1/*
2 * Copyright (C) 2006 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 android.graphics;
18
19/**
20 * LargeBitmap can be used to decode a rectangle region from an image.
21 * LargeBimap is particularly useful when an original image is large and
22 * you only need parts of the image.
23 *
24 * To create a LargeBitmap, call BitmapFactory.createLargeBitmap().
25 * Given a LargeBitmap, users can call decodeRegion() repeatedly
26 * to get a decoded Bitmap of the specified region.
27 * @hide
28 */
29public final class LargeBitmap {
30    private long mNativeLargeBitmap;
31    private boolean mRecycled;
32
33    /*  Private constructor that must received an already allocated native
34        large bitmap int (pointer).
35
36        This can be called from JNI code.
37    */
38    private LargeBitmap(long nativeLbm) {
39        mNativeLargeBitmap = nativeLbm;
40        mRecycled = false;
41    }
42
43    /**
44     * Decodes a rectangle region in the image specified by rect.
45     *
46     * @param rect The rectangle that specified the region to be decode.
47     * @param opts null-ok; Options that control downsampling.
48     *             inPurgeable is not supported.
49     * @return The decoded bitmap, or null if the image data could not be
50     *         decoded.
51     */
52    public Bitmap decodeRegion(Rect rect, BitmapFactory.Options options) {
53        checkRecycled("decodeRegion called on recycled large bitmap");
54        if (rect.left < 0 || rect.top < 0 || rect.right > getWidth() || rect.bottom > getHeight())
55            throw new IllegalArgumentException("rectangle is not inside the image");
56        return nativeDecodeRegion(mNativeLargeBitmap, rect.left, rect.top,
57                rect.right - rect.left, rect.bottom - rect.top, options);
58    }
59
60    /** Returns the original image's width */
61    public int getWidth() {
62        checkRecycled("getWidth called on recycled large bitmap");
63        return nativeGetWidth(mNativeLargeBitmap);
64    }
65
66    /** Returns the original image's height */
67    public int getHeight() {
68        checkRecycled("getHeight called on recycled large bitmap");
69        return nativeGetHeight(mNativeLargeBitmap);
70    }
71
72    /**
73     * Frees up the memory associated with this large bitmap, and mark the
74     * large bitmap as "dead", meaning it will throw an exception if decodeRegion(),
75     * getWidth() or getHeight() is called.
76     * This operation cannot be reversed, so it should only be called if you are
77     * sure there are no further uses for the large bitmap. This is an advanced call,
78     * and normally need not be called, since the normal GC process will free up this
79     * memory when there are no more references to this bitmap.
80     */
81    public void recycle() {
82        if (!mRecycled) {
83            nativeClean(mNativeLargeBitmap);
84            mRecycled = true;
85        }
86    }
87
88    /**
89     * Returns true if this large bitmap has been recycled.
90     * If so, then it is an error to try use its method.
91     *
92     * @return true if the large bitmap has been recycled
93     */
94    public final boolean isRecycled() {
95        return mRecycled;
96    }
97
98    /**
99     * Called by methods that want to throw an exception if the bitmap
100     * has already been recycled.
101     */
102    private void checkRecycled(String errorMessage) {
103        if (mRecycled) {
104            throw new IllegalStateException(errorMessage);
105        }
106    }
107
108    protected void finalize() {
109        recycle();
110    }
111
112    private static native Bitmap nativeDecodeRegion(long nativeLbm,
113            int start_x, int start_y, int width, int height,
114            BitmapFactory.Options options);
115    private static native int nativeGetWidth(long nativeLbm);
116    private static native int nativeGetHeight(long nativeLbm);
117    private static native void nativeClean(long nativeLbm);
118}
119