com/android/server/wm/SystemGesturesPointerEventListener.java - platform/prebuilts/fullsdk/sources/android-30 - Git at Google

 /*
  * Copyright (C) 2018 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 com.android.server.wm;

 import android.content.Context;
 import android.graphics.Rect;
 import android.graphics.Region;
 import android.hardware.display.DisplayManagerGlobal;
 import android.os.Handler;
 import android.os.SystemClock;
 import android.util.Slog;
 import android.view.Display;
 import android.view.DisplayCutout;
 import android.view.GestureDetector;
 import android.view.InputDevice;
 import android.view.MotionEvent;
 import android.view.WindowManagerPolicyConstants.PointerEventListener;
 import android.widget.OverScroller;

 /**
  * Listens for system-wide input gestures, firing callbacks when detected.
  * @hide
  */
 class SystemGesturesPointerEventListener implements PointerEventListener {
     private static final String TAG = "SystemGestures";
     private static final boolean DEBUG = false;
     private static final long SWIPE_TIMEOUT_MS = 500;
     private static final int MAX_TRACKED_POINTERS = 32;  // max per input system
     private static final int UNTRACKED_POINTER = -1;
     private static final int MAX_FLING_TIME_MILLIS = 5000;

     private static final int SWIPE_NONE = 0;
     private static final int SWIPE_FROM_TOP = 1;
     private static final int SWIPE_FROM_BOTTOM = 2;
     private static final int SWIPE_FROM_RIGHT = 3;
     private static final int SWIPE_FROM_LEFT = 4;

     private final Context mContext;
     private final Handler mHandler;
     private int mDisplayCutoutTouchableRegionSize;
     private int mSwipeStartThreshold;
     private int mSwipeDistanceThreshold;
     private final Callbacks mCallbacks;
     private final int[] mDownPointerId = new int[MAX_TRACKED_POINTERS];
     private final float[] mDownX = new float[MAX_TRACKED_POINTERS];
     private final float[] mDownY = new float[MAX_TRACKED_POINTERS];
     private final long[] mDownTime = new long[MAX_TRACKED_POINTERS];

     private GestureDetector mGestureDetector;

     int screenHeight;
     int screenWidth;
     private int mDownPointers;
     private boolean mSwipeFireable;
     private boolean mDebugFireable;
     private boolean mMouseHoveringAtEdge;
     private long mLastFlingTime;

     SystemGesturesPointerEventListener(Context context, Handler handler, Callbacks callbacks) {
         mContext = checkNull("context", context);
         mHandler = handler;
         mCallbacks = checkNull("callbacks", callbacks);

         onConfigurationChanged();
     }

     void onConfigurationChanged() {
         mSwipeStartThreshold = mContext.getResources()
                 .getDimensionPixelSize(com.android.internal.R.dimen.status_bar_height);

         final Display display = DisplayManagerGlobal.getInstance()
                 .getRealDisplay(Display.DEFAULT_DISPLAY);
         final DisplayCutout displayCutout = display.getCutout();
         if (displayCutout != null) {
             final Rect bounds = displayCutout.getBoundingRectTop();
             if (!bounds.isEmpty()) {
                 // Expand swipe start threshold such that we can catch touches that just start below
                 // the notch area
                 mDisplayCutoutTouchableRegionSize = mContext.getResources().getDimensionPixelSize(
                         com.android.internal.R.dimen.display_cutout_touchable_region_size);
                 mSwipeStartThreshold += mDisplayCutoutTouchableRegionSize;
             }
         }
         mSwipeDistanceThreshold = mSwipeStartThreshold;
         if (DEBUG) Slog.d(TAG,  "mSwipeStartThreshold=" + mSwipeStartThreshold
             + " mSwipeDistanceThreshold=" + mSwipeDistanceThreshold);
     }

     private static <T> T checkNull(String name, T arg) {
         if (arg == null) {
             throw new IllegalArgumentException(name + " must not be null");
         }
         return arg;
     }

     public void systemReady() {
         // GestureDetector records statistics about gesture classification events to inform gesture
         // usage trends. SystemGesturesPointerEventListener creates a lot of noise in these
         // statistics because it passes every touch event though a GestureDetector. By creating an
         // anonymous subclass of GestureDetector, these statistics will be recorded with a unique
         // source name that can be filtered.

         // GestureDetector would get a ViewConfiguration instance by context, that may also
         // create a new WindowManagerImpl for the new display, and lock WindowManagerGlobal
         // temporarily in the constructor that would make a deadlock.
         mHandler.post(() -> mGestureDetector =
                 new GestureDetector(mContext, new FlingGestureDetector(), mHandler) {});
     }

     @Override
     public void onPointerEvent(MotionEvent event) {
         if (mGestureDetector != null && event.isTouchEvent()) {
             mGestureDetector.onTouchEvent(event);
         }
         switch (event.getActionMasked()) {
             case MotionEvent.ACTION_DOWN:
                 mSwipeFireable = true;
                 mDebugFireable = true;
                 mDownPointers = 0;
                 captureDown(event, 0);
                 if (mMouseHoveringAtEdge) {
                     mMouseHoveringAtEdge = false;
                     mCallbacks.onMouseLeaveFromEdge();
                 }
                 mCallbacks.onDown();
                 break;
             case MotionEvent.ACTION_POINTER_DOWN:
                 captureDown(event, event.getActionIndex());
                 if (mDebugFireable) {
                     mDebugFireable = event.getPointerCount() < 5;
                     if (!mDebugFireable) {
                         if (DEBUG) Slog.d(TAG, "Firing debug");
                         mCallbacks.onDebug();
                     }
                 }
                 break;
             case MotionEvent.ACTION_MOVE:
                 if (mSwipeFireable) {
                     final int swipe = detectSwipe(event);
                     mSwipeFireable = swipe == SWIPE_NONE;
                     if (swipe == SWIPE_FROM_TOP) {
                         if (DEBUG) Slog.d(TAG, "Firing onSwipeFromTop");
                         mCallbacks.onSwipeFromTop();
                     } else if (swipe == SWIPE_FROM_BOTTOM) {
                         if (DEBUG) Slog.d(TAG, "Firing onSwipeFromBottom");
                         mCallbacks.onSwipeFromBottom();
                     } else if (swipe == SWIPE_FROM_RIGHT) {
                         if (DEBUG) Slog.d(TAG, "Firing onSwipeFromRight");
                         mCallbacks.onSwipeFromRight();
                     } else if (swipe == SWIPE_FROM_LEFT) {
                         if (DEBUG) Slog.d(TAG, "Firing onSwipeFromLeft");
                         mCallbacks.onSwipeFromLeft();
                     }
                 }
                 break;
             case MotionEvent.ACTION_HOVER_MOVE:
                 if (event.isFromSource(InputDevice.SOURCE_MOUSE)) {
                     if (!mMouseHoveringAtEdge && event.getY() == 0) {
                         mCallbacks.onMouseHoverAtTop();
                         mMouseHoveringAtEdge = true;
                     } else if (!mMouseHoveringAtEdge && event.getY() >= screenHeight - 1) {
                         mCallbacks.onMouseHoverAtBottom();
                         mMouseHoveringAtEdge = true;
                     } else if (mMouseHoveringAtEdge
                             && (event.getY() > 0 && event.getY() < screenHeight - 1)) {
                         mCallbacks.onMouseLeaveFromEdge();
                         mMouseHoveringAtEdge = false;
                     }
                 }
                 break;
             case MotionEvent.ACTION_UP:
             case MotionEvent.ACTION_CANCEL:
                 mSwipeFireable = false;
                 mDebugFireable = false;
                 mCallbacks.onUpOrCancel();
                 break;
             default:
                 if (DEBUG) Slog.d(TAG, "Ignoring " + event);
         }
     }

     private void captureDown(MotionEvent event, int pointerIndex) {
         final int pointerId = event.getPointerId(pointerIndex);
         final int i = findIndex(pointerId);
         if (DEBUG) Slog.d(TAG, "pointer " + pointerId
                 + " down pointerIndex=" + pointerIndex + " trackingIndex=" + i);
         if (i != UNTRACKED_POINTER) {
             mDownX[i] = event.getX(pointerIndex);
             mDownY[i] = event.getY(pointerIndex);
             mDownTime[i] = event.getEventTime();
             if (DEBUG) Slog.d(TAG, "pointer " + pointerId
                     + " down x=" + mDownX[i] + " y=" + mDownY[i]);
         }
     }

     protected boolean currentGestureStartedInRegion(Region r) {
         return r.contains((int) mDownX[0], (int) mDownY[0]);
     }

     private int findIndex(int pointerId) {
         for (int i = 0; i < mDownPointers; i++) {
             if (mDownPointerId[i] == pointerId) {
                 return i;
             }
         }
         if (mDownPointers == MAX_TRACKED_POINTERS || pointerId == MotionEvent.INVALID_POINTER_ID) {
             return UNTRACKED_POINTER;
         }
         mDownPointerId[mDownPointers++] = pointerId;
         return mDownPointers - 1;
     }

     private int detectSwipe(MotionEvent move) {
         final int historySize = move.getHistorySize();
         final int pointerCount = move.getPointerCount();
         for (int p = 0; p < pointerCount; p++) {
             final int pointerId = move.getPointerId(p);
             final int i = findIndex(pointerId);
             if (i != UNTRACKED_POINTER) {
                 for (int h = 0; h < historySize; h++) {
                     final long time = move.getHistoricalEventTime(h);
                     final float x = move.getHistoricalX(p, h);
                     final float y = move.getHistoricalY(p,  h);
                     final int swipe = detectSwipe(i, time, x, y);
                     if (swipe != SWIPE_NONE) {
                         return swipe;
                     }
                 }
                 final int swipe = detectSwipe(i, move.getEventTime(), move.getX(p), move.getY(p));
                 if (swipe != SWIPE_NONE) {
                     return swipe;
                 }
             }
         }
         return SWIPE_NONE;
     }

     private int detectSwipe(int i, long time, float x, float y) {
         final float fromX = mDownX[i];
         final float fromY = mDownY[i];
         final long elapsed = time - mDownTime[i];
         if (DEBUG) Slog.d(TAG, "pointer " + mDownPointerId[i]
                 + " moved (" + fromX + "->" + x + "," + fromY + "->" + y + ") in " + elapsed);
         if (fromY <= mSwipeStartThreshold
                 && y > fromY + mSwipeDistanceThreshold
                 && elapsed < SWIPE_TIMEOUT_MS) {
             return SWIPE_FROM_TOP;
         }
         if (fromY >= screenHeight - mSwipeStartThreshold
                 && y < fromY - mSwipeDistanceThreshold
                 && elapsed < SWIPE_TIMEOUT_MS) {
             return SWIPE_FROM_BOTTOM;
         }
         if (fromX >= screenWidth - mSwipeStartThreshold
                 && x < fromX - mSwipeDistanceThreshold
                 && elapsed < SWIPE_TIMEOUT_MS) {
             return SWIPE_FROM_RIGHT;
         }
         if (fromX <= mSwipeStartThreshold
                 && x > fromX + mSwipeDistanceThreshold
                 && elapsed < SWIPE_TIMEOUT_MS) {
             return SWIPE_FROM_LEFT;
         }
         return SWIPE_NONE;
     }

     private final class FlingGestureDetector extends GestureDetector.SimpleOnGestureListener {

         private OverScroller mOverscroller;

         FlingGestureDetector() {
             mOverscroller = new OverScroller(mContext);
         }

         @Override
         public boolean onSingleTapUp(MotionEvent e) {
             if (!mOverscroller.isFinished()) {
                 mOverscroller.forceFinished(true);
             }
             return true;
         }
         @Override
         public boolean onFling(MotionEvent down, MotionEvent up,
                 float velocityX, float velocityY) {
             mOverscroller.computeScrollOffset();
             long now = SystemClock.uptimeMillis();

             if (mLastFlingTime != 0 && now > mLastFlingTime + MAX_FLING_TIME_MILLIS) {
                 mOverscroller.forceFinished(true);
             }
             mOverscroller.fling(0, 0, (int)velocityX, (int)velocityY,
                     Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MAX_VALUE);
             int duration = mOverscroller.getDuration();
             if (duration > MAX_FLING_TIME_MILLIS) {
                 duration = MAX_FLING_TIME_MILLIS;
             }
             mLastFlingTime = now;
             mCallbacks.onFling(duration);
             return true;
         }
     }

     interface Callbacks {
         void onSwipeFromTop();
         void onSwipeFromBottom();
         void onSwipeFromRight();
         void onSwipeFromLeft();
         void onFling(int durationMs);
         void onDown();
         void onUpOrCancel();
         void onMouseHoverAtTop();
         void onMouseHoverAtBottom();
         void onMouseLeaveFromEdge();
         void onDebug();
     }
 }
	/*
	* Copyright (C) 2018 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 com.android.server.wm;

	import android.content.Context;
	import android.graphics.Rect;
	import android.graphics.Region;
	import android.hardware.display.DisplayManagerGlobal;
	import android.os.Handler;
	import android.os.SystemClock;
	import android.util.Slog;
	import android.view.Display;
	import android.view.DisplayCutout;
	import android.view.GestureDetector;
	import android.view.InputDevice;
	import android.view.MotionEvent;
	import android.view.WindowManagerPolicyConstants.PointerEventListener;
	import android.widget.OverScroller;

	/**
	* Listens for system-wide input gestures, firing callbacks when detected.
	* @hide
	*/
	class SystemGesturesPointerEventListener implements PointerEventListener {
	private static final String TAG = "SystemGestures";
	private static final boolean DEBUG = false;
	private static final long SWIPE_TIMEOUT_MS = 500;
	private static final int MAX_TRACKED_POINTERS = 32; // max per input system
	private static final int UNTRACKED_POINTER = -1;
	private static final int MAX_FLING_TIME_MILLIS = 5000;

	private static final int SWIPE_NONE = 0;
	private static final int SWIPE_FROM_TOP = 1;
	private static final int SWIPE_FROM_BOTTOM = 2;
	private static final int SWIPE_FROM_RIGHT = 3;
	private static final int SWIPE_FROM_LEFT = 4;

	private final Context mContext;
	private final Handler mHandler;
	private int mDisplayCutoutTouchableRegionSize;
	private int mSwipeStartThreshold;
	private int mSwipeDistanceThreshold;
	private final Callbacks mCallbacks;
	private final int[] mDownPointerId = new int[MAX_TRACKED_POINTERS];
	private final float[] mDownX = new float[MAX_TRACKED_POINTERS];
	private final float[] mDownY = new float[MAX_TRACKED_POINTERS];
	private final long[] mDownTime = new long[MAX_TRACKED_POINTERS];

	private GestureDetector mGestureDetector;

	int screenHeight;
	int screenWidth;
	private int mDownPointers;
	private boolean mSwipeFireable;
	private boolean mDebugFireable;
	private boolean mMouseHoveringAtEdge;
	private long mLastFlingTime;

	SystemGesturesPointerEventListener(Context context, Handler handler, Callbacks callbacks) {
	mContext = checkNull("context", context);
	mHandler = handler;
	mCallbacks = checkNull("callbacks", callbacks);

	onConfigurationChanged();
	}

	void onConfigurationChanged() {
	mSwipeStartThreshold = mContext.getResources()
	.getDimensionPixelSize(com.android.internal.R.dimen.status_bar_height);

	final Display display = DisplayManagerGlobal.getInstance()
	.getRealDisplay(Display.DEFAULT_DISPLAY);
	final DisplayCutout displayCutout = display.getCutout();
	if (displayCutout != null) {
	final Rect bounds = displayCutout.getBoundingRectTop();
	if (!bounds.isEmpty()) {
	// Expand swipe start threshold such that we can catch touches that just start below
	// the notch area
	mDisplayCutoutTouchableRegionSize = mContext.getResources().getDimensionPixelSize(
	com.android.internal.R.dimen.display_cutout_touchable_region_size);
	mSwipeStartThreshold += mDisplayCutoutTouchableRegionSize;
	}
	}
	mSwipeDistanceThreshold = mSwipeStartThreshold;
	if (DEBUG) Slog.d(TAG, "mSwipeStartThreshold=" + mSwipeStartThreshold
	+ " mSwipeDistanceThreshold=" + mSwipeDistanceThreshold);
	}

	private static <T> T checkNull(String name, T arg) {
	if (arg == null) {
	throw new IllegalArgumentException(name + " must not be null");
	}
	return arg;
	}

	public void systemReady() {
	// GestureDetector records statistics about gesture classification events to inform gesture
	// usage trends. SystemGesturesPointerEventListener creates a lot of noise in these
	// statistics because it passes every touch event though a GestureDetector. By creating an
	// anonymous subclass of GestureDetector, these statistics will be recorded with a unique
	// source name that can be filtered.

	// GestureDetector would get a ViewConfiguration instance by context, that may also
	// create a new WindowManagerImpl for the new display, and lock WindowManagerGlobal
	// temporarily in the constructor that would make a deadlock.
	mHandler.post(() -> mGestureDetector =
	new GestureDetector(mContext, new FlingGestureDetector(), mHandler) {});
	}

	@Override
	public void onPointerEvent(MotionEvent event) {
	if (mGestureDetector != null && event.isTouchEvent()) {
	mGestureDetector.onTouchEvent(event);
	}
	switch (event.getActionMasked()) {
	case MotionEvent.ACTION_DOWN:
	mSwipeFireable = true;
	mDebugFireable = true;
	mDownPointers = 0;
	captureDown(event, 0);
	if (mMouseHoveringAtEdge) {
	mMouseHoveringAtEdge = false;
	mCallbacks.onMouseLeaveFromEdge();
	}
	mCallbacks.onDown();
	break;
	case MotionEvent.ACTION_POINTER_DOWN:
	captureDown(event, event.getActionIndex());
	if (mDebugFireable) {
	mDebugFireable = event.getPointerCount() < 5;
	if (!mDebugFireable) {
	if (DEBUG) Slog.d(TAG, "Firing debug");
	mCallbacks.onDebug();
	}
	}
	break;
	case MotionEvent.ACTION_MOVE:
	if (mSwipeFireable) {
	final int swipe = detectSwipe(event);
	mSwipeFireable = swipe == SWIPE_NONE;
	if (swipe == SWIPE_FROM_TOP) {
	if (DEBUG) Slog.d(TAG, "Firing onSwipeFromTop");
	mCallbacks.onSwipeFromTop();
	} else if (swipe == SWIPE_FROM_BOTTOM) {
	if (DEBUG) Slog.d(TAG, "Firing onSwipeFromBottom");
	mCallbacks.onSwipeFromBottom();
	} else if (swipe == SWIPE_FROM_RIGHT) {
	if (DEBUG) Slog.d(TAG, "Firing onSwipeFromRight");
	mCallbacks.onSwipeFromRight();
	} else if (swipe == SWIPE_FROM_LEFT) {
	if (DEBUG) Slog.d(TAG, "Firing onSwipeFromLeft");
	mCallbacks.onSwipeFromLeft();
	}
	}
	break;
	case MotionEvent.ACTION_HOVER_MOVE:
	if (event.isFromSource(InputDevice.SOURCE_MOUSE)) {
	if (!mMouseHoveringAtEdge && event.getY() == 0) {
	mCallbacks.onMouseHoverAtTop();
	mMouseHoveringAtEdge = true;
	} else if (!mMouseHoveringAtEdge && event.getY() >= screenHeight - 1) {
	mCallbacks.onMouseHoverAtBottom();
	mMouseHoveringAtEdge = true;
	} else if (mMouseHoveringAtEdge
	&& (event.getY() > 0 && event.getY() < screenHeight - 1)) {
	mCallbacks.onMouseLeaveFromEdge();
	mMouseHoveringAtEdge = false;
	}
	}
	break;
	case MotionEvent.ACTION_UP:
	case MotionEvent.ACTION_CANCEL:
	mSwipeFireable = false;
	mDebugFireable = false;
	mCallbacks.onUpOrCancel();
	break;
	default:
	if (DEBUG) Slog.d(TAG, "Ignoring " + event);
	}
	}

	private void captureDown(MotionEvent event, int pointerIndex) {
	final int pointerId = event.getPointerId(pointerIndex);
	final int i = findIndex(pointerId);
	if (DEBUG) Slog.d(TAG, "pointer " + pointerId
	+ " down pointerIndex=" + pointerIndex + " trackingIndex=" + i);
	if (i != UNTRACKED_POINTER) {
	mDownX[i] = event.getX(pointerIndex);
	mDownY[i] = event.getY(pointerIndex);
	mDownTime[i] = event.getEventTime();
	if (DEBUG) Slog.d(TAG, "pointer " + pointerId
	+ " down x=" + mDownX[i] + " y=" + mDownY[i]);
	}
	}

	protected boolean currentGestureStartedInRegion(Region r) {
	return r.contains((int) mDownX[0], (int) mDownY[0]);
	}

	private int findIndex(int pointerId) {
	for (int i = 0; i < mDownPointers; i++) {
	if (mDownPointerId[i] == pointerId) {
	return i;
	}
	}
	if (mDownPointers == MAX_TRACKED_POINTERS \|\| pointerId == MotionEvent.INVALID_POINTER_ID) {
	return UNTRACKED_POINTER;
	}
	mDownPointerId[mDownPointers++] = pointerId;
	return mDownPointers - 1;
	}

	private int detectSwipe(MotionEvent move) {
	final int historySize = move.getHistorySize();
	final int pointerCount = move.getPointerCount();
	for (int p = 0; p < pointerCount; p++) {
	final int pointerId = move.getPointerId(p);
	final int i = findIndex(pointerId);
	if (i != UNTRACKED_POINTER) {
	for (int h = 0; h < historySize; h++) {
	final long time = move.getHistoricalEventTime(h);
	final float x = move.getHistoricalX(p, h);
	final float y = move.getHistoricalY(p, h);
	final int swipe = detectSwipe(i, time, x, y);
	if (swipe != SWIPE_NONE) {
	return swipe;
	}
	}
	final int swipe = detectSwipe(i, move.getEventTime(), move.getX(p), move.getY(p));
	if (swipe != SWIPE_NONE) {
	return swipe;
	}
	}
	}
	return SWIPE_NONE;
	}

	private int detectSwipe(int i, long time, float x, float y) {
	final float fromX = mDownX[i];
	final float fromY = mDownY[i];
	final long elapsed = time - mDownTime[i];
	if (DEBUG) Slog.d(TAG, "pointer " + mDownPointerId[i]
	+ " moved (" + fromX + "->" + x + "," + fromY + "->" + y + ") in " + elapsed);
	if (fromY <= mSwipeStartThreshold
	&& y > fromY + mSwipeDistanceThreshold
	&& elapsed < SWIPE_TIMEOUT_MS) {
	return SWIPE_FROM_TOP;
	}
	if (fromY >= screenHeight - mSwipeStartThreshold
	&& y < fromY - mSwipeDistanceThreshold
	&& elapsed < SWIPE_TIMEOUT_MS) {
	return SWIPE_FROM_BOTTOM;
	}
	if (fromX >= screenWidth - mSwipeStartThreshold
	&& x < fromX - mSwipeDistanceThreshold
	&& elapsed < SWIPE_TIMEOUT_MS) {
	return SWIPE_FROM_RIGHT;
	}
	if (fromX <= mSwipeStartThreshold
	&& x > fromX + mSwipeDistanceThreshold
	&& elapsed < SWIPE_TIMEOUT_MS) {
	return SWIPE_FROM_LEFT;
	}
	return SWIPE_NONE;
	}

	private final class FlingGestureDetector extends GestureDetector.SimpleOnGestureListener {

	private OverScroller mOverscroller;

	FlingGestureDetector() {
	mOverscroller = new OverScroller(mContext);
	}

	@Override
	public boolean onSingleTapUp(MotionEvent e) {
	if (!mOverscroller.isFinished()) {
	mOverscroller.forceFinished(true);
	}
	return true;
	}
	@Override
	public boolean onFling(MotionEvent down, MotionEvent up,
	float velocityX, float velocityY) {
	mOverscroller.computeScrollOffset();
	long now = SystemClock.uptimeMillis();

	if (mLastFlingTime != 0 && now > mLastFlingTime + MAX_FLING_TIME_MILLIS) {
	mOverscroller.forceFinished(true);
	}
	mOverscroller.fling(0, 0, (int)velocityX, (int)velocityY,
	Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MAX_VALUE);
	int duration = mOverscroller.getDuration();
	if (duration > MAX_FLING_TIME_MILLIS) {
	duration = MAX_FLING_TIME_MILLIS;
	}
	mLastFlingTime = now;
	mCallbacks.onFling(duration);
	return true;
	}
	}

	interface Callbacks {
	void onSwipeFromTop();
	void onSwipeFromBottom();
	void onSwipeFromRight();
	void onSwipeFromLeft();
	void onFling(int durationMs);
	void onDown();
	void onUpOrCancel();
	void onMouseHoverAtTop();
	void onMouseHoverAtBottom();
	void onMouseLeaveFromEdge();
	void onDebug();
	}
	}