SystemGesturesPointerEventListener.java revision a4d22d718affbc7145d1012157feb819557b5c06 
1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.server.policy;
18
19import android.content.Context;
20import android.os.Handler;
21import android.os.Looper;
22import android.os.SystemClock;
23import android.util.Slog;
24import android.view.GestureDetector;
25import android.view.MotionEvent;
26import android.view.WindowManagerPolicy.PointerEventListener;
27import android.widget.OverScroller;
28
29/*
30 * Listens for system-wide input gestures, firing callbacks when detected.
31 * @hide
32 */
33public class SystemGesturesPointerEventListener implements PointerEventListener {
34    private static final String TAG = "SystemGestures";
35    private static final boolean DEBUG = false;
36    private static final long SWIPE_TIMEOUT_MS = 500;
37    private static final int MAX_TRACKED_POINTERS = 32;  // max per input system
38    private static final int UNTRACKED_POINTER = -1;
39    private static final int MAX_FLING_TIME_MILLIS = 5000;
40
41    private static final int SWIPE_NONE = 0;
42    private static final int SWIPE_FROM_TOP = 1;
43    private static final int SWIPE_FROM_BOTTOM = 2;
44    private static final int SWIPE_FROM_RIGHT = 3;
45
46    private final Context mContext;
47    private final int mSwipeStartThreshold;
48    private final int mSwipeDistanceThreshold;
49    private final Callbacks mCallbacks;
50    private final int[] mDownPointerId = new int[MAX_TRACKED_POINTERS];
51    private final float[] mDownX = new float[MAX_TRACKED_POINTERS];
52    private final float[] mDownY = new float[MAX_TRACKED_POINTERS];
53    private final long[] mDownTime = new long[MAX_TRACKED_POINTERS];
54
55    private GestureDetector mGestureDetector;
56    private OverScroller mOverscroller;
57
58    int screenHeight;
59    int screenWidth;
60    private int mDownPointers;
61    private boolean mSwipeFireable;
62    private boolean mDebugFireable;
63    private long mLastFlingTime;
64
65    public SystemGesturesPointerEventListener(Context context, Callbacks callbacks) {
66        mContext = context;
67        mCallbacks = checkNull("callbacks", callbacks);
68        mSwipeStartThreshold = checkNull("context", context).getResources()
69                .getDimensionPixelSize(com.android.internal.R.dimen.status_bar_height);
70        mSwipeDistanceThreshold = mSwipeStartThreshold;
71        if (DEBUG) Slog.d(TAG,  "mSwipeStartThreshold=" + mSwipeStartThreshold
72                + " mSwipeDistanceThreshold=" + mSwipeDistanceThreshold);
73    }
74
75    private static <T> T checkNull(String name, T arg) {
76        if (arg == null) {
77            throw new IllegalArgumentException(name + " must not be null");
78        }
79        return arg;
80    }
81
82    public void systemReady() {
83        Handler h = new Handler(Looper.myLooper());
84        mGestureDetector = new GestureDetector(mContext, new FlingGestureDetector(), h);
85        mOverscroller = new OverScroller(mContext);
86    }
87
88    @Override
89    public void onPointerEvent(MotionEvent event) {
90        if (mGestureDetector != null) {
91            mGestureDetector.onTouchEvent(event);
92        }
93        switch (event.getActionMasked()) {
94            case MotionEvent.ACTION_DOWN:
95                mSwipeFireable = true;
96                mDebugFireable = true;
97                mDownPointers = 0;
98                captureDown(event, 0);
99                mCallbacks.onDown();
100                break;
101            case MotionEvent.ACTION_POINTER_DOWN:
102                captureDown(event, event.getActionIndex());
103                if (mDebugFireable) {
104                    mDebugFireable = event.getPointerCount() < 5;
105                    if (!mDebugFireable) {
106                        if (DEBUG) Slog.d(TAG, "Firing debug");
107                        mCallbacks.onDebug();
108                    }
109                }
110                break;
111            case MotionEvent.ACTION_MOVE:
112                if (mSwipeFireable) {
113                    final int swipe = detectSwipe(event);
114                    mSwipeFireable = swipe == SWIPE_NONE;
115                    if (swipe == SWIPE_FROM_TOP) {
116                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromTop");
117                        mCallbacks.onSwipeFromTop();
118                    } else if (swipe == SWIPE_FROM_BOTTOM) {
119                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromBottom");
120                        mCallbacks.onSwipeFromBottom();
121                    } else if (swipe == SWIPE_FROM_RIGHT) {
122                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromRight");
123                        mCallbacks.onSwipeFromRight();
124                    }
125                }
126                break;
127            case MotionEvent.ACTION_UP:
128            case MotionEvent.ACTION_CANCEL:
129                mSwipeFireable = false;
130                mDebugFireable = false;
131                mCallbacks.onUpOrCancel();
132                break;
133            default:
134                if (DEBUG) Slog.d(TAG, "Ignoring " + event);
135        }
136    }
137
138    private void captureDown(MotionEvent event, int pointerIndex) {
139        final int pointerId = event.getPointerId(pointerIndex);
140        final int i = findIndex(pointerId);
141        if (DEBUG) Slog.d(TAG, "pointer " + pointerId +
142                " down pointerIndex=" + pointerIndex + " trackingIndex=" + i);
143        if (i != UNTRACKED_POINTER) {
144            mDownX[i] = event.getX(pointerIndex);
145            mDownY[i] = event.getY(pointerIndex);
146            mDownTime[i] = event.getEventTime();
147            if (DEBUG) Slog.d(TAG, "pointer " + pointerId +
148                    " down x=" + mDownX[i] + " y=" + mDownY[i]);
149        }
150    }
151
152    private int findIndex(int pointerId) {
153        for (int i = 0; i < mDownPointers; i++) {
154            if (mDownPointerId[i] == pointerId) {
155                return i;
156            }
157        }
158        if (mDownPointers == MAX_TRACKED_POINTERS || pointerId == MotionEvent.INVALID_POINTER_ID) {
159            return UNTRACKED_POINTER;
160        }
161        mDownPointerId[mDownPointers++] = pointerId;
162        return mDownPointers - 1;
163    }
164
165    private int detectSwipe(MotionEvent move) {
166        final int historySize = move.getHistorySize();
167        final int pointerCount = move.getPointerCount();
168        for (int p = 0; p < pointerCount; p++) {
169            final int pointerId = move.getPointerId(p);
170            final int i = findIndex(pointerId);
171            if (i != UNTRACKED_POINTER) {
172                for (int h = 0; h < historySize; h++) {
173                    final long time = move.getHistoricalEventTime(h);
174                    final float x = move.getHistoricalX(p, h);
175                    final float y = move.getHistoricalY(p,  h);
176                    final int swipe = detectSwipe(i, time, x, y);
177                    if (swipe != SWIPE_NONE) {
178                        return swipe;
179                    }
180                }
181                final int swipe = detectSwipe(i, move.getEventTime(), move.getX(p), move.getY(p));
182                if (swipe != SWIPE_NONE) {
183                    return swipe;
184                }
185            }
186        }
187        return SWIPE_NONE;
188    }
189
190    private int detectSwipe(int i, long time, float x, float y) {
191        final float fromX = mDownX[i];
192        final float fromY = mDownY[i];
193        final long elapsed = time - mDownTime[i];
194        if (DEBUG) Slog.d(TAG, "pointer " + mDownPointerId[i]
195                + " moved (" + fromX + "->" + x + "," + fromY + "->" + y + ") in " + elapsed);
196        if (fromY <= mSwipeStartThreshold
197                && y > fromY + mSwipeDistanceThreshold
198                && elapsed < SWIPE_TIMEOUT_MS) {
199            return SWIPE_FROM_TOP;
200        }
201        if (fromY >= screenHeight - mSwipeStartThreshold
202                && y < fromY - mSwipeDistanceThreshold
203                && elapsed < SWIPE_TIMEOUT_MS) {
204            return SWIPE_FROM_BOTTOM;
205        }
206        if (fromX >= screenWidth - mSwipeStartThreshold
207                && x < fromX - mSwipeDistanceThreshold
208                && elapsed < SWIPE_TIMEOUT_MS) {
209            return SWIPE_FROM_RIGHT;
210        }
211        return SWIPE_NONE;
212    }
213
214    private final class FlingGestureDetector extends GestureDetector.SimpleOnGestureListener {
215        @Override
216        public boolean onSingleTapUp(MotionEvent e) {
217            if (!mOverscroller.isFinished()) {
218                mOverscroller.forceFinished(true);
219            }
220            return true;
221        }
222        @Override
223        public boolean onFling(MotionEvent down, MotionEvent up,
224                float velocityX, float velocityY) {
225            mOverscroller.computeScrollOffset();
226            long now = SystemClock.uptimeMillis();
227
228            if (mLastFlingTime != 0 && now > mLastFlingTime + MAX_FLING_TIME_MILLIS) {
229                mOverscroller.forceFinished(true);
230            }
231            mOverscroller.fling(0, 0, (int)velocityX, (int)velocityY,
232                    Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MAX_VALUE);
233            int duration = mOverscroller.getDuration();
234            if (duration > MAX_FLING_TIME_MILLIS) {
235                duration = MAX_FLING_TIME_MILLIS;
236            }
237            mLastFlingTime = now;
238            mCallbacks.onFling(duration);
239            return true;
240        }
241    }
242
243    interface Callbacks {
244        void onSwipeFromTop();
245        void onSwipeFromBottom();
246        void onSwipeFromRight();
247        void onFling(int durationMs);
248        void onDown();
249        void onUpOrCancel();
250        void onDebug();
251    }
252}
253