SystemGesturesPointerEventListener.java revision 3595be4d19caaa7ddfbff0b979d135aaf5ac20b1 
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.util.Slog;
21import android.view.MotionEvent;
22import android.view.WindowManagerPolicy.PointerEventListener;
23
24/*
25 * Listens for system-wide input gestures, firing callbacks when detected.
26 * @hide
27 */
28public class SystemGesturesPointerEventListener implements PointerEventListener {
29    private static final String TAG = "SystemGestures";
30    private static final boolean DEBUG = false;
31    private static final long SWIPE_TIMEOUT_MS = 500;
32    private static final int MAX_TRACKED_POINTERS = 32;  // max per input system
33    private static final int UNTRACKED_POINTER = -1;
34
35    private static final int SWIPE_NONE = 0;
36    private static final int SWIPE_FROM_TOP = 1;
37    private static final int SWIPE_FROM_BOTTOM = 2;
38    private static final int SWIPE_FROM_RIGHT = 3;
39
40    private final int mSwipeStartThreshold;
41    private final int mSwipeDistanceThreshold;
42    private final Callbacks mCallbacks;
43    private final int[] mDownPointerId = new int[MAX_TRACKED_POINTERS];
44    private final float[] mDownX = new float[MAX_TRACKED_POINTERS];
45    private final float[] mDownY = new float[MAX_TRACKED_POINTERS];
46    private final long[] mDownTime = new long[MAX_TRACKED_POINTERS];
47
48    int screenHeight;
49    int screenWidth;
50    private int mDownPointers;
51    private boolean mSwipeFireable;
52    private boolean mDebugFireable;
53
54    public SystemGesturesPointerEventListener(Context context, Callbacks callbacks) {
55        mCallbacks = checkNull("callbacks", callbacks);
56        mSwipeStartThreshold = checkNull("context", context).getResources()
57                .getDimensionPixelSize(com.android.internal.R.dimen.status_bar_height);
58        mSwipeDistanceThreshold = mSwipeStartThreshold;
59        if (DEBUG) Slog.d(TAG,  "mSwipeStartThreshold=" + mSwipeStartThreshold
60                + " mSwipeDistanceThreshold=" + mSwipeDistanceThreshold);
61    }
62
63    private static <T> T checkNull(String name, T arg) {
64        if (arg == null) {
65            throw new IllegalArgumentException(name + " must not be null");
66        }
67        return arg;
68    }
69
70    @Override
71    public void onPointerEvent(MotionEvent event) {
72        switch (event.getActionMasked()) {
73            case MotionEvent.ACTION_DOWN:
74                mSwipeFireable = true;
75                mDebugFireable = true;
76                mDownPointers = 0;
77                captureDown(event, 0);
78                mCallbacks.onDown();
79                break;
80            case MotionEvent.ACTION_POINTER_DOWN:
81                captureDown(event, event.getActionIndex());
82                if (mDebugFireable) {
83                    mDebugFireable = event.getPointerCount() < 5;
84                    if (!mDebugFireable) {
85                        if (DEBUG) Slog.d(TAG, "Firing debug");
86                        mCallbacks.onDebug();
87                    }
88                }
89                break;
90            case MotionEvent.ACTION_MOVE:
91                if (mSwipeFireable) {
92                    final int swipe = detectSwipe(event);
93                    mSwipeFireable = swipe == SWIPE_NONE;
94                    if (swipe == SWIPE_FROM_TOP) {
95                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromTop");
96                        mCallbacks.onSwipeFromTop();
97                    } else if (swipe == SWIPE_FROM_BOTTOM) {
98                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromBottom");
99                        mCallbacks.onSwipeFromBottom();
100                    } else if (swipe == SWIPE_FROM_RIGHT) {
101                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromRight");
102                        mCallbacks.onSwipeFromRight();
103                    }
104                }
105                break;
106            case MotionEvent.ACTION_UP:
107            case MotionEvent.ACTION_CANCEL:
108                mSwipeFireable = false;
109                mDebugFireable = false;
110                mCallbacks.onUpOrCancel();
111                break;
112            default:
113                if (DEBUG) Slog.d(TAG, "Ignoring " + event);
114        }
115    }
116
117    private void captureDown(MotionEvent event, int pointerIndex) {
118        final int pointerId = event.getPointerId(pointerIndex);
119        final int i = findIndex(pointerId);
120        if (DEBUG) Slog.d(TAG, "pointer " + pointerId +
121                " down pointerIndex=" + pointerIndex + " trackingIndex=" + i);
122        if (i != UNTRACKED_POINTER) {
123            mDownX[i] = event.getX(pointerIndex);
124            mDownY[i] = event.getY(pointerIndex);
125            mDownTime[i] = event.getEventTime();
126            if (DEBUG) Slog.d(TAG, "pointer " + pointerId +
127                    " down x=" + mDownX[i] + " y=" + mDownY[i]);
128        }
129    }
130
131    private int findIndex(int pointerId) {
132        for (int i = 0; i < mDownPointers; i++) {
133            if (mDownPointerId[i] == pointerId) {
134                return i;
135            }
136        }
137        if (mDownPointers == MAX_TRACKED_POINTERS || pointerId == MotionEvent.INVALID_POINTER_ID) {
138            return UNTRACKED_POINTER;
139        }
140        mDownPointerId[mDownPointers++] = pointerId;
141        return mDownPointers - 1;
142    }
143
144    private int detectSwipe(MotionEvent move) {
145        final int historySize = move.getHistorySize();
146        final int pointerCount = move.getPointerCount();
147        for (int p = 0; p < pointerCount; p++) {
148            final int pointerId = move.getPointerId(p);
149            final int i = findIndex(pointerId);
150            if (i != UNTRACKED_POINTER) {
151                for (int h = 0; h < historySize; h++) {
152                    final long time = move.getHistoricalEventTime(h);
153                    final float x = move.getHistoricalX(p, h);
154                    final float y = move.getHistoricalY(p,  h);
155                    final int swipe = detectSwipe(i, time, x, y);
156                    if (swipe != SWIPE_NONE) {
157                        return swipe;
158                    }
159                }
160                final int swipe = detectSwipe(i, move.getEventTime(), move.getX(p), move.getY(p));
161                if (swipe != SWIPE_NONE) {
162                    return swipe;
163                }
164            }
165        }
166        return SWIPE_NONE;
167    }
168
169    private int detectSwipe(int i, long time, float x, float y) {
170        final float fromX = mDownX[i];
171        final float fromY = mDownY[i];
172        final long elapsed = time - mDownTime[i];
173        if (DEBUG) Slog.d(TAG, "pointer " + mDownPointerId[i]
174                + " moved (" + fromX + "->" + x + "," + fromY + "->" + y + ") in " + elapsed);
175        if (fromY <= mSwipeStartThreshold
176                && y > fromY + mSwipeDistanceThreshold
177                && elapsed < SWIPE_TIMEOUT_MS) {
178            return SWIPE_FROM_TOP;
179        }
180        if (fromY >= screenHeight - mSwipeStartThreshold
181                && y < fromY - mSwipeDistanceThreshold
182                && elapsed < SWIPE_TIMEOUT_MS) {
183            return SWIPE_FROM_BOTTOM;
184        }
185        if (fromX >= screenWidth - mSwipeStartThreshold
186                && x < fromX - mSwipeDistanceThreshold
187                && elapsed < SWIPE_TIMEOUT_MS) {
188            return SWIPE_FROM_RIGHT;
189        }
190        return SWIPE_NONE;
191    }
192
193    interface Callbacks {
194        void onSwipeFromTop();
195        void onSwipeFromBottom();
196        void onSwipeFromRight();
197        void onDown();
198        void onUpOrCancel();
199        void onDebug();
200    }
201}
202