AssetAtlas.h revision 877cfe0e32a845d5a58252b8a6e1f54f95b4379c 
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
17#ifndef ANDROID_HWUI_ASSET_ATLAS_H
18#define ANDROID_HWUI_ASSET_ATLAS_H
19
20#include <GLES2/gl2.h>
21
22#include <ui/GraphicBuffer.h>
23
24#include <utils/KeyedVector.h>
25
26#include <cutils/compiler.h>
27
28#include <SkBitmap.h>
29
30#include "Image.h"
31#include "Texture.h"
32#include "UvMapper.h"
33
34namespace android {
35namespace uirenderer {
36
37/**
38 * An asset atlas holds a collection of framework bitmaps in a single OpenGL
39 * texture. Each bitmap is associated with a location, defined in pixels,
40 * inside the atlas. The atlas is generated by the framework and bound as
41 * an external texture using the EGLImageKHR extension.
42 */
43class AssetAtlas {
44public:
45    /**
46     * Entry representing the position and rotation of a
47     * bitmap inside the atlas.
48     */
49    struct Entry {
50        /**
51         * The bitmap that generated this atlas entry.
52         */
53        SkBitmap* bitmap;
54
55        /**
56         * Location of the bitmap inside the atlas, in pixels.
57         */
58        int x;
59        int y;
60
61        /**
62         * If set, the bitmap is rotated 90 degrees (clockwise)
63         * inside the atlas.
64         */
65        bool rotated;
66
67        /**
68         * Maps texture coordinates in the [0..1] range into the
69         * correct range to sample this entry from the atlas.
70         */
71        const UvMapper uvMapper;
72
73        /**
74         * Atlas this entry belongs to.
75         */
76        const AssetAtlas& atlas;
77
78        /*
79         * A "virtual texture" object that represents the texture
80         * this entry belongs to. This texture should never be
81         * modified.
82         */
83        Texture texture;
84
85    private:
86        Entry(SkBitmap* bitmap, int x, int y, bool rotated,
87                const UvMapper& mapper, const AssetAtlas& atlas):
88                bitmap(bitmap), x(x), y(y), rotated(rotated), uvMapper(mapper), atlas(atlas) { }
89
90        friend class AssetAtlas;
91    };
92
93    AssetAtlas(): mWidth(0), mHeight(0), mTexture(0), mImage(NULL) { }
94    ~AssetAtlas() { terminate(); }
95
96    /**
97     * Initializes the atlas with the specified buffer and
98     * map. The buffer is a gralloc'd texture that will be
99     * used as an EGLImage. The map is a list of SkBitmap*
100     * and their (x, y) positions as well as their rotation
101     * flags.
102     *
103     * This method returns immediately if the atlas is already
104     * initialized. To re-initialize the atlas, you must
105     * first call terminate().
106     */
107    ANDROID_API void init(sp<GraphicBuffer> buffer, int* map, int count);
108
109    /**
110     * Destroys the atlas texture. This object can be
111     * re-initialized after calling this method.
112     *
113     * After calling this method, the width, height
114     * and texture are set to 0.
115     */
116    ANDROID_API void terminate();
117
118    /**
119     * Returns the width of this atlas in pixels.
120     * Can return 0 if the atlas is not initialized.
121     */
122    uint32_t getWidth() const {
123        return mWidth;
124    }
125
126    /**
127     * Returns the height of this atlas in pixels.
128     * Can return 0 if the atlas is not initialized.
129     */
130    uint32_t getHeight() const {
131        return mHeight;
132    }
133
134    /**
135     * Returns the OpenGL name of the texture backing this atlas.
136     * Can return 0 if the atlas is not initialized.
137     */
138    GLuint getTexture() const {
139        return mTexture;
140    }
141
142    /**
143     * Returns the entry in the atlas associated with the specified
144     * bitmap. If the bitmap is not in the atlas, return NULL.
145     */
146    Entry* getEntry(SkBitmap* const bitmap) const;
147
148    /**
149     * Returns the texture for the atlas entry associated with the
150     * specified bitmap. If the bitmap is not in the atlas, return NULL.
151     */
152    Texture* getEntryTexture(SkBitmap* const bitmap) const;
153
154private:
155    void createEntries(int* map, int count);
156
157    uint32_t mWidth;
158    uint32_t mHeight;
159
160    GLuint mTexture;
161    Image* mImage;
162
163    KeyedVector<SkBitmap*, Entry*> mEntries;
164}; // class AssetAtlas
165
166}; // namespace uirenderer
167}; // namespace android
168
169#endif // ANDROID_HWUI_ASSET_ATLAS_H
170