content: /*
   * Copyright (C) 2015 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.widget;
  
  import android.os.SystemClock;
  import android.view.MotionEvent;
  import android.view.View;
  import android.view.ViewConfiguration;
  import android.view.ViewParent;
  
  import com.android.internal.view.menu.ShowableListMenu;
  
  /**
   * Abstract class that forwards touch events to a {@link ShowableListMenu}.
   *
   * @hide
   */
  public abstract class ForwardingListener
          implements View.OnTouchListener, View.OnAttachStateChangeListener {
  
      /** Scaled touch slop, used for detecting movement outside bounds. */
      private final float mScaledTouchSlop;
  
      /** Timeout before disallowing intercept on the source's parent. */
      private final int mTapTimeout;
  
      /** Timeout before accepting a long-press to start forwarding. */
      private final int mLongPressTimeout;
  
      /** Source view from which events are forwarded. */
      private final View mSrc;
  
      /** Runnable used to prevent conflicts with scrolling parents. */
      private Runnable mDisallowIntercept;
  
      /** Runnable used to trigger forwarding on long-press. */
      private Runnable mTriggerLongPress;
  
      /** Whether this listener is currently forwarding touch events. */
      private boolean mForwarding;
  
      /** The id of the first pointer down in the current event stream. */
      private int mActivePointerId;
  
      public ForwardingListener(View src) {
          mSrc = src;
          src.setLongClickable(true);
          src.addOnAttachStateChangeListener(this);
  
          mScaledTouchSlop = ViewConfiguration.get(src.getContext()).getScaledTouchSlop();
          mTapTimeout = ViewConfiguration.getTapTimeout();
  
          // Use a medium-press timeout. Halfway between tap and long-press.
          mLongPressTimeout = (mTapTimeout + ViewConfiguration.getLongPressTimeout()) / 2;
      }
  
      /**
       * Returns the popup to which this listener is forwarding events.
       * <p>
       * Override this to return the correct popup. If the popup is displayed
       * asynchronously, you may also need to override
       * {@link #onForwardingStopped} to prevent premature cancellation of
       * forwarding.
       *
       * @return the popup to which this listener is forwarding events
       */
      public abstract ShowableListMenu getPopup();
  
      @Override
      public boolean onTouch(View v, MotionEvent event) {
          final boolean wasForwarding = mForwarding;
          final boolean forwarding;
          if (wasForwarding) {
              forwarding = onTouchForwarded(event) || !onForwardingStopped();
          } else {
              forwarding = onTouchObserved(event) && onForwardingStarted();
  
              if (forwarding) {
                  // Make sure we cancel any ongoing source event stream.
                  final long now = SystemClock.uptimeMillis();
                  final MotionEvent e = MotionEvent.obtain(now, now, MotionEvent.ACTION_CANCEL,
                          0.0f, 0.0f, 0);
                  mSrc.onTouchEvent(e);
                  e.recycle();
              }
          }
  
          mForwarding = forwarding;
          return forwarding || wasForwarding;
      }
  
      @Override
      public void onViewAttachedToWindow(View v) {
      }
  
      @Override
      public void onViewDetachedFromWindow(View v) {
          mForwarding = false;
          mActivePointerId = MotionEvent.INVALID_POINTER_ID;
  
          if (mDisallowIntercept != null) {
              mSrc.removeCallbacks(mDisallowIntercept);
          }
      }
  
      /**
       * Called when forwarding would like to start.
       * <p>
       * By default, this will show the popup returned by {@link #getPopup()}.
       * It may be overridden to perform another action, like clicking the
       * source view or preparing the popup before showing it.
       *
       * @return true to start forwarding, false otherwise
       */
      protected boolean onForwardingStarted() {
          final ShowableListMenu popup = getPopup();
          if (popup != null && !popup.isShowing()) {
              popup.show();
          }
          return true;
      }
  
      /**
       * Called when forwarding would like to stop.
       * <p>
       * By default, this will dismiss the popup returned by
       * {@link #getPopup()}. It may be overridden to perform some other
       * action.
       *
       * @return true to stop forwarding, false otherwise
       */
      protected boolean onForwardingStopped() {
          final ShowableListMenu popup = getPopup();
          if (popup != null && popup.isShowing()) {
              popup.dismiss();
          }
          return true;
      }
  
      /**
       * Observes motion events and determines when to start forwarding.
       *
       * @param srcEvent motion event in source view coordinates
       * @return true to start forwarding motion events, false otherwise
       */
      private boolean onTouchObserved(MotionEvent srcEvent) {
          final View src = mSrc;
          if (!src.isEnabled()) {
              return false;
          }
  
          final int actionMasked = srcEvent.getActionMasked();
          switch (actionMasked) {
              case MotionEvent.ACTION_DOWN:
                  mActivePointerId = srcEvent.getPointerId(0);
  
                  if (mDisallowIntercept == null) {
                      mDisallowIntercept = new DisallowIntercept();
                  }
                  src.postDelayed(mDisallowIntercept, mTapTimeout);
  
                  if (mTriggerLongPress == null) {
                      mTriggerLongPress = new TriggerLongPress();
                  }
                  src.postDelayed(mTriggerLongPress, mLongPressTimeout);
                  break;
              case MotionEvent.ACTION_MOVE:
                  final int activePointerIndex = srcEvent.findPointerIndex(mActivePointerId);
                  if (activePointerIndex >= 0) {
                      final float x = srcEvent.getX(activePointerIndex);
                      final float y = srcEvent.getY(activePointerIndex);
  
                      // Has the pointer moved outside of the view?
                      if (!src.pointInView(x, y, mScaledTouchSlop)) {
                          clearCallbacks();
  
                          // Don't let the parent intercept our events.
                          src.getParent().requestDisallowInterceptTouchEvent(true);
                          return true;
                      }
                  }
                  break;
              case MotionEvent.ACTION_CANCEL:
              case MotionEvent.ACTION_UP:
                  clearCallbacks();
                  break;
          }
  
          return false;
      }
  
      private void clearCallbacks() {
          if (mTriggerLongPress != null) {
              mSrc.removeCallbacks(mTriggerLongPress);
          }
  
          if (mDisallowIntercept != null) {
              mSrc.removeCallbacks(mDisallowIntercept);
          }
      }
  
      private void onLongPress() {
          clearCallbacks();
  
          final View src = mSrc;
          if (!src.isEnabled() || src.isLongClickable()) {
              // Ignore long-press if the view is disabled or has its own
              // handler.
              return;
          }
  
          if (!onForwardingStarted()) {
              return;
          }
  
          // Don't let the parent intercept our events.
          src.getParent().requestDisallowInterceptTouchEvent(true);
  
          // Make sure we cancel any ongoing source event stream.
          final long now = SystemClock.uptimeMillis();
          final MotionEvent e = MotionEvent.obtain(now, now, MotionEvent.ACTION_CANCEL, 0, 0, 0);
          src.onTouchEvent(e);
          e.recycle();
  
          mForwarding = true;
      }
  
      /**
       * Handles forwarded motion events and determines when to stop
       * forwarding.
       *
       * @param srcEvent motion event in source view coordinates
       * @return true to continue forwarding motion events, false to cancel
       */
      private boolean onTouchForwarded(MotionEvent srcEvent) {
          final View src = mSrc;
          final ShowableListMenu popup = getPopup();
          if (popup == null || !popup.isShowing()) {
              return false;
          }
  
          final DropDownListView dst = (DropDownListView) popup.getListView();
          if (dst == null || !dst.isShown()) {
              return false;
          }
  
          // Convert event to destination-local coordinates.
          final MotionEvent dstEvent = MotionEvent.obtainNoHistory(srcEvent);
          src.toGlobalMotionEvent(dstEvent);
          dst.toLocalMotionEvent(dstEvent);
  
          // Forward converted event to destination view, then recycle it.
          final boolean handled = dst.onForwardedEvent(dstEvent, mActivePointerId);
          dstEvent.recycle();
  
          // Always cancel forwarding when the touch stream ends.
          final int action = srcEvent.getActionMasked();
          final boolean keepForwarding = action != MotionEvent.ACTION_UP
                  && action != MotionEvent.ACTION_CANCEL;
  
          return handled && keepForwarding;
      }
  
      private class DisallowIntercept implements Runnable {
          @Override
          public void run() {
              final ViewParent parent = mSrc.getParent();
              if (parent != null) {
                  parent.requestDisallowInterceptTouchEvent(true);
              }
          }
      }
  
      private class TriggerLongPress implements Runnable {
          @Override
          public void run() {
              onLongPress();
          }
      }
  }
  