AssetAtlas.h revision 3b748a44c6bd2ea05fe16839caf73dbe50bd7ae9 
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 <EGL/egl.h>
23#include <EGL/eglext.h>
24
25#include <ui/GraphicBuffer.h>
26
27#include <utils/KeyedVector.h>
28
29#include <cutils/compiler.h>
30
31#include <SkBitmap.h>
32
33#include "Texture.h"
34#include "UvMapper.h"
35
36namespace android {
37namespace uirenderer {
38
39/**
40 * An asset atlas holds a collection of framework bitmaps in a single OpenGL
41 * texture. Each bitmap is associated with a location, defined in pixels,
42 * inside the atlas. The atlas is generated by the framework and bound as
43 * an external texture using the EGLImageKHR extension.
44 */
45class AssetAtlas {
46public:
47    /**
48     * Entry representing the position and rotation of a
49     * bitmap inside the atlas.
50     */
51    struct Entry {
52        /**
53         * The bitmap that generated this atlas entry.
54         */
55        SkBitmap* bitmap;
56
57        /**
58         * Location of the bitmap inside the atlas, in pixels.
59         */
60        int x;
61        int y;
62
63        /**
64         * If set, the bitmap is rotated 90 degrees (clockwise)
65         * inside the atlas.
66         */
67        bool rotated;
68
69        /**
70         * Maps texture coordinates in the [0..1] range into the
71         * correct range to sample this entry from the atlas.
72         */
73        const UvMapper uvMapper;
74
75        /**
76         * Atlas this entry belongs to.
77         */
78        const AssetAtlas& atlas;
79
80        /*
81         * A "virtual texture" object that represents the texture
82         * this entry belongs to. This texture should never be
83         * modified.
84         */
85        Texture texture;
86
87    private:
88        Entry(SkBitmap* bitmap, int x, int y, bool rotated,
89                const UvMapper& mapper, const AssetAtlas& atlas):
90                bitmap(bitmap), x(x), y(y), rotated(rotated), uvMapper(mapper), atlas(atlas) { }
91
92        friend class AssetAtlas;
93    };
94
95    AssetAtlas(): mWidth(0), mHeight(0), mTexture(0), mImage(EGL_NO_IMAGE_KHR) { }
96    ~AssetAtlas() { terminate(); }
97
98    /**
99     * Initializes the atlas with the specified buffer and
100     * map. The buffer is a gralloc'd texture that will be
101     * used as an EGLImage. The map is a list of SkBitmap*
102     * and their (x, y) positions as well as their rotation
103     * flags.
104     *
105     * This method returns immediately if the atlas is already
106     * initialized. To re-initialize the atlas, you must
107     * first call terminate().
108     */
109    ANDROID_API void init(sp<GraphicBuffer> buffer, int* map, int count);
110
111    /**
112     * Destroys the atlas texture. This object can be
113     * re-initialized after calling this method.
114     *
115     * After calling this method, the width, height
116     * and texture are set to 0.
117     */
118    ANDROID_API void terminate();
119
120    /**
121     * Returns the width of this atlas in pixels.
122     * Can return 0 if the atlas is not initialized.
123     */
124    uint32_t getWidth() const {
125        return mWidth;
126    }
127
128    /**
129     * Returns the height of this atlas in pixels.
130     * Can return 0 if the atlas is not initialized.
131     */
132    uint32_t getHeight() const {
133        return mHeight;
134    }
135
136    /**
137     * Returns the OpenGL name of the texture backing this atlas.
138     * Can return 0 if the atlas is not initialized.
139     */
140    GLuint getTexture() const {
141        return mTexture;
142    }
143
144    /**
145     * Returns the entry in the atlas associated with the specified
146     * bitmap. If the bitmap is not in the atlas, return NULL.
147     */
148    Entry* getEntry(SkBitmap* const bitmap) const;
149
150    /**
151     * Returns the texture for the atlas entry associated with the
152     * specified bitmap. If the bitmap is not in the atlas, return NULL.
153     */
154    Texture* getEntryTexture(SkBitmap* const bitmap) const;
155
156private:
157    void createEntries(int* map, int count);
158
159    uint32_t mWidth;
160    uint32_t mHeight;
161
162    GLuint mTexture;
163    EGLImageKHR mImage;
164
165    KeyedVector<SkBitmap*, Entry*> mEntries;
166}; // class AssetAtlas
167
168}; // namespace uirenderer
169}; // namespace android
170
171#endif // ANDROID_HWUI_ASSET_ATLAS_H
172