ContentReadbackHandler.java revision 0de6073388f4e2780db8536178b129cd8f6ab386 
1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5package org.chromium.content.browser;
6
7import android.graphics.Bitmap;
8import android.graphics.Rect;
9import android.util.SparseArray;
10
11import org.chromium.base.CalledByNative;
12import org.chromium.base.JNINamespace;
13import org.chromium.base.ThreadUtils;
14
15/**
16 * A class for reading back content.
17 */
18@JNINamespace("content")
19public abstract class ContentReadbackHandler {
20    /**
21     * A callback interface for content readback into a bitmap.
22     */
23    public static interface GetContentBitmapCallback {
24        /**
25         * Called when the content readback finishes.
26         * @param success    Indicates whether the readback succeeded or not.
27         * @param bitmap     The {@link Bitmap} of the content.
28         */
29        public void onFinishGetContentBitmap(boolean success, Bitmap bitmap);
30    }
31
32    private int mNextReadbackId = 1;
33    private SparseArray<GetContentBitmapCallback> mGetContentBitmapRequests;
34
35    private long mNativeContentReadbackHandler;
36
37    /**
38     * Creates a {@link ContentReadbackHandler}.
39     */
40    public ContentReadbackHandler() {
41        mGetContentBitmapRequests = new SparseArray<GetContentBitmapCallback>();
42    }
43
44    /**
45     * Initialize the native object.
46     */
47    public void initNativeContentReadbackHandler() {
48        mNativeContentReadbackHandler = nativeInit();
49    }
50
51    /**
52     * Should be called when the ContentReadackHandler is not needed anymore.
53     */
54    public void destroy() {
55        nativeDestroy(mNativeContentReadbackHandler);
56        mNativeContentReadbackHandler = 0;
57    }
58
59
60    @CalledByNative
61    private void notifyGetContentBitmapFinished(int readbackId, boolean success, Bitmap bitmap) {
62        GetContentBitmapCallback callback = mGetContentBitmapRequests.get(readbackId);
63        if (callback != null) {
64            mGetContentBitmapRequests.delete(readbackId);
65            callback.onFinishGetContentBitmap(success, bitmap);
66        } else {
67            // readback Id is unregistered.
68            assert false : "Readback finished for unregistered Id: " + readbackId;
69        }
70    }
71
72    /**
73     * Asynchronously, generate and grab a bitmap representing what is currently on the screen
74     * for {@code view}.
75     *
76     * @param scale The scale that should be applied to the content.
77     * @param srcRect  A subrect of the original content to capture. If this is empty, it will grab
78     *                 the whole surface.
79     * @param view  The {@link ContentViewCore} to grab the bitmap from.
80     * @param callback The callback to be executed after readback completes.
81     */
82    public void getContentBitmapAsync(float scale, Rect srcRect, ContentViewCore view,
83            GetContentBitmapCallback callback) {
84        if (!readyForReadback()) {
85            callback.onFinishGetContentBitmap(false, null);
86            return;
87        }
88        ThreadUtils.assertOnUiThread();
89
90        int readbackId = mNextReadbackId++;
91        mGetContentBitmapRequests.put(readbackId, callback);
92        nativeGetContentBitmap(mNativeContentReadbackHandler, readbackId, scale,
93                Bitmap.Config.ARGB_8888, srcRect.top, srcRect.left, srcRect.width(),
94                srcRect.height(), view);
95    }
96
97    /**
98     * Implemented by the owner of this class to signal whether readback is possible or not.
99     * @return Whether readback is possible or not.
100     */
101    protected abstract boolean readyForReadback();
102
103    private native long nativeInit();
104    private native void nativeDestroy(long nativeContentReadbackHandler);
105    private native void nativeGetContentBitmap(long nativeContentReadbackHandler, int readback_id,
106            float scale, Bitmap.Config config, float x, float y, float width, float height,
107            Object contentViewCore);
108}
109