CacheTexture.h revision 574cf6070d34e66dfd6f2006937986eddd1f09e7 
1/*
2 * Copyright (C) 2012 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_CACHE_TEXTURE_H
18#define ANDROID_HWUI_CACHE_TEXTURE_H
19
20#include <GLES2/gl2.h>
21
22#include <SkScalerContext.h>
23
24#include <utils/Log.h>
25
26#include "FontUtil.h"
27
28namespace android {
29namespace uirenderer {
30
31/**
32 * CacheBlock is a node in a linked list of current free space areas in a CacheTexture.
33 * Using CacheBlocks enables us to pack the cache from top to bottom as well as left to right.
34 * When we add a glyph to the cache, we see if it fits within one of the existing columns that
35 * have already been started (this is the case if the glyph fits vertically as well as
36 * horizontally, and if its width is sufficiently close to the column width to avoid
37 * sub-optimal packing of small glyphs into wide columns). If there is no column in which the
38 * glyph fits, we check the final node, which is the remaining space in the cache, creating
39 * a new column as appropriate.
40 *
41 * As columns fill up, we remove their CacheBlock from the list to avoid having to check
42 * small blocks in the future.
43 */
44struct CacheBlock {
45    uint16_t mX;
46    uint16_t mY;
47    uint16_t mWidth;
48    uint16_t mHeight;
49    CacheBlock* mNext;
50    CacheBlock* mPrev;
51
52    CacheBlock(uint16_t x, uint16_t y, uint16_t width, uint16_t height, bool empty = false):
53            mX(x), mY(y), mWidth(width), mHeight(height), mNext(NULL), mPrev(NULL) {
54    }
55
56    static CacheBlock* insertBlock(CacheBlock* head, CacheBlock* newBlock);
57
58    static CacheBlock* removeBlock(CacheBlock* head, CacheBlock* blockToRemove);
59
60    void output() {
61        CacheBlock* currBlock = this;
62        while (currBlock) {
63            ALOGD("Block: this, x, y, w, h = %p, %d, %d, %d, %d",
64                    currBlock, currBlock->mX, currBlock->mY, currBlock->mWidth, currBlock->mHeight);
65            currBlock = currBlock->mNext;
66        }
67    }
68};
69
70class CacheTexture {
71public:
72    CacheTexture(uint16_t width, uint16_t height) :
73            mTexture(NULL), mTextureId(0), mWidth(width), mHeight(height),
74            mLinearFiltering(false), mDirty(false), mNumGlyphs(0) {
75        mCacheBlocks = new CacheBlock(TEXTURE_BORDER_SIZE, TEXTURE_BORDER_SIZE,
76                mWidth - TEXTURE_BORDER_SIZE, mHeight - TEXTURE_BORDER_SIZE, true);
77    }
78
79    ~CacheTexture() {
80        releaseTexture();
81        reset();
82    }
83
84    void reset() {
85        // Delete existing cache blocks
86        while (mCacheBlocks != NULL) {
87            CacheBlock* tmpBlock = mCacheBlocks;
88            mCacheBlocks = mCacheBlocks->mNext;
89            delete tmpBlock;
90        }
91        mNumGlyphs = 0;
92    }
93
94    void init() {
95        // reset, then create a new remainder space to start again
96        reset();
97        mCacheBlocks = new CacheBlock(TEXTURE_BORDER_SIZE, TEXTURE_BORDER_SIZE,
98                mWidth - TEXTURE_BORDER_SIZE, mHeight - TEXTURE_BORDER_SIZE, true);
99    }
100
101    void releaseTexture() {
102        if (mTexture) {
103            delete[] mTexture;
104            mTexture = NULL;
105        }
106        if (mTextureId) {
107            glDeleteTextures(1, &mTextureId);
108            mTextureId = 0;
109        }
110        mDirty = false;
111    }
112
113    /**
114     * This method assumes that the proper texture unit is active.
115     */
116    void allocateTexture() {
117        if (!mTexture) {
118            mTexture = new uint8_t[mWidth * mHeight];
119        }
120
121        if (!mTextureId) {
122            glGenTextures(1, &mTextureId);
123
124            glBindTexture(GL_TEXTURE_2D, mTextureId);
125            glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
126            // Initialize texture dimensions
127            glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, mWidth, mHeight, 0,
128                    GL_ALPHA, GL_UNSIGNED_BYTE, 0);
129
130            const GLenum filtering = getLinearFiltering() ? GL_LINEAR : GL_NEAREST;
131            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filtering);
132            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filtering);
133
134            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
135            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
136        }
137    }
138
139    bool fitBitmap(const SkGlyph& glyph, uint32_t* retOriginX, uint32_t* retOriginY);
140
141    inline uint16_t getWidth() const {
142        return mWidth;
143    }
144
145    inline uint16_t getHeight() const {
146        return mHeight;
147    }
148
149    inline uint8_t* getTexture() const {
150        return mTexture;
151    }
152
153    GLuint getTextureId() {
154        allocateTexture();
155        return mTextureId;
156    }
157
158    inline bool isDirty() const {
159        return mDirty;
160    }
161
162    inline void setDirty(bool dirty) {
163        mDirty = dirty;
164    }
165
166    inline bool getLinearFiltering() const {
167        return mLinearFiltering;
168    }
169
170    /**
171     * This method assumes that the proper texture unit is active.
172     */
173    void setLinearFiltering(bool linearFiltering, bool bind = true) {
174        if (linearFiltering != mLinearFiltering) {
175            mLinearFiltering = linearFiltering;
176
177            const GLenum filtering = linearFiltering ? GL_LINEAR : GL_NEAREST;
178            if (bind) glBindTexture(GL_TEXTURE_2D, getTextureId());
179            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filtering);
180            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filtering);
181        }
182    }
183
184    inline uint16_t getGlyphCount() const {
185        return mNumGlyphs;
186    }
187
188private:
189    uint8_t* mTexture;
190    GLuint mTextureId;
191    uint16_t mWidth;
192    uint16_t mHeight;
193    bool mLinearFiltering;
194    bool mDirty;
195    uint16_t mNumGlyphs;
196    CacheBlock* mCacheBlocks;
197};
198
199}; // namespace uirenderer
200}; // namespace android
201
202#endif // ANDROID_HWUI_CACHE_TEXTURE_H
203