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.InputDevice;
26import android.view.MotionEvent;
27import android.view.WindowManagerPolicy.PointerEventListener;
28import android.widget.OverScroller;
29
30/*
31 * Listens for system-wide input gestures, firing callbacks when detected.
32 * @hide
33 */
34public class SystemGesturesPointerEventListener implements PointerEventListener {
35    private static final String TAG = "SystemGestures";
36    private static final boolean DEBUG = false;
37    private static final long SWIPE_TIMEOUT_MS = 500;
38    private static final int MAX_TRACKED_POINTERS = 32;  // max per input system
39    private static final int UNTRACKED_POINTER = -1;
40    private static final int MAX_FLING_TIME_MILLIS = 5000;
41
42    private static final int SWIPE_NONE = 0;
43    private static final int SWIPE_FROM_TOP = 1;
44    private static final int SWIPE_FROM_BOTTOM = 2;
45    private static final int SWIPE_FROM_RIGHT = 3;
46
47    private final Context mContext;
48    private final int mSwipeStartThreshold;
49    private final int mSwipeDistanceThreshold;
50    private final Callbacks mCallbacks;
51    private final int[] mDownPointerId = new int[MAX_TRACKED_POINTERS];
52    private final float[] mDownX = new float[MAX_TRACKED_POINTERS];
53    private final float[] mDownY = new float[MAX_TRACKED_POINTERS];
54    private final long[] mDownTime = new long[MAX_TRACKED_POINTERS];
55
56    private GestureDetector mGestureDetector;
57    private OverScroller mOverscroller;
58
59    int screenHeight;
60    int screenWidth;
61    private int mDownPointers;
62    private boolean mSwipeFireable;
63    private boolean mDebugFireable;
64    private boolean mMouseHoveringAtEdge;
65    private long mLastFlingTime;
66
67    public SystemGesturesPointerEventListener(Context context, Callbacks callbacks) {
68        mContext = context;
69        mCallbacks = checkNull("callbacks", callbacks);
70        mSwipeStartThreshold = checkNull("context", context).getResources()
71                .getDimensionPixelSize(com.android.internal.R.dimen.status_bar_height);
72        mSwipeDistanceThreshold = mSwipeStartThreshold;
73        if (DEBUG) Slog.d(TAG,  "mSwipeStartThreshold=" + mSwipeStartThreshold
74                + " mSwipeDistanceThreshold=" + mSwipeDistanceThreshold);
75    }
76
77    private static <T> T checkNull(String name, T arg) {
78        if (arg == null) {
79            throw new IllegalArgumentException(name + " must not be null");
80        }
81        return arg;
82    }
83
84    public void systemReady() {
85        Handler h = new Handler(Looper.myLooper());
86        mGestureDetector = new GestureDetector(mContext, new FlingGestureDetector(), h);
87        mOverscroller = new OverScroller(mContext);
88    }
89
90    @Override
91    public void onPointerEvent(MotionEvent event) {
92        if (mGestureDetector != null && event.isTouchEvent()) {
93            mGestureDetector.onTouchEvent(event);
94        }
95        switch (event.getActionMasked()) {
96            case MotionEvent.ACTION_DOWN:
97                mSwipeFireable = true;
98                mDebugFireable = true;
99                mDownPointers = 0;
100                captureDown(event, 0);
101                if (mMouseHoveringAtEdge) {
102                    mMouseHoveringAtEdge = false;
103                    mCallbacks.onMouseLeaveFromEdge();
104                }
105                mCallbacks.onDown();
106                break;
107            case MotionEvent.ACTION_POINTER_DOWN:
108                captureDown(event, event.getActionIndex());
109                if (mDebugFireable) {
110                    mDebugFireable = event.getPointerCount() < 5;
111                    if (!mDebugFireable) {
112                        if (DEBUG) Slog.d(TAG, "Firing debug");
113                        mCallbacks.onDebug();
114                    }
115                }
116                break;
117            case MotionEvent.ACTION_MOVE:
118                if (mSwipeFireable) {
119                    final int swipe = detectSwipe(event);
120                    mSwipeFireable = swipe == SWIPE_NONE;
121                    if (swipe == SWIPE_FROM_TOP) {
122                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromTop");
123                        mCallbacks.onSwipeFromTop();
124                    } else if (swipe == SWIPE_FROM_BOTTOM) {
125                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromBottom");
126                        mCallbacks.onSwipeFromBottom();
127                    } else if (swipe == SWIPE_FROM_RIGHT) {
128                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromRight");
129                        mCallbacks.onSwipeFromRight();
130                    }
131                }
132                break;
133            case MotionEvent.ACTION_HOVER_MOVE:
134                if (event.isFromSource(InputDevice.SOURCE_MOUSE)) {
135                    if (!mMouseHoveringAtEdge && event.getY() == 0) {
136                        mCallbacks.onMouseHoverAtTop();
137                        mMouseHoveringAtEdge = true;
138                    } else if (!mMouseHoveringAtEdge && event.getY() >= screenHeight - 1) {
139                        mCallbacks.onMouseHoverAtBottom();
140                        mMouseHoveringAtEdge = true;
141                    } else if (mMouseHoveringAtEdge
142                            && (event.getY() > 0 && event.getY() < screenHeight - 1)) {
143                        mCallbacks.onMouseLeaveFromEdge();
144                        mMouseHoveringAtEdge = false;
145                    }
146                }
147                break;
148            case MotionEvent.ACTION_UP:
149            case MotionEvent.ACTION_CANCEL:
150                mSwipeFireable = false;
151                mDebugFireable = false;
152                mCallbacks.onUpOrCancel();
153                break;
154            default:
155                if (DEBUG) Slog.d(TAG, "Ignoring " + event);
156        }
157    }
158
159    private void captureDown(MotionEvent event, int pointerIndex) {
160        final int pointerId = event.getPointerId(pointerIndex);
161        final int i = findIndex(pointerId);
162        if (DEBUG) Slog.d(TAG, "pointer " + pointerId +
163                " down pointerIndex=" + pointerIndex + " trackingIndex=" + i);
164        if (i != UNTRACKED_POINTER) {
165            mDownX[i] = event.getX(pointerIndex);
166            mDownY[i] = event.getY(pointerIndex);
167            mDownTime[i] = event.getEventTime();
168            if (DEBUG) Slog.d(TAG, "pointer " + pointerId +
169                    " down x=" + mDownX[i] + " y=" + mDownY[i]);
170        }
171    }
172
173    private int findIndex(int pointerId) {
174        for (int i = 0; i < mDownPointers; i++) {
175            if (mDownPointerId[i] == pointerId) {
176                return i;
177            }
178        }
179        if (mDownPointers == MAX_TRACKED_POINTERS || pointerId == MotionEvent.INVALID_POINTER_ID) {
180            return UNTRACKED_POINTER;
181        }
182        mDownPointerId[mDownPointers++] = pointerId;
183        return mDownPointers - 1;
184    }
185
186    private int detectSwipe(MotionEvent move) {
187        final int historySize = move.getHistorySize();
188        final int pointerCount = move.getPointerCount();
189        for (int p = 0; p < pointerCount; p++) {
190            final int pointerId = move.getPointerId(p);
191            final int i = findIndex(pointerId);
192            if (i != UNTRACKED_POINTER) {
193                for (int h = 0; h < historySize; h++) {
194                    final long time = move.getHistoricalEventTime(h);
195                    final float x = move.getHistoricalX(p, h);
196                    final float y = move.getHistoricalY(p,  h);
197                    final int swipe = detectSwipe(i, time, x, y);
198                    if (swipe != SWIPE_NONE) {
199                        return swipe;
200                    }
201                }
202                final int swipe = detectSwipe(i, move.getEventTime(), move.getX(p), move.getY(p));
203                if (swipe != SWIPE_NONE) {
204                    return swipe;
205                }
206            }
207        }
208        return SWIPE_NONE;
209    }
210
211    private int detectSwipe(int i, long time, float x, float y) {
212        final float fromX = mDownX[i];
213        final float fromY = mDownY[i];
214        final long elapsed = time - mDownTime[i];
215        if (DEBUG) Slog.d(TAG, "pointer " + mDownPointerId[i]
216                + " moved (" + fromX + "->" + x + "," + fromY + "->" + y + ") in " + elapsed);
217        if (fromY <= mSwipeStartThreshold
218                && y > fromY + mSwipeDistanceThreshold
219                && elapsed < SWIPE_TIMEOUT_MS) {
220            return SWIPE_FROM_TOP;
221        }
222        if (fromY >= screenHeight - mSwipeStartThreshold
223                && y < fromY - mSwipeDistanceThreshold
224                && elapsed < SWIPE_TIMEOUT_MS) {
225            return SWIPE_FROM_BOTTOM;
226        }
227        if (fromX >= screenWidth - mSwipeStartThreshold
228                && x < fromX - mSwipeDistanceThreshold
229                && elapsed < SWIPE_TIMEOUT_MS) {
230            return SWIPE_FROM_RIGHT;
231        }
232        return SWIPE_NONE;
233    }
234
235    private final class FlingGestureDetector extends GestureDetector.SimpleOnGestureListener {
236        @Override
237        public boolean onSingleTapUp(MotionEvent e) {
238            if (!mOverscroller.isFinished()) {
239                mOverscroller.forceFinished(true);
240            }
241            return true;
242        }
243        @Override
244        public boolean onFling(MotionEvent down, MotionEvent up,
245                float velocityX, float velocityY) {
246            mOverscroller.computeScrollOffset();
247            long now = SystemClock.uptimeMillis();
248
249            if (mLastFlingTime != 0 && now > mLastFlingTime + MAX_FLING_TIME_MILLIS) {
250                mOverscroller.forceFinished(true);
251            }
252            mOverscroller.fling(0, 0, (int)velocityX, (int)velocityY,
253                    Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MAX_VALUE);
254            int duration = mOverscroller.getDuration();
255            if (duration > MAX_FLING_TIME_MILLIS) {
256                duration = MAX_FLING_TIME_MILLIS;
257            }
258            mLastFlingTime = now;
259            mCallbacks.onFling(duration);
260            return true;
261        }
262    }
263
264    interface Callbacks {
265        void onSwipeFromTop();
266        void onSwipeFromBottom();
267        void onSwipeFromRight();
268        void onFling(int durationMs);
269        void onDown();
270        void onUpOrCancel();
271        void onMouseHoverAtTop();
272        void onMouseHoverAtBottom();
273        void onMouseLeaveFromEdge();
274        void onDebug();
275    }
276}
277