GradientCache.h revision ee916f14cbd1fe1422c063ce2ef7b185e2bc5c6f 
1/*
2 * Copyright (C) 2010 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_UI_GRADIENT_CACHE_H
18#define ANDROID_UI_GRADIENT_CACHE_H
19
20#include <SkShader.h>
21
22#include "Texture.h"
23#include "GenerationCache.h"
24
25namespace android {
26namespace uirenderer {
27
28/**
29 * A simple LRU gradient cache. The cache has a maximum size expressed in bytes.
30 * Any texture added to the cache causing the cache to grow beyond the maximum
31 * allowed size will also cause the oldest texture to be kicked out.
32 */
33class GradientCache: public OnEntryRemoved<SkShader*, Texture*> {
34public:
35    GradientCache();
36    GradientCache(uint32_t maxByteSize);
37    ~GradientCache();
38
39    /**
40     * Used as a callback when an entry is removed from the cache.
41     * Do not invoke directly.
42     */
43    void operator()(SkShader*& shader, Texture*& texture);
44
45    /**
46     * Adds a new linear gradient to the cache. The generated texture is
47     * returned.
48     */
49    Texture* addLinearGradient(SkShader* shader, uint32_t* colors, float* positions,
50            int count, SkShader::TileMode tileMode = SkShader::kClamp_TileMode);
51    /**
52     * Returns the texture associated with the specified shader.
53     */
54    Texture* get(SkShader* shader);
55    /**
56     * Removes the texture associated with the specified shader. Returns NULL
57     * if the texture cannot be found. Upon remove the texture is freed.
58     */
59    void remove(SkShader* shader);
60    /**
61     * Clears the cache. This causes all textures to be deleted.
62     */
63    void clear();
64
65    /**
66     * Sets the maximum size of the cache in bytes.
67     */
68    void setMaxSize(uint32_t maxSize);
69    /**
70     * Returns the maximum size of the cache in bytes.
71     */
72    uint32_t getMaxSize();
73    /**
74     * Returns the current size of the cache in bytes.
75     */
76    uint32_t getSize();
77
78private:
79    void generateTexture(SkBitmap* bitmap, Texture* texture);
80
81    GenerationCache<SkShader*, Texture*> mCache;
82
83    uint32_t mSize;
84    uint32_t mMaxSize;
85
86    /**
87     * Used to access mCache and mSize. All methods are accessed from a single
88     * thread except for remove().
89     */
90    mutable Mutex mLock;
91}; // class GradientCache
92
93}; // namespace uirenderer
94}; // namespace android
95
96#endif // ANDROID_UI_GRADIENT_CACHE_H
97