } else {
              mGroupFlags &= ~FLAG_IS_TRANSITION_GROUP;
          }
      }
  
      @Override
      public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
  
          if (disallowIntercept == ((mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0)) {
              // We're already in this state, assume our ancestors are too
              return;
          }
  
          if (disallowIntercept) {
              mGroupFlags |= FLAG_DISALLOW_INTERCEPT;
          } else {
              mGroupFlags &= ~FLAG_DISALLOW_INTERCEPT;
          }
  
          // Pass it up to our parent
          if (mParent != null) {
              mParent.requestDisallowInterceptTouchEvent(disallowIntercept);
          }
      }
  
      /**
       * Implement this method to intercept all touch screen motion events.  This
       * allows you to watch events as they are dispatched to your children, and
       * take ownership of the current gesture at any point.
       *
       * <p>Using this function takes some care, as it has a fairly complicated
       * interaction with {@link View#onTouchEvent(MotionEvent)
       * View.onTouchEvent(MotionEvent)}, and using it requires implementing
       * that method as well as this one in the correct way.  Events will be
       * received in the following order:
       *
       * <ol>
       * <li> You will receive the down event here.
       * <li> The down event will be handled either by a child of this view
       * group, or given to your own onTouchEvent() method to handle; this means
       * you should implement onTouchEvent() to return true, so you will
       * continue to see the rest of the gesture (instead of looking for
       * a parent view to handle it).  Also, by returning true from
       * onTouchEvent(), you will not receive any following
       * events in onInterceptTouchEvent() and all touch processing must
       * happen in onTouchEvent() like normal.
       * <li> For as long as you return false from this function, each following
       * event (up to and including the final up) will be delivered first here
       * and then to the target's onTouchEvent().
       * <li> If you return true from here, you will not receive any
       * following events: the target view will receive the same event but
       * with the action {@link MotionEvent#ACTION_CANCEL}, and all further
       * events will be delivered to your onTouchEvent() method and no longer
       * appear here.
       * </ol>
       *
       * @param ev The motion event being dispatched down the hierarchy.
       * @return Return true to steal motion events from the children and have
       * them dispatched to this ViewGroup through onTouchEvent().
       * The current target will receive an ACTION_CANCEL event, and no further
       * messages will be delivered here.
       */
      public boolean onInterceptTouchEvent(MotionEvent ev) {
          if (ev.isFromSource(InputDevice.SOURCE_MOUSE)
                  && ev.getAction() == MotionEvent.ACTION_DOWN
                  && ev.isButtonPressed(MotionEvent.BUTTON_PRIMARY)
                  && isOnScrollbarThumb(ev.getX(), ev.getY())) {
              return true;
          }
          return false;
      }
  
      /**
       * {@inheritDoc}
       *
       * Looks for a view to give focus to respecting the setting specified by
       * {@link #getDescendantFocusability()}.
       *
       * Uses {@link #onRequestFocusInDescendants(int, android.graphics.Rect)} to
       * find focus within the children of this group when appropriate.
       *
       * @see #FOCUS_BEFORE_DESCENDANTS
       * @see #FOCUS_AFTER_DESCENDANTS
       * @see #FOCUS_BLOCK_DESCENDANTS
       * @see #onRequestFocusInDescendants(int, android.graphics.Rect)
       */
      @Override
      public boolean requestFocus(int direction, Rect previouslyFocusedRect) {
          if (DBG) {
              System.out.println(this + " ViewGroup.requestFocus direction="
                      + direction);
          }
          int descendantFocusability = getDescendantFocusability();
  
          boolean result;
          switch (descendantFocusability) {
              case FOCUS_BLOCK_DESCENDANTS:
                  result = super.requestFocus(direction, previouslyFocusedRect);
                  break;
              case FOCUS_BEFORE_DESCENDANTS: {
                  final boolean took = super.requestFocus(direction, previouslyFocusedRect);
                  result = took ? took : onRequestFocusInDescendants(direction,
                          previouslyFocusedRect);
                  break;
              }
              case FOCUS_AFTER_DESCENDANTS: {
                  final boolean took = onRequestFocusInDescendants(direction, previouslyFocusedRect);
                  result = took ? took : super.requestFocus(direction, previouslyFocusedRect);
                  break;
              }
              default:
                  throw new IllegalStateException("descendant focusability must be "
                          + "one of FOCUS_BEFORE_DESCENDANTS, FOCUS_AFTER_DESCENDANTS, FOCUS_BLOCK_DESCENDANTS "
                          + "but is " + descendantFocusability);
          }
          if (result && !isLayoutValid() && ((mPrivateFlags & PFLAG_WANTS_FOCUS) == 0)) {
              mPrivateFlags |= PFLAG_WANTS_FOCUS;
          }
          return result;
      }
  
      /**
       * Look for a descendant to call {@link View#requestFocus} on.
       * Called by {@link ViewGroup#requestFocus(int, android.graphics.Rect)}
       * when it wants to request focus within its children.  Override this to
       * customize how your {@link ViewGroup} requests focus within its children.
       * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT
       * @param previouslyFocusedRect The rectangle (in this View's coordinate system)
       *        to give a finer grained hint about where focus is coming from.  May be null
       *        if there is no hint.
       * @return Whether focus was taken.
       */
      @SuppressWarnings({"ConstantConditions"})
      protected boolean onRequestFocusInDescendants(int direction,
              Rect previouslyFocusedRect) {
          int index;
          int increment;
          int end;
          int count = mChildrenCount;
          if ((direction & FOCUS_FORWARD) != 0) {
              index = 0;
              increment = 1;
              end = count;
          } else {
              index = count - 1;
              increment = -1;
              end = -1;
          }
          final View[] children = mChildren;
          for (int i = index; i != end; i += increment) {
              View child = children[i];
              if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                  if (child.requestFocus(direction, previouslyFocusedRect)) {
                      return true;
                  }
              }
          }
          return false;
      }
  
      @Override
      public boolean restoreDefaultFocus() {
          if (mDefaultFocus != null
                  && getDescendantFocusability() != FOCUS_BLOCK_DESCENDANTS
                  && (mDefaultFocus.mViewFlags & VISIBILITY_MASK) == VISIBLE
                  && mDefaultFocus.restoreDefaultFocus()) {
              return true;
          }
          return super.restoreDefaultFocus();
      }
  
      /**
       * @hide
       */
      @TestApi
      @Override
      public boolean restoreFocusInCluster(@FocusRealDirection int direction) {
          // Allow cluster-navigation to enter touchscreenBlocksFocus ViewGroups.
          if (isKeyboardNavigationCluster()) {
              final boolean blockedFocus = getTouchscreenBlocksFocus();
              try {
                  setTouchscreenBlocksFocusNoRefocus(false);
                  return restoreFocusInClusterInternal(direction);
              } finally {
                  setTouchscreenBlocksFocusNoRefocus(blockedFocus);
              }
          } else {
              return restoreFocusInClusterInternal(direction);
          }
      }
  
      private boolean restoreFocusInClusterInternal(@FocusRealDirection int direction) {
          if (mFocusedInCluster != null && getDescendantFocusability() != FOCUS_BLOCK_DESCENDANTS
                  && (mFocusedInCluster.mViewFlags & VISIBILITY_MASK) == VISIBLE
                  && mFocusedInCluster.restoreFocusInCluster(direction)) {
              return true;
          }
          return super.restoreFocusInCluster(direction);
      }
  
      /**
       * @hide
       */
      @Override
      public boolean restoreFocusNotInCluster() {
          if (mFocusedInCluster != null) {
              // since clusters don't nest; we can assume that a non-null mFocusedInCluster
              // will refer to a view not-in a cluster.
              return restoreFocusInCluster(View.FOCUS_DOWN);
          }
          if (isKeyboardNavigationCluster() || (mViewFlags & VISIBILITY_MASK) != VISIBLE) {
              return false;
          }
          int descendentFocusability = getDescendantFocusability();
          if (descendentFocusability == FOCUS_BLOCK_DESCENDANTS) {
              return super.requestFocus(FOCUS_DOWN, null);
          }
          if (descendentFocusability == FOCUS_BEFORE_DESCENDANTS
                  && super.requestFocus(FOCUS_DOWN, null)) {
              return true;
          }
          for (int i = 0; i < mChildrenCount; ++i) {
              View child = mChildren[i];
              if (!child.isKeyboardNavigationCluster()
                      && child.restoreFocusNotInCluster()) {
                  return true;
              }
          }
          if (descendentFocusability == FOCUS_AFTER_DESCENDANTS && !hasFocusableChild(false)) {
              return super.requestFocus(FOCUS_DOWN, null);
          }
          return false;
      }
  
      /**
       * {@inheritDoc}
       *
       * @hide
       */
      @Override
      public void dispatchStartTemporaryDetach() {
          super.dispatchStartTemporaryDetach();
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchStartTemporaryDetach();
          }
      }
  
      /**
       * {@inheritDoc}
       *
       * @hide
       */
      @Override
      public void dispatchFinishTemporaryDetach() {
          super.dispatchFinishTemporaryDetach();
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchFinishTemporaryDetach();
          }
      }
  
      @Override
      @UnsupportedAppUsage
      void dispatchAttachedToWindow(AttachInfo info, int visibility) {
          mGroupFlags |= FLAG_PREVENT_DISPATCH_ATTACHED_TO_WINDOW;
          super.dispatchAttachedToWindow(info, visibility);
          mGroupFlags &= ~FLAG_PREVENT_DISPATCH_ATTACHED_TO_WINDOW;
  
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              final View child = children[i];
              child.dispatchAttachedToWindow(info,
                      combineVisibility(visibility, child.getVisibility()));
          }
          final int transientCount = mTransientIndices == null ? 0 : mTransientIndices.size();
          for (int i = 0; i < transientCount; ++i) {
              View view = mTransientViews.get(i);
              view.dispatchAttachedToWindow(info,
                      combineVisibility(visibility, view.getVisibility()));
          }
      }
  
      @Override
      void dispatchScreenStateChanged(int screenState) {
          super.dispatchScreenStateChanged(screenState);
  
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchScreenStateChanged(screenState);
          }
      }
  
      @Override
      void dispatchMovedToDisplay(Display display, Configuration config) {
          super.dispatchMovedToDisplay(display, config);
  
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchMovedToDisplay(display, config);
          }
      }
  
      /** @hide */
      @Override
      public boolean dispatchPopulateAccessibilityEventInternal(AccessibilityEvent event) {
          boolean handled = false;
          if (includeForAccessibility()) {
              handled = super.dispatchPopulateAccessibilityEventInternal(event);
              if (handled) {
                  return handled;
              }
          }
          // Let our children have a shot in populating the event.
          ChildListForAccessibility children = ChildListForAccessibility.obtain(this, true);
          try {
              final int childCount = children.getChildCount();
              for (int i = 0; i < childCount; i++) {
                  View child = children.getChildAt(i);
                  if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                      handled = child.dispatchPopulateAccessibilityEvent(event);
                      if (handled) {
                          return handled;
                      }
                  }
              }
          } finally {
              children.recycle();
          }
          return false;
      }
  
      /**
       * Dispatch creation of {@link ViewStructure} down the hierarchy.  This implementation
       * adds in all child views of the view group, in addition to calling the default View
       * implementation.
       */
      @Override
      public void dispatchProvideStructure(ViewStructure structure) {
          super.dispatchProvideStructure(structure);
          if (isAssistBlocked() || structure.getChildCount() != 0) {
              return;
          }
          final int childrenCount = mChildrenCount;
          if (childrenCount <= 0) {
              return;
          }
  
          if (!isLaidOut()) {
              if (Helper.sVerbose) {
                  Log.v(VIEW_LOG_TAG, "dispatchProvideStructure(): not laid out, ignoring "
                          + childrenCount + " children of " + getAccessibilityViewId());
              }
              return;
          }
  
          structure.setChildCount(childrenCount);
          ArrayList<View> preorderedList = buildOrderedChildList();
          boolean customOrder = preorderedList == null
                  && isChildrenDrawingOrderEnabled();
          for (int i = 0; i < childrenCount; i++) {
              int childIndex;
              try {
                  childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
              } catch (IndexOutOfBoundsException e) {
                  childIndex = i;
                  if (mContext.getApplicationInfo().targetSdkVersion < Build.VERSION_CODES.M) {
                      Log.w(TAG, "Bad getChildDrawingOrder while collecting assist @ "
                              + i + " of " + childrenCount, e);
                      // At least one app is failing when we call getChildDrawingOrder
                      // at this point, so deal semi-gracefully with it by falling back
                      // on the basic order.
                      customOrder = false;
                      if (i > 0) {
                          // If we failed at the first index, there really isn't
                          // anything to do -- we will just proceed with the simple
                          // sequence order.
                          // Otherwise, we failed in the middle, so need to come up
                          // with an order for the remaining indices and use that.
                          // Failed at the first one, easy peasy.
                          int[] permutation = new int[childrenCount];
                          SparseBooleanArray usedIndices = new SparseBooleanArray();
                          // Go back and collected the indices we have done so far.
                          for (int j = 0; j < i; j++) {
                              permutation[j] = getChildDrawingOrder(childrenCount, j);
                              usedIndices.put(permutation[j], true);
                          }
                          // Fill in the remaining indices with indices that have not
                          // yet been used.
                          int nextIndex = 0;
                          for (int j = i; j < childrenCount; j++) {
                              while (usedIndices.get(nextIndex, false)) {
                                  nextIndex++;
                              }
                              permutation[j] = nextIndex;
                              nextIndex++;
                          }
                          // Build the final view list.
                          preorderedList = new ArrayList<>(childrenCount);
                          for (int j = 0; j < childrenCount; j++) {
                              final int index = permutation[j];
                              final View child = mChildren[index];
                              preorderedList.add(child);
                          }
                      }
                  } else {
                      throw e;
                  }
              }
              final View child = getAndVerifyPreorderedView(preorderedList, mChildren,
                      childIndex);
              final ViewStructure cstructure = structure.newChild(i);
              child.dispatchProvideStructure(cstructure);
          }
          if (preorderedList != null) {
              preorderedList.clear();
          }
      }
  
      /**
       * {@inheritDoc}
       *
       * <p>This implementation adds in all child views of the view group, in addition to calling the
       * default {@link View} implementation.
       */
      @Override
      public void dispatchProvideAutofillStructure(ViewStructure structure,
              @AutofillFlags int flags) {
          super.dispatchProvideAutofillStructure(structure, flags);
  
          if (structure.getChildCount() != 0) {
              return;
          }
  
          if (!isLaidOut()) {
              if (Helper.sVerbose) {
                  Log.v(VIEW_LOG_TAG, "dispatchProvideAutofillStructure(): not laid out, ignoring "
                          + mChildrenCount + " children of " + getAutofillId());
              }
              return;
          }
  
          final ChildListForAutoFillOrContentCapture children = getChildrenForAutofill(flags);
          final int childrenCount = children.size();
          structure.setChildCount(childrenCount);
          for (int i = 0; i < childrenCount; i++) {
              final View child = children.get(i);
              final ViewStructure cstructure = structure.newChild(i);
              child.dispatchProvideAutofillStructure(cstructure, flags);
          }
          children.recycle();
      }
  
      /** @hide */
      @Override
      public void dispatchProvideContentCaptureStructure() {
          super.dispatchProvideContentCaptureStructure();
  
          if (!isLaidOut()) return;
  
          final ChildListForAutoFillOrContentCapture children = getChildrenForContentCapture();
          final int childrenCount = children.size();
          for (int i = 0; i < childrenCount; i++) {
              final View child = children.get(i);
              child.dispatchProvideContentCaptureStructure();
          }
          children.recycle();
      }
  
      /**
       * Gets the children for autofill. Children for autofill are the first
       * level descendants that are important for autofill. The returned
       * child list object is pooled and the caller must recycle it once done.
       * @hide */
      private @NonNull ChildListForAutoFillOrContentCapture getChildrenForAutofill(
              @AutofillFlags int flags) {
          final ChildListForAutoFillOrContentCapture children = ChildListForAutoFillOrContentCapture
                  .obtain();
          populateChildrenForAutofill(children, flags);
          return children;
      }
  
      /** @hide */
      private void populateChildrenForAutofill(ArrayList<View> list, @AutofillFlags int flags) {
          final int childrenCount = mChildrenCount;
          if (childrenCount <= 0) {
              return;
          }
          final ArrayList<View> preorderedList = buildOrderedChildList();
          final boolean customOrder = preorderedList == null
                  && isChildrenDrawingOrderEnabled();
          for (int i = 0; i < childrenCount; i++) {
              final int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
              final View child = (preorderedList == null)
                      ? mChildren[childIndex] : preorderedList.get(childIndex);
              if ((flags & AUTOFILL_FLAG_INCLUDE_NOT_IMPORTANT_VIEWS) != 0
                      || child.isImportantForAutofill()) {
                  list.add(child);
              } else if (child instanceof ViewGroup) {
                  ((ViewGroup) child).populateChildrenForAutofill(list, flags);
              }
          }
      }
  
      private @NonNull ChildListForAutoFillOrContentCapture getChildrenForContentCapture() {
          final ChildListForAutoFillOrContentCapture children = ChildListForAutoFillOrContentCapture
                  .obtain();
          populateChildrenForContentCapture(children);
          return children;
      }
  
      /** @hide */
      private void populateChildrenForContentCapture(ArrayList<View> list) {
          final int childrenCount = mChildrenCount;
          if (childrenCount <= 0) {
              return;
          }
          final ArrayList<View> preorderedList = buildOrderedChildList();
          final boolean customOrder = preorderedList == null
                  && isChildrenDrawingOrderEnabled();
          for (int i = 0; i < childrenCount; i++) {
              final int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
              final View child = (preorderedList == null)
                      ? mChildren[childIndex] : preorderedList.get(childIndex);
              if (child.isImportantForContentCapture()) {
                  list.add(child);
              } else if (child instanceof ViewGroup) {
                  ((ViewGroup) child).populateChildrenForContentCapture(list);
              }
          }
      }
  
      private static View getAndVerifyPreorderedView(ArrayList<View> preorderedList, View[] children,
              int childIndex) {
          final View child;
          if (preorderedList != null) {
              child = preorderedList.get(childIndex);
              if (child == null) {
                  throw new RuntimeException("Invalid preorderedList contained null child at index "
                          + childIndex);
              }
          } else {
              child = children[childIndex];
          }
          return child;
      }
  
      /** @hide */
      @Override
      @UnsupportedAppUsage
      public void onInitializeAccessibilityNodeInfoInternal(AccessibilityNodeInfo info) {
          super.onInitializeAccessibilityNodeInfoInternal(info);
          if (getAccessibilityNodeProvider() != null) {
              return;
          }
          if (mAttachInfo != null) {
              final ArrayList<View> childrenForAccessibility = mAttachInfo.mTempArrayList;
              childrenForAccessibility.clear();
              addChildrenForAccessibility(childrenForAccessibility);
              final int childrenForAccessibilityCount = childrenForAccessibility.size();
              for (int i = 0; i < childrenForAccessibilityCount; i++) {
                  final View child = childrenForAccessibility.get(i);
                  info.addChildUnchecked(child);
              }
              childrenForAccessibility.clear();
          }
      }
  
      @Override
      public CharSequence getAccessibilityClassName() {
          return ViewGroup.class.getName();
      }
  
      @Override
      public void notifySubtreeAccessibilityStateChanged(View child, View source, int changeType) {
          // If this is a live region, we should send a subtree change event
          // from this view. Otherwise, we can let it propagate up.
          if (getAccessibilityLiveRegion() != ACCESSIBILITY_LIVE_REGION_NONE) {
              notifyViewAccessibilityStateChangedIfNeeded(
                      AccessibilityEvent.CONTENT_CHANGE_TYPE_SUBTREE);
          } else if (mParent != null) {
              try {
                  mParent.notifySubtreeAccessibilityStateChanged(this, source, changeType);
              } catch (AbstractMethodError e) {
                  Log.e(VIEW_LOG_TAG, mParent.getClass().getSimpleName() +
                          " does not fully implement ViewParent", e);
              }
          }
      }
  
      /** @hide */
      @Override
      public void notifySubtreeAccessibilityStateChangedIfNeeded() {
          if (!AccessibilityManager.getInstance(mContext).isEnabled() || mAttachInfo == null) {
              return;
          }
          // If something important for a11y is happening in this subtree, make sure it's dispatched
          // from a view that is important for a11y so it doesn't get lost.
          if ((getImportantForAccessibility() != IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS)
                  && !isImportantForAccessibility() && (getChildCount() > 0)) {
              ViewParent a11yParent = getParentForAccessibility();
              if (a11yParent instanceof View) {
                  ((View) a11yParent).notifySubtreeAccessibilityStateChangedIfNeeded();
                  return;
              }
          }
          super.notifySubtreeAccessibilityStateChangedIfNeeded();
      }
  
      @Override
      void resetSubtreeAccessibilityStateChanged() {
          super.resetSubtreeAccessibilityStateChanged();
          View[] children = mChildren;
          final int childCount = mChildrenCount;
          for (int i = 0; i < childCount; i++) {
              children[i].resetSubtreeAccessibilityStateChanged();
          }
      }
  
      /**
       * Counts the number of children of this View that will be sent to an accessibility service.
       *
       * @return The number of children an {@code AccessibilityNodeInfo} rooted at this View
       * would have.
       */
      int getNumChildrenForAccessibility() {
          int numChildrenForAccessibility = 0;
          for (int i = 0; i < getChildCount(); i++) {
              View child = getChildAt(i);
              if (child.includeForAccessibility()) {
                  numChildrenForAccessibility++;
              } else if (child instanceof ViewGroup) {
                  numChildrenForAccessibility += ((ViewGroup) child)
                          .getNumChildrenForAccessibility();
              }
          }
          return numChildrenForAccessibility;
      }
  
      /**
       * {@inheritDoc}
       *
       * <p>Subclasses should always call <code>super.onNestedPrePerformAccessibilityAction</code></p>
       *
       * @param target The target view dispatching this action
       * @param action Action being performed; see
       *               {@link android.view.accessibility.AccessibilityNodeInfo}
       * @param args Optional action arguments
       * @return false by default. Subclasses should return true if they handle the event.
       */
      @Override
      public boolean onNestedPrePerformAccessibilityAction(View target, int action, Bundle args) {
          return false;
      }
  
      @Override
      @UnsupportedAppUsage
      void dispatchDetachedFromWindow() {
          // If we still have a touch target, we are still in the process of
          // dispatching motion events to a child; we need to get rid of that
          // child to avoid dispatching events to it after the window is torn
          // down. To make sure we keep the child in a consistent state, we
          // first send it an ACTION_CANCEL motion event.
          cancelAndClearTouchTargets(null);
  
          // Similarly, set ACTION_EXIT to all hover targets and clear them.
          exitHoverTargets();
          exitTooltipHoverTargets();
  
          // In case view is detached while transition is running
          mLayoutCalledWhileSuppressed = false;
  
          // Tear down our drag tracking
          mChildrenInterestedInDrag = null;
          mIsInterestedInDrag = false;
          if (mCurrentDragStartEvent != null) {
              mCurrentDragStartEvent.recycle();
              mCurrentDragStartEvent = null;
          }
  
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              children[i].dispatchDetachedFromWindow();
          }
          clearDisappearingChildren();
          final int transientCount = mTransientViews == null ? 0 : mTransientIndices.size();
          for (int i = 0; i < transientCount; ++i) {
              View view = mTransientViews.get(i);
              view.dispatchDetachedFromWindow();
          }
          super.dispatchDetachedFromWindow();
      }
  
      /**
       * @hide
       */
      @Override
      protected void internalSetPadding(int left, int top, int right, int bottom) {
          super.internalSetPadding(left, top, right, bottom);
  
          if ((mPaddingLeft | mPaddingTop | mPaddingRight | mPaddingBottom) != 0) {
              mGroupFlags |= FLAG_PADDING_NOT_NULL;
          } else {
              mGroupFlags &= ~FLAG_PADDING_NOT_NULL;
          }
      }
  
      @Override
      protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) {
          super.dispatchSaveInstanceState(container);
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              View c = children[i];
              if ((c.mViewFlags & PARENT_SAVE_DISABLED_MASK) != PARENT_SAVE_DISABLED) {
                  c.dispatchSaveInstanceState(container);
              }
          }
      }
  
      /**
       * Perform dispatching of a {@link #saveHierarchyState(android.util.SparseArray)}  freeze()}
       * to only this view, not to its children.  For use when overriding
       * {@link #dispatchSaveInstanceState(android.util.SparseArray)}  dispatchFreeze()} to allow
       * subclasses to freeze their own state but not the state of their children.
       *
       * @param container the container
       */
      protected void dispatchFreezeSelfOnly(SparseArray<Parcelable> container) {
          super.dispatchSaveInstanceState(container);
      }
  
      @Override
      protected void dispatchRestoreInstanceState(SparseArray<Parcelable> container) {
          super.dispatchRestoreInstanceState(container);
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              View c = children[i];
              if ((c.mViewFlags & PARENT_SAVE_DISABLED_MASK) != PARENT_SAVE_DISABLED) {
                  c.dispatchRestoreInstanceState(container);
              }
          }
      }
  
      /**
       * Perform dispatching of a {@link #restoreHierarchyState(android.util.SparseArray)}
       * to only this view, not to its children.  For use when overriding
       * {@link #dispatchRestoreInstanceState(android.util.SparseArray)} to allow
       * subclasses to thaw their own state but not the state of their children.
       *
       * @param container the container
       */
      protected void dispatchThawSelfOnly(SparseArray<Parcelable> container) {
          super.dispatchRestoreInstanceState(container);
      }
  
      /**
       * Enables or disables the drawing cache for each child of this view group.
       *
       * @param enabled true to enable the cache, false to dispose of it
       *
       * @deprecated The view drawing cache was largely made obsolete with the introduction of
       * hardware-accelerated rendering in API 11. With hardware-acceleration, intermediate cache
       * layers are largely unnecessary and can easily result in a net loss in performance due to the
       * cost of creating and updating the layer. In the rare cases where caching layers are useful,
       * such as for alpha animations, {@link #setLayerType(int, Paint)} handles this with hardware
       * rendering. For software-rendered snapshots of a small part of the View hierarchy or
       * individual Views it is recommended to create a {@link Canvas} from either a {@link Bitmap} or
       * {@link android.graphics.Picture} and call {@link #draw(Canvas)} on the View. However these
       * software-rendered usages are discouraged and have compatibility issues with hardware-only
       * rendering features such as {@link android.graphics.Bitmap.Config#HARDWARE Config.HARDWARE}
       * bitmaps, real-time shadows, and outline clipping. For screenshots of the UI for feedback
       * reports or unit testing the {@link PixelCopy} API is recommended.
       */
      @Deprecated
      protected void setChildrenDrawingCacheEnabled(boolean enabled) {
          if (enabled || (mPersistentDrawingCache & PERSISTENT_ALL_CACHES) != PERSISTENT_ALL_CACHES) {
              final View[] children = mChildren;
              final int count = mChildrenCount;
              for (int i = 0; i < count; i++) {
                  children[i].setDrawingCacheEnabled(enabled);
              }
          }
      }
  
      /**
       * @hide
       */
      @Override
      public Bitmap createSnapshot(ViewDebug.CanvasProvider canvasProvider, boolean skipChildren) {
          int count = mChildrenCount;
          int[] visibilities = null;
  
          if (skipChildren) {
              visibilities = new int[count];
              for (int i = 0; i < count; i++) {
                  View child = getChildAt(i);
                  visibilities[i] = child.getVisibility();
                  if (visibilities[i] == View.VISIBLE) {
                      child.mViewFlags = (child.mViewFlags & ~View.VISIBILITY_MASK)
                              | (View.INVISIBLE & View.VISIBILITY_MASK);
                  }
              }
          }
  
          try {
              return super.createSnapshot(canvasProvider, skipChildren);
          } finally {
              if (skipChildren) {
                  for (int i = 0; i < count; i++) {
                      View child = getChildAt(i);
                      child.mViewFlags = (child.mViewFlags & ~View.VISIBILITY_MASK)
                              | (visibilities[i] & View.VISIBILITY_MASK);
                  }
              }
          }
      }
  
      /** Return true if this ViewGroup is laying out using optical bounds. */
      boolean isLayoutModeOptical() {
          return mLayoutMode == LAYOUT_MODE_OPTICAL_BOUNDS;
      }
  
      @Override
      Insets computeOpticalInsets() {
          if (isLayoutModeOptical()) {
              int left = 0;
              int top = 0;
              int right = 0;
              int bottom = 0;
              for (int i = 0; i < mChildrenCount; i++) {
                  View child = getChildAt(i);
                  if (child.getVisibility() == VISIBLE) {
                      Insets insets = child.getOpticalInsets();
                      left =   Math.max(left,   insets.left);
                      top =    Math.max(top,    insets.top);
                      right =  Math.max(right,  insets.right);
                      bottom = Math.max(bottom, insets.bottom);
                  }
              }
              return Insets.of(left, top, right, bottom);
          } else {
              return Insets.NONE;
          }
      }
  
      private static void fillRect(Canvas canvas, Paint paint, int x1, int y1, int x2, int y2) {
          if (x1 != x2 && y1 != y2) {
              if (x1 > x2) {
                  int tmp = x1; x1 = x2; x2 = tmp;
              }
              if (y1 > y2) {
                  int tmp = y1; y1 = y2; y2 = tmp;
              }
              canvas.drawRect(x1, y1, x2, y2, paint);
          }
      }
  
      private static int sign(int x) {
          return (x >= 0) ? 1 : -1;
      }
  
      private static void drawCorner(Canvas c, Paint paint, int x1, int y1, int dx, int dy, int lw) {
          fillRect(c, paint, x1, y1, x1 + dx, y1 + lw * sign(dy));
          fillRect(c, paint, x1, y1, x1 + lw * sign(dx), y1 + dy);
      }
  
      private static void drawRectCorners(Canvas canvas, int x1, int y1, int x2, int y2, Paint paint,
              int lineLength, int lineWidth) {
          drawCorner(canvas, paint, x1, y1, lineLength, lineLength, lineWidth);
          drawCorner(canvas, paint, x1, y2, lineLength, -lineLength, lineWidth);
          drawCorner(canvas, paint, x2, y1, -lineLength, lineLength, lineWidth);
          drawCorner(canvas, paint, x2, y2, -lineLength, -lineLength, lineWidth);
      }
  
      private static void fillDifference(Canvas canvas,
              int x2, int y2, int x3, int y3,
              int dx1, int dy1, int dx2, int dy2, Paint paint) {
          int x1 = x2 - dx1;
          int y1 = y2 - dy1;
  
          int x4 = x3 + dx2;
          int y4 = y3 + dy2;
  
          fillRect(canvas, paint, x1, y1, x4, y2);
          fillRect(canvas, paint, x1, y2, x2, y3);
          fillRect(canvas, paint, x3, y2, x4, y3);
          fillRect(canvas, paint, x1, y3, x4, y4);
      }
  
      /**
       * @hide
       */
      protected void onDebugDrawMargins(Canvas canvas, Paint paint) {
          for (int i = 0; i < getChildCount(); i++) {
              View c = getChildAt(i);
              c.getLayoutParams().onDebugDraw(c, canvas, paint);
          }
      }
  
      /**
       * @hide
       */
      protected void onDebugDraw(Canvas canvas) {
          Paint paint = getDebugPaint();
  
          // Draw optical bounds
          {
              paint.setColor(Color.RED);
              paint.setStyle(Paint.Style.STROKE);
  
              for (int i = 0; i < getChildCount(); i++) {
                  View c = getChildAt(i);
                  if (c.getVisibility() != View.GONE) {
                      Insets insets = c.getOpticalInsets();
  
                      drawRect(canvas, paint,
                              c.getLeft() + insets.left,
                              c.getTop() + insets.top,
                              c.getRight() - insets.right - 1,
                              c.getBottom() - insets.bottom - 1);
                  }
              }
          }
  
          // Draw margins
          {
              paint.setColor(Color.argb(63, 255, 0, 255));
              paint.setStyle(Paint.Style.FILL);
  
              onDebugDrawMargins(canvas, paint);
          }
  
          // Draw clip bounds
          {
              paint.setColor(DEBUG_CORNERS_COLOR);
              paint.setStyle(Paint.Style.FILL);
  
              int lineLength = dipsToPixels(DEBUG_CORNERS_SIZE_DIP);
              int lineWidth = dipsToPixels(1);
              for (int i = 0; i < getChildCount(); i++) {
                  View c = getChildAt(i);
                  if (c.getVisibility() != View.GONE) {
                      drawRectCorners(canvas, c.getLeft(), c.getTop(), c.getRight(), c.getBottom(),
                              paint, lineLength, lineWidth);
                  }
              }
          }
      }
  
      @Override
      protected void dispatchDraw(Canvas canvas) {
          boolean usingRenderNodeProperties = canvas.isRecordingFor(mRenderNode);
          final int childrenCount = mChildrenCount;
          final View[] children = mChildren;
          int flags = mGroupFlags;
  
          if ((flags & FLAG_RUN_ANIMATION) != 0 && canAnimate()) {
              final boolean buildCache = !isHardwareAccelerated();
              for (int i = 0; i < childrenCount; i++) {
                  final View child = children[i];
                  if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                      final LayoutParams params = child.getLayoutParams();
                      attachLayoutAnimationParameters(child, params, i, childrenCount);
                      bindLayoutAnimation(child);
                  }
              }
  
              final LayoutAnimationController controller = mLayoutAnimationController;
              if (controller.willOverlap()) {
                  mGroupFlags |= FLAG_OPTIMIZE_INVALIDATE;
              }
  
              controller.start();
  
              mGroupFlags &= ~FLAG_RUN_ANIMATION;
              mGroupFlags &= ~FLAG_ANIMATION_DONE;
  
              if (mAnimationListener != null) {
                  mAnimationListener.onAnimationStart(controller.getAnimation());
              }
          }
  
          int clipSaveCount = 0;
          final boolean clipToPadding = (flags & CLIP_TO_PADDING_MASK) == CLIP_TO_PADDING_MASK;
          if (clipToPadding) {
              clipSaveCount = canvas.save(Canvas.CLIP_SAVE_FLAG);
              canvas.clipRect(mScrollX + mPaddingLeft, mScrollY + mPaddingTop,
                      mScrollX + mRight - mLeft - mPaddingRight,
                      mScrollY + mBottom - mTop - mPaddingBottom);
          }
  
          // We will draw our child's animation, let's reset the flag
          mPrivateFlags &= ~PFLAG_DRAW_ANIMATION;
          mGroupFlags &= ~FLAG_INVALIDATE_REQUIRED;
  
          boolean more = false;
          final long drawingTime = getDrawingTime();
  
          if (usingRenderNodeProperties) canvas.insertReorderBarrier();
          final int transientCount = mTransientIndices == null ? 0 : mTransientIndices.size();
          int transientIndex = transientCount != 0 ? 0 : -1;
          // Only use the preordered list if not HW accelerated, since the HW pipeline will do the
          // draw reordering internally
          final ArrayList<View> preorderedList = usingRenderNodeProperties
                  ? null : buildOrderedChildList();
          final boolean customOrder = preorderedList == null
                  && isChildrenDrawingOrderEnabled();
          for (int i = 0; i < childrenCount; i++) {
              while (transientIndex >= 0 && mTransientIndices.get(transientIndex) == i) {
                  final View transientChild = mTransientViews.get(transientIndex);
                  if ((transientChild.mViewFlags & VISIBILITY_MASK) == VISIBLE ||
                          transientChild.getAnimation() != null) {
                      more |= drawChild(canvas, transientChild, drawingTime);
                  }
                  transientIndex++;
                  if (transientIndex >= transientCount) {
                      transientIndex = -1;
                  }
              }
  
              final int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
              final View child = getAndVerifyPreorderedView(preorderedList, children, childIndex);
              if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE || child.getAnimation() != null) {
                  more |= drawChild(canvas, child, drawingTime);
              }
          }
          while (transientIndex >= 0) {
              // there may be additional transient views after the normal views
              final View transientChild = mTransientViews.get(transientIndex);
              if ((transientChild.mViewFlags & VISIBILITY_MASK) == VISIBLE ||
                      transientChild.getAnimation() != null) {
                  more |= drawChild(canvas, transientChild, drawingTime);
              }
              transientIndex++;
              if (transientIndex >= transientCount) {
                  break;
              }
          }
          if (preorderedList != null) preorderedList.clear();
  
          // Draw any disappearing views that have animations
          if (mDisappearingChildren != null) {
              final ArrayList<View> disappearingChildren = mDisappearingChildren;
              final int disappearingCount = disappearingChildren.size() - 1;
              // Go backwards -- we may delete as animations finish
              for (int i = disappearingCount; i >= 0; i--) {
                  final View child = disappearingChildren.get(i);
                  more |= drawChild(canvas, child, drawingTime);
              }
          }
          if (usingRenderNodeProperties) canvas.insertInorderBarrier();
  
          if (debugDraw()) {
              onDebugDraw(canvas);
          }
  
          if (clipToPadding) {
              canvas.restoreToCount(clipSaveCount);
          }
  
          // mGroupFlags might have been updated by drawChild()
          flags = mGroupFlags;
  
          if ((flags & FLAG_INVALIDATE_REQUIRED) == FLAG_INVALIDATE_REQUIRED) {
              invalidate(true);
          }
  
          if ((flags & FLAG_ANIMATION_DONE) == 0 && (flags & FLAG_NOTIFY_ANIMATION_LISTENER) == 0 &&
                  mLayoutAnimationController.isDone() && !more) {
              // We want to erase the drawing cache and notify the listener after the
              // next frame is drawn because one extra invalidate() is caused by
              // drawChild() after the animation is over
              mGroupFlags |= FLAG_NOTIFY_ANIMATION_LISTENER;
              final Runnable end = new Runnable() {
                 @Override
                 public void run() {
                     notifyAnimationListener();
                 }
              };
              post(end);
          }
      }
  
      /**
       * Returns the ViewGroupOverlay for this view group, creating it if it does
       * not yet exist. In addition to {@link ViewOverlay}'s support for drawables,
       * {@link ViewGroupOverlay} allows views to be added to the overlay. These
       * views, like overlay drawables, are visual-only; they do not receive input
       * events and should not be used as anything other than a temporary
       * representation of a view in a parent container, such as might be used
       * by an animation effect.
       *
       * <p>Note: Overlays do not currently work correctly with {@link
       * SurfaceView} or {@link TextureView}; contents in overlays for these
       * types of views may not display correctly.</p>
       *
       * @return The ViewGroupOverlay object for this view.
       * @see ViewGroupOverlay
       */
      @Override
      public ViewGroupOverlay getOverlay() {
          if (mOverlay == null) {
              mOverlay = new ViewGroupOverlay(mContext, this);
          }
          return (ViewGroupOverlay) mOverlay;
      }
  
      /**
       * Converts drawing order position to container position. Override this
       * if you want to change the drawing order of children. By default, it
       * returns drawingPosition.
       * <p>
       * NOTE: In order for this method to be called, you must enable child ordering
       * first by calling {@link #setChildrenDrawingOrderEnabled(boolean)}.
       *
       * @param drawingPosition the drawing order position.
       * @return the container position of a child for this drawing order position.
       *
       * @see #setChildrenDrawingOrderEnabled(boolean)
       * @see #isChildrenDrawingOrderEnabled()
       */
      protected int getChildDrawingOrder(int childCount, int drawingPosition) {
          return drawingPosition;
      }
  
      /**
       * Converts drawing order position to container position.
       * <p>
       * Children are not necessarily drawn in the order in which they appear in the container.
       * ViewGroups can enable a custom ordering via {@link #setChildrenDrawingOrderEnabled(boolean)}.
       * This method returns the container position of a child that appears in the given position
       * in the current drawing order.
       *
       * @param drawingPosition the drawing order position.
       * @return the container position of a child for this drawing order position.
       *
       * @see #getChildDrawingOrder(int, int)}
       */
      public final int getChildDrawingOrder(int drawingPosition) {
          return getChildDrawingOrder(getChildCount(), drawingPosition);
      }
  
      private boolean hasChildWithZ() {
          for (int i = 0; i < mChildrenCount; i++) {
              if (mChildren[i].getZ() != 0) return true;
          }
          return false;
      }
  
      /**
       * Populates (and returns) mPreSortedChildren with a pre-ordered list of the View's children,
       * sorted first by Z, then by child drawing order (if applicable). This list must be cleared
       * after use to avoid leaking child Views.
       *
       * Uses a stable, insertion sort which is commonly O(n) for ViewGroups with very few elevated
       * children.
       */
      ArrayList<View> buildOrderedChildList() {
          final int childrenCount = mChildrenCount;
          if (childrenCount <= 1 || !hasChildWithZ()) return null;
  
          if (mPreSortedChildren == null) {
              mPreSortedChildren = new ArrayList<>(childrenCount);
          } else {
              // callers should clear, so clear shouldn't be necessary, but for safety...
              mPreSortedChildren.clear();
              mPreSortedChildren.ensureCapacity(childrenCount);
          }
  
          final boolean customOrder = isChildrenDrawingOrderEnabled();
          for (int i = 0; i < childrenCount; i++) {
              // add next child (in child order) to end of list
              final int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
              final View nextChild = mChildren[childIndex];
              final float currentZ = nextChild.getZ();
  
              // insert ahead of any Views with greater Z
              int insertIndex = i;
              while (insertIndex > 0 && mPreSortedChildren.get(insertIndex - 1).getZ() > currentZ) {
                  insertIndex--;
              }
              mPreSortedChildren.add(insertIndex, nextChild);
          }
          return mPreSortedChildren;
      }
  
      private void notifyAnimationListener() {
          mGroupFlags &= ~FLAG_NOTIFY_ANIMATION_LISTENER;
          mGroupFlags |= FLAG_ANIMATION_DONE;
  
          if (mAnimationListener != null) {
             final Runnable end = new Runnable() {
                 @Override
                 public void run() {
                     mAnimationListener.onAnimationEnd(mLayoutAnimationController.getAnimation());
                 }
             };
             post(end);
          }
  
          invalidate(true);
      }
  
      /**
       * This method is used to cause children of this ViewGroup to restore or recreate their
       * display lists. It is called by getDisplayList() when the parent ViewGroup does not need
       * to recreate its own display list, which would happen if it went through the normal
       * draw/dispatchDraw mechanisms.
       *
       * @hide
       */
      @Override
      @UnsupportedAppUsage
      protected void dispatchGetDisplayList() {
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              final View child = children[i];
              if (((child.mViewFlags & VISIBILITY_MASK) == VISIBLE || child.getAnimation() != null)) {
                  recreateChildDisplayList(child);
              }
          }
          final int transientCount = mTransientViews == null ? 0 : mTransientIndices.size();
          for (int i = 0; i < transientCount; ++i) {
              View child = mTransientViews.get(i);
              if (((child.mViewFlags & VISIBILITY_MASK) == VISIBLE || child.getAnimation() != null)) {
                  recreateChildDisplayList(child);
              }
          }
          if (mOverlay != null) {
              View overlayView = mOverlay.getOverlayView();
              recreateChildDisplayList(overlayView);
          }
          if (mDisappearingChildren != null) {
              final ArrayList<View> disappearingChildren = mDisappearingChildren;
              final int disappearingCount = disappearingChildren.size();
              for (int i = 0; i < disappearingCount; ++i) {
                  final View child = disappearingChildren.get(i);
                  recreateChildDisplayList(child);
              }
          }
      }
  
      private void recreateChildDisplayList(View child) {
          child.mRecreateDisplayList = (child.mPrivateFlags & PFLAG_INVALIDATED) != 0;
          child.mPrivateFlags &= ~PFLAG_INVALIDATED;
          child.updateDisplayListIfDirty();
          child.mRecreateDisplayList = false;
      }
  
      /**
       * Draw one child of this View Group. This method is responsible for getting
       * the canvas in the right state. This includes clipping, translating so
       * that the child's scrolled origin is at 0, 0, and applying any animation
       * transformations.
       *
       * @param canvas The canvas on which to draw the child
       * @param child Who to draw
       * @param drawingTime The time at which draw is occurring
       * @return True if an invalidate() was issued
       */
      protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
          return child.draw(canvas, this, drawingTime);
      }
  
      @Override
      void getScrollIndicatorBounds(@NonNull Rect out) {
          super.getScrollIndicatorBounds(out);
  
          // If we have padding and we're supposed to clip children to that
          // padding, offset the scroll indicators to match our clip bounds.
          final boolean clipToPadding = (mGroupFlags & CLIP_TO_PADDING_MASK) == CLIP_TO_PADDING_MASK;
          if (clipToPadding) {
              out.left += mPaddingLeft;
              out.right -= mPaddingRight;
              out.top += mPaddingTop;
              out.bottom -= mPaddingBottom;
          }
      }
  
      /**
       * Returns whether this group's children are clipped to their bounds before drawing.
       * The default value is true.
       * @see #setClipChildren(boolean)
       *
       * @return True if the group's children will be clipped to their bounds,
       * false otherwise.
       */
      @ViewDebug.ExportedProperty(category = "drawing")
      @InspectableProperty
      public boolean getClipChildren() {
          return ((mGroupFlags & FLAG_CLIP_CHILDREN) != 0);
      }
  
      /**
       * By default, children are clipped to their bounds before drawing. This
       * allows view groups to override this behavior for animations, etc.
       *
       * @param clipChildren true to clip children to their bounds,
       *        false otherwise
       * @attr ref android.R.styleable#ViewGroup_clipChildren
       */
      public void setClipChildren(boolean clipChildren) {
          boolean previousValue = (mGroupFlags & FLAG_CLIP_CHILDREN) == FLAG_CLIP_CHILDREN;
          if (clipChildren != previousValue) {
              setBooleanFlag(FLAG_CLIP_CHILDREN, clipChildren);
              for (int i = 0; i < mChildrenCount; ++i) {
                  View child = getChildAt(i);
                  if (child.mRenderNode != null) {
                      child.mRenderNode.setClipToBounds(clipChildren);
                  }
              }
              invalidate(true);
          }
      }
  
      /**
       * Sets whether this ViewGroup will clip its children to its padding and resize (but not
       * clip) any EdgeEffect to the padded region, if padding is present.
       * <p>
       * By default, children are clipped to the padding of their parent
       * ViewGroup. This clipping behavior is only enabled if padding is non-zero.
       *
       * @param clipToPadding true to clip children to the padding of the group, and resize (but
       *        not clip) any EdgeEffect to the padded region. False otherwise.
       * @attr ref android.R.styleable#ViewGroup_clipToPadding
       */
      public void setClipToPadding(boolean clipToPadding) {
          if (hasBooleanFlag(FLAG_CLIP_TO_PADDING) != clipToPadding) {
              setBooleanFlag(FLAG_CLIP_TO_PADDING, clipToPadding);
              invalidate(true);
          }
      }
  
      /**
       * Returns whether this ViewGroup will clip its children to its padding, and resize (but
       * not clip) any EdgeEffect to the padded region, if padding is present.
       * <p>
       * By default, children are clipped to the padding of their parent
       * Viewgroup. This clipping behavior is only enabled if padding is non-zero.
       *
       * @return true if this ViewGroup clips children to its padding and resizes (but doesn't
       *         clip) any EdgeEffect to the padded region, false otherwise.
       *
       * @attr ref android.R.styleable#ViewGroup_clipToPadding
       */
      @ViewDebug.ExportedProperty(category = "drawing")
      @InspectableProperty
      public boolean getClipToPadding() {
          return hasBooleanFlag(FLAG_CLIP_TO_PADDING);
      }
  
      @Override
      public void dispatchSetSelected(boolean selected) {
          final View[] children = mChildren;
          final int count = mChildrenCount;
          for (int i = 0; i < count; i++) {
              children[i].setSelected(selected);
          }
      }
  
      @Override
      public void dispatchSetActivated(boolean activated) {
          final View[] children = mChildren;
          final int count = mChildrenCount;
          for (int i = 0; i < count; i++) {
              children[i].setActivated(activated);
          }
      }
  
      @Override
      protected void dispatchSetPressed(boolean pressed) {
          final View[] children = mChildren;
          final int count = mChildrenCount;
          for (int i = 0; i < count; i++) {
              final View child = children[i];
              // Children that are clickable on their own should not
              // show a pressed state when their parent view does.
              // Clearing a pressed state always propagates.
              if (!pressed || (!child.isClickable() && !child.isLongClickable())) {
                  child.setPressed(pressed);
              }
          }
      }
  
      /**
       * Dispatches drawable hotspot changes to child views that meet at least
       * one of the following criteria:
       * <ul>
       *     <li>Returns {@code false} from both {@link View#isClickable()} and
       *     {@link View#isLongClickable()}</li>
       *     <li>Requests duplication of parent state via
       *     {@link View#setDuplicateParentStateEnabled(boolean)}</li>
       * </ul>
       *
       * @param x hotspot x coordinate
       * @param y hotspot y coordinate
       * @see #drawableHotspotChanged(float, float)
       */
      @Override
      public void dispatchDrawableHotspotChanged(float x, float y) {
          final int count = mChildrenCount;
          if (count == 0) {
              return;
          }
  
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              final View child = children[i];
              // Children that are clickable on their own should not
              // receive hotspots when their parent view does.
              final boolean nonActionable = !child.isClickable() && !child.isLongClickable();
              final boolean duplicatesState = (child.mViewFlags & DUPLICATE_PARENT_STATE) != 0;
              if (nonActionable || duplicatesState) {
                  final float[] point = getTempPoint();
                  point[0] = x;
                  point[1] = y;
                  transformPointToViewLocal(point, child);
                  child.drawableHotspotChanged(point[0], point[1]);
              }
          }
      }
  
      @Override
      void dispatchCancelPendingInputEvents() {
          super.dispatchCancelPendingInputEvents();
  
          final View[] children = mChildren;
          final int count = mChildrenCount;
          for (int i = 0; i < count; i++) {
              children[i].dispatchCancelPendingInputEvents();
          }
      }
  
      /**
       * When this property is set to true, this ViewGroup supports static transformations on
       * children; this causes
       * {@link #getChildStaticTransformation(View, android.view.animation.Transformation)} to be
       * invoked when a child is drawn.
       *
       * Any subclass overriding
       * {@link #getChildStaticTransformation(View, android.view.animation.Transformation)} should
       * set this property to true.
       *
       * @param enabled True to enable static transformations on children, false otherwise.
       *
       * @see #getChildStaticTransformation(View, android.view.animation.Transformation)
       */
      protected void setStaticTransformationsEnabled(boolean enabled) {
          setBooleanFlag(FLAG_SUPPORT_STATIC_TRANSFORMATIONS, enabled);
      }
  
      /**
       * Sets  <code>t</code> to be the static transformation of the child, if set, returning a
       * boolean to indicate whether a static transform was set. The default implementation
       * simply returns <code>false</code>; subclasses may override this method for different
       * behavior. {@link #setStaticTransformationsEnabled(boolean)} must be set to true
       * for this method to be called.
       *
       * @param child The child view whose static transform is being requested
       * @param t The Transformation which will hold the result
       * @return true if the transformation was set, false otherwise
       * @see #setStaticTransformationsEnabled(boolean)
       */
      protected boolean getChildStaticTransformation(View child, Transformation t) {
          return false;
      }
  
      Transformation getChildTransformation() {
          if (mChildTransformation == null) {
              mChildTransformation = new Transformation();
          }
          return mChildTransformation;
      }
  
      /**
       * {@hide}
       */
      @Override
      protected <T extends View> T findViewTraversal(@IdRes int id) {
          if (id == mID) {
              return (T) this;
          }
  
          final View[] where = mChildren;
          final int len = mChildrenCount;
  
          for (int i = 0; i < len; i++) {
              View v = where[i];
  
              if ((v.mPrivateFlags & PFLAG_IS_ROOT_NAMESPACE) == 0) {
                  v = v.findViewById(id);
  
                  if (v != null) {
                      return (T) v;
                  }
              }
          }
  
          return null;
      }
  
      /**
       * {@hide}
       */
      @Override
      protected <T extends View> T findViewWithTagTraversal(Object tag) {
          if (tag != null && tag.equals(mTag)) {
              return (T) this;
          }
  
          final View[] where = mChildren;
          final int len = mChildrenCount;
  
          for (int i = 0; i < len; i++) {
              View v = where[i];
  
              if ((v.mPrivateFlags & PFLAG_IS_ROOT_NAMESPACE) == 0) {
                  v = v.findViewWithTag(tag);
  
                  if (v != null) {
                      return (T) v;
                  }
              }
          }
  
          return null;
      }
  
      /**
       * {@hide}
       */
      @Override
      protected <T extends View> T findViewByPredicateTraversal(Predicate<View> predicate,
              View childToSkip) {
          if (predicate.test(this)) {
              return (T) this;
          }
  
          final View[] where = mChildren;
          final int len = mChildrenCount;
  
          for (int i = 0; i < len; i++) {
              View v = where[i];
  
              if (v != childToSkip && (v.mPrivateFlags & PFLAG_IS_ROOT_NAMESPACE) == 0) {
                  v = v.findViewByPredicate(predicate);
  
                  if (v != null) {
                      return (T) v;
                  }
              }
          }
  
          return null;
      }
  
      /**
       * This method adds a view to this container at the specified index purely for the
       * purposes of allowing that view to draw even though it is not a normal child of
       * the container. That is, the view does not participate in layout, focus, accessibility,
       * input, or other normal view operations; it is purely an item to be drawn during the normal
       * rendering operation of this container. The index that it is added at is the order
       * in which it will be drawn, with respect to the other views in the container.
       * For example, a transient view added at index 0 will be drawn before all other views
       * in the container because it will be drawn first (including before any real view
       * at index 0). There can be more than one transient view at any particular index;
       * these views will be drawn in the order in which they were added to the list of
       * transient views. The index of transient views can also be greater than the number
       * of normal views in the container; that just means that they will be drawn after all
       * other views are drawn.
       *
       * <p>Note that since transient views do not participate in layout, they must be sized
       * manually or, more typically, they should just use the size that they had before they
       * were removed from their container.</p>
       *
       * <p>Transient views are useful for handling animations of views that have been removed
       * from the container, but which should be animated out after the removal. Adding these
       * views as transient views allows them to participate in drawing without side-effecting
       * the layout of the container.</p>
       *
       * <p>Transient views must always be explicitly {@link #removeTransientView(View) removed}
       * from the container when they are no longer needed. For example, a transient view
       * which is added in order to fade it out in its old location should be removed
       * once the animation is complete.</p>
       *
       * @param view The view to be added. The view must not have a parent.
       * @param index The index at which this view should be drawn, must be >= 0.
       * This value is relative to the {@link #getChildAt(int) index} values in the normal
       * child list of this container, where any transient view at a particular index will
       * be drawn before any normal child at that same index.
       *
       * @hide
       */
      @UnsupportedAppUsage
      public void addTransientView(View view, int index) {
          if (index < 0 || view == null) {
              return;
          }
          if (view.mParent != null) {
              throw new IllegalStateException("The specified view already has a parent "
                      + view.mParent);
          }
  
          if (mTransientIndices == null) {
              mTransientIndices = new ArrayList<Integer>();
              mTransientViews = new ArrayList<View>();
          }
          final int oldSize = mTransientIndices.size();
          if (oldSize > 0) {
              int insertionIndex;
              for (insertionIndex = 0; insertionIndex < oldSize; ++insertionIndex) {
                  if (index < mTransientIndices.get(insertionIndex)) {
                      break;
                  }
              }
              mTransientIndices.add(insertionIndex, index);
              mTransientViews.add(insertionIndex, view);
          } else {
              mTransientIndices.add(index);
              mTransientViews.add(view);
          }
          view.mParent = this;
          if (mAttachInfo != null) {
              view.dispatchAttachedToWindow(mAttachInfo, (mViewFlags & VISIBILITY_MASK));
          }
          invalidate(true);
      }
  
      /**
       * Removes a view from the list of transient views in this container. If there is no
       * such transient view, this method does nothing.
       *
       * @param view The transient view to be removed
       *
       * @hide
       */
      @UnsupportedAppUsage
      public void removeTransientView(View view) {
          if (mTransientViews == null) {
              return;
          }
          final int size = mTransientViews.size();
          for (int i = 0; i < size; ++i) {
              if (view == mTransientViews.get(i)) {
                  mTransientViews.remove(i);
                  mTransientIndices.remove(i);
                  view.mParent = null;
                  if (view.mAttachInfo != null) {
                      view.dispatchDetachedFromWindow();
                  }
                  invalidate(true);
                  return;
              }
          }
      }
  
      /**
       * Returns the number of transient views in this container. Specific transient
       * views and the index at which they were added can be retrieved via
       * {@link #getTransientView(int)} and {@link #getTransientViewIndex(int)}.
       *
       * @see #addTransientView(View, int)
       * @return The number of transient views in this container
       *
       * @hide
       */
      @UnsupportedAppUsage
      public int getTransientViewCount() {
          return mTransientIndices == null ? 0 : mTransientIndices.size();
      }
  
      /**
       * Given a valid position within the list of transient views, returns the index of
       * the transient view at that position.
       *
       * @param position The position of the index being queried. Must be at least 0
       * and less than the value returned by {@link #getTransientViewCount()}.
       * @return The index of the transient view stored in the given position if the
       * position is valid, otherwise -1
       *
       * @hide
       */
      public int getTransientViewIndex(int position) {
          if (position < 0 || mTransientIndices == null || position >= mTransientIndices.size()) {
              return -1;
          }
          return mTransientIndices.get(position);
      }
  
      /**
       * Given a valid position within the list of transient views, returns the
       * transient view at that position.
       *
       * @param position The position of the view being queried. Must be at least 0
       * and less than the value returned by {@link #getTransientViewCount()}.
       * @return The transient view stored in the given position if the
       * position is valid, otherwise null
       *
       * @hide
       */
      @UnsupportedAppUsage
      public View getTransientView(int position) {
          if (mTransientViews == null || position >= mTransientViews.size()) {
              return null;
          }
          return mTransientViews.get(position);
      }
  
      /**
       * <p>Adds a child view. If no layout parameters are already set on the child, the
       * default parameters for this ViewGroup are set on the child.</p>
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       *
       * @param child the child view to add
       *
       * @see #generateDefaultLayoutParams()
       */
      public void addView(View child) {
          addView(child, -1);
      }
  
      /**
       * Adds a child view. If no layout parameters are already set on the child, the
       * default parameters for this ViewGroup are set on the child.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       *
       * @param child the child view to add
       * @param index the position at which to add the child
       *
       * @see #generateDefaultLayoutParams()
       */
      public void addView(View child, int index) {
          if (child == null) {
              throw new IllegalArgumentException("Cannot add a null child view to a ViewGroup");
          }
          LayoutParams params = child.getLayoutParams();
          if (params == null) {
              params = generateDefaultLayoutParams();
              if (params == null) {
                  throw new IllegalArgumentException("generateDefaultLayoutParams() cannot return null");
              }
          }
          addView(child, index, params);
      }
  
      /**
       * Adds a child view with this ViewGroup's default layout parameters and the
       * specified width and height.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       *
       * @param child the child view to add
       */
      public void addView(View child, int width, int height) {
          final LayoutParams params = generateDefaultLayoutParams();
          params.width = width;
          params.height = height;
          addView(child, -1, params);
      }
  
      /**
       * Adds a child view with the specified layout parameters.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       *
       * @param child the child view to add
       * @param params the layout parameters to set on the child
       */
      @Override
      public void addView(View child, LayoutParams params) {
          addView(child, -1, params);
      }
  
      /**
       * Adds a child view with the specified layout parameters.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       *
       * @param child the child view to add
       * @param index the position at which to add the child or -1 to add last
       * @param params the layout parameters to set on the child
       */
      public void addView(View child, int index, LayoutParams params) {
          if (DBG) {
              System.out.println(this + " addView");
          }
  
          if (child == null) {
              throw new IllegalArgumentException("Cannot add a null child view to a ViewGroup");
          }
  
          // addViewInner() will call child.requestLayout() when setting the new LayoutParams
          // therefore, we call requestLayout() on ourselves before, so that the child's request
          // will be blocked at our level
          requestLayout();
          invalidate(true);
          addViewInner(child, index, params, false);
      }
  
      @Override
      public void updateViewLayout(View view, ViewGroup.LayoutParams params) {
          if (!checkLayoutParams(params)) {
              throw new IllegalArgumentException("Invalid LayoutParams supplied to " + this);
          }
          if (view.mParent != this) {
              throw new IllegalArgumentException("Given view not a child of " + this);
          }
          view.setLayoutParams(params);
      }
  
      protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
          return  p != null;
      }
  
      /**
       * Interface definition for a callback to be invoked when the hierarchy
       * within this view changed. The hierarchy changes whenever a child is added
       * to or removed from this view.
       */
      public interface OnHierarchyChangeListener {
          /**
           * Called when a new child is added to a parent view.
           *
           * @param parent the view in which a child was added
           * @param child the new child view added in the hierarchy
           */
          void onChildViewAdded(View parent, View child);
  
          /**
           * Called when a child is removed from a parent view.
           *
           * @param parent the view from which the child was removed
           * @param child the child removed from the hierarchy
           */
          void onChildViewRemoved(View parent, View child);
      }
  
      /**
       * Register a callback to be invoked when a child is added to or removed
       * from this view.
       *
       * @param listener the callback to invoke on hierarchy change
       */
      public void setOnHierarchyChangeListener(OnHierarchyChangeListener listener) {
          mOnHierarchyChangeListener = listener;
      }
  
      @UnsupportedAppUsage
      void dispatchViewAdded(View child) {
          onViewAdded(child);
          if (mOnHierarchyChangeListener != null) {
              mOnHierarchyChangeListener.onChildViewAdded(this, child);
          }
      }
  
      /**
       * Called when a new child is added to this ViewGroup. Overrides should always
       * call super.onViewAdded.
       *
       * @param child the added child view
       */
      public void onViewAdded(View child) {
      }
  
      @UnsupportedAppUsage
      void dispatchViewRemoved(View child) {
          onViewRemoved(child);
          if (mOnHierarchyChangeListener != null) {
              mOnHierarchyChangeListener.onChildViewRemoved(this, child);
          }
      }
  
      /**
       * Called when a child view is removed from this ViewGroup. Overrides should always
       * call super.onViewRemoved.
       *
       * @param child the removed child view
       */
      public void onViewRemoved(View child) {
      }
  
      private void clearCachedLayoutMode() {
          if (!hasBooleanFlag(FLAG_LAYOUT_MODE_WAS_EXPLICITLY_SET)) {
             mLayoutMode = LAYOUT_MODE_UNDEFINED;
          }
      }
  
      @Override
      protected void onAttachedToWindow() {
          super.onAttachedToWindow();
          clearCachedLayoutMode();
      }
  
      @Override
      protected void onDetachedFromWindow() {
          super.onDetachedFromWindow();
          clearCachedLayoutMode();
      }
  
      /** @hide */
      @Override
      protected void destroyHardwareResources() {
          super.destroyHardwareResources();
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              getChildAt(i).destroyHardwareResources();
          }
      }
  
      /**
       * Adds a view during layout. This is useful if in your onLayout() method,
       * you need to add more views (as does the list view for example).
       *
       * If index is negative, it means put it at the end of the list.
       *
       * @param child the view to add to the group
       * @param index the index at which the child must be added or -1 to add last
       * @param params the layout parameters to associate with the child
       * @return true if the child was added, false otherwise
       */
      protected boolean addViewInLayout(View child, int index, LayoutParams params) {
          return addViewInLayout(child, index, params, false);
      }
  
      /**
       * Adds a view during layout. This is useful if in your onLayout() method,
       * you need to add more views (as does the list view for example).
       *
       * If index is negative, it means put it at the end of the list.
       *
       * @param child the view to add to the group
       * @param index the index at which the child must be added or -1 to add last
       * @param params the layout parameters to associate with the child
       * @param preventRequestLayout if true, calling this method will not trigger a
       *        layout request on child
       * @return true if the child was added, false otherwise
       */
      protected boolean addViewInLayout(View child, int index, LayoutParams params,
              boolean preventRequestLayout) {
          if (child == null) {
              throw new IllegalArgumentException("Cannot add a null child view to a ViewGroup");
          }
          child.mParent = null;
          addViewInner(child, index, params, preventRequestLayout);
          child.mPrivateFlags = (child.mPrivateFlags & ~PFLAG_DIRTY_MASK) | PFLAG_DRAWN;
          return true;
      }
  
      /**
       * Prevents the specified child to be laid out during the next layout pass.
       *
       * @param child the child on which to perform the cleanup
       */
      protected void cleanupLayoutState(View child) {
          child.mPrivateFlags &= ~View.PFLAG_FORCE_LAYOUT;
      }
  
      private void addViewInner(View child, int index, LayoutParams params,
              boolean preventRequestLayout) {
  
          if (mTransition != null) {
              // Don't prevent other add transitions from completing, but cancel remove
              // transitions to let them complete the process before we add to the container
              mTransition.cancel(LayoutTransition.DISAPPEARING);
          }
  
          if (child.getParent() != null) {
              throw new IllegalStateException("The specified child already has a parent. " +
                      "You must call removeView() on the child's parent first.");
          }
  
          if (mTransition != null) {
              mTransition.addChild(this, child);
          }
  
          if (!checkLayoutParams(params)) {
              params = generateLayoutParams(params);
          }
  
          if (preventRequestLayout) {
              child.mLayoutParams = params;
          } else {
              child.setLayoutParams(params);
          }
  
          if (index < 0) {
              index = mChildrenCount;
          }
  
          addInArray(child, index);
  
          // tell our children
          if (preventRequestLayout) {
              child.assignParent(this);
          } else {
              child.mParent = this;
          }
          if (child.hasUnhandledKeyListener()) {
              incrementChildUnhandledKeyListeners();
          }
  
          final boolean childHasFocus = child.hasFocus();
          if (childHasFocus) {
              requestChildFocus(child, child.findFocus());
          }
  
          AttachInfo ai = mAttachInfo;
          if (ai != null && (mGroupFlags & FLAG_PREVENT_DISPATCH_ATTACHED_TO_WINDOW) == 0) {
              boolean lastKeepOn = ai.mKeepScreenOn;
              ai.mKeepScreenOn = false;
              child.dispatchAttachedToWindow(mAttachInfo, (mViewFlags&VISIBILITY_MASK));
              if (ai.mKeepScreenOn) {
                  needGlobalAttributesUpdate(true);
              }
              ai.mKeepScreenOn = lastKeepOn;
          }
  
          if (child.isLayoutDirectionInherited()) {
              child.resetRtlProperties();
          }
  
          dispatchViewAdded(child);
  
          if ((child.mViewFlags & DUPLICATE_PARENT_STATE) == DUPLICATE_PARENT_STATE) {
              mGroupFlags |= FLAG_NOTIFY_CHILDREN_ON_DRAWABLE_STATE_CHANGE;
          }
  
          if (child.hasTransientState()) {
              childHasTransientStateChanged(child, true);
          }
  
          if (child.getVisibility() != View.GONE) {
              notifySubtreeAccessibilityStateChangedIfNeeded();
          }
  
          if (mTransientIndices != null) {
              final int transientCount = mTransientIndices.size();
              for (int i = 0; i < transientCount; ++i) {
                  final int oldIndex = mTransientIndices.get(i);
                  if (index <= oldIndex) {
                      mTransientIndices.set(i, oldIndex + 1);
                  }
              }
          }
  
          if (mCurrentDragStartEvent != null && child.getVisibility() == VISIBLE) {
              notifyChildOfDragStart(child);
          }
  
          if (child.hasDefaultFocus()) {
              // When adding a child that contains default focus, either during inflation or while
              // manually assembling the hierarchy, update the ancestor default-focus chain.
              setDefaultFocus(child);
          }
  
          touchAccessibilityNodeProviderIfNeeded(child);
      }
  
      /**
       * We may need to touch the provider to bring up the a11y layer. In a11y mode
       * clients inspect the screen or the user touches it which triggers bringing up
       * of the a11y infrastructure while in autofill mode we want the infra up and
       * running from the beginning since we watch for a11y events to drive autofill.
       */
      private void touchAccessibilityNodeProviderIfNeeded(View child) {
          if (mContext.isAutofillCompatibilityEnabled()) {
              child.getAccessibilityNodeProvider();
          }
      }
  
      private void addInArray(View child, int index) {
          View[] children = mChildren;
          final int count = mChildrenCount;
          final int size = children.length;
          if (index == count) {
              if (size == count) {
                  mChildren = new View[size + ARRAY_CAPACITY_INCREMENT];
                  System.arraycopy(children, 0, mChildren, 0, size);
                  children = mChildren;
              }
              children[mChildrenCount++] = child;
          } else if (index < count) {
              if (size == count) {
                  mChildren = new View[size + ARRAY_CAPACITY_INCREMENT];
                  System.arraycopy(children, 0, mChildren, 0, index);
                  System.arraycopy(children, index, mChildren, index + 1, count - index);
                  children = mChildren;
              } else {
                  System.arraycopy(children, index, children, index + 1, count - index);
              }
              children[index] = child;
              mChildrenCount++;
              if (mLastTouchDownIndex >= index) {
                  mLastTouchDownIndex++;
              }
          } else {
              throw new IndexOutOfBoundsException("index=" + index + " count=" + count);
          }
      }
  
      // This method also sets the child's mParent to null
      private void removeFromArray(int index) {
          final View[] children = mChildren;
          if (!(mTransitioningViews != null && mTransitioningViews.contains(children[index]))) {
              children[index].mParent = null;
          }
          final int count = mChildrenCount;
          if (index == count - 1) {
              children[--mChildrenCount] = null;
          } else if (index >= 0 && index < count) {
              System.arraycopy(children, index + 1, children, index, count - index - 1);
              children[--mChildrenCount] = null;
          } else {
              throw new IndexOutOfBoundsException();
          }
          if (mLastTouchDownIndex == index) {
              mLastTouchDownTime = 0;
              mLastTouchDownIndex = -1;
          } else if (mLastTouchDownIndex > index) {
              mLastTouchDownIndex--;
          }
      }
  
      // This method also sets the children's mParent to null
      private void removeFromArray(int start, int count) {
          final View[] children = mChildren;
          final int childrenCount = mChildrenCount;
  
          start = Math.max(0, start);
          final int end = Math.min(childrenCount, start + count);
  
          if (start == end) {
              return;
          }
  
          if (end == childrenCount) {
              for (int i = start; i < end; i++) {
                  children[i].mParent = null;
                  children[i] = null;
              }
          } else {
              for (int i = start; i < end; i++) {
                  children[i].mParent = null;
              }
  
              // Since we're looping above, we might as well do the copy, but is arraycopy()
              // faster than the extra 2 bounds checks we would do in the loop?
              System.arraycopy(children, end, children, start, childrenCount - end);
  
              for (int i = childrenCount - (end - start); i < childrenCount; i++) {
                  children[i] = null;
              }
          }
  
          mChildrenCount -= (end - start);
      }
  
      private void bindLayoutAnimation(View child) {
          Animation a = mLayoutAnimationController.getAnimationForView(child);
          child.setAnimation(a);
      }
  
      /**
       * Subclasses should override this method to set layout animation
       * parameters on the supplied child.
       *
       * @param child the child to associate with animation parameters
       * @param params the child's layout parameters which hold the animation
       *        parameters
       * @param index the index of the child in the view group
       * @param count the number of children in the view group
       */
      protected void attachLayoutAnimationParameters(View child,
              LayoutParams params, int index, int count) {
          LayoutAnimationController.AnimationParameters animationParams =
                      params.layoutAnimationParameters;
          if (animationParams == null) {
              animationParams = new LayoutAnimationController.AnimationParameters();
              params.layoutAnimationParameters = animationParams;
          }
  
          animationParams.count = count;
          animationParams.index = index;
      }
  
      /**
       * {@inheritDoc}
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       */
      @Override
      public void removeView(View view) {
          if (removeViewInternal(view)) {
              requestLayout();
              invalidate(true);
          }
      }
  
      /**
       * Removes a view during layout. This is useful if in your onLayout() method,
       * you need to remove more views.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       *
       * @param view the view to remove from the group
       */
      public void removeViewInLayout(View view) {
          removeViewInternal(view);
      }
  
      /**
       * Removes a range of views during layout. This is useful if in your onLayout() method,
       * you need to remove more views.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       *
       * @param start the index of the first view to remove from the group
       * @param count the number of views to remove from the group
       */
      public void removeViewsInLayout(int start, int count) {
          removeViewsInternal(start, count);
      }
  
      /**
       * Removes the view at the specified position in the group.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       *
       * @param index the position in the group of the view to remove
       */
      public void removeViewAt(int index) {
          removeViewInternal(index, getChildAt(index));
          requestLayout();
          invalidate(true);
      }
  
      /**
       * Removes the specified range of views from the group.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       *
       * @param start the first position in the group of the range of views to remove
       * @param count the number of views to remove
       */
      public void removeViews(int start, int count) {
          removeViewsInternal(start, count);
          requestLayout();
          invalidate(true);
      }
  
      private boolean removeViewInternal(View view) {
          final int index = indexOfChild(view);
          if (index >= 0) {
              removeViewInternal(index, view);
              return true;
          }
          return false;
      }
  
      private void removeViewInternal(int index, View view) {
          if (mTransition != null) {
              mTransition.removeChild(this, view);
          }
  
          boolean clearChildFocus = false;
          if (view == mFocused) {
              view.unFocus(null);
              clearChildFocus = true;
          }
          if (view == mFocusedInCluster) {
              clearFocusedInCluster(view);
          }
  
          view.clearAccessibilityFocus();
  
          cancelTouchTarget(view);
          cancelHoverTarget(view);
  
          if (view.getAnimation() != null ||
                  (mTransitioningViews != null && mTransitioningViews.contains(view))) {
              addDisappearingView(view);
          } else if (view.mAttachInfo != null) {
             view.dispatchDetachedFromWindow();
          }
  
          if (view.hasTransientState()) {
              childHasTransientStateChanged(view, false);
          }
  
          needGlobalAttributesUpdate(false);
  
          removeFromArray(index);
  
          if (view.hasUnhandledKeyListener()) {
              decrementChildUnhandledKeyListeners();
          }
  
          if (view == mDefaultFocus) {
              clearDefaultFocus(view);
          }
          if (clearChildFocus) {
              clearChildFocus(view);
              if (!rootViewRequestFocus()) {
                  notifyGlobalFocusCleared(this);
              }
          }
  
          dispatchViewRemoved(view);
  
          if (view.getVisibility() != View.GONE) {
              notifySubtreeAccessibilityStateChangedIfNeeded();
          }
  
          int transientCount = mTransientIndices == null ? 0 : mTransientIndices.size();
          for (int i = 0; i < transientCount; ++i) {
              final int oldIndex = mTransientIndices.get(i);
              if (index < oldIndex) {
                  mTransientIndices.set(i, oldIndex - 1);
              }
          }
  
          if (mCurrentDragStartEvent != null) {
              mChildrenInterestedInDrag.remove(view);
          }
      }
  
      /**
       * Sets the LayoutTransition object for this ViewGroup. If the LayoutTransition object is
       * not null, changes in layout which occur because of children being added to or removed from
       * the ViewGroup will be animated according to the animations defined in that LayoutTransition
       * object. By default, the transition object is null (so layout changes are not animated).
       *
       * <p>Replacing a non-null transition will cause that previous transition to be
       * canceled, if it is currently running, to restore this container to
       * its correct post-transition state.</p>
       *
       * @param transition The LayoutTransition object that will animated changes in layout. A value
       * of <code>null</code> means no transition will run on layout changes.
       * @attr ref android.R.styleable#ViewGroup_animateLayoutChanges
       */
      public void setLayoutTransition(LayoutTransition transition) {
          if (mTransition != null) {
              LayoutTransition previousTransition = mTransition;
              previousTransition.cancel();
              previousTransition.removeTransitionListener(mLayoutTransitionListener);
          }
          mTransition = transition;
          if (mTransition != null) {
              mTransition.addTransitionListener(mLayoutTransitionListener);
          }
      }
  
      /**
       * Gets the LayoutTransition object for this ViewGroup. If the LayoutTransition object is
       * not null, changes in layout which occur because of children being added to or removed from
       * the ViewGroup will be animated according to the animations defined in that LayoutTransition
       * object. By default, the transition object is null (so layout changes are not animated).
       *
       * @return LayoutTranstion The LayoutTransition object that will animated changes in layout.
       * A value of <code>null</code> means no transition will run on layout changes.
       */
      public LayoutTransition getLayoutTransition() {
          return mTransition;
      }
  
      private void removeViewsInternal(int start, int count) {
          final int end = start + count;
  
          if (start < 0 || count < 0 || end > mChildrenCount) {
              throw new IndexOutOfBoundsException();
          }
  
          final View focused = mFocused;
          final boolean detach = mAttachInfo != null;
          boolean clearChildFocus = false;
          View clearDefaultFocus = null;
  
          final View[] children = mChildren;
  
          for (int i = start; i < end; i++) {
              final View view = children[i];
  
              if (mTransition != null) {
                  mTransition.removeChild(this, view);
              }
  
              if (view == focused) {
                  view.unFocus(null);
                  clearChildFocus = true;
              }
              if (view == mDefaultFocus) {
                  clearDefaultFocus = view;
              }
              if (view == mFocusedInCluster) {
                  clearFocusedInCluster(view);
              }
  
              view.clearAccessibilityFocus();
  
              cancelTouchTarget(view);
              cancelHoverTarget(view);
  
              if (view.getAnimation() != null ||
                  (mTransitioningViews != null && mTransitioningViews.contains(view))) {
                  addDisappearingView(view);
              } else if (detach) {
                 view.dispatchDetachedFromWindow();
              }
  
              if (view.hasTransientState()) {
                  childHasTransientStateChanged(view, false);
              }
  
              needGlobalAttributesUpdate(false);
  
              dispatchViewRemoved(view);
          }
  
          removeFromArray(start, count);
  
          if (clearDefaultFocus != null) {
              clearDefaultFocus(clearDefaultFocus);
          }
          if (clearChildFocus) {
              clearChildFocus(focused);
              if (!rootViewRequestFocus()) {
                  notifyGlobalFocusCleared(focused);
              }
          }
      }
  
      /**
       * Call this method to remove all child views from the
       * ViewGroup.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       */
      public void removeAllViews() {
          removeAllViewsInLayout();
          requestLayout();
          invalidate(true);
      }
  
      /**
       * Called by a ViewGroup subclass to remove child views from itself,
       * when it must first know its size on screen before it can calculate how many
       * child views it will render. An example is a Gallery or a ListView, which
       * may "have" 50 children, but actually only render the number of children
       * that can currently fit inside the object on screen. Do not call
       * this method unless you are extending ViewGroup and understand the
       * view measuring and layout pipeline.
       *
       * <p><strong>Note:</strong> do not invoke this method from
       * {@link #draw(android.graphics.Canvas)}, {@link #onDraw(android.graphics.Canvas)},
       * {@link #dispatchDraw(android.graphics.Canvas)} or any related method.</p>
       */
      public void removeAllViewsInLayout() {
          final int count = mChildrenCount;
          if (count <= 0) {
              return;
          }
  
          final View[] children = mChildren;
          mChildrenCount = 0;
  
          final View focused = mFocused;
          final boolean detach = mAttachInfo != null;
          boolean clearChildFocus = false;
  
          needGlobalAttributesUpdate(false);
  
          for (int i = count - 1; i >= 0; i--) {
              final View view = children[i];
  
              if (mTransition != null) {
                  mTransition.removeChild(this, view);
              }
  
              if (view == focused) {
                  view.unFocus(null);
                  clearChildFocus = true;
              }
  
              view.clearAccessibilityFocus();
  
              cancelTouchTarget(view);
              cancelHoverTarget(view);
  
              if (view.getAnimation() != null ||
                      (mTransitioningViews != null && mTransitioningViews.contains(view))) {
                  addDisappearingView(view);
              } else if (detach) {
                 view.dispatchDetachedFromWindow();
              }
  
              if (view.hasTransientState()) {
                  childHasTransientStateChanged(view, false);
              }
  
              dispatchViewRemoved(view);
  
              view.mParent = null;
              children[i] = null;
          }
  
          if (mDefaultFocus != null) {
              clearDefaultFocus(mDefaultFocus);
          }
          if (mFocusedInCluster != null) {
              clearFocusedInCluster(mFocusedInCluster);
          }
          if (clearChildFocus) {
              clearChildFocus(focused);
              if (!rootViewRequestFocus()) {
                  notifyGlobalFocusCleared(focused);
              }
          }
      }
  
      /**
       * Finishes the removal of a detached view. This method will dispatch the detached from
       * window event and notify the hierarchy change listener.
       * <p>
       * This method is intended to be lightweight and makes no assumptions about whether the
       * parent or child should be redrawn. Proper use of this method will include also making
       * any appropriate {@link #requestLayout()} or {@link #invalidate()} calls.
       * For example, callers can {@link #post(Runnable) post} a {@link Runnable}
       * which performs a {@link #requestLayout()} on the next frame, after all detach/remove
       * calls are finished, causing layout to be run prior to redrawing the view hierarchy.
       *
       * @param child the child to be definitely removed from the view hierarchy
       * @param animate if true and the view has an animation, the view is placed in the
       *                disappearing views list, otherwise, it is detached from the window
       *
       * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
       * @see #detachAllViewsFromParent()
       * @see #detachViewFromParent(View)
       * @see #detachViewFromParent(int)
       */
      protected void removeDetachedView(View child, boolean animate) {
          if (mTransition != null) {
              mTransition.removeChild(this, child);
          }
  
          if (child == mFocused) {
              child.clearFocus();
          }
          if (child == mDefaultFocus) {
              clearDefaultFocus(child);
          }
          if (child == mFocusedInCluster) {
              clearFocusedInCluster(child);
          }
  
          child.clearAccessibilityFocus();
  
          cancelTouchTarget(child);
          cancelHoverTarget(child);
  
          if ((animate && child.getAnimation() != null) ||
                  (mTransitioningViews != null && mTransitioningViews.contains(child))) {
              addDisappearingView(child);
          } else if (child.mAttachInfo != null) {
              child.dispatchDetachedFromWindow();
          }
  
          if (child.hasTransientState()) {
              childHasTransientStateChanged(child, false);
          }
  
          dispatchViewRemoved(child);
      }
  
      /**
       * Attaches a view to this view group. Attaching a view assigns this group as the parent,
       * sets the layout parameters and puts the view in the list of children so that
       * it can be retrieved by calling {@link #getChildAt(int)}.
       * <p>
       * This method is intended to be lightweight and makes no assumptions about whether the
       * parent or child should be redrawn. Proper use of this method will include also making
       * any appropriate {@link #requestLayout()} or {@link #invalidate()} calls.
       * For example, callers can {@link #post(Runnable) post} a {@link Runnable}
       * which performs a {@link #requestLayout()} on the next frame, after all detach/attach
       * calls are finished, causing layout to be run prior to redrawing the view hierarchy.
       * <p>
       * This method should be called only for views which were detached from their parent.
       *
       * @param child the child to attach
       * @param index the index at which the child should be attached
       * @param params the layout parameters of the child
       *
       * @see #removeDetachedView(View, boolean)
       * @see #detachAllViewsFromParent()
       * @see #detachViewFromParent(View)
       * @see #detachViewFromParent(int)
       */
      protected void attachViewToParent(View child, int index, LayoutParams params) {
          child.mLayoutParams = params;
  
          if (index < 0) {
              index = mChildrenCount;
          }
  
          addInArray(child, index);
  
          child.mParent = this;
          child.mPrivateFlags = (child.mPrivateFlags & ~PFLAG_DIRTY_MASK
                          & ~PFLAG_DRAWING_CACHE_VALID)
                  | PFLAG_DRAWN | PFLAG_INVALIDATED;
          this.mPrivateFlags |= PFLAG_INVALIDATED;
  
          if (child.hasFocus()) {
              requestChildFocus(child, child.findFocus());
          }
          dispatchVisibilityAggregated(isAttachedToWindow() && getWindowVisibility() == VISIBLE
                  && isShown());
          notifySubtreeAccessibilityStateChangedIfNeeded();
      }
  
      /**
       * Detaches a view from its parent. Detaching a view should be followed
       * either by a call to
       * {@link #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)}
       * or a call to {@link #removeDetachedView(View, boolean)}. Detachment should only be
       * temporary; reattachment or removal should happen within the same drawing cycle as
       * detachment. When a view is detached, its parent is null and cannot be retrieved by a
       * call to {@link #getChildAt(int)}.
       *
       * @param child the child to detach
       *
       * @see #detachViewFromParent(int)
       * @see #detachViewsFromParent(int, int)
       * @see #detachAllViewsFromParent()
       * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
       * @see #removeDetachedView(View, boolean)
       */
      protected void detachViewFromParent(View child) {
          removeFromArray(indexOfChild(child));
      }
  
      /**
       * Detaches a view from its parent. Detaching a view should be followed
       * either by a call to
       * {@link #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)}
       * or a call to {@link #removeDetachedView(View, boolean)}. Detachment should only be
       * temporary; reattachment or removal should happen within the same drawing cycle as
       * detachment. When a view is detached, its parent is null and cannot be retrieved by a
       * call to {@link #getChildAt(int)}.
       *
       * @param index the index of the child to detach
       *
       * @see #detachViewFromParent(View)
       * @see #detachAllViewsFromParent()
       * @see #detachViewsFromParent(int, int)
       * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
       * @see #removeDetachedView(View, boolean)
       */
      protected void detachViewFromParent(int index) {
          removeFromArray(index);
      }
  
      /**
       * Detaches a range of views from their parents. Detaching a view should be followed
       * either by a call to
       * {@link #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)}
       * or a call to {@link #removeDetachedView(View, boolean)}. Detachment should only be
       * temporary; reattachment or removal should happen within the same drawing cycle as
       * detachment. When a view is detached, its parent is null and cannot be retrieved by a
       * call to {@link #getChildAt(int)}.
       *
       * @param start the first index of the childrend range to detach
       * @param count the number of children to detach
       *
       * @see #detachViewFromParent(View)
       * @see #detachViewFromParent(int)
       * @see #detachAllViewsFromParent()
       * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
       * @see #removeDetachedView(View, boolean)
       */
      protected void detachViewsFromParent(int start, int count) {
          removeFromArray(start, count);
      }
  
      /**
       * Detaches all views from the parent. Detaching a view should be followed
       * either by a call to
       * {@link #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)}
       * or a call to {@link #removeDetachedView(View, boolean)}. Detachment should only be
       * temporary; reattachment or removal should happen within the same drawing cycle as
       * detachment. When a view is detached, its parent is null and cannot be retrieved by a
       * call to {@link #getChildAt(int)}.
       *
       * @see #detachViewFromParent(View)
       * @see #detachViewFromParent(int)
       * @see #detachViewsFromParent(int, int)
       * @see #attachViewToParent(View, int, android.view.ViewGroup.LayoutParams)
       * @see #removeDetachedView(View, boolean)
       */
      protected void detachAllViewsFromParent() {
          final int count = mChildrenCount;
          if (count <= 0) {
              return;
          }
  
          final View[] children = mChildren;
          mChildrenCount = 0;
  
          for (int i = count - 1; i >= 0; i--) {
              children[i].mParent = null;
              children[i] = null;
          }
      }
  
      @Override
      @CallSuper
      public void onDescendantInvalidated(@NonNull View child, @NonNull View target) {
          /*
           * HW-only, Rect-ignoring damage codepath
           *
           * We don't deal with rectangles here, since RenderThread native code computes damage for
           * everything drawn by HWUI (and SW layer / drawing cache doesn't keep track of damage area)
           */
  
          // if set, combine the animation flag into the parent
          mPrivateFlags |= (target.mPrivateFlags & PFLAG_DRAW_ANIMATION);
  
          if ((target.mPrivateFlags & ~PFLAG_DIRTY_MASK) != 0) {
              // We lazily use PFLAG_DIRTY, since computing opaque isn't worth the potential
              // optimization in provides in a DisplayList world.
              mPrivateFlags = (mPrivateFlags & ~PFLAG_DIRTY_MASK) | PFLAG_DIRTY;
  
              // simplified invalidateChildInParent behavior: clear cache validity to be safe...
              mPrivateFlags &= ~PFLAG_DRAWING_CACHE_VALID;
          }
  
          // ... and mark inval if in software layer that needs to repaint (hw handled in native)
          if (mLayerType == LAYER_TYPE_SOFTWARE) {
              // Layered parents should be invalidated. Escalate to a full invalidate (and note that
              // we do this after consuming any relevant flags from the originating descendant)
              mPrivateFlags |= PFLAG_INVALIDATED | PFLAG_DIRTY;
              target = this;
          }
  
          if (mParent != null) {
              mParent.onDescendantInvalidated(this, target);
          }
      }
  
  
      /**
       * Don't call or override this method. It is used for the implementation of
       * the view hierarchy.
       *
       * @deprecated Use {@link #onDescendantInvalidated(View, View)} instead to observe updates to
       * draw state in descendants.
       */
      @Deprecated
      @Override
      public final void invalidateChild(View child, final Rect dirty) {
          final AttachInfo attachInfo = mAttachInfo;
          if (attachInfo != null && attachInfo.mHardwareAccelerated) {
              // HW accelerated fast path
              onDescendantInvalidated(child, child);
              return;
          }
  
          ViewParent parent = this;
          if (attachInfo != null) {
              // If the child is drawing an animation, we want to copy this flag onto
              // ourselves and the parent to make sure the invalidate request goes
              // through
              final boolean drawAnimation = (child.mPrivateFlags & PFLAG_DRAW_ANIMATION) != 0;
  
              // Check whether the child that requests the invalidate is fully opaque
              // Views being animated or transformed are not considered opaque because we may
              // be invalidating their old position and need the parent to paint behind them.
              Matrix childMatrix = child.getMatrix();
              // Mark the child as dirty, using the appropriate flag
              // Make sure we do not set both flags at the same time
  
              if (child.mLayerType != LAYER_TYPE_NONE) {
                  mPrivateFlags |= PFLAG_INVALIDATED;
                  mPrivateFlags &= ~PFLAG_DRAWING_CACHE_VALID;
              }
  
              final int[] location = attachInfo.mInvalidateChildLocation;
              location[CHILD_LEFT_INDEX] = child.mLeft;
              location[CHILD_TOP_INDEX] = child.mTop;
              if (!childMatrix.isIdentity() ||
                      (mGroupFlags & ViewGroup.FLAG_SUPPORT_STATIC_TRANSFORMATIONS) != 0) {
                  RectF boundingRect = attachInfo.mTmpTransformRect;
                  boundingRect.set(dirty);
                  Matrix transformMatrix;
                  if ((mGroupFlags & ViewGroup.FLAG_SUPPORT_STATIC_TRANSFORMATIONS) != 0) {
                      Transformation t = attachInfo.mTmpTransformation;
                      boolean transformed = getChildStaticTransformation(child, t);
                      if (transformed) {
                          transformMatrix = attachInfo.mTmpMatrix;
                          transformMatrix.set(t.getMatrix());
                          if (!childMatrix.isIdentity()) {
                              transformMatrix.preConcat(childMatrix);
                          }
                      } else {
                          transformMatrix = childMatrix;
                      }
                  } else {
                      transformMatrix = childMatrix;
                  }
                  transformMatrix.mapRect(boundingRect);
                  dirty.set((int) Math.floor(boundingRect.left),
                          (int) Math.floor(boundingRect.top),
                          (int) Math.ceil(boundingRect.right),
                          (int) Math.ceil(boundingRect.bottom));
              }
  
              do {
                  View view = null;
                  if (parent instanceof View) {
                      view = (View) parent;
                  }
  
                  if (drawAnimation) {
                      if (view != null) {
                          view.mPrivateFlags |= PFLAG_DRAW_ANIMATION;
                      } else if (parent instanceof ViewRootImpl) {
                          ((ViewRootImpl) parent).mIsAnimating = true;
                      }
                  }
  
                  // If the parent is dirty opaque or not dirty, mark it dirty with the opaque
                  // flag coming from the child that initiated the invalidate
                  if (view != null) {
                      if ((view.mPrivateFlags & PFLAG_DIRTY_MASK) != PFLAG_DIRTY) {
                          view.mPrivateFlags = (view.mPrivateFlags & ~PFLAG_DIRTY_MASK) | PFLAG_DIRTY;
                      }
                  }
  
                  parent = parent.invalidateChildInParent(location, dirty);
                  if (view != null) {
                      // Account for transform on current parent
                      Matrix m = view.getMatrix();
                      if (!m.isIdentity()) {
                          RectF boundingRect = attachInfo.mTmpTransformRect;
                          boundingRect.set(dirty);
                          m.mapRect(boundingRect);
                          dirty.set((int) Math.floor(boundingRect.left),
                                  (int) Math.floor(boundingRect.top),
                                  (int) Math.ceil(boundingRect.right),
                                  (int) Math.ceil(boundingRect.bottom));
                      }
                  }
              } while (parent != null);
          }
      }
  
      /**
       * Don't call or override this method. It is used for the implementation of
       * the view hierarchy.
       *
       * This implementation returns null if this ViewGroup does not have a parent,
       * if this ViewGroup is already fully invalidated or if the dirty rectangle
       * does not intersect with this ViewGroup's bounds.
       *
       * @deprecated Use {@link #onDescendantInvalidated(View, View)} instead to observe updates to
       * draw state in descendants.
       */
      @Deprecated
      @Override
      public ViewParent invalidateChildInParent(final int[] location, final Rect dirty) {
          if ((mPrivateFlags & (PFLAG_DRAWN | PFLAG_DRAWING_CACHE_VALID)) != 0) {
              // either DRAWN, or DRAWING_CACHE_VALID
              if ((mGroupFlags & (FLAG_OPTIMIZE_INVALIDATE | FLAG_ANIMATION_DONE))
                      != FLAG_OPTIMIZE_INVALIDATE) {
                  dirty.offset(location[CHILD_LEFT_INDEX] - mScrollX,
                          location[CHILD_TOP_INDEX] - mScrollY);
                  if ((mGroupFlags & FLAG_CLIP_CHILDREN) == 0) {
                      dirty.union(0, 0, mRight - mLeft, mBottom - mTop);
                  }
  
                  final int left = mLeft;
                  final int top = mTop;
  
                  if ((mGroupFlags & FLAG_CLIP_CHILDREN) == FLAG_CLIP_CHILDREN) {
                      if (!dirty.intersect(0, 0, mRight - left, mBottom - top)) {
                          dirty.setEmpty();
                      }
                  }
  
                  location[CHILD_LEFT_INDEX] = left;
                  location[CHILD_TOP_INDEX] = top;
              } else {
  
                  if ((mGroupFlags & FLAG_CLIP_CHILDREN) == FLAG_CLIP_CHILDREN) {
                      dirty.set(0, 0, mRight - mLeft, mBottom - mTop);
                  } else {
                      // in case the dirty rect extends outside the bounds of this container
                      dirty.union(0, 0, mRight - mLeft, mBottom - mTop);
                  }
                  location[CHILD_LEFT_INDEX] = mLeft;
                  location[CHILD_TOP_INDEX] = mTop;
  
                  mPrivateFlags &= ~PFLAG_DRAWN;
              }
              mPrivateFlags &= ~PFLAG_DRAWING_CACHE_VALID;
              if (mLayerType != LAYER_TYPE_NONE) {
                  mPrivateFlags |= PFLAG_INVALIDATED;
              }
  
              return mParent;
          }
  
          return null;
      }
  
      /**
       * Offset a rectangle that is in a descendant's coordinate
       * space into our coordinate space.
       * @param descendant A descendant of this view
       * @param rect A rectangle defined in descendant's coordinate space.
       */
      public final void offsetDescendantRectToMyCoords(View descendant, Rect rect) {
          offsetRectBetweenParentAndChild(descendant, rect, true, false);
      }
  
      /**
       * Offset a rectangle that is in our coordinate space into an ancestor's
       * coordinate space.
       * @param descendant A descendant of this view
       * @param rect A rectangle defined in descendant's coordinate space.
       */
      public final void offsetRectIntoDescendantCoords(View descendant, Rect rect) {
          offsetRectBetweenParentAndChild(descendant, rect, false, false);
      }
  
      /**
       * Helper method that offsets a rect either from parent to descendant or
       * descendant to parent.
       */
      void offsetRectBetweenParentAndChild(View descendant, Rect rect,
              boolean offsetFromChildToParent, boolean clipToBounds) {
  
          // already in the same coord system :)
          if (descendant == this) {
              return;
          }
  
          ViewParent theParent = descendant.mParent;
  
          // search and offset up to the parent
          while ((theParent != null)
                  && (theParent instanceof View)
                  && (theParent != this)) {
  
              if (offsetFromChildToParent) {
                  rect.offset(descendant.mLeft - descendant.mScrollX,
                          descendant.mTop - descendant.mScrollY);
                  if (clipToBounds) {
                      View p = (View) theParent;
                      boolean intersected = rect.intersect(0, 0, p.mRight - p.mLeft,
                              p.mBottom - p.mTop);
                      if (!intersected) {
                          rect.setEmpty();
                      }
                  }
              } else {
                  if (clipToBounds) {
                      View p = (View) theParent;
                      boolean intersected = rect.intersect(0, 0, p.mRight - p.mLeft,
                              p.mBottom - p.mTop);
                      if (!intersected) {
                          rect.setEmpty();
                      }
                  }
                  rect.offset(descendant.mScrollX - descendant.mLeft,
                          descendant.mScrollY - descendant.mTop);
              }
  
              descendant = (View) theParent;
              theParent = descendant.mParent;
          }
  
          // now that we are up to this view, need to offset one more time
          // to get into our coordinate space
          if (theParent == this) {
              if (offsetFromChildToParent) {
                  rect.offset(descendant.mLeft - descendant.mScrollX,
                          descendant.mTop - descendant.mScrollY);
              } else {
                  rect.offset(descendant.mScrollX - descendant.mLeft,
                          descendant.mScrollY - descendant.mTop);
              }
          } else {
              throw new IllegalArgumentException("parameter must be a descendant of this view");
          }
      }
  
      /**
       * Offset the vertical location of all children of this view by the specified number of pixels.
       *
       * @param offset the number of pixels to offset
       *
       * @hide
       */
      @UnsupportedAppUsage
      public void offsetChildrenTopAndBottom(int offset) {
          final int count = mChildrenCount;
          final View[] children = mChildren;
          boolean invalidate = false;
  
          for (int i = 0; i < count; i++) {
              final View v = children[i];
              v.mTop += offset;
              v.mBottom += offset;
              if (v.mRenderNode != null) {
                  invalidate = true;
                  v.mRenderNode.offsetTopAndBottom(offset);
              }
          }
  
          if (invalidate) {
              invalidateViewProperty(false, false);
          }
          notifySubtreeAccessibilityStateChangedIfNeeded();
      }
  
      @Override
      public boolean getChildVisibleRect(View child, Rect r, android.graphics.Point offset) {
          return getChildVisibleRect(child, r, offset, false);
      }
  
      /**
       * @param forceParentCheck true to guarantee that this call will propagate to all ancestors,
       *      false otherwise
       *
       * @hide
       */
      public boolean getChildVisibleRect(
              View child, Rect r, android.graphics.Point offset, boolean forceParentCheck) {
          // It doesn't make a whole lot of sense to call this on a view that isn't attached,
          // but for some simple tests it can be useful. If we don't have attach info this
          // will allocate memory.
          final RectF rect = mAttachInfo != null ? mAttachInfo.mTmpTransformRect : new RectF();
          rect.set(r);
  
          if (!child.hasIdentityMatrix()) {
              child.getMatrix().mapRect(rect);
          }
  
          final int dx = child.mLeft - mScrollX;
          final int dy = child.mTop - mScrollY;
  
          rect.offset(dx, dy);
  
          if (offset != null) {
              if (!child.hasIdentityMatrix()) {
                  float[] position = mAttachInfo != null ? mAttachInfo.mTmpTransformLocation
                          : new float[2];
                  position[0] = offset.x;
                  position[1] = offset.y;
                  child.getMatrix().mapPoints(position);
                  offset.x = Math.round(position[0]);
                  offset.y = Math.round(position[1]);
              }
              offset.x += dx;
              offset.y += dy;
          }
  
          final int width = mRight - mLeft;
          final int height = mBottom - mTop;
  
          boolean rectIsVisible = true;
          if (mParent == null ||
                  (mParent instanceof ViewGroup && ((ViewGroup) mParent).getClipChildren())) {
              // Clip to bounds.
              rectIsVisible = rect.intersect(0, 0, width, height);
          }
  
          if ((forceParentCheck || rectIsVisible)
                  && (mGroupFlags & CLIP_TO_PADDING_MASK) == CLIP_TO_PADDING_MASK) {
              // Clip to padding.
              rectIsVisible = rect.intersect(mPaddingLeft, mPaddingTop,
                      width - mPaddingRight, height - mPaddingBottom);
          }
  
          if ((forceParentCheck || rectIsVisible) && mClipBounds != null) {
              // Clip to clipBounds.
              rectIsVisible = rect.intersect(mClipBounds.left, mClipBounds.top, mClipBounds.right,
                      mClipBounds.bottom);
          }
          r.set((int) Math.floor(rect.left), (int) Math.floor(rect.top),
                  (int) Math.ceil(rect.right), (int) Math.ceil(rect.bottom));
  
          if ((forceParentCheck || rectIsVisible) && mParent != null) {
              if (mParent instanceof ViewGroup) {
                  rectIsVisible = ((ViewGroup) mParent)
                          .getChildVisibleRect(this, r, offset, forceParentCheck);
              } else {
                  rectIsVisible = mParent.getChildVisibleRect(this, r, offset);
              }
          }
          return rectIsVisible;
      }
  
      @Override
      public final void layout(int l, int t, int r, int b) {
          if (!mSuppressLayout && (mTransition == null || !mTransition.isChangingLayout())) {
              if (mTransition != null) {
                  mTransition.layoutChange(this);
              }
              super.layout(l, t, r, b);
          } else {
              // record the fact that we noop'd it; request layout when transition finishes
              mLayoutCalledWhileSuppressed = true;
          }
      }
  
      @Override
      protected abstract void onLayout(boolean changed,
              int l, int t, int r, int b);
  
      /**
       * Indicates whether the view group has the ability to animate its children
       * after the first layout.
       *
       * @return true if the children can be animated, false otherwise
       */
      protected boolean canAnimate() {
          return mLayoutAnimationController != null;
      }
  
      /**
       * Runs the layout animation. Calling this method triggers a relayout of
       * this view group.
       */
      public void startLayoutAnimation() {
          if (mLayoutAnimationController != null) {
              mGroupFlags |= FLAG_RUN_ANIMATION;
              requestLayout();
          }
      }
  
      /**
       * Schedules the layout animation to be played after the next layout pass
       * of this view group. This can be used to restart the layout animation
       * when the content of the view group changes or when the activity is
       * paused and resumed.
       */
      public void scheduleLayoutAnimation() {
          mGroupFlags |= FLAG_RUN_ANIMATION;
      }
  
      /**
       * Sets the layout animation controller used to animate the group's
       * children after the first layout.
       *
       * @param controller the animation controller
       */
      public void setLayoutAnimation(LayoutAnimationController controller) {
          mLayoutAnimationController = controller;
          if (mLayoutAnimationController != null) {
              mGroupFlags |= FLAG_RUN_ANIMATION;
          }
      }
  
      /**
       * Returns the layout animation controller used to animate the group's
       * children.
       *
       * @return the current animation controller
       */
      @InspectableProperty
      public LayoutAnimationController getLayoutAnimation() {
          return mLayoutAnimationController;
      }
  
      /**
       * Indicates whether the children's drawing cache is used during a layout
       * animation. By default, the drawing cache is enabled but this will prevent
       * nested layout animations from working. To nest animations, you must disable
       * the cache.
       *
       * @return true if the animation cache is enabled, false otherwise
       *
       * @see #setAnimationCacheEnabled(boolean)
       * @see View#setDrawingCacheEnabled(boolean)
       *
       * @deprecated As of {@link android.os.Build.VERSION_CODES#M}, this property is ignored.
       * Caching behavior of children may be controlled through {@link View#setLayerType(int, Paint)}.
       */
      @Deprecated
      @InspectableProperty(name = "animationCache")
      public boolean isAnimationCacheEnabled() {
          return (mGroupFlags & FLAG_ANIMATION_CACHE) == FLAG_ANIMATION_CACHE;
      }
  
      /**
       * Enables or disables the children's drawing cache during a layout animation.
       * By default, the drawing cache is enabled but this will prevent nested
       * layout animations from working. To nest animations, you must disable the
       * cache.
       *
       * @param enabled true to enable the animation cache, false otherwise
       *
       * @see #isAnimationCacheEnabled()
       * @see View#setDrawingCacheEnabled(boolean)
       *
       * @deprecated As of {@link android.os.Build.VERSION_CODES#M}, this property is ignored.
       * Caching behavior of children may be controlled through {@link View#setLayerType(int, Paint)}.
       */
      @Deprecated
      public void setAnimationCacheEnabled(boolean enabled) {
          setBooleanFlag(FLAG_ANIMATION_CACHE, enabled);
      }
  
      /**
       * Indicates whether this ViewGroup will always try to draw its children using their
       * drawing cache. By default this property is enabled.
       *
       * @return true if the animation cache is enabled, false otherwise
       *
       * @see #setAlwaysDrawnWithCacheEnabled(boolean)
       * @see #setChildrenDrawnWithCacheEnabled(boolean)
       * @see View#setDrawingCacheEnabled(boolean)
       *
       * @deprecated As of {@link android.os.Build.VERSION_CODES#M}, this property is ignored.
       * Child views may no longer have their caching behavior disabled by parents.
       */
      @Deprecated
      @InspectableProperty(name = "alwaysDrawnWithCache")
      public boolean isAlwaysDrawnWithCacheEnabled() {
          return (mGroupFlags & FLAG_ALWAYS_DRAWN_WITH_CACHE) == FLAG_ALWAYS_DRAWN_WITH_CACHE;
      }
  
      /**
       * Indicates whether this ViewGroup will always try to draw its children using their
       * drawing cache. This property can be set to true when the cache rendering is
       * slightly different from the children's normal rendering. Renderings can be different,
       * for instance, when the cache's quality is set to low.
       *
       * When this property is disabled, the ViewGroup will use the drawing cache of its
       * children only when asked to. It's usually the task of subclasses to tell ViewGroup
       * when to start using the drawing cache and when to stop using it.
       *
       * @param always true to always draw with the drawing cache, false otherwise
       *
       * @see #isAlwaysDrawnWithCacheEnabled()
       * @see #setChildrenDrawnWithCacheEnabled(boolean)
       * @see View#setDrawingCacheEnabled(boolean)
       * @see View#setDrawingCacheQuality(int)
       *
       * @deprecated As of {@link android.os.Build.VERSION_CODES#M}, this property is ignored.
       * Child views may no longer have their caching behavior disabled by parents.
       */
      @Deprecated
      public void setAlwaysDrawnWithCacheEnabled(boolean always) {
          setBooleanFlag(FLAG_ALWAYS_DRAWN_WITH_CACHE, always);
      }
  
      /**
       * Indicates whether the ViewGroup is currently drawing its children using
       * their drawing cache.
       *
       * @return true if children should be drawn with their cache, false otherwise
       *
       * @see #setAlwaysDrawnWithCacheEnabled(boolean)
       * @see #setChildrenDrawnWithCacheEnabled(boolean)
       *
       * @deprecated As of {@link android.os.Build.VERSION_CODES#M}, this property is ignored.
       * Child views may no longer be forced to cache their rendering state by their parents.
       * Use {@link View#setLayerType(int, Paint)} on individual Views instead.
       */
      @Deprecated
      protected boolean isChildrenDrawnWithCacheEnabled() {
          return (mGroupFlags & FLAG_CHILDREN_DRAWN_WITH_CACHE) == FLAG_CHILDREN_DRAWN_WITH_CACHE;
      }
  
      /**
       * Tells the ViewGroup to draw its children using their drawing cache. This property
       * is ignored when {@link #isAlwaysDrawnWithCacheEnabled()} is true. A child's drawing cache
       * will be used only if it has been enabled.
       *
       * Subclasses should call this method to start and stop using the drawing cache when
       * they perform performance sensitive operations, like scrolling or animating.
       *
       * @param enabled true if children should be drawn with their cache, false otherwise
       *
       * @see #setAlwaysDrawnWithCacheEnabled(boolean)
       * @see #isChildrenDrawnWithCacheEnabled()
       *
       * @deprecated As of {@link android.os.Build.VERSION_CODES#M}, this property is ignored.
       * Child views may no longer be forced to cache their rendering state by their parents.
       * Use {@link View#setLayerType(int, Paint)} on individual Views instead.
       */
      @Deprecated
      protected void setChildrenDrawnWithCacheEnabled(boolean enabled) {
          setBooleanFlag(FLAG_CHILDREN_DRAWN_WITH_CACHE, enabled);
      }
  
      /**
       * Indicates whether the ViewGroup is drawing its children in the order defined by
       * {@link #getChildDrawingOrder(int, int)}.
       *
       * @return true if children drawing order is defined by {@link #getChildDrawingOrder(int, int)},
       *         false otherwise
       *
       * @see #setChildrenDrawingOrderEnabled(boolean)
       * @see #getChildDrawingOrder(int, int)
       */
      @ViewDebug.ExportedProperty(category = "drawing")
      protected boolean isChildrenDrawingOrderEnabled() {
          return (mGroupFlags & FLAG_USE_CHILD_DRAWING_ORDER) == FLAG_USE_CHILD_DRAWING_ORDER;
      }
  
      /**
       * Tells the ViewGroup whether to draw its children in the order defined by the method
       * {@link #getChildDrawingOrder(int, int)}.
       * <p>
       * Note that {@link View#getZ() Z} reordering, done by {@link #dispatchDraw(Canvas)},
       * will override custom child ordering done via this method.
       *
       * @param enabled true if the order of the children when drawing is determined by
       *        {@link #getChildDrawingOrder(int, int)}, false otherwise
       *
       * @see #isChildrenDrawingOrderEnabled()
       * @see #getChildDrawingOrder(int, int)
       */
      protected void setChildrenDrawingOrderEnabled(boolean enabled) {
          setBooleanFlag(FLAG_USE_CHILD_DRAWING_ORDER, enabled);
      }
  
      private boolean hasBooleanFlag(int flag) {
          return (mGroupFlags & flag) == flag;
      }
  
      private void setBooleanFlag(int flag, boolean value) {
          if (value) {
              mGroupFlags |= flag;
          } else {
              mGroupFlags &= ~flag;
          }
      }
  
      /**
       * Returns an integer indicating what types of drawing caches are kept in memory.
       *
       * @see #setPersistentDrawingCache(int)
       * @see #setAnimationCacheEnabled(boolean)
       *
       * @return one or a combination of {@link #PERSISTENT_NO_CACHE},
       *         {@link #PERSISTENT_ANIMATION_CACHE}, {@link #PERSISTENT_SCROLLING_CACHE}
       *         and {@link #PERSISTENT_ALL_CACHES}
       *
       * @deprecated The view drawing cache was largely made obsolete with the introduction of
       * hardware-accelerated rendering in API 11. With hardware-acceleration, intermediate cache
       * layers are largely unnecessary and can easily result in a net loss in performance due to the
       * cost of creating and updating the layer. In the rare cases where caching layers are useful,
       * such as for alpha animations, {@link #setLayerType(int, Paint)} handles this with hardware
       * rendering. For software-rendered snapshots of a small part of the View hierarchy or
       * individual Views it is recommended to create a {@link Canvas} from either a {@link Bitmap} or
       * {@link android.graphics.Picture} and call {@link #draw(Canvas)} on the View. However these
       * software-rendered usages are discouraged and have compatibility issues with hardware-only
       * rendering features such as {@link android.graphics.Bitmap.Config#HARDWARE Config.HARDWARE}
       * bitmaps, real-time shadows, and outline clipping. For screenshots of the UI for feedback
       * reports or unit testing the {@link PixelCopy} API is recommended.
       */
      @Deprecated
      @ViewDebug.ExportedProperty(category = "drawing", mapping = {
          @ViewDebug.IntToString(from = PERSISTENT_NO_CACHE,        to = "NONE"),
          @ViewDebug.IntToString(from = PERSISTENT_ANIMATION_CACHE, to = "ANIMATION"),
          @ViewDebug.IntToString(from = PERSISTENT_SCROLLING_CACHE, to = "SCROLLING"),
          @ViewDebug.IntToString(from = PERSISTENT_ALL_CACHES,      to = "ALL")
      })
      @InspectableProperty(enumMapping = {
              @EnumEntry(value = PERSISTENT_NO_CACHE, name = "none"),
              @EnumEntry(value = PERSISTENT_ANIMATION_CACHE, name = "animation"),
              @EnumEntry(value = PERSISTENT_SCROLLING_CACHE, name = "scrolling"),
              @EnumEntry(value = PERSISTENT_ALL_CACHES, name = "all"),
      })
      public int getPersistentDrawingCache() {
          return mPersistentDrawingCache;
      }
  
      /**
       * Indicates what types of drawing caches should be kept in memory after
       * they have been created.
       *
       * @see #getPersistentDrawingCache()
       * @see #setAnimationCacheEnabled(boolean)
       *
       * @param drawingCacheToKeep one or a combination of {@link #PERSISTENT_NO_CACHE},
       *        {@link #PERSISTENT_ANIMATION_CACHE}, {@link #PERSISTENT_SCROLLING_CACHE}
       *        and {@link #PERSISTENT_ALL_CACHES}
       *
       * @deprecated The view drawing cache was largely made obsolete with the introduction of
       * hardware-accelerated rendering in API 11. With hardware-acceleration, intermediate cache
       * layers are largely unnecessary and can easily result in a net loss in performance due to the
       * cost of creating and updating the layer. In the rare cases where caching layers are useful,
       * such as for alpha animations, {@link #setLayerType(int, Paint)} handles this with hardware
       * rendering. For software-rendered snapshots of a small part of the View hierarchy or
       * individual Views it is recommended to create a {@link Canvas} from either a {@link Bitmap} or
       * {@link android.graphics.Picture} and call {@link #draw(Canvas)} on the View. However these
       * software-rendered usages are discouraged and have compatibility issues with hardware-only
       * rendering features such as {@link android.graphics.Bitmap.Config#HARDWARE Config.HARDWARE}
       * bitmaps, real-time shadows, and outline clipping. For screenshots of the UI for feedback
       * reports or unit testing the {@link PixelCopy} API is recommended.
       */
      @Deprecated
      public void setPersistentDrawingCache(int drawingCacheToKeep) {
          mPersistentDrawingCache = drawingCacheToKeep & PERSISTENT_ALL_CACHES;
      }
  
      private void setLayoutMode(int layoutMode, boolean explicitly) {
          mLayoutMode = layoutMode;
          setBooleanFlag(FLAG_LAYOUT_MODE_WAS_EXPLICITLY_SET, explicitly);
      }
  
      /**
       * Recursively traverse the view hierarchy, resetting the layoutMode of any
       * descendants that had inherited a different layoutMode from a previous parent.
       * Recursion terminates when a descendant's mode is:
       * <ul>
       *     <li>Undefined</li>
       *     <li>The same as the root node's</li>
       *     <li>A mode that had been explicitly set</li>
       * <ul/>
       * The first two clauses are optimizations.
       * @param layoutModeOfRoot
       */
      @Override
      void invalidateInheritedLayoutMode(int layoutModeOfRoot) {
          if (mLayoutMode == LAYOUT_MODE_UNDEFINED ||
              mLayoutMode == layoutModeOfRoot ||
              hasBooleanFlag(FLAG_LAYOUT_MODE_WAS_EXPLICITLY_SET)) {
              return;
          }
          setLayoutMode(LAYOUT_MODE_UNDEFINED, false);
  
          // apply recursively
          for (int i = 0, N = getChildCount(); i < N; i++) {
              getChildAt(i).invalidateInheritedLayoutMode(layoutModeOfRoot);
          }
      }
  
      /**
       * Returns the basis of alignment during layout operations on this ViewGroup:
       * either {@link #LAYOUT_MODE_CLIP_BOUNDS} or {@link #LAYOUT_MODE_OPTICAL_BOUNDS}.
       * <p>
       * If no layoutMode was explicitly set, either programmatically or in an XML resource,
       * the method returns the layoutMode of the view's parent ViewGroup if such a parent exists,
       * otherwise the method returns a default value of {@link #LAYOUT_MODE_CLIP_BOUNDS}.
       *
       * @return the layout mode to use during layout operations
       *
       * @see #setLayoutMode(int)
       */
      @InspectableProperty(enumMapping = {
              @EnumEntry(value = LAYOUT_MODE_CLIP_BOUNDS, name = "clipBounds"),
              @EnumEntry(value = LAYOUT_MODE_OPTICAL_BOUNDS, name = "opticalBounds")
      })
      public int getLayoutMode() {
          if (mLayoutMode == LAYOUT_MODE_UNDEFINED) {
              int inheritedLayoutMode = (mParent instanceof ViewGroup) ?
                      ((ViewGroup) mParent).getLayoutMode() : LAYOUT_MODE_DEFAULT;
              setLayoutMode(inheritedLayoutMode, false);
          }
          return mLayoutMode;
      }
  
      /**
       * Sets the basis of alignment during the layout of this ViewGroup.
       * Valid values are either {@link #LAYOUT_MODE_CLIP_BOUNDS} or
       * {@link #LAYOUT_MODE_OPTICAL_BOUNDS}.
       *
       * @param layoutMode the layout mode to use during layout operations
       *
       * @see #getLayoutMode()
       * @attr ref android.R.styleable#ViewGroup_layoutMode
       */
      public void setLayoutMode(int layoutMode) {
          if (mLayoutMode != layoutMode) {
              invalidateInheritedLayoutMode(layoutMode);
              setLayoutMode(layoutMode, layoutMode != LAYOUT_MODE_UNDEFINED);
              requestLayout();
          }
      }
  
      /**
       * Returns a new set of layout parameters based on the supplied attributes set.
       *
       * @param attrs the attributes to build the layout parameters from
       *
       * @return an instance of {@link android.view.ViewGroup.LayoutParams} or one
       *         of its descendants
       */
      public LayoutParams generateLayoutParams(AttributeSet attrs) {
          return new LayoutParams(getContext(), attrs);
      }
  
      /**
       * Returns a safe set of layout parameters based on the supplied layout params.
       * When a ViewGroup is passed a View whose layout params do not pass the test of
       * {@link #checkLayoutParams(android.view.ViewGroup.LayoutParams)}, this method
       * is invoked. This method should return a new set of layout params suitable for
       * this ViewGroup, possibly by copying the appropriate attributes from the
       * specified set of layout params.
       *
       * @param p The layout parameters to convert into a suitable set of layout parameters
       *          for this ViewGroup.
       *
       * @return an instance of {@link android.view.ViewGroup.LayoutParams} or one
       *         of its descendants
       */
      protected LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
          return p;
      }
  
      /**
       * Returns a set of default layout parameters. These parameters are requested
       * when the View passed to {@link #addView(View)} has no layout parameters
       * already set. If null is returned, an exception is thrown from addView.
       *
       * @return a set of default layout parameters or null
       */
      protected LayoutParams generateDefaultLayoutParams() {
          return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
      }
  
      @Override
      protected void debug(int depth) {
          super.debug(depth);
          String output;
  
          if (mFocused != null) {
              output = debugIndent(depth);
              output += "mFocused";
              Log.d(VIEW_LOG_TAG, output);
              mFocused.debug(depth + 1);
          }
          if (mDefaultFocus != null) {
              output = debugIndent(depth);
              output += "mDefaultFocus";
              Log.d(VIEW_LOG_TAG, output);
              mDefaultFocus.debug(depth + 1);
          }
          if (mFocusedInCluster != null) {
              output = debugIndent(depth);
              output += "mFocusedInCluster";
              Log.d(VIEW_LOG_TAG, output);
              mFocusedInCluster.debug(depth + 1);
          }
          if (mChildrenCount != 0) {
              output = debugIndent(depth);
              output += "{";
              Log.d(VIEW_LOG_TAG, output);
          }
          int count = mChildrenCount;
          for (int i = 0; i < count; i++) {
              View child = mChildren[i];
              child.debug(depth + 1);
          }
  
          if (mChildrenCount != 0) {
              output = debugIndent(depth);
              output += "}";
              Log.d(VIEW_LOG_TAG, output);
          }
      }
  
      /**
       * Returns the position in the group of the specified child view.
       *
       * @param child the view for which to get the position
       * @return a positive integer representing the position of the view in the
       *         group, or -1 if the view does not exist in the group
       */
      public int indexOfChild(View child) {
          final int count = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < count; i++) {
              if (children[i] == child) {
                  return i;
              }
          }
          return -1;
      }
  
      /**
       * Returns the number of children in the group.
       *
       * @return a positive integer representing the number of children in
       *         the group
       */
      public int getChildCount() {
          return mChildrenCount;
      }
  
      /**
       * Returns the view at the specified position in the group.
       *
       * @param index the position at which to get the view from
       * @return the view at the specified position or null if the position
       *         does not exist within the group
       */
      public View getChildAt(int index) {
          if (index < 0 || index >= mChildrenCount) {
              return null;
          }
          return mChildren[index];
      }
  
      /**
       * Ask all of the children of this view to measure themselves, taking into
       * account both the MeasureSpec requirements for this view and its padding.
       * We skip children that are in the GONE state The heavy lifting is done in
       * getChildMeasureSpec.
       *
       * @param widthMeasureSpec The width requirements for this view
       * @param heightMeasureSpec The height requirements for this view
       */
      protected void measureChildren(int widthMeasureSpec, int heightMeasureSpec) {
          final int size = mChildrenCount;
          final View[] children = mChildren;
          for (int i = 0; i < size; ++i) {
              final View child = children[i];
              if ((child.mViewFlags & VISIBILITY_MASK) != GONE) {
                  measureChild(child, widthMeasureSpec, heightMeasureSpec);
              }
          }
      }
  
      /**
       * Ask one of the children of this view to measure itself, taking into
       * account both the MeasureSpec requirements for this view and its padding.
       * The heavy lifting is done in getChildMeasureSpec.
       *
       * @param child The child to measure
       * @param parentWidthMeasureSpec The width requirements for this view
       * @param parentHeightMeasureSpec The height requirements for this view
       */
      protected void measureChild(View child, int parentWidthMeasureSpec,
              int parentHeightMeasureSpec) {
          final LayoutParams lp = child.getLayoutParams();
  
          final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
                  mPaddingLeft + mPaddingRight, lp.width);
          final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec,
                  mPaddingTop + mPaddingBottom, lp.height);
  
          child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
      }
  
      /**
       * Ask one of the children of this view to measure itself, taking into
       * account both the MeasureSpec requirements for this view and its padding
       * and margins. The child must have MarginLayoutParams The heavy lifting is
       * done in getChildMeasureSpec.
       *
       * @param child The child to measure
       * @param parentWidthMeasureSpec The width requirements for this view
       * @param widthUsed Extra space that has been used up by the parent
       *        horizontally (possibly by other children of the parent)
       * @param parentHeightMeasureSpec The height requirements for this view
       * @param heightUsed Extra space that has been used up by the parent
       *        vertically (possibly by other children of the parent)
       */
      protected void measureChildWithMargins(View child,
              int parentWidthMeasureSpec, int widthUsed,
              int parentHeightMeasureSpec, int heightUsed) {
          final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
  
          final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
                  mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin
                          + widthUsed, lp.width);
          final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec,
                  mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin
                          + heightUsed, lp.height);
  
          child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
      }
  
      /**
       * Does the hard part of measureChildren: figuring out the MeasureSpec to
       * pass to a particular child. This method figures out the right MeasureSpec
       * for one dimension (height or width) of one child view.
       *
       * The goal is to combine information from our MeasureSpec with the
       * LayoutParams of the child to get the best possible results. For example,
       * if the this view knows its size (because its MeasureSpec has a mode of
       * EXACTLY), and the child has indicated in its LayoutParams that it wants
       * to be the same size as the parent, the parent should ask the child to
       * layout given an exact size.
       *
       * @param spec The requirements for this view
       * @param padding The padding of this view for the current dimension and
       *        margins, if applicable
       * @param childDimension How big the child wants to be in the current
       *        dimension
       * @return a MeasureSpec integer for the child
       */
      public static int getChildMeasureSpec(int spec, int padding, int childDimension) {
          int specMode = MeasureSpec.getMode(spec);
          int specSize = MeasureSpec.getSize(spec);
  
          int size = Math.max(0, specSize - padding);
  
          int resultSize = 0;
          int resultMode = 0;
  
          switch (specMode) {
          // Parent has imposed an exact size on us
          case MeasureSpec.EXACTLY:
              if (childDimension >= 0) {
                  resultSize = childDimension;
                  resultMode = MeasureSpec.EXACTLY;
              } else if (childDimension == LayoutParams.MATCH_PARENT) {
                  // Child wants to be our size. So be it.
                  resultSize = size;
                  resultMode = MeasureSpec.EXACTLY;
              } else if (childDimension == LayoutParams.WRAP_CONTENT) {
                  // Child wants to determine its own size. It can't be
                  // bigger than us.
                  resultSize = size;
                  resultMode = MeasureSpec.AT_MOST;
              }
              break;
  
          // Parent has imposed a maximum size on us
          case MeasureSpec.AT_MOST:
              if (childDimension >= 0) {
                  // Child wants a specific size... so be it
                  resultSize = childDimension;
                  resultMode = MeasureSpec.EXACTLY;
              } else if (childDimension == LayoutParams.MATCH_PARENT) {
                  // Child wants to be our size, but our size is not fixed.
                  // Constrain child to not be bigger than us.
                  resultSize = size;
                  resultMode = MeasureSpec.AT_MOST;
              } else if (childDimension == LayoutParams.WRAP_CONTENT) {
                  // Child wants to determine its own size. It can't be
                  // bigger than us.
                  resultSize = size;
                  resultMode = MeasureSpec.AT_MOST;
              }
              break;
  
          // Parent asked to see how big we want to be
          case MeasureSpec.UNSPECIFIED:
              if (childDimension >= 0) {
                  // Child wants a specific size... let him have it
                  resultSize = childDimension;
                  resultMode = MeasureSpec.EXACTLY;
              } else if (childDimension == LayoutParams.MATCH_PARENT) {
                  // Child wants to be our size... find out how big it should
                  // be
                  resultSize = View.sUseZeroUnspecifiedMeasureSpec ? 0 : size;
                  resultMode = MeasureSpec.UNSPECIFIED;
              } else if (childDimension == LayoutParams.WRAP_CONTENT) {
                  // Child wants to determine its own size.... find out how
                  // big it should be
                  resultSize = View.sUseZeroUnspecifiedMeasureSpec ? 0 : size;
                  resultMode = MeasureSpec.UNSPECIFIED;
              }
              break;
          }
          //noinspection ResourceType
          return MeasureSpec.makeMeasureSpec(resultSize, resultMode);
      }
  
  
      /**
       * Removes any pending animations for views that have been removed. Call
       * this if you don't want animations for exiting views to stack up.
       */
      public void clearDisappearingChildren() {
          final ArrayList<View> disappearingChildren = mDisappearingChildren;
          if (disappearingChildren != null) {
              final int count = disappearingChildren.size();
              for (int i = 0; i < count; i++) {
                  final View view = disappearingChildren.get(i);
                  if (view.mAttachInfo != null) {
                      view.dispatchDetachedFromWindow();
                  }
                  view.clearAnimation();
              }
              disappearingChildren.clear();
              invalidate();
          }
      }
  
      /**
       * Add a view which is removed from mChildren but still needs animation
       *
       * @param v View to add
       */
      private void addDisappearingView(View v) {
          ArrayList<View> disappearingChildren = mDisappearingChildren;
  
          if (disappearingChildren == null) {
              disappearingChildren = mDisappearingChildren = new ArrayList<View>();
          }
  
          disappearingChildren.add(v);
      }
  
      /**
       * Cleanup a view when its animation is done. This may mean removing it from
       * the list of disappearing views.
       *
       * @param view The view whose animation has finished
       * @param animation The animation, cannot be null
       */
      void finishAnimatingView(final View view, Animation animation) {
          final ArrayList<View> disappearingChildren = mDisappearingChildren;
          if (disappearingChildren != null) {
              if (disappearingChildren.contains(view)) {
                  disappearingChildren.remove(view);
  
                  if (view.mAttachInfo != null) {
                      view.dispatchDetachedFromWindow();
                  }
  
                  view.clearAnimation();
                  mGroupFlags |= FLAG_INVALIDATE_REQUIRED;
              }
          }
  
          if (animation != null && !animation.getFillAfter()) {
              view.clearAnimation();
          }
  
          if ((view.mPrivateFlags & PFLAG_ANIMATION_STARTED) == PFLAG_ANIMATION_STARTED) {
              view.onAnimationEnd();
              // Should be performed by onAnimationEnd() but this avoid an infinite loop,
              // so we'd rather be safe than sorry
              view.mPrivateFlags &= ~PFLAG_ANIMATION_STARTED;
              // Draw one more frame after the animation is done
              mGroupFlags |= FLAG_INVALIDATE_REQUIRED;
          }
      }
  
      /**
       * Utility function called by View during invalidation to determine whether a view that
       * is invisible or gone should still be invalidated because it is being transitioned (and
       * therefore still needs to be drawn).
       */
      boolean isViewTransitioning(View view) {
          return (mTransitioningViews != null && mTransitioningViews.contains(view));
      }
  
      /**
       * This method tells the ViewGroup that the given View object, which should have this
       * ViewGroup as its parent,
       * should be kept around  (re-displayed when the ViewGroup draws its children) even if it
       * is removed from its parent. This allows animations, such as those used by
       * {@link android.app.Fragment} and {@link android.animation.LayoutTransition} to animate
       * the removal of views. A call to this method should always be accompanied by a later call
       * to {@link #endViewTransition(View)}, such as after an animation on the View has finished,
       * so that the View finally gets removed.
       *
       * @param view The View object to be kept visible even if it gets removed from its parent.
       */
      public void startViewTransition(View view) {
          if (view.mParent == this) {
              if (mTransitioningViews == null) {
                  mTransitioningViews = new ArrayList<View>();
              }
              mTransitioningViews.add(view);
          }
      }
  
      /**
       * This method should always be called following an earlier call to
       * {@link #startViewTransition(View)}. The given View is finally removed from its parent
       * and will no longer be displayed. Note that this method does not perform the functionality
       * of removing a view from its parent; it just discontinues the display of a View that
       * has previously been removed.
       *
       * @return view The View object that has been removed but is being kept around in the visible
       * hierarchy by an earlier call to {@link #startViewTransition(View)}.
       */
      public void endViewTransition(View view) {
          if (mTransitioningViews != null) {
              mTransitioningViews.remove(view);
              final ArrayList<View> disappearingChildren = mDisappearingChildren;
              if (disappearingChildren != null && disappearingChildren.contains(view)) {
                  disappearingChildren.remove(view);
                  if (mVisibilityChangingChildren != null &&
                          mVisibilityChangingChildren.contains(view)) {
                      mVisibilityChangingChildren.remove(view);
                  } else {
                      if (view.mAttachInfo != null) {
                          view.dispatchDetachedFromWindow();
                      }
                      if (view.mParent != null) {
                          view.mParent = null;
                      }
                  }
                  invalidate();
              }
          }
      }
  
      private LayoutTransition.TransitionListener mLayoutTransitionListener =
              new LayoutTransition.TransitionListener() {
          @Override
          public void startTransition(LayoutTransition transition, ViewGroup container,
                  View view, int transitionType) {
              // We only care about disappearing items, since we need special logic to keep
              // those items visible after they've been 'removed'
              if (transitionType == LayoutTransition.DISAPPEARING) {
                  startViewTransition(view);
              }
          }
  
          @Override
          public void endTransition(LayoutTransition transition, ViewGroup container,
                  View view, int transitionType) {
              if (mLayoutCalledWhileSuppressed && !transition.isChangingLayout()) {
                  requestLayout();
                  mLayoutCalledWhileSuppressed = false;
              }
              if (transitionType == LayoutTransition.DISAPPEARING && mTransitioningViews != null) {
                  endViewTransition(view);
              }
          }
      };
  
      /**
       * Tells this ViewGroup to suppress all layout() calls until layout
       * suppression is disabled with a later call to suppressLayout(false).
       * When layout suppression is disabled, a requestLayout() call is sent
       * if layout() was attempted while layout was being suppressed.
       */
      public void suppressLayout(boolean suppress) {
          mSuppressLayout = suppress;
          if (!suppress) {
              if (mLayoutCalledWhileSuppressed) {
                  requestLayout();
                  mLayoutCalledWhileSuppressed = false;
              }
          }
      }
  
      /**
       * Returns whether layout calls on this container are currently being
       * suppressed, due to an earlier call to {@link #suppressLayout(boolean)}.
       *
       * @return true if layout calls are currently suppressed, false otherwise.
       */
      public boolean isLayoutSuppressed() {
          return mSuppressLayout;
      }
  
      @Override
      public boolean gatherTransparentRegion(Region region) {
          // If no transparent regions requested, we are always opaque.
          final boolean meOpaque = (mPrivateFlags & View.PFLAG_REQUEST_TRANSPARENT_REGIONS) == 0;
          if (meOpaque && region == null) {
              // The caller doesn't care about the region, so stop now.
              return true;
          }
          super.gatherTransparentRegion(region);
          // Instead of naively traversing the view tree, we have to traverse according to the Z
          // order here. We need to go with the same order as dispatchDraw().
          // One example is that after surfaceView punch a hole, we will still allow other views drawn
          // on top of that hole. In this case, those other views should be able to cut the
          // transparent region into smaller area.
          final int childrenCount = mChildrenCount;
          boolean noneOfTheChildrenAreTransparent = true;
          if (childrenCount > 0) {
              final ArrayList<View> preorderedList = buildOrderedChildList();
              final boolean customOrder = preorderedList == null
                      && isChildrenDrawingOrderEnabled();
              final View[] children = mChildren;
              for (int i = 0; i < childrenCount; i++) {
                  final int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
                  final View child = getAndVerifyPreorderedView(preorderedList, children, childIndex);
                  if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE || child.getAnimation() != null) {
                      if (!child.gatherTransparentRegion(region)) {
                          noneOfTheChildrenAreTransparent = false;
                      }
                  }
              }
              if (preorderedList != null) preorderedList.clear();
          }
          return meOpaque || noneOfTheChildrenAreTransparent;
      }
  
      @Override
      public void requestTransparentRegion(View child) {
          if (child != null) {
              child.mPrivateFlags |= View.PFLAG_REQUEST_TRANSPARENT_REGIONS;
              if (mParent != null) {
                  mParent.requestTransparentRegion(this);
              }
          }
      }
  
      /**
       * @hide
       */
      @Override
      public void subtractObscuredTouchableRegion(Region touchableRegion, View view) {
          final int childrenCount = mChildrenCount;
          final ArrayList<View> preorderedList = buildTouchDispatchChildList();
          final boolean customOrder = preorderedList == null && isChildrenDrawingOrderEnabled();
          final View[] children = mChildren;
          for (int i = childrenCount - 1; i >= 0; i--) {
              final int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
              final View child = getAndVerifyPreorderedView(preorderedList, children, childIndex);
              if (child == view) {
                  // We've reached the target view.
                  break;
              }
              if (!child.canReceivePointerEvents()) {
                  // This child cannot be touched. Skip it.
                  continue;
              }
              applyOpToRegionByBounds(touchableRegion, child, Region.Op.DIFFERENCE);
          }
  
          // The touchable region should not exceed the bounds of its container.
          applyOpToRegionByBounds(touchableRegion, this, Region.Op.INTERSECT);
  
          final ViewParent parent = getParent();
          if (parent != null) {
              parent.subtractObscuredTouchableRegion(touchableRegion, this);
          }
      }
  
      private static void applyOpToRegionByBounds(Region region, View view, Region.Op op) {
          final int[] locationInWindow = new int[2];
          view.getLocationInWindow(locationInWindow);
          final int x = locationInWindow[0];
          final int y = locationInWindow[1];
          region.op(x, y, x + view.getWidth(), y + view.getHeight(), op);
      }
  
      @Override
      public WindowInsets dispatchApplyWindowInsets(WindowInsets insets) {
          insets = super.dispatchApplyWindowInsets(insets);
          if (View.sBrokenInsetsDispatch) {
              return brokenDispatchApplyWindowInsets(insets);
          } else {
              return newDispatchApplyWindowInsets(insets);
          }
      }
  
      private WindowInsets brokenDispatchApplyWindowInsets(WindowInsets insets) {
          if (!insets.isConsumed()) {
              final int count = getChildCount();
              for (int i = 0; i < count; i++) {
                  insets = getChildAt(i).dispatchApplyWindowInsets(insets);
                  if (insets.isConsumed()) {
                      break;
                  }
              }
          }
          return insets;
      }
  
      private WindowInsets newDispatchApplyWindowInsets(WindowInsets insets) {
          final int count = getChildCount();
          for (int i = 0; i < count; i++) {
              getChildAt(i).dispatchApplyWindowInsets(insets);
          }
          return insets;
      }
  
      @Override
      void dispatchWindowInsetsAnimationStarted(InsetsAnimation animation) {
          super.dispatchWindowInsetsAnimationStarted(animation);
          final int count = getChildCount();
          for (int i = 0; i < count; i++) {
              getChildAt(i).dispatchWindowInsetsAnimationStarted(animation);
          }
      }
  
      @Override
      WindowInsets dispatchWindowInsetsAnimationProgress(WindowInsets insets) {
          insets = super.dispatchWindowInsetsAnimationProgress(insets);
          final int count = getChildCount();
          for (int i = 0; i < count; i++) {
              getChildAt(i).dispatchWindowInsetsAnimationProgress(insets);
          }
          return insets;
      }
  
      @Override
      void dispatchWindowInsetsAnimationFinished(InsetsAnimation animation) {
          super.dispatchWindowInsetsAnimationFinished(animation);
          final int count = getChildCount();
          for (int i = 0; i < count; i++) {
              getChildAt(i).dispatchWindowInsetsAnimationFinished(animation);
          }
      }
  
      /**
       * Returns the animation listener to which layout animation events are
       * sent.
       *
       * @return an {@link android.view.animation.Animation.AnimationListener}
       */
      public Animation.AnimationListener getLayoutAnimationListener() {
          return mAnimationListener;
      }
  
      @Override
      protected void drawableStateChanged() {
          super.drawableStateChanged();
  
          if ((mGroupFlags & FLAG_NOTIFY_CHILDREN_ON_DRAWABLE_STATE_CHANGE) != 0) {
              if ((mGroupFlags & FLAG_ADD_STATES_FROM_CHILDREN) != 0) {
                  throw new IllegalStateException("addStateFromChildren cannot be enabled if a"
                          + " child has duplicateParentState set to true");
              }
  
              final View[] children = mChildren;
              final int count = mChildrenCount;
  
              for (int i = 0; i < count; i++) {
                  final View child = children[i];
                  if ((child.mViewFlags & DUPLICATE_PARENT_STATE) != 0) {
                      child.refreshDrawableState();
                  }
              }
          }
      }
  
      @Override
      public void jumpDrawablesToCurrentState() {
          super.jumpDrawablesToCurrentState();
          final View[] children = mChildren;
          final int count = mChildrenCount;
          for (int i = 0; i < count; i++) {
              children[i].jumpDrawablesToCurrentState();
          }
      }
  
      @Override
      protected int[] onCreateDrawableState(int extraSpace) {
          if ((mGroupFlags & FLAG_ADD_STATES_FROM_CHILDREN) == 0) {
              return super.onCreateDrawableState(extraSpace);
          }
  
          int need = 0;
          int n = getChildCount();
          for (int i = 0; i < n; i++) {
              int[] childState = getChildAt(i).getDrawableState();
  
              if (childState != null) {
                  need += childState.length;
              }
          }
  
          int[] state = super.onCreateDrawableState(extraSpace + need);
  
          for (int i = 0; i < n; i++) {
              int[] childState = getChildAt(i).getDrawableState();
  
              if (childState != null) {
                  state = mergeDrawableStates(state, childState);
              }
          }
  
          return state;
      }
  
      /**
       * Sets whether this ViewGroup's drawable states also include
       * its children's drawable states.  This is used, for example, to
       * make a group appear to be focused when its child EditText or button
       * is focused.
       */
      public void setAddStatesFromChildren(boolean addsStates) {
          if (addsStates) {
              mGroupFlags |= FLAG_ADD_STATES_FROM_CHILDREN;
          } else {
              mGroupFlags &= ~FLAG_ADD_STATES_FROM_CHILDREN;
          }
  
          refreshDrawableState();
      }
  
      /**
       * Returns whether this ViewGroup's drawable states also include
       * its children's drawable states.  This is used, for example, to
       * make a group appear to be focused when its child EditText or button
       * is focused.
       */
      @InspectableProperty
      public boolean addStatesFromChildren() {
          return (mGroupFlags & FLAG_ADD_STATES_FROM_CHILDREN) != 0;
      }
  
      /**
       * If {@link #addStatesFromChildren} is true, refreshes this group's
       * drawable state (to include the states from its children).
       */
      @Override
      public void childDrawableStateChanged(View child) {
          if ((mGroupFlags & FLAG_ADD_STATES_FROM_CHILDREN) != 0) {
              refreshDrawableState();
          }
      }
  
      /**
       * Specifies the animation listener to which layout animation events must
       * be sent. Only
       * {@link android.view.animation.Animation.AnimationListener#onAnimationStart(Animation)}
       * and
       * {@link android.view.animation.Animation.AnimationListener#onAnimationEnd(Animation)}
       * are invoked.
       *
       * @param animationListener the layout animation listener
       */
      public void setLayoutAnimationListener(Animation.AnimationListener animationListener) {
          mAnimationListener = animationListener;
      }
  
      /**
       * This method is called by LayoutTransition when there are 'changing' animations that need
       * to start after the layout/setup phase. The request is forwarded to the ViewAncestor, who
       * starts all pending transitions prior to the drawing phase in the current traversal.
       *
       * @param transition The LayoutTransition to be started on the next traversal.
       *
       * @hide
       */
      public void requestTransitionStart(LayoutTransition transition) {
          ViewRootImpl viewAncestor = getViewRootImpl();
          if (viewAncestor != null) {
              viewAncestor.requestTransitionStart(transition);
          }
      }
  
      /**
       * @hide
       */
      @Override
      public boolean resolveRtlPropertiesIfNeeded() {
          final boolean result = super.resolveRtlPropertiesIfNeeded();
          // We dont need to resolve the children RTL properties if nothing has changed for the parent
          if (result) {
              int count = getChildCount();
              for (int i = 0; i < count; i++) {
                  final View child = getChildAt(i);
                  if (child.isLayoutDirectionInherited()) {
                      child.resolveRtlPropertiesIfNeeded();
                  }
              }
          }
          return result;
      }
  
      /**
       * @hide
       */
      @Override
      public boolean resolveLayoutDirection() {
          final boolean result = super.resolveLayoutDirection();
          if (result) {
              int count = getChildCount();
              for (int i = 0; i < count; i++) {
                  final View child = getChildAt(i);
                  if (child.isLayoutDirectionInherited()) {
                      child.resolveLayoutDirection();
                  }
              }
          }
          return result;
      }
  
      /**
       * @hide
       */
      @Override
      public boolean resolveTextDirection() {
          final boolean result = super.resolveTextDirection();
          if (result) {
              int count = getChildCount();
              for (int i = 0; i < count; i++) {
                  final View child = getChildAt(i);
                  if (child.isTextDirectionInherited()) {
                      child.resolveTextDirection();
                  }
              }
          }
          return result;
      }
  
      /**
       * @hide
       */
      @Override
      public boolean resolveTextAlignment() {
          final boolean result = super.resolveTextAlignment();
          if (result) {
              int count = getChildCount();
              for (int i = 0; i < count; i++) {
                  final View child = getChildAt(i);
                  if (child.isTextAlignmentInherited()) {
                      child.resolveTextAlignment();
                  }
              }
          }
          return result;
      }
  
      /**
       * @hide
       */
      @Override
      @UnsupportedAppUsage
      public void resolvePadding() {
          super.resolvePadding();
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              final View child = getChildAt(i);
              if (child.isLayoutDirectionInherited() && !child.isPaddingResolved()) {
                  child.resolvePadding();
              }
          }
      }
  
      /**
       * @hide
       */
      @Override
      protected void resolveDrawables() {
          super.resolveDrawables();
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              final View child = getChildAt(i);
              if (child.isLayoutDirectionInherited() && !child.areDrawablesResolved()) {
                  child.resolveDrawables();
              }
          }
      }
  
      /**
       * @hide
       */
      @Override
      public void resolveLayoutParams() {
          super.resolveLayoutParams();
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              final View child = getChildAt(i);
              child.resolveLayoutParams();
          }
      }
  
      /**
       * @hide
       */
      @TestApi
      @Override
      public void resetResolvedLayoutDirection() {
          super.resetResolvedLayoutDirection();
  
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              final View child = getChildAt(i);
              if (child.isLayoutDirectionInherited()) {
                  child.resetResolvedLayoutDirection();
              }
          }
      }
  
      /**
       * @hide
       */
      @TestApi
      @Override
      public void resetResolvedTextDirection() {
          super.resetResolvedTextDirection();
  
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              final View child = getChildAt(i);
              if (child.isTextDirectionInherited()) {
                  child.resetResolvedTextDirection();
              }
          }
      }
  
      /**
       * @hide
       */
      @TestApi
      @Override
      public void resetResolvedTextAlignment() {
          super.resetResolvedTextAlignment();
  
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              final View child = getChildAt(i);
              if (child.isTextAlignmentInherited()) {
                  child.resetResolvedTextAlignment();
              }
          }
      }
  
      /**
       * @hide
       */
      @TestApi
      @Override
      public void resetResolvedPadding() {
          super.resetResolvedPadding();
  
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              final View child = getChildAt(i);
              if (child.isLayoutDirectionInherited()) {
                  child.resetResolvedPadding();
              }
          }
      }
  
      /**
       * @hide
       */
      @TestApi
      @Override
      protected void resetResolvedDrawables() {
          super.resetResolvedDrawables();
  
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              final View child = getChildAt(i);
              if (child.isLayoutDirectionInherited()) {
                  child.resetResolvedDrawables();
              }
          }
      }
  
      /**
       * Return true if the pressed state should be delayed for children or descendants of this
       * ViewGroup. Generally, this should be done for containers that can scroll, such as a List.
       * This prevents the pressed state from appearing when the user is actually trying to scroll
       * the content.
       *
       * The default implementation returns true for compatibility reasons. Subclasses that do
       * not scroll should generally override this method and return false.
       */
      public boolean shouldDelayChildPressedState() {
          return true;
      }
  
      /**
       * @inheritDoc
       */
      @Override
      public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
          return false;
      }
  
      /**
       * @inheritDoc
       */
      @Override
      public void onNestedScrollAccepted(View child, View target, int axes) {
          mNestedScrollAxes = axes;
      }
  
      /**
       * @inheritDoc
       *
       * <p>The default implementation of onStopNestedScroll calls
       * {@link #stopNestedScroll()} to halt any recursive nested scrolling in progress.</p>
       */
      @Override
      public void onStopNestedScroll(View child) {
          // Stop any recursive nested scrolling.
          stopNestedScroll();
          mNestedScrollAxes = 0;
      }
  
      /**
       * @inheritDoc
       */
      @Override
      public void onNestedScroll(View target, int dxConsumed, int dyConsumed,
              int dxUnconsumed, int dyUnconsumed) {
          // Re-dispatch up the tree by default
          dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, null);
      }
  
      /**
       * @inheritDoc
       */
      @Override
      public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) {
          // Re-dispatch up the tree by default
          dispatchNestedPreScroll(dx, dy, consumed, null);
      }
  
      /**
       * @inheritDoc
       */
      @Override
      public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) {
          // Re-dispatch up the tree by default
          return dispatchNestedFling(velocityX, velocityY, consumed);
      }
  
      /**
       * @inheritDoc
       */
      @Override
      public boolean onNestedPreFling(View target, float velocityX, float velocityY) {
          // Re-dispatch up the tree by default
          return dispatchNestedPreFling(velocityX, velocityY);
      }
  
      /**
       * Return the current axes of nested scrolling for this ViewGroup.
       *
       * <p>A ViewGroup returning something other than {@link #SCROLL_AXIS_NONE} is currently
       * acting as a nested scrolling parent for one or more descendant views in the hierarchy.</p>
       *
       * @return Flags indicating the current axes of nested scrolling
       * @see #SCROLL_AXIS_HORIZONTAL
       * @see #SCROLL_AXIS_VERTICAL
       * @see #SCROLL_AXIS_NONE
       */
      public int getNestedScrollAxes() {
          return mNestedScrollAxes;
      }
  
      /** @hide */
      protected void onSetLayoutParams(View child, LayoutParams layoutParams) {
          requestLayout();
      }
  
      /** @hide */
      @Override
      public void captureTransitioningViews(List<View> transitioningViews) {
          if (getVisibility() != View.VISIBLE) {
              return;
          }
          if (isTransitionGroup()) {
              transitioningViews.add(this);
          } else {
              int count = getChildCount();
              for (int i = 0; i < count; i++) {
                  View child = getChildAt(i);
                  child.captureTransitioningViews(transitioningViews);
              }
          }
      }
  
      /** @hide */
      @Override
      public void findNamedViews(Map<String, View> namedElements) {
          if (getVisibility() != VISIBLE && mGhostView == null) {
              return;
          }
          super.findNamedViews(namedElements);
          int count = getChildCount();
          for (int i = 0; i < count; i++) {
              View child = getChildAt(i);
              child.findNamedViews(namedElements);
          }
      }
  
      @Override
      boolean hasUnhandledKeyListener() {
          return (mChildUnhandledKeyListeners > 0) || super.hasUnhandledKeyListener();
      }
  
      void incrementChildUnhandledKeyListeners() {
          mChildUnhandledKeyListeners += 1;
          if (mChildUnhandledKeyListeners == 1) {
              if (mParent instanceof ViewGroup) {
                  ((ViewGroup) mParent).incrementChildUnhandledKeyListeners();
              }
          }
      }
  
      void decrementChildUnhandledKeyListeners() {
          mChildUnhandledKeyListeners -= 1;
          if (mChildUnhandledKeyListeners == 0) {
              if (mParent instanceof ViewGroup) {
                  ((ViewGroup) mParent).decrementChildUnhandledKeyListeners();
              }
          }
      }
  
      @Override
      View dispatchUnhandledKeyEvent(KeyEvent evt) {
          if (!hasUnhandledKeyListener()) {
              return null;
          }
          ArrayList<View> orderedViews = buildOrderedChildList();
          if (orderedViews != null) {
              try {
                  for (int i = orderedViews.size() - 1; i >= 0; --i) {
                      View v = orderedViews.get(i);
                      View consumer = v.dispatchUnhandledKeyEvent(evt);
                      if (consumer != null) {
                          return consumer;
                      }
                  }
              } finally {
                  orderedViews.clear();
              }
          } else {
              for (int i = getChildCount() - 1; i >= 0; --i) {
                  View v = getChildAt(i);
                  View consumer = v.dispatchUnhandledKeyEvent(evt);
                  if (consumer != null) {
                      return consumer;
                  }
              }
          }
          if (onUnhandledKeyEvent(evt)) {
              return this;
          }
          return null;
      }
  
      /**
       * LayoutParams are used by views to tell their parents how they want to be
       * laid out. See
       * {@link android.R.styleable#ViewGroup_Layout ViewGroup Layout Attributes}
       * for a list of all child view attributes that this class supports.
       *
       * <p>
       * The base LayoutParams class just describes how big the view wants to be
       * for both width and height. For each dimension, it can specify one of:
       * <ul>
       * <li>FILL_PARENT (renamed MATCH_PARENT in API Level 8 and higher), which
       * means that the view wants to be as big as its parent (minus padding)
       * <li> WRAP_CONTENT, which means that the view wants to be just big enough
       * to enclose its content (plus padding)
       * <li> an exact number
       * </ul>
       * There are subclasses of LayoutParams for different subclasses of
       * ViewGroup. For example, AbsoluteLayout has its own subclass of
       * LayoutParams which adds an X and Y value.</p>
       *
       * <div class="special reference">
       * <h3>Developer Guides</h3>
       * <p>For more information about creating user interface layouts, read the
       * <a href="{@docRoot}guide/topics/ui/declaring-layout.html">XML Layouts</a> developer
       * guide.</p></div>
       *
       * @attr ref android.R.styleable#ViewGroup_Layout_layout_height
       * @attr ref android.R.styleable#ViewGroup_Layout_layout_width
       */
      public static class LayoutParams {
          /**
           * Special value for the height or width requested by a View.
           * FILL_PARENT means that the view wants to be as big as its parent,
           * minus the parent's padding, if any. This value is deprecated
           * starting in API Level 8 and replaced by {@link #MATCH_PARENT}.
           */
          @SuppressWarnings({"UnusedDeclaration"})
          @Deprecated
          public static final int FILL_PARENT = -1;
  
          /**
           * Special value for the height or width requested by a View.
           * MATCH_PARENT means that the view wants to be as big as its parent,
           * minus the parent's padding, if any. Introduced in API Level 8.
           */
          public static final int MATCH_PARENT = -1;
  
          /**
           * Special value for the height or width requested by a View.
           * WRAP_CONTENT means that the view wants to be just large enough to fit
           * its own internal content, taking its own padding into account.
           */
          public static final int WRAP_CONTENT = -2;
  
          /**
           * Information about how wide the view wants to be. Can be one of the
           * constants FILL_PARENT (replaced by MATCH_PARENT
           * in API Level 8) or WRAP_CONTENT, or an exact size.
           */
          @ViewDebug.ExportedProperty(category = "layout", mapping = {
              @ViewDebug.IntToString(from = MATCH_PARENT, to = "MATCH_PARENT"),
              @ViewDebug.IntToString(from = WRAP_CONTENT, to = "WRAP_CONTENT")
          })
          @InspectableProperty(name = "layout_width", enumMapping = {
                  @EnumEntry(name = "match_parent", value = MATCH_PARENT),
                  @EnumEntry(name = "wrap_content", value = WRAP_CONTENT)
          })
          public int width;
  
          /**
           * Information about how tall the view wants to be. Can be one of the
           * constants FILL_PARENT (replaced by MATCH_PARENT
           * in API Level 8) or WRAP_CONTENT, or an exact size.
           */
          @ViewDebug.ExportedProperty(category = "layout", mapping = {
              @ViewDebug.IntToString(from = MATCH_PARENT, to = "MATCH_PARENT"),
              @ViewDebug.IntToString(from = WRAP_CONTENT, to = "WRAP_CONTENT")
          })
          @InspectableProperty(name = "layout_height", enumMapping = {
                  @EnumEntry(name = "match_parent", value = MATCH_PARENT),
                  @EnumEntry(name = "wrap_content", value = WRAP_CONTENT)
          })
          public int height;
  
          /**
           * Used to animate layouts.
           */
          public LayoutAnimationController.AnimationParameters layoutAnimationParameters;
  
          /**
           * Creates a new set of layout parameters. The values are extracted from
           * the supplied attributes set and context. The XML attributes mapped
           * to this set of layout parameters are:
           *
           * <ul>
           *   <li><code>layout_width</code>: the width, either an exact value,
           *   {@link #WRAP_CONTENT}, or {@link #FILL_PARENT} (replaced by
           *   {@link #MATCH_PARENT} in API Level 8)</li>
           *   <li><code>layout_height</code>: the height, either an exact value,
           *   {@link #WRAP_CONTENT}, or {@link #FILL_PARENT} (replaced by
           *   {@link #MATCH_PARENT} in API Level 8)</li>
           * </ul>
           *
           * @param c the application environment
           * @param attrs the set of attributes from which to extract the layout
           *              parameters' values
           */
          public LayoutParams(Context c, AttributeSet attrs) {
              TypedArray a = c.obtainStyledAttributes(attrs, R.styleable.ViewGroup_Layout);
              setBaseAttributes(a,
                      R.styleable.ViewGroup_Layout_layout_width,
                      R.styleable.ViewGroup_Layout_layout_height);
              a.recycle();
          }
  
          /**
           * Creates a new set of layout parameters with the specified width
           * and height.
           *
           * @param width the width, either {@link #WRAP_CONTENT},
           *        {@link #FILL_PARENT} (replaced by {@link #MATCH_PARENT} in
           *        API Level 8), or a fixed size in pixels
           * @param height the height, either {@link #WRAP_CONTENT},
           *        {@link #FILL_PARENT} (replaced by {@link #MATCH_PARENT} in
           *        API Level 8), or a fixed size in pixels
           */
          public LayoutParams(int width, int height) {
              this.width = width;
              this.height = height;
          }
  
          /**
           * Copy constructor. Clones the width and height values of the source.
           *
           * @param source The layout params to copy from.
           */
          public LayoutParams(LayoutParams source) {
              this.width = source.width;
              this.height = source.height;
          }
  
          /**
           * Used internally by MarginLayoutParams.
           * @hide
           */
          @UnsupportedAppUsage
          LayoutParams() {
          }
  
          /**
           * Extracts the layout parameters from the supplied attributes.
           *
           * @param a the style attributes to extract the parameters from
           * @param widthAttr the identifier of the width attribute
           * @param heightAttr the identifier of the height attribute
           */
          protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr) {
              width = a.getLayoutDimension(widthAttr, "layout_width");
              height = a.getLayoutDimension(heightAttr, "layout_height");
          }
  
          /**
           * Resolve layout parameters depending on the layout direction. Subclasses that care about
           * layoutDirection changes should override this method. The default implementation does
           * nothing.
           *
           * @param layoutDirection the direction of the layout
           *
           * {@link View#LAYOUT_DIRECTION_LTR}
           * {@link View#LAYOUT_DIRECTION_RTL}
           */
          public void resolveLayoutDirection(int layoutDirection) {
          }
  
          /**
           * Returns a String representation of this set of layout parameters.
           *
           * @param output the String to prepend to the internal representation
           * @return a String with the following format: output +
           *         "ViewGroup.LayoutParams={ width=WIDTH, height=HEIGHT }"
           *
           * @hide
           */
          public String debug(String output) {
              return output + "ViewGroup.LayoutParams={ width="
                      + sizeToString(width) + ", height=" + sizeToString(height) + " }";
          }
  
          /**
           * Use {@code canvas} to draw suitable debugging annotations for these LayoutParameters.
           *
           * @param view the view that contains these layout parameters
           * @param canvas the canvas on which to draw
           *
           * @hide
           */
          public void onDebugDraw(View view, Canvas canvas, Paint paint) {
          }
  
          /**
           * Converts the specified size to a readable String.
           *
           * @param size the size to convert
           * @return a String instance representing the supplied size
           *
           * @hide
           */
          protected static String sizeToString(int size) {
              if (size == WRAP_CONTENT) {
                  return "wrap-content";
              }
              if (size == MATCH_PARENT) {
                  return "match-parent";
              }
              return String.valueOf(size);
          }
  
          /** @hide */
          void encode(@NonNull ViewHierarchyEncoder encoder) {
              encoder.beginObject(this);
              encodeProperties(encoder);
              encoder.endObject();
          }
  
          /** @hide */
          protected void encodeProperties(@NonNull ViewHierarchyEncoder encoder) {
              encoder.addProperty("width", width);
              encoder.addProperty("height", height);
          }
      }
  
      /**
       * Per-child layout information for layouts that support margins.
       * See
       * {@link android.R.styleable#ViewGroup_MarginLayout ViewGroup Margin Layout Attributes}
       * for a list of all child view attributes that this class supports.
       *
       * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_margin
       * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginHorizontal
       * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginVertical
       * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginLeft
       * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginTop
       * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginRight
       * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginBottom
       * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginStart
       * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginEnd
       */
      public static class MarginLayoutParams extends ViewGroup.LayoutParams {
          /**
           * The left margin in pixels of the child. Margin values should be positive.
           * Call {@link ViewGroup#setLayoutParams(LayoutParams)} after reassigning a new value
           * to this field.
           */
          @ViewDebug.ExportedProperty(category = "layout")
          @InspectableProperty(name = "layout_marginLeft")
          public int leftMargin;
  
          /**
           * The top margin in pixels of the child. Margin values should be positive.
           * Call {@link ViewGroup#setLayoutParams(LayoutParams)} after reassigning a new value
           * to this field.
           */
          @ViewDebug.ExportedProperty(category = "layout")
          @InspectableProperty(name = "layout_marginTop")
          public int topMargin;
  
          /**
           * The right margin in pixels of the child. Margin values should be positive.
           * Call {@link ViewGroup#setLayoutParams(LayoutParams)} after reassigning a new value
           * to this field.
           */
          @ViewDebug.ExportedProperty(category = "layout")
          @InspectableProperty(name = "layout_marginRight")
          public int rightMargin;
  
          /**
           * The bottom margin in pixels of the child. Margin values should be positive.
           * Call {@link ViewGroup#setLayoutParams(LayoutParams)} after reassigning a new value
           * to this field.
           */
          @ViewDebug.ExportedProperty(category = "layout")
          @InspectableProperty(name = "layout_marginBottom")
          public int bottomMargin;
  
          /**
           * The start margin in pixels of the child. Margin values should be positive.
           * Call {@link ViewGroup#setLayoutParams(LayoutParams)} after reassigning a new value
           * to this field.
           */
          @ViewDebug.ExportedProperty(category = "layout")
          @UnsupportedAppUsage
          private int startMargin = DEFAULT_MARGIN_RELATIVE;
  
          /**
           * The end margin in pixels of the child. Margin values should be positive.
           * Call {@link ViewGroup#setLayoutParams(LayoutParams)} after reassigning a new value
           * to this field.
           */
          @ViewDebug.ExportedProperty(category = "layout")
          @UnsupportedAppUsage
          private int endMargin = DEFAULT_MARGIN_RELATIVE;
  
          /**
           * The default start and end margin.
           * @hide
           */
          public static final int DEFAULT_MARGIN_RELATIVE = Integer.MIN_VALUE;
  
          /**
           * Bit  0: layout direction
           * Bit  1: layout direction
           * Bit  2: left margin undefined
           * Bit  3: right margin undefined
           * Bit  4: is RTL compatibility mode
           * Bit  5: need resolution
           *
           * Bit 6 to 7 not used
           *
           * @hide
           */
          @ViewDebug.ExportedProperty(category = "layout", flagMapping = {
                  @ViewDebug.FlagToString(mask = LAYOUT_DIRECTION_MASK,
                          equals = LAYOUT_DIRECTION_MASK, name = "LAYOUT_DIRECTION"),
                  @ViewDebug.FlagToString(mask = LEFT_MARGIN_UNDEFINED_MASK,
                          equals = LEFT_MARGIN_UNDEFINED_MASK, name = "LEFT_MARGIN_UNDEFINED_MASK"),
                  @ViewDebug.FlagToString(mask = RIGHT_MARGIN_UNDEFINED_MASK,
                          equals = RIGHT_MARGIN_UNDEFINED_MASK, name = "RIGHT_MARGIN_UNDEFINED_MASK"),
                  @ViewDebug.FlagToString(mask = RTL_COMPATIBILITY_MODE_MASK,
                          equals = RTL_COMPATIBILITY_MODE_MASK, name = "RTL_COMPATIBILITY_MODE_MASK"),
                  @ViewDebug.FlagToString(mask = NEED_RESOLUTION_MASK,
                          equals = NEED_RESOLUTION_MASK, name = "NEED_RESOLUTION_MASK")
          }, formatToHexString = true)
          byte mMarginFlags;
  
          private static final int LAYOUT_DIRECTION_MASK = 0x00000003;
          private static final int LEFT_MARGIN_UNDEFINED_MASK = 0x00000004;
          private static final int RIGHT_MARGIN_UNDEFINED_MASK = 0x00000008;
          private static final int RTL_COMPATIBILITY_MODE_MASK = 0x00000010;
          private static final int NEED_RESOLUTION_MASK = 0x00000020;
  
          private static final int DEFAULT_MARGIN_RESOLVED = 0;
          private static final int UNDEFINED_MARGIN = DEFAULT_MARGIN_RELATIVE;
  
          /**
           * Creates a new set of layout parameters. The values are extracted from
           * the supplied attributes set and context.
           *
           * @param c the application environment
           * @param attrs the set of attributes from which to extract the layout
           *              parameters' values
           */
          public MarginLayoutParams(Context c, AttributeSet attrs) {
              super();
  
              TypedArray a = c.obtainStyledAttributes(attrs, R.styleable.ViewGroup_MarginLayout);
              setBaseAttributes(a,
                      R.styleable.ViewGroup_MarginLayout_layout_width,
                      R.styleable.ViewGroup_MarginLayout_layout_height);
  
              int margin = a.getDimensionPixelSize(
                      com.android.internal.R.styleable.ViewGroup_MarginLayout_layout_margin, -1);
              if (margin >= 0) {
                  leftMargin = margin;
                  topMargin = margin;
                  rightMargin= margin;
                  bottomMargin = margin;
              } else {
                  int horizontalMargin = a.getDimensionPixelSize(
                          R.styleable.ViewGroup_MarginLayout_layout_marginHorizontal, -1);
                  int verticalMargin = a.getDimensionPixelSize(
                          R.styleable.ViewGroup_MarginLayout_layout_marginVertical, -1);
  
                  if (horizontalMargin >= 0) {
                      leftMargin = horizontalMargin;
                      rightMargin = horizontalMargin;
                  } else {
                      leftMargin = a.getDimensionPixelSize(
                              R.styleable.ViewGroup_MarginLayout_layout_marginLeft,
                              UNDEFINED_MARGIN);
                      if (leftMargin == UNDEFINED_MARGIN) {
                          mMarginFlags |= LEFT_MARGIN_UNDEFINED_MASK;
                          leftMargin = DEFAULT_MARGIN_RESOLVED;
                      }
                      rightMargin = a.getDimensionPixelSize(
                              R.styleable.ViewGroup_MarginLayout_layout_marginRight,
                              UNDEFINED_MARGIN);
                      if (rightMargin == UNDEFINED_MARGIN) {
                          mMarginFlags |= RIGHT_MARGIN_UNDEFINED_MASK;
                          rightMargin = DEFAULT_MARGIN_RESOLVED;
                      }
                  }
  
                  startMargin = a.getDimensionPixelSize(
                          R.styleable.ViewGroup_MarginLayout_layout_marginStart,
                          DEFAULT_MARGIN_RELATIVE);
                  endMargin = a.getDimensionPixelSize(
                          R.styleable.ViewGroup_MarginLayout_layout_marginEnd,
                          DEFAULT_MARGIN_RELATIVE);
  
                  if (verticalMargin >= 0) {
                      topMargin = verticalMargin;
                      bottomMargin = verticalMargin;
                  } else {
                      topMargin = a.getDimensionPixelSize(
                              R.styleable.ViewGroup_MarginLayout_layout_marginTop,
                              DEFAULT_MARGIN_RESOLVED);
                      bottomMargin = a.getDimensionPixelSize(
                              R.styleable.ViewGroup_MarginLayout_layout_marginBottom,
                              DEFAULT_MARGIN_RESOLVED);
                  }
  
                  if (isMarginRelative()) {
                     mMarginFlags |= NEED_RESOLUTION_MASK;
                  }
              }
  
              final boolean hasRtlSupport = c.getApplicationInfo().hasRtlSupport();
              final int targetSdkVersion = c.getApplicationInfo().targetSdkVersion;
              if (targetSdkVersion < JELLY_BEAN_MR1 || !hasRtlSupport) {
                  mMarginFlags |= RTL_COMPATIBILITY_MODE_MASK;
              }
  
              // Layout direction is LTR by default
              mMarginFlags |= LAYOUT_DIRECTION_LTR;
  
              a.recycle();
          }
  
          public MarginLayoutParams(int width, int height) {
              super(width, height);
  
              mMarginFlags |= LEFT_MARGIN_UNDEFINED_MASK;
              mMarginFlags |= RIGHT_MARGIN_UNDEFINED_MASK;
  
              mMarginFlags &= ~NEED_RESOLUTION_MASK;
              mMarginFlags &= ~RTL_COMPATIBILITY_MODE_MASK;
          }
  
          /**
           * Copy constructor. Clones the width, height and margin values of the source.
           *
           * @param source The layout params to copy from.
           */
          public MarginLayoutParams(MarginLayoutParams source) {
              this.width = source.width;
              this.height = source.height;
  
              this.leftMargin = source.leftMargin;
              this.topMargin = source.topMargin;
              this.rightMargin = source.rightMargin;
              this.bottomMargin = source.bottomMargin;
              this.startMargin = source.startMargin;
              this.endMargin = source.endMargin;
  
              this.mMarginFlags = source.mMarginFlags;
          }
  
          public MarginLayoutParams(LayoutParams source) {
              super(source);
  
              mMarginFlags |= LEFT_MARGIN_UNDEFINED_MASK;
              mMarginFlags |= RIGHT_MARGIN_UNDEFINED_MASK;
  
              mMarginFlags &= ~NEED_RESOLUTION_MASK;
              mMarginFlags &= ~RTL_COMPATIBILITY_MODE_MASK;
          }
  
          /**
           * @hide Used internally.
           */
          public final void copyMarginsFrom(MarginLayoutParams source) {
              this.leftMargin = source.leftMargin;
              this.topMargin = source.topMargin;
              this.rightMargin = source.rightMargin;
              this.bottomMargin = source.bottomMargin;
              this.startMargin = source.startMargin;
              this.endMargin = source.endMargin;
  
              this.mMarginFlags = source.mMarginFlags;
          }
  
          /**
           * Sets the margins, in pixels. A call to {@link android.view.View#requestLayout()} needs
           * to be done so that the new margins are taken into account. Left and right margins may be
           * overridden by {@link android.view.View#requestLayout()} depending on layout direction.
           * Margin values should be positive.
           *
           * @param left the left margin size
           * @param top the top margin size
           * @param right the right margin size
           * @param bottom the bottom margin size
           *
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginLeft
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginTop
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginRight
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginBottom
           */
          public void setMargins(int left, int top, int right, int bottom) {
              leftMargin = left;
              topMargin = top;
              rightMargin = right;
              bottomMargin = bottom;
              mMarginFlags &= ~LEFT_MARGIN_UNDEFINED_MASK;
              mMarginFlags &= ~RIGHT_MARGIN_UNDEFINED_MASK;
              if (isMarginRelative()) {
                  mMarginFlags |= NEED_RESOLUTION_MASK;
              } else {
                  mMarginFlags &= ~NEED_RESOLUTION_MASK;
              }
          }
  
          /**
           * Sets the relative margins, in pixels. A call to {@link android.view.View#requestLayout()}
           * needs to be done so that the new relative margins are taken into account. Left and right
           * margins may be overridden by {@link android.view.View#requestLayout()} depending on
           * layout direction. Margin values should be positive.
           *
           * @param start the start margin size
           * @param top the top margin size
           * @param end the right margin size
           * @param bottom the bottom margin size
           *
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginStart
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginTop
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginEnd
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginBottom
           *
           * @hide
           */
          @UnsupportedAppUsage
          public void setMarginsRelative(int start, int top, int end, int bottom) {
              startMargin = start;
              topMargin = top;
              endMargin = end;
              bottomMargin = bottom;
              mMarginFlags |= NEED_RESOLUTION_MASK;
          }
  
          /**
           * Sets the relative start margin. Margin values should be positive.
           *
           * @param start the start margin size
           *
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginStart
           */
          public void setMarginStart(int start) {
              startMargin = start;
              mMarginFlags |= NEED_RESOLUTION_MASK;
          }
  
          /**
           * Returns the start margin in pixels.
           *
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginStart
           *
           * @return the start margin in pixels.
           */
          public int getMarginStart() {
              if (startMargin != DEFAULT_MARGIN_RELATIVE) return startMargin;
              if ((mMarginFlags & NEED_RESOLUTION_MASK) == NEED_RESOLUTION_MASK) {
                  doResolveMargins();
              }
              switch(mMarginFlags & LAYOUT_DIRECTION_MASK) {
                  case View.LAYOUT_DIRECTION_RTL:
                      return rightMargin;
                  case View.LAYOUT_DIRECTION_LTR:
                  default:
                      return leftMargin;
              }
          }
  
          /**
           * Sets the relative end margin. Margin values should be positive.
           *
           * @param end the end margin size
           *
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginEnd
           */
          public void setMarginEnd(int end) {
              endMargin = end;
              mMarginFlags |= NEED_RESOLUTION_MASK;
          }
  
          /**
           * Returns the end margin in pixels.
           *
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginEnd
           *
           * @return the end margin in pixels.
           */
          public int getMarginEnd() {
              if (endMargin != DEFAULT_MARGIN_RELATIVE) return endMargin;
              if ((mMarginFlags & NEED_RESOLUTION_MASK) == NEED_RESOLUTION_MASK) {
                  doResolveMargins();
              }
              switch(mMarginFlags & LAYOUT_DIRECTION_MASK) {
                  case View.LAYOUT_DIRECTION_RTL:
                      return leftMargin;
                  case View.LAYOUT_DIRECTION_LTR:
                  default:
                      return rightMargin;
              }
          }
  
          /**
           * Check if margins are relative.
           *
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginStart
           * @attr ref android.R.styleable#ViewGroup_MarginLayout_layout_marginEnd
           *
           * @return true if either marginStart or marginEnd has been set.
           */
          public boolean isMarginRelative() {
              return (startMargin != DEFAULT_MARGIN_RELATIVE || endMargin != DEFAULT_MARGIN_RELATIVE);
          }
  
          /**
           * Set the layout direction
           * @param layoutDirection the layout direction.
           *        Should be either {@link View#LAYOUT_DIRECTION_LTR}
           *                     or {@link View#LAYOUT_DIRECTION_RTL}.
           */
          public void setLayoutDirection(int layoutDirection) {
              if (layoutDirection != View.LAYOUT_DIRECTION_LTR &&
                      layoutDirection != View.LAYOUT_DIRECTION_RTL) return;
              if (layoutDirection != (mMarginFlags & LAYOUT_DIRECTION_MASK)) {
                  mMarginFlags &= ~LAYOUT_DIRECTION_MASK;
                  mMarginFlags |= (layoutDirection & LAYOUT_DIRECTION_MASK);
                  if (isMarginRelative()) {
                      mMarginFlags |= NEED_RESOLUTION_MASK;
                  } else {
                      mMarginFlags &= ~NEED_RESOLUTION_MASK;
                  }
              }
          }
  
          /**
           * Retuns the layout direction. Can be either {@link View#LAYOUT_DIRECTION_LTR} or
           * {@link View#LAYOUT_DIRECTION_RTL}.
           *
           * @return the layout direction.
           */
          public int getLayoutDirection() {
              return (mMarginFlags & LAYOUT_DIRECTION_MASK);
          }
  
          /**
           * This will be called by {@link android.view.View#requestLayout()}. Left and Right margins
           * may be overridden depending on layout direction.
           */
          @Override
          public void resolveLayoutDirection(int layoutDirection) {
              setLayoutDirection(layoutDirection);
  
              // No relative margin or pre JB-MR1 case or no need to resolve, just dont do anything
              // Will use the left and right margins if no relative margin is defined.
              if (!isMarginRelative() ||
                      (mMarginFlags & NEED_RESOLUTION_MASK) != NEED_RESOLUTION_MASK) return;
  
              // Proceed with resolution
              doResolveMargins();
          }
  
          private void doResolveMargins() {
              if ((mMarginFlags & RTL_COMPATIBILITY_MODE_MASK) == RTL_COMPATIBILITY_MODE_MASK) {
                  // if left or right margins are not defined and if we have some start or end margin
                  // defined then use those start and end margins.
                  if ((mMarginFlags & LEFT_MARGIN_UNDEFINED_MASK) == LEFT_MARGIN_UNDEFINED_MASK
                          && startMargin > DEFAULT_MARGIN_RELATIVE) {
                      leftMargin = startMargin;
                  }
                  if ((mMarginFlags & RIGHT_MARGIN_UNDEFINED_MASK) == RIGHT_MARGIN_UNDEFINED_MASK
                          && endMargin > DEFAULT_MARGIN_RELATIVE) {
                      rightMargin = endMargin;
                  }
              } else {
                  // We have some relative margins (either the start one or the end one or both). So use
                  // them and override what has been defined for left and right margins. If either start
                  // or end margin is not defined, just set it to default "0".
                  switch(mMarginFlags & LAYOUT_DIRECTION_MASK) {
                      case View.LAYOUT_DIRECTION_RTL:
                          leftMargin = (endMargin > DEFAULT_MARGIN_RELATIVE) ?
                                  endMargin : DEFAULT_MARGIN_RESOLVED;
                          rightMargin = (startMargin > DEFAULT_MARGIN_RELATIVE) ?
                                  startMargin : DEFAULT_MARGIN_RESOLVED;
                          break;
                      case View.LAYOUT_DIRECTION_LTR:
                      default:
                          leftMargin = (startMargin > DEFAULT_MARGIN_RELATIVE) ?
                                  startMargin : DEFAULT_MARGIN_RESOLVED;
                          rightMargin = (endMargin > DEFAULT_MARGIN_RELATIVE) ?
                                  endMargin : DEFAULT_MARGIN_RESOLVED;
                          break;
                  }
              }
              mMarginFlags &= ~NEED_RESOLUTION_MASK;
          }
  
          /**
           * @hide
           */
          public boolean isLayoutRtl() {
              return ((mMarginFlags & LAYOUT_DIRECTION_MASK) == View.LAYOUT_DIRECTION_RTL);
          }
  
          /**
           * @hide
           */
          @Override
          public void onDebugDraw(View view, Canvas canvas, Paint paint) {
              Insets oi = isLayoutModeOptical(view.mParent) ? view.getOpticalInsets() : Insets.NONE;
  
              fillDifference(canvas,
                      view.getLeft()   + oi.left,
                      view.getTop()    + oi.top,
                      view.getRight()  - oi.right,
                      view.getBottom() - oi.bottom,
                      leftMargin,
                      topMargin,
                      rightMargin,
                      bottomMargin,
                      paint);
          }
  
          /** @hide */
          @Override
          protected void encodeProperties(@NonNull ViewHierarchyEncoder encoder) {
              super.encodeProperties(encoder);
              encoder.addProperty("leftMargin", leftMargin);
              encoder.addProperty("topMargin", topMargin);
              encoder.addProperty("rightMargin", rightMargin);
              encoder.addProperty("bottomMargin", bottomMargin);
              encoder.addProperty("startMargin", startMargin);
              encoder.addProperty("endMargin", endMargin);
          }
      }
  
      /* Describes a touched view and the ids of the pointers that it has captured.
       *
       * This code assumes that pointer ids are always in the range 0..31 such that
       * it can use a bitfield to track which pointer ids are present.
       * As it happens, the lower layers of the input dispatch pipeline also use the
       * same trick so the assumption should be safe here...
       */
      private static final class TouchTarget {
          private static final int MAX_RECYCLED = 32;
          private static final Object sRecycleLock = new Object[0];
          private static TouchTarget sRecycleBin;
          private static int sRecycledCount;
  
          public static final int ALL_POINTER_IDS = -1; // all ones
  
          // The touched child view.
          @UnsupportedAppUsage
          public View child;
  
          // The combined bit mask of pointer ids for all pointers captured by the target.
          public int pointerIdBits;
  
          // The next target in the target list.
          public TouchTarget next;
  
          @UnsupportedAppUsage
          private TouchTarget() {
          }
  
          public static TouchTarget obtain(@NonNull View child, int pointerIdBits) {
              if (child == null) {
                  throw new IllegalArgumentException("child must be non-null");
              }
  
              final TouchTarget target;
              synchronized (sRecycleLock) {
                  if (sRecycleBin == null) {
                      target = new TouchTarget();
                  } else {
                      target = sRecycleBin;
                      sRecycleBin = target.next;
                       sRecycledCount--;
                      target.next = null;
                  }
              }
              target.child = child;
              target.pointerIdBits = pointerIdBits;
              return target;
          }
  
          public void recycle() {
              if (child == null) {
                  throw new IllegalStateException("already recycled once");
              }
  
              synchronized (sRecycleLock) {
                  if (sRecycledCount < MAX_RECYCLED) {
                      next = sRecycleBin;
                      sRecycleBin = this;
                      sRecycledCount += 1;
                  } else {
                      next = null;
                  }
                  child = null;
              }
          }
      }
  
      /* Describes a hovered view. */
      private static final class HoverTarget {
          private static final int MAX_RECYCLED = 32;
          private static final Object sRecycleLock = new Object[0];
          private static HoverTarget sRecycleBin;
          private static int sRecycledCount;
  
          // The hovered child view.
          public View child;
  
          // The next target in the target list.
          public HoverTarget next;
  
          private HoverTarget() {
          }
  
          public static HoverTarget obtain(@NonNull View child) {
              if (child == null) {
                  throw new IllegalArgumentException("child must be non-null");
              }
  
              final HoverTarget target;
              synchronized (sRecycleLock) {
                  if (sRecycleBin == null) {
                      target = new HoverTarget();
                  } else {
                      target = sRecycleBin;
                      sRecycleBin = target.next;
                      sRecycledCount--;
                      target.next = null;
                  }
              }
              target.child = child;
              return target;
          }
  
          public void recycle() {
              if (child == null) {
                  throw new IllegalStateException("already recycled once");
              }
  
              synchronized (sRecycleLock) {
                  if (sRecycledCount < MAX_RECYCLED) {
                      next = sRecycleBin;
                      sRecycleBin = this;
                      sRecycledCount += 1;
                  } else {
                      next = null;
                  }
                  child = null;
              }
          }
      }
  
      /**
       * Pooled class that to hold the children for autifill.
       */
      private static class ChildListForAutoFillOrContentCapture extends ArrayList<View> {
          private static final int MAX_POOL_SIZE = 32;
  
          private static final Pools.SimplePool<ChildListForAutoFillOrContentCapture> sPool =
                  new Pools.SimplePool<>(MAX_POOL_SIZE);
  
          public static ChildListForAutoFillOrContentCapture obtain() {
              ChildListForAutoFillOrContentCapture list = sPool.acquire();
              if (list == null) {
                  list = new ChildListForAutoFillOrContentCapture();
              }
              return list;
          }
  
          public void recycle() {
              clear();
              sPool.release(this);
          }
      }
  
      /**
       * Pooled class that orderes the children of a ViewGroup from start
       * to end based on how they are laid out and the layout direction.
       */
      static class ChildListForAccessibility {
  
          private static final int MAX_POOL_SIZE = 32;
  
          private static final SynchronizedPool<ChildListForAccessibility> sPool =
                  new SynchronizedPool<ChildListForAccessibility>(MAX_POOL_SIZE);
  
          private final ArrayList<View> mChildren = new ArrayList<View>();
  
          private final ArrayList<ViewLocationHolder> mHolders = new ArrayList<ViewLocationHolder>();
  
          public static ChildListForAccessibility obtain(ViewGroup parent, boolean sort) {
              ChildListForAccessibility list = sPool.acquire();
              if (list == null) {
                  list = new ChildListForAccessibility();
              }
              list.init(parent, sort);
              return list;
          }
  
          public void recycle() {
              clear();
              sPool.release(this);
          }
  
          public int getChildCount() {
              return mChildren.size();
          }
  
          public View getChildAt(int index) {
              return mChildren.get(index);
          }
  
          private void init(ViewGroup parent, boolean sort) {
              ArrayList<View> children = mChildren;
              final int childCount = parent.getChildCount();
              for (int i = 0; i < childCount; i++) {
                  View child = parent.getChildAt(i);
                  children.add(child);
              }
              if (sort) {
                  ArrayList<ViewLocationHolder> holders = mHolders;
                  for (int i = 0; i < childCount; i++) {
                      View child = children.get(i);
                      ViewLocationHolder holder = ViewLocationHolder.obtain(parent, child);
                      holders.add(holder);
                  }
                  sort(holders);
                  for (int i = 0; i < childCount; i++) {
                      ViewLocationHolder holder = holders.get(i);
                      children.set(i, holder.mView);
                      holder.recycle();
                  }
                  holders.clear();
              }
          }
  
          private void sort(ArrayList<ViewLocationHolder> holders) {
              // This is gross but the least risky solution. The current comparison
              // strategy breaks transitivity but produces very good results. Coming
              // up with a new strategy requires time which we do not have, so ...
              try {
                  ViewLocationHolder.setComparisonStrategy(
                          ViewLocationHolder.COMPARISON_STRATEGY_STRIPE);
                  Collections.sort(holders);
              } catch (IllegalArgumentException iae) {
                  // Note that in practice this occurs extremely rarely in a couple
                  // of pathological cases.
                  ViewLocationHolder.setComparisonStrategy(
                          ViewLocationHolder.COMPARISON_STRATEGY_LOCATION);
                  Collections.sort(holders);
              }
          }
  
          private void clear() {
              mChildren.clear();
          }
      }
  
      /**
       * Pooled class that holds a View and its location with respect to
       * a specified root. This enables sorting of views based on their
       * coordinates without recomputing the position relative to the root
       * on every comparison.
       */
      static class ViewLocationHolder implements Comparable<ViewLocationHolder> {
  
          private static final int MAX_POOL_SIZE = 32;
  
          private static final SynchronizedPool<ViewLocationHolder> sPool =
                  new SynchronizedPool<ViewLocationHolder>(MAX_POOL_SIZE);
  
          public static final int COMPARISON_STRATEGY_STRIPE = 1;
  
          public static final int COMPARISON_STRATEGY_LOCATION = 2;
  
          private static int sComparisonStrategy = COMPARISON_STRATEGY_STRIPE;
  
          private final Rect mLocation = new Rect();
  
          private ViewGroup mRoot;
  
          public View mView;
  
          private int mLayoutDirection;
  
          public static ViewLocationHolder obtain(ViewGroup root, View view) {
              ViewLocationHolder holder = sPool.acquire();
              if (holder == null) {
                  holder = new ViewLocationHolder();
              }
              holder.init(root, view);
              return holder;
          }
  
          public static void setComparisonStrategy(int strategy) {
              sComparisonStrategy = strategy;
          }
  
          public void recycle() {
              clear();
              sPool.release(this);
          }
  
          @Override
          public int compareTo(ViewLocationHolder another) {
              // This instance is greater than an invalid argument.
              if (another == null) {
                  return 1;
              }
  
              int boundsResult = compareBoundsOfTree(this, another);
              if (boundsResult != 0) {
                  return boundsResult;
              }
  
              // Just break the tie somehow. The accessibility ids are unique
              // and stable, hence this is deterministic tie breaking.
              return mView.getAccessibilityViewId() - another.mView.getAccessibilityViewId();
          }
  
          /**
           * Compare two views based on their bounds. Use the bounds of their children to break ties.
           *
           * @param holder1 Holder of first view to compare
           * @param holder2 Holder of second view to compare. Must have the same root as holder1.
           * @return The compare result, with equality if no good comparison was found.
           */
          private static int compareBoundsOfTree(
                  ViewLocationHolder holder1, ViewLocationHolder holder2) {
              if (sComparisonStrategy == COMPARISON_STRATEGY_STRIPE) {
                  // First is above second.
                  if (holder1.mLocation.bottom - holder2.mLocation.top <= 0) {
                      return -1;
                  }
                  // First is below second.
                  if (holder1.mLocation.top - holder2.mLocation.bottom >= 0) {
                      return 1;
                  }
              }
  
              // We are ordering left-to-right, top-to-bottom.
              if (holder1.mLayoutDirection == LAYOUT_DIRECTION_LTR) {
                  final int leftDifference = holder1.mLocation.left - holder2.mLocation.left;
                  if (leftDifference != 0) {
                      return leftDifference;
                  }
              } else { // RTL
                  final int rightDifference = holder1.mLocation.right - holder2.mLocation.right;
                  if (rightDifference != 0) {
                      return -rightDifference;
                  }
              }
              // We are ordering left-to-right, top-to-bottom.
              final int topDifference = holder1.mLocation.top - holder2.mLocation.top;
              if (topDifference != 0) {
                  return topDifference;
              }
              // Break tie by height.
              final int heightDiference = holder1.mLocation.height() - holder2.mLocation.height();
              if (heightDiference != 0) {
                  return -heightDiference;
              }
              // Break tie by width.
              final int widthDifference = holder1.mLocation.width() - holder2.mLocation.width();
              if (widthDifference != 0) {
                  return -widthDifference;
              }
  
              // Find a child of each view with different screen bounds.
              final Rect view1Bounds = new Rect();
              final Rect view2Bounds = new Rect();
              final Rect tempRect = new Rect();
              holder1.mView.getBoundsOnScreen(view1Bounds, true);
              holder2.mView.getBoundsOnScreen(view2Bounds, true);
              final View child1 = holder1.mView.findViewByPredicateTraversal((view) -> {
                  view.getBoundsOnScreen(tempRect, true);
                  return !tempRect.equals(view1Bounds);
              }, null);
              final View child2 = holder2.mView.findViewByPredicateTraversal((view) -> {
                  view.getBoundsOnScreen(tempRect, true);
                  return !tempRect.equals(view2Bounds);
              }, null);
  
  
              // Compare the children recursively
              if ((child1 != null) && (child2 != null)) {
                  final ViewLocationHolder childHolder1 =
                          ViewLocationHolder.obtain(holder1.mRoot, child1);
                  final ViewLocationHolder childHolder2 =
                          ViewLocationHolder.obtain(holder1.mRoot, child2);
                  return compareBoundsOfTree(childHolder1, childHolder2);
              }
  
              // If only one has a child, use that one
              if (child1 != null) {
                  return 1;
              }
  
              if (child2 != null) {
                  return -1;
              }
  
              // Give up
              return 0;
          }
  
          private void init(ViewGroup root, View view) {
              Rect viewLocation = mLocation;
              view.getDrawingRect(viewLocation);
              root.offsetDescendantRectToMyCoords(view, viewLocation);
              mView = view;
              mRoot = root;
              mLayoutDirection = root.getLayoutDirection();
          }
  
          private void clear() {
              mView = null;
              mRoot = null;
              mLocation.set(0, 0, 0, 0);
          }
      }
  
      private static void drawRect(Canvas canvas, Paint paint, int x1, int y1, int x2, int y2) {
          if (sDebugLines== null) {
              // TODO: This won't work with multiple UI threads in a single process
              sDebugLines = new float[16];
          }
  
          sDebugLines[0] = x1;
          sDebugLines[1] = y1;
          sDebugLines[2] = x2;
          sDebugLines[3] = y1;
  
          sDebugLines[4] = x2;
          sDebugLines[5] = y1;
          sDebugLines[6] = x2;
          sDebugLines[7] = y2;
  
          sDebugLines[8] = x2;
          sDebugLines[9] = y2;
          sDebugLines[10] = x1;
          sDebugLines[11] = y2;
  
          sDebugLines[12] = x1;
          sDebugLines[13] = y2;
          sDebugLines[14] = x1;
          sDebugLines[15] = y1;
  
          canvas.drawLines(sDebugLines, paint);
      }
  
      /** @hide */
      @Override
      @UnsupportedAppUsage
      protected void encodeProperties(@NonNull ViewHierarchyEncoder encoder) {
          super.encodeProperties(encoder);
  
          encoder.addProperty("focus:descendantFocusability", getDescendantFocusability());
          encoder.addProperty("drawing:clipChildren", getClipChildren());
          encoder.addProperty("drawing:clipToPadding", getClipToPadding());
          encoder.addProperty("drawing:childrenDrawingOrderEnabled", isChildrenDrawingOrderEnabled());
          encoder.addProperty("drawing:persistentDrawingCache", getPersistentDrawingCache());
  
          int n = getChildCount();
          encoder.addProperty("meta:__childCount__", (short)n);
          for (int i = 0; i < n; i++) {
              encoder.addPropertyKey("meta:__child__" + i);
              getChildAt(i).encode(encoder);
          }
      }
  }
  