GestureTrailsDrawingPreview.java revision e2a6253cb581f9ab70cfb723d32b14f9ac7d2ab7 
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.content.res.TypedArray;
20import android.graphics.Bitmap;
21import android.graphics.Canvas;
22import android.graphics.Color;
23import android.graphics.Paint;
24import android.graphics.PorterDuff;
25import android.graphics.PorterDuffXfermode;
26import android.graphics.Rect;
27import android.os.Message;
28import android.util.SparseArray;
29import android.view.View;
30
31import com.android.inputmethod.keyboard.PointerTracker;
32import com.android.inputmethod.latin.utils.CollectionUtils;
33import com.android.inputmethod.latin.utils.LeakGuardHandlerWrapper;
34
35/**
36 * Draw preview graphics of multiple gesture trails during gesture input.
37 */
38public final class GestureTrailsDrawingPreview extends AbstractDrawingPreview {
39    private final SparseArray<GestureTrailDrawingPoints> mGestureTrails =
40            CollectionUtils.newSparseArray();
41    private final GestureTrailDrawingParams mDrawingParams;
42    private final Paint mGesturePaint;
43    private int mOffscreenWidth;
44    private int mOffscreenHeight;
45    private int mOffscreenOffsetY;
46    private Bitmap mOffscreenBuffer;
47    private final Canvas mOffscreenCanvas = new Canvas();
48    private final Rect mOffscreenSrcRect = new Rect();
49    private final Rect mDirtyRect = new Rect();
50    private final Rect mGestureTrailBoundsRect = new Rect(); // per trail
51
52    private final DrawingHandler mDrawingHandler;
53
54    private static final class DrawingHandler
55            extends LeakGuardHandlerWrapper<GestureTrailsDrawingPreview> {
56        private static final int MSG_UPDATE_GESTURE_TRAIL = 0;
57
58        private final GestureTrailDrawingParams mDrawingParams;
59
60        public DrawingHandler(final GestureTrailsDrawingPreview ownerInstance,
61                final GestureTrailDrawingParams drawingParams) {
62            super(ownerInstance);
63            mDrawingParams = drawingParams;
64        }
65
66        @Override
67        public void handleMessage(final Message msg) {
68            final GestureTrailsDrawingPreview preview = getOwnerInstance();
69            if (preview == null) {
70                return;
71            }
72            switch (msg.what) {
73            case MSG_UPDATE_GESTURE_TRAIL:
74                preview.getDrawingView().invalidate();
75                break;
76            }
77        }
78
79        public void postUpdateGestureTrailPreview() {
80            removeMessages(MSG_UPDATE_GESTURE_TRAIL);
81            sendMessageDelayed(obtainMessage(MSG_UPDATE_GESTURE_TRAIL),
82                    mDrawingParams.mUpdateInterval);
83        }
84    }
85
86    public GestureTrailsDrawingPreview(final View drawingView,
87            final TypedArray mainKeyboardViewAttr) {
88        super(drawingView);
89        mDrawingParams = new GestureTrailDrawingParams(mainKeyboardViewAttr);
90        mDrawingHandler = new DrawingHandler(this, mDrawingParams);
91        final Paint gesturePaint = new Paint();
92        gesturePaint.setAntiAlias(true);
93        gesturePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
94        mGesturePaint = gesturePaint;
95    }
96
97    @Override
98    public void setKeyboardGeometry(final int[] originCoords, final int width, final int height) {
99        mOffscreenOffsetY = (int)(height
100                * GestureStrokeRecognitionPoints.EXTRA_GESTURE_TRAIL_AREA_ABOVE_KEYBOARD_RATIO);
101        mOffscreenWidth = width;
102        mOffscreenHeight = mOffscreenOffsetY + height;
103    }
104
105    @Override
106    public void onDeallocateMemory() {
107        freeOffscreenBuffer();
108    }
109
110    private void freeOffscreenBuffer() {
111        mOffscreenCanvas.setBitmap(null);
112        mOffscreenCanvas.setMatrix(null);
113        if (mOffscreenBuffer != null) {
114            mOffscreenBuffer.recycle();
115            mOffscreenBuffer = null;
116        }
117    }
118
119    private void mayAllocateOffscreenBuffer() {
120        if (mOffscreenBuffer != null && mOffscreenBuffer.getWidth() == mOffscreenWidth
121                && mOffscreenBuffer.getHeight() == mOffscreenHeight) {
122            return;
123        }
124        freeOffscreenBuffer();
125        mOffscreenBuffer = Bitmap.createBitmap(
126                mOffscreenWidth, mOffscreenHeight, Bitmap.Config.ARGB_8888);
127        mOffscreenCanvas.setBitmap(mOffscreenBuffer);
128        mOffscreenCanvas.translate(0, mOffscreenOffsetY);
129    }
130
131    private boolean drawGestureTrails(final Canvas offscreenCanvas, final Paint paint,
132            final Rect dirtyRect) {
133        // Clear previous dirty rectangle.
134        if (!dirtyRect.isEmpty()) {
135            paint.setColor(Color.TRANSPARENT);
136            paint.setStyle(Paint.Style.FILL);
137            offscreenCanvas.drawRect(dirtyRect, paint);
138        }
139        dirtyRect.setEmpty();
140        boolean needsUpdatingGestureTrail = false;
141        // Draw gesture trails to offscreen buffer.
142        synchronized (mGestureTrails) {
143            // Trails count == fingers count that have ever been active.
144            final int trailsCount = mGestureTrails.size();
145            for (int index = 0; index < trailsCount; index++) {
146                final GestureTrailDrawingPoints trail = mGestureTrails.valueAt(index);
147                needsUpdatingGestureTrail |= trail.drawGestureTrail(offscreenCanvas, paint,
148                        mGestureTrailBoundsRect, mDrawingParams);
149                // {@link #mGestureTrailBoundsRect} has bounding box of the trail.
150                dirtyRect.union(mGestureTrailBoundsRect);
151            }
152        }
153        return needsUpdatingGestureTrail;
154    }
155
156    /**
157     * Draws the preview
158     * @param canvas The canvas where the preview is drawn.
159     */
160    @Override
161    public void drawPreview(final Canvas canvas) {
162        if (!isPreviewEnabled()) {
163            return;
164        }
165        mayAllocateOffscreenBuffer();
166        // Draw gesture trails to offscreen buffer.
167        final boolean needsUpdatingGestureTrail = drawGestureTrails(
168                mOffscreenCanvas, mGesturePaint, mDirtyRect);
169        if (needsUpdatingGestureTrail) {
170            mDrawingHandler.postUpdateGestureTrailPreview();
171        }
172        // Transfer offscreen buffer to screen.
173        if (!mDirtyRect.isEmpty()) {
174            mOffscreenSrcRect.set(mDirtyRect);
175            mOffscreenSrcRect.offset(0, mOffscreenOffsetY);
176            canvas.drawBitmap(mOffscreenBuffer, mOffscreenSrcRect, mDirtyRect, null);
177            // Note: Defer clearing the dirty rectangle here because we will get cleared
178            // rectangle on the canvas.
179        }
180    }
181
182    /**
183     * Set the position of the preview.
184     * @param tracker The new location of the preview is based on the points in PointerTracker.
185     */
186    @Override
187    public void setPreviewPosition(final PointerTracker tracker) {
188        if (!isPreviewEnabled()) {
189            return;
190        }
191        GestureTrailDrawingPoints trail;
192        synchronized (mGestureTrails) {
193            trail = mGestureTrails.get(tracker.mPointerId);
194            if (trail == null) {
195                trail = new GestureTrailDrawingPoints();
196                mGestureTrails.put(tracker.mPointerId, trail);
197            }
198        }
199        trail.addStroke(tracker.getGestureStrokeDrawingPoints(), tracker.getDownTime());
200
201        // TODO: Should narrow the invalidate region.
202        getDrawingView().invalidate();
203    }
204}
205