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.inputmethod.keyboard.internal;
18
19import android.util.Log;
20import android.view.MotionEvent;
21
22import com.android.inputmethod.keyboard.Key;
23import com.android.inputmethod.keyboard.KeyDetector;
24import com.android.inputmethod.keyboard.PointerTracker;
25import com.android.inputmethod.latin.utils.CoordinateUtils;
26
27public final class NonDistinctMultitouchHelper {
28    private static final String TAG = NonDistinctMultitouchHelper.class.getSimpleName();
29
30    private static final int MAIN_POINTER_TRACKER_ID = 0;
31    private int mOldPointerCount = 1;
32    private Key mOldKey;
33    private int[] mLastCoords = CoordinateUtils.newInstance();
34
35    public void processMotionEvent(final MotionEvent me, final KeyDetector keyDetector) {
36        final int pointerCount = me.getPointerCount();
37        final int oldPointerCount = mOldPointerCount;
38        mOldPointerCount = pointerCount;
39        // Ignore continuous multi-touch events because we can't trust the coordinates
40        // in multi-touch events.
41        if (pointerCount > 1 && oldPointerCount > 1) {
42            return;
43        }
44
45        // Use only main pointer tracker.
46        final PointerTracker mainTracker = PointerTracker.getPointerTracker(
47                MAIN_POINTER_TRACKER_ID);
48        final int action = me.getActionMasked();
49        final int index = me.getActionIndex();
50        final long eventTime = me.getEventTime();
51        final long downTime = me.getDownTime();
52
53        // In single-touch.
54        if (oldPointerCount == 1 && pointerCount == 1) {
55            if (me.getPointerId(index) == mainTracker.mPointerId) {
56                mainTracker.processMotionEvent(me, keyDetector);
57                return;
58            }
59            // Inject a copied event.
60            injectMotionEvent(action, me.getX(index), me.getY(index), downTime, eventTime,
61                    mainTracker, keyDetector);
62            return;
63        }
64
65        // Single-touch to multi-touch transition.
66        if (oldPointerCount == 1 && pointerCount == 2) {
67            // Send an up event for the last pointer, be cause we can't trust the coordinates of
68            // this multi-touch event.
69            mainTracker.getLastCoordinates(mLastCoords);
70            final int x = CoordinateUtils.x(mLastCoords);
71            final int y = CoordinateUtils.y(mLastCoords);
72            mOldKey = mainTracker.getKeyOn(x, y);
73            // Inject an artifact up event for the old key.
74            injectMotionEvent(MotionEvent.ACTION_UP, x, y, downTime, eventTime,
75                    mainTracker, keyDetector);
76            return;
77        }
78
79        // Multi-touch to single-touch transition.
80        if (oldPointerCount == 2 && pointerCount == 1) {
81            // Send a down event for the latest pointer if the key is different from the previous
82            // key.
83            final int x = (int)me.getX(index);
84            final int y = (int)me.getY(index);
85            final Key newKey = mainTracker.getKeyOn(x, y);
86            if (mOldKey != newKey) {
87                // Inject an artifact down event for the new key.
88                // An artifact up event for the new key will usually be injected as a single-touch.
89                injectMotionEvent(MotionEvent.ACTION_DOWN, x, y, downTime, eventTime,
90                        mainTracker, keyDetector);
91                if (action == MotionEvent.ACTION_UP) {
92                    // Inject an artifact up event for the new key also.
93                    injectMotionEvent(MotionEvent.ACTION_UP, x, y, downTime, eventTime,
94                            mainTracker, keyDetector);
95                }
96            }
97            return;
98        }
99
100        Log.w(TAG, "Unknown touch panel behavior: pointer count is "
101                + pointerCount + " (previously " + oldPointerCount + ")");
102    }
103
104    private static void injectMotionEvent(final int action, final float x, final float y,
105            final long downTime, final long eventTime, final PointerTracker tracker,
106            final KeyDetector keyDetector) {
107        final MotionEvent me = MotionEvent.obtain(
108                downTime, eventTime, action, x, y, 0 /* metaState */);
109        try {
110            tracker.processMotionEvent(me, keyDetector);
111        } finally {
112            me.recycle();
113        }
114    }
115}
116