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 android.annotation.NonNull;
  import android.graphics.Rect;
  import android.graphics.Region;
  import android.os.Bundle;
  import android.view.accessibility.AccessibilityEvent;
  
  /**
   * Defines the responsibilities for a class that will be a parent of a View.
   * This is the API that a view sees when it wants to interact with its parent.
   * 
   */
  public interface ViewParent {
      /**
       * Called when something has changed which has invalidated the layout of a
       * child of this view parent. This will schedule a layout pass of the view
       * tree.
       */
      public void requestLayout();
  
      /**
       * Indicates whether layout was requested on this view parent.
       *
       * @return true if layout was requested, false otherwise
       */
      public boolean isLayoutRequested();
  
      /**
       * Called when a child wants the view hierarchy to gather and report
       * transparent regions to the window compositor. Views that "punch" holes in
       * the view hierarchy, such as SurfaceView can use this API to improve
       * performance of the system. When no such a view is present in the
       * hierarchy, this optimization in unnecessary and might slightly reduce the
       * view hierarchy performance.
       * 
       * @param child the view requesting the transparent region computation
       * 
       */
      public void requestTransparentRegion(View child);
  
  
      /**
       * The target View has been invalidated, or has had a drawing property changed that
       * requires the hierarchy to re-render.
       *
       * This method is called by the View hierarchy to signal ancestors that a View either needs to
       * re-record its drawing commands, or drawing properties have changed. This is how Views
       * schedule a drawing traversal.
       *
       * This signal is generally only dispatched for attached Views, since only they need to draw.
       *
       * @param child Direct child of this ViewParent containing target
       * @param target The view that needs to redraw
       */
      default void onDescendantInvalidated(@NonNull View child, @NonNull View target) {
          if (getParent() != null) {
              // Note: should pass 'this' as default, but can't since we may not be a View
              getParent().onDescendantInvalidated(child, target);
          }
      }
  
      /**
       * All or part of a child is dirty and needs to be redrawn.
       * 
       * @param child The child which is dirty
       * @param r The area within the child that is invalid
       *
       * @deprecated Use {@link #onDescendantInvalidated(View, View)} instead.
       */
      @Deprecated
      public void invalidateChild(View child, Rect r);
  
      /**
       * All or part of a child is dirty and needs to be redrawn.
       *
       * <p>The location array is an array of two int values which respectively
       * define the left and the top position of the dirty child.</p>
       *
       * <p>This method must return the parent of this ViewParent if the specified
       * rectangle must be invalidated in the parent. If the specified rectangle
       * does not require invalidation in the parent or if the parent does not
       * exist, this method must return null.</p>
       *
       * <p>When this method returns a non-null value, the location array must
       * have been updated with the left and top coordinates of this ViewParent.</p>
       *
       * @param location An array of 2 ints containing the left and top
       *        coordinates of the child to invalidate
       * @param r The area within the child that is invalid
       *
       * @return the parent of this ViewParent or null
       *
       * @deprecated Use {@link #onDescendantInvalidated(View, View)} instead.
       */
      @Deprecated
      public ViewParent invalidateChildInParent(int[] location, Rect r);
  
      /**
       * Returns the parent if it exists, or null.
       *
       * @return a ViewParent or null if this ViewParent does not have a parent
       */
      public ViewParent getParent();
  
      /**
       * Called when a child of this parent wants focus
       * 
       * @param child The child of this ViewParent that wants focus. This view
       *        will contain the focused view. It is not necessarily the view that
       *        actually has focus.
       * @param focused The view that is a descendant of child that actually has
       *        focus
       */
      public void requestChildFocus(View child, View focused);
  
      /**
       * Tell view hierarchy that the global view attributes need to be
       * re-evaluated.
       * 
       * @param child View whose attributes have changed.
       */
      public void recomputeViewAttributes(View child);
      
      /**
       * Called when a child of this parent is giving up focus
       * 
       * @param child The view that is giving up focus
       */
      public void clearChildFocus(View child);
  
      /**
       * Compute the visible part of a rectangular region defined in terms of a child view's
       * coordinates.
       *
       * <p>Returns the clipped visible part of the rectangle <code>r</code>, defined in the
       * <code>child</code>'s local coordinate system. <code>r</code> is modified by this method to
       * contain the result, expressed in the global (root) coordinate system.</p>
       *
       * <p>The resulting rectangle is always axis aligned. If a rotation is applied to a node in the
       * View hierarchy, the result is the axis-aligned bounding box of the visible rectangle.</p>
       *
       * @param child A child View, whose rectangular visible region we want to compute
       * @param r The input rectangle, defined in the child coordinate system. Will be overwritten to
       * contain the resulting visible rectangle, expressed in global (root) coordinates
       * @param offset The input coordinates of a point, defined in the child coordinate system.
       * As with the <code>r</code> parameter, this will be overwritten to contain the global (root)
       * coordinates of that point.
       * A <code>null</code> value is valid (in case you are not interested in this result)
       * @return true if the resulting rectangle is not empty, false otherwise
       */
      public boolean getChildVisibleRect(View child, Rect r, android.graphics.Point offset);
  
      /**
       * Find the nearest view in the specified direction that wants to take focus
       * 
       * @param v The view that currently has focus
       * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT
       */
      public View focusSearch(View v, int direction);
  
      /**
       * Find the nearest keyboard navigation cluster in the specified direction.
       * This does not actually give focus to that cluster.
       *
       * @param currentCluster The starting point of the search. Null means the current cluster is not
       *                       found yet
       * @param direction Direction to look
       *
       * @return The nearest keyboard navigation cluster in the specified direction, or null if none
       *         can be found
       */
      View keyboardNavigationClusterSearch(View currentCluster, int direction);
  
      /**
       * Change the z order of the child so it's on top of all other children.
       * This ordering change may affect layout, if this container
       * uses an order-dependent layout scheme (e.g., LinearLayout). Prior
       * to {@link android.os.Build.VERSION_CODES#KITKAT} this
       * method should be followed by calls to {@link #requestLayout()} and
       * {@link View#invalidate()} on this parent to force the parent to redraw
       * with the new child ordering.
       * 
       * @param child The child to bring to the top of the z order
       */
      public void bringChildToFront(View child);
  
      /**
       * Tells the parent that a new focusable view has become available. This is
       * to handle transitions from the case where there are no focusable views to
       * the case where the first focusable view appears.
       * 
       * @param v The view that has become newly focusable
       */
      public void focusableViewAvailable(View v);
  
      /**
       * Shows the context menu for the specified view or its ancestors.
       * <p>
       * In most cases, a subclass does not need to override this. However, if
       * the subclass is added directly to the window manager (for example,
       * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)})
       * then it should override this and show the context menu.
       *
       * @param originalView the source view where the context menu was first
       *                     invoked
       * @return {@code true} if the context menu was shown, {@code false}
       *         otherwise
       * @see #showContextMenuForChild(View, float, float)
       */
      public boolean showContextMenuForChild(View originalView);
  
      /**
       * Shows the context menu for the specified view or its ancestors anchored
       * to the specified view-relative coordinate.
       * <p>
       * In most cases, a subclass does not need to override this. However, if
       * the subclass is added directly to the window manager (for example,
       * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)})
       * then it should override this and show the context menu.
       * <p>
       * If a subclass overrides this method it should also override
       * {@link #showContextMenuForChild(View)}.
       *
       * @param originalView the source view where the context menu was first
       *                     invoked
       * @param x the X coordinate in pixels relative to the original view to
       *          which the menu should be anchored, or {@link Float#NaN} to
       *          disable anchoring
       * @param y the Y coordinate in pixels relative to the original view to
       *          which the menu should be anchored, or {@link Float#NaN} to
       *          disable anchoring
       * @return {@code true} if the context menu was shown, {@code false}
       *         otherwise
       */
      boolean showContextMenuForChild(View originalView, float x, float y);
  
      /**
       * Have the parent populate the specified context menu if it has anything to
       * add (and then recurse on its parent).
       * 
       * @param menu The menu to populate
       */
      public void createContextMenu(ContextMenu menu);
  
      /**
       * Start an action mode for the specified view with the default type
       * {@link ActionMode#TYPE_PRIMARY}.
       *
       * <p>In most cases, a subclass does not need to override this. However, if the
       * subclass is added directly to the window manager (for example,
       * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)})
       * then it should override this and start the action mode.</p>
       *
       * @param originalView The source view where the action mode was first invoked
       * @param callback The callback that will handle lifecycle events for the action mode
       * @return The new action mode if it was started, null otherwise
       *
       * @see #startActionModeForChild(View, android.view.ActionMode.Callback, int)
       */
      public ActionMode startActionModeForChild(View originalView, ActionMode.Callback callback);
  
      /**
       * Start an action mode of a specific type for the specified view.
       *
       * <p>In most cases, a subclass does not need to override this. However, if the
       * subclass is added directly to the window manager (for example,
       * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)})
       * then it should override this and start the action mode.</p>
       *
       * @param originalView The source view where the action mode was first invoked
       * @param callback The callback that will handle lifecycle events for the action mode
       * @param type One of {@link ActionMode#TYPE_PRIMARY} or {@link ActionMode#TYPE_FLOATING}.
       * @return The new action mode if it was started, null otherwise
       */
      public ActionMode startActionModeForChild(
              View originalView, ActionMode.Callback callback, int type);
  
      /**
       * This method is called on the parent when a child's drawable state
       * has changed.
       *
       * @param child The child whose drawable state has changed.
       */
      public void childDrawableStateChanged(View child);
  
      /**
       * Called when a child does not want this parent and its ancestors to
       * intercept touch events with
       * {@link ViewGroup#onInterceptTouchEvent(MotionEvent)}.
       *
       * <p>This parent should pass this call onto its parents. This parent must obey
       * this request for the duration of the touch (that is, only clear the flag
       * after this parent has received an up or a cancel.</p>
       * 
       * @param disallowIntercept True if the child does not want the parent to
       *            intercept touch events.
       */
      public void requestDisallowInterceptTouchEvent(boolean disallowIntercept);
  
      /**
       * Called when a child of this group wants a particular rectangle to be
       * positioned onto the screen.  {@link ViewGroup}s overriding this can trust
       * that:
       * <ul>
       *   <li>child will be a direct child of this group</li>
       *   <li>rectangle will be in the child's content coordinates</li>
       * </ul>
       *
       * <p>{@link ViewGroup}s overriding this should uphold the contract:</p>
       * <ul>
       *   <li>nothing will change if the rectangle is already visible</li>
       *   <li>the view port will be scrolled only just enough to make the
       *       rectangle visible</li>
       * <ul>
       *
       * @param child The direct child making the request.
       * @param rectangle The rectangle in the child's coordinates the child
       *        wishes to be on the screen.
       * @param immediate True to forbid animated or delayed scrolling,
       *        false otherwise
       * @return Whether the group scrolled to handle the operation
       */
      public boolean requestChildRectangleOnScreen(View child, Rect rectangle,
              boolean immediate);
  
      /**
       * Called by a child to request from its parent to send an {@link AccessibilityEvent}.
       * The child has already populated a record for itself in the event and is delegating
       * to its parent to send the event. The parent can optionally add a record for itself.
       * <p>
       * Note: An accessibility event is fired by an individual view which populates the
       *       event with a record for its state and requests from its parent to perform
       *       the sending. The parent can optionally add a record for itself before
       *       dispatching the request to its parent. A parent can also choose not to
       *       respect the request for sending the event. The accessibility event is sent
       *       by the topmost view in the view tree.</p>
       *
       * @param child The child which requests sending the event.
       * @param event The event to be sent.
       * @return True if the event was sent.
       */
      public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event);
  
      /**
       * Called when a child view now has or no longer is tracking transient state.
       *
       * <p>"Transient state" is any state that a View might hold that is not expected to
       * be reflected in the data model that the View currently presents. This state only
       * affects the presentation to the user within the View itself, such as the current
       * state of animations in progress or the state of a text selection operation.</p>
       *
       * <p>Transient state is useful for hinting to other components of the View system
       * that a particular view is tracking something complex but encapsulated.
       * A <code>ListView</code> for example may acknowledge that list item Views
       * with transient state should be preserved within their position or stable item ID
       * instead of treating that view as trivially replaceable by the backing adapter.
       * This allows adapter implementations to be simpler instead of needing to track
       * the state of item view animations in progress such that they could be restored
       * in the event of an unexpected recycling and rebinding of attached item views.</p>
       *
       * <p>This method is called on a parent view when a child view or a view within
       * its subtree begins or ends tracking of internal transient state.</p>
       *
       * @param child Child view whose state has changed
       * @param hasTransientState true if this child has transient state
       */
      public void childHasTransientStateChanged(View child, boolean hasTransientState);
  
      /**
       * Ask that a new dispatch of {@link View#fitSystemWindows(Rect)
       * View.fitSystemWindows(Rect)} be performed.
       */
      public void requestFitSystemWindows();
  
      /**
       * Gets the parent of a given View for accessibility. Since some Views are not
       * exposed to the accessibility layer the parent for accessibility is not
       * necessarily the direct parent of the View, rather it is a predecessor.
       *
       * @return The parent or <code>null</code> if no such is found.
       */
      public ViewParent getParentForAccessibility();
  
      /**
       * Notifies a view parent that the accessibility state of one of its
       * descendants has changed and that the structure of the subtree is
       * different.
       * @param child The direct child whose subtree has changed.
       * @param source The descendant view that changed. May not be {@code null}.
       * @param changeType A bit mask of the types of changes that occurred. One
       *            or more of:
       *            <ul>
       *            <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_CONTENT_DESCRIPTION}
       *            <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_SUBTREE}
       *            <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_TEXT}
       *            <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_UNDEFINED}
       *            </ul>
       */
      public void notifySubtreeAccessibilityStateChanged(
              View child, @NonNull View source, int changeType);
  
      /**
       * Tells if this view parent can resolve the layout direction.
       * See {@link View#setLayoutDirection(int)}
       *
       * @return True if this view parent can resolve the layout direction.
       */
      public boolean canResolveLayoutDirection();
  
      /**
       * Tells if this view parent layout direction is resolved.
       * See {@link View#setLayoutDirection(int)}
       *
       * @return True if this view parent layout direction is resolved.
       */
      public boolean isLayoutDirectionResolved();
  
      /**
       * Return this view parent layout direction. See {@link View#getLayoutDirection()}
       *
       * @return {@link View#LAYOUT_DIRECTION_RTL} if the layout direction is RTL or returns
       * {@link View#LAYOUT_DIRECTION_LTR} if the layout direction is not RTL.
       */
      public int getLayoutDirection();
  
      /**
       * Tells if this view parent can resolve the text direction.
       * See {@link View#setTextDirection(int)}
       *
       * @return True if this view parent can resolve the text direction.
       */
      public boolean canResolveTextDirection();
  
      /**
       * Tells if this view parent text direction is resolved.
       * See {@link View#setTextDirection(int)}
       *
       * @return True if this view parent text direction is resolved.
       */
      public boolean isTextDirectionResolved();
  
      /**
       * Return this view parent text direction. See {@link View#getTextDirection()}
       *
       * @return the resolved text direction. Returns one of:
       *
       * {@link View#TEXT_DIRECTION_FIRST_STRONG}
       * {@link View#TEXT_DIRECTION_ANY_RTL},
       * {@link View#TEXT_DIRECTION_LTR},
       * {@link View#TEXT_DIRECTION_RTL},
       * {@link View#TEXT_DIRECTION_LOCALE}
       */
      public int getTextDirection();
  
      /**
       * Tells if this view parent can resolve the text alignment.
       * See {@link View#setTextAlignment(int)}
       *
       * @return True if this view parent can resolve the text alignment.
       */
      public boolean canResolveTextAlignment();
  
      /**
       * Tells if this view parent text alignment is resolved.
       * See {@link View#setTextAlignment(int)}
       *
       * @return True if this view parent text alignment is resolved.
       */
      public boolean isTextAlignmentResolved();
  
      /**
       * Return this view parent text alignment. See {@link android.view.View#getTextAlignment()}
       *
       * @return the resolved text alignment. Returns one of:
       *
       * {@link View#TEXT_ALIGNMENT_GRAVITY},
       * {@link View#TEXT_ALIGNMENT_CENTER},
       * {@link View#TEXT_ALIGNMENT_TEXT_START},
       * {@link View#TEXT_ALIGNMENT_TEXT_END},
       * {@link View#TEXT_ALIGNMENT_VIEW_START},
       * {@link View#TEXT_ALIGNMENT_VIEW_END}
       */
      public int getTextAlignment();
  
      /**
       * React to a descendant view initiating a nestable scroll operation, claiming the
       * nested scroll operation if appropriate.
       *
       * <p>This method will be called in response to a descendant view invoking
       * {@link View#startNestedScroll(int)}. Each parent up the view hierarchy will be
       * given an opportunity to respond and claim the nested scrolling operation by returning
       * <code>true</code>.</p>
       *
       * <p>This method may be overridden by ViewParent implementations to indicate when the view
       * is willing to support a nested scrolling operation that is about to begin. If it returns
       * true, this ViewParent will become the target view's nested scrolling parent for the duration
       * of the scroll operation in progress. When the nested scroll is finished this ViewParent
       * will receive a call to {@link #onStopNestedScroll(View)}.
       * </p>
       *
       * @param child Direct child of this ViewParent containing target
       * @param target View that initiated the nested scroll
       * @param nestedScrollAxes Flags consisting of {@link View#SCROLL_AXIS_HORIZONTAL},
       *                         {@link View#SCROLL_AXIS_VERTICAL} or both
       * @return true if this ViewParent accepts the nested scroll operation
       */
      public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes);
  
      /**
       * React to the successful claiming of a nested scroll operation.
       *
       * <p>This method will be called after
       * {@link #onStartNestedScroll(View, View, int) onStartNestedScroll} returns true. It offers
       * an opportunity for the view and its superclasses to perform initial configuration
       * for the nested scroll. Implementations of this method should always call their superclass's
       * implementation of this method if one is present.</p>
       *
       * @param child Direct child of this ViewParent containing target
       * @param target View that initiated the nested scroll
       * @param nestedScrollAxes Flags consisting of {@link View#SCROLL_AXIS_HORIZONTAL},
       *                         {@link View#SCROLL_AXIS_VERTICAL} or both
       * @see #onStartNestedScroll(View, View, int)
       * @see #onStopNestedScroll(View)
       */
      public void onNestedScrollAccepted(View child, View target, int nestedScrollAxes);
  
      /**
       * React to a nested scroll operation ending.
       *
       * <p>Perform cleanup after a nested scrolling operation.
       * This method will be called when a nested scroll stops, for example when a nested touch
       * scroll ends with a {@link MotionEvent#ACTION_UP} or {@link MotionEvent#ACTION_CANCEL} event.
       * Implementations of this method should always call their superclass's implementation of this
       * method if one is present.</p>
       *
       * @param target View that initiated the nested scroll
       */
      public void onStopNestedScroll(View target);
  
      /**
       * React to a nested scroll in progress.
       *
       * <p>This method will be called when the ViewParent's current nested scrolling child view
       * dispatches a nested scroll event. To receive calls to this method the ViewParent must have
       * previously returned <code>true</code> for a call to
       * {@link #onStartNestedScroll(View, View, int)}.</p>
       *
       * <p>Both the consumed and unconsumed portions of the scroll distance are reported to the
       * ViewParent. An implementation may choose to use the consumed portion to match or chase scroll
       * position of multiple child elements, for example. The unconsumed portion may be used to
       * allow continuous dragging of multiple scrolling or draggable elements, such as scrolling
       * a list within a vertical drawer where the drawer begins dragging once the edge of inner
       * scrolling content is reached.</p>
       *
       * @param target The descendent view controlling the nested scroll
       * @param dxConsumed Horizontal scroll distance in pixels already consumed by target
       * @param dyConsumed Vertical scroll distance in pixels already consumed by target
       * @param dxUnconsumed Horizontal scroll distance in pixels not consumed by target
       * @param dyUnconsumed Vertical scroll distance in pixels not consumed by target
       */
      public void onNestedScroll(View target, int dxConsumed, int dyConsumed,
              int dxUnconsumed, int dyUnconsumed);
  
      /**
       * React to a nested scroll in progress before the target view consumes a portion of the scroll.
       *
       * <p>When working with nested scrolling often the parent view may want an opportunity
       * to consume the scroll before the nested scrolling child does. An example of this is a
       * drawer that contains a scrollable list. The user will want to be able to scroll the list
       * fully into view before the list itself begins scrolling.</p>
       *
       * <p><code>onNestedPreScroll</code> is called when a nested scrolling child invokes
       * {@link View#dispatchNestedPreScroll(int, int, int[], int[])}. The implementation should
       * report how any pixels of the scroll reported by dx, dy were consumed in the
       * <code>consumed</code> array. Index 0 corresponds to dx and index 1 corresponds to dy.
       * This parameter will never be null. Initial values for consumed[0] and consumed[1]
       * will always be 0.</p>
       *
       * @param target View that initiated the nested scroll
       * @param dx Horizontal scroll distance in pixels
       * @param dy Vertical scroll distance in pixels
       * @param consumed Output. The horizontal and vertical scroll distance consumed by this parent
       */
      public void onNestedPreScroll(View target, int dx, int dy, int[] consumed);
  
      /**
       * Request a fling from a nested scroll.
       *
       * <p>This method signifies that a nested scrolling child has detected suitable conditions
       * for a fling. Generally this means that a touch scroll has ended with a
       * {@link VelocityTracker velocity} in the direction of scrolling that meets or exceeds
       * the {@link ViewConfiguration#getScaledMinimumFlingVelocity() minimum fling velocity}
       * along a scrollable axis.</p>
       *
       * <p>If a nested scrolling child view would normally fling but it is at the edge of
       * its own content, it can use this method to delegate the fling to its nested scrolling
       * parent instead. The parent may optionally consume the fling or observe a child fling.</p>
       *
       * @param target View that initiated the nested scroll
       * @param velocityX Horizontal velocity in pixels per second
       * @param velocityY Vertical velocity in pixels per second
       * @param consumed true if the child consumed the fling, false otherwise
       * @return true if this parent consumed or otherwise reacted to the fling
       */
      public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed);
  
      /**
       * React to a nested fling before the target view consumes it.
       *
       * <p>This method siginfies that a nested scrolling child has detected a fling with the given
       * velocity along each axis. Generally this means that a touch scroll has ended with a
       * {@link VelocityTracker velocity} in the direction of scrolling that meets or exceeds
       * the {@link ViewConfiguration#getScaledMinimumFlingVelocity() minimum fling velocity}
       * along a scrollable axis.</p>
       *
       * <p>If a nested scrolling parent is consuming motion as part of a
       * {@link #onNestedPreScroll(View, int, int, int[]) pre-scroll}, it may be appropriate for
       * it to also consume the pre-fling to complete that same motion. By returning
       * <code>true</code> from this method, the parent indicates that the child should not
       * fling its own internal content as well.</p>
       *
       * @param target View that initiated the nested scroll
       * @param velocityX Horizontal velocity in pixels per second
       * @param velocityY Vertical velocity in pixels per second
       * @return true if this parent consumed the fling ahead of the target view
       */
      public boolean onNestedPreFling(View target, float velocityX, float velocityY);
  
      /**
       * React to an accessibility action delegated by a target descendant view before the target
       * processes it.
       *
       * <p>This method may be called by a target descendant view if the target wishes to give
       * a view in its parent chain a chance to react to the event before normal processing occurs.
       * Most commonly this will be a scroll event such as
       * {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_SCROLL_FORWARD}.
       * A ViewParent that supports acting as a nested scrolling parent should override this
       * method and act accordingly to implement scrolling via accesibility systems.</p>
       *
       * @param target The target view dispatching this action
       * @param action Action being performed; see
       *               {@link android.view.accessibility.AccessibilityNodeInfo}
       * @param arguments Optional action arguments
       * @return true if the action was consumed by this ViewParent
       */
      public boolean onNestedPrePerformAccessibilityAction(View target, int action, Bundle arguments);
  
      /**
       * Given a touchable region of a child, this method reduces region by the bounds of all views on
       * top of the child for which {@link View#canReceivePointerEvents} returns {@code true}. This
       * applies recursively for all views in the view hierarchy on top of this one.
       *
       * @param touchableRegion The touchable region we want to modify.
       * @param view A child view of this ViewGroup which indicates the z-order of the touchable
       *             region.
       * @hide
       */
      default void subtractObscuredTouchableRegion(Region touchableRegion, View view) {
      }
  }
  