LayerCache.h revision 8550c4c7b5952b7a4e1e0ede95c9492d03099a13 
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_LAYER_CACHE_H
18#define ANDROID_UI_LAYER_CACHE_H
19
20#include "Layer.h"
21#include "utils/SortedList.h"
22
23namespace android {
24namespace uirenderer {
25
26///////////////////////////////////////////////////////////////////////////////
27// Defines
28///////////////////////////////////////////////////////////////////////////////
29
30// Debug
31#define DEBUG_LAYERS 0
32
33// Textures used by layers must have dimensions multiples of this number
34#define LAYER_SIZE 64
35
36// Debug
37#if DEBUG_LAYERS
38    #define LAYER_LOGD(...) LOGD(__VA_ARGS__)
39#else
40    #define LAYER_LOGD(...)
41#endif
42
43///////////////////////////////////////////////////////////////////////////////
44// Cache
45///////////////////////////////////////////////////////////////////////////////
46
47class LayerCache {
48public:
49    LayerCache();
50    ~LayerCache();
51
52    /**
53     * Returns a layer large enough for the specified dimensions. If no suitable
54     * layer can be found, a new one is created and returned. If creating a new
55     * layer fails, NULL is returned.
56     *
57     * When a layer is obtained from the cache, it is removed and the total
58     * size of the cache goes down.
59     *
60     * @param width The desired width of the layer
61     * @param width The desired height of the layer
62     */
63    Layer* get(const uint32_t width, const uint32_t height);
64
65    /**
66     * Adds the layer to the cache. The layer will not be added if there is
67     * not enough space available. Adding a layer can cause other layers to
68     * be removed from the cache.
69     *
70     * @param layer The layer to add to the cache
71     *
72     * @return True if the layer was added, false otherwise.
73     */
74    bool put(Layer* layer);
75    /**
76     * Clears the cache. This causes all layers to be deleted.
77     */
78    void clear();
79
80    /**
81     * Sets the maximum size of the cache in bytes.
82     */
83    void setMaxSize(uint32_t maxSize);
84    /**
85     * Returns the maximum size of the cache in bytes.
86     */
87    uint32_t getMaxSize();
88    /**
89     * Returns the current size of the cache in bytes.
90     */
91    uint32_t getSize();
92
93private:
94    void deleteLayer(Layer* layer);
95
96    struct LayerEntry {
97        LayerEntry():
98            mLayer(NULL), mWidth(0), mHeight(0) {
99        }
100
101        LayerEntry(const uint32_t layerWidth, const uint32_t layerHeight): mLayer(NULL) {
102            mWidth = uint32_t(ceilf(layerWidth / float(LAYER_SIZE)) * LAYER_SIZE);
103            mHeight = uint32_t(ceilf(layerHeight / float(LAYER_SIZE)) * LAYER_SIZE);
104        }
105
106        LayerEntry(const LayerEntry& entry):
107            mLayer(entry.mLayer), mWidth(entry.mWidth), mHeight(entry.mHeight) {
108        }
109
110        LayerEntry(Layer* layer):
111            mLayer(layer), mWidth(layer->width), mHeight(layer->height) {
112        }
113
114        bool operator<(const LayerEntry& rhs) const {
115            if (mWidth == rhs.mWidth) {
116                return mHeight < rhs.mHeight;
117            }
118            return mWidth < rhs.mWidth;
119        }
120
121        bool operator==(const LayerEntry& rhs) const {
122            return mWidth == rhs.mWidth && mHeight == rhs.mHeight;
123        }
124
125        Layer* mLayer;
126        uint32_t mWidth;
127        uint32_t mHeight;
128    }; // struct LayerEntry
129
130    SortedList<LayerEntry> mCache;
131
132    uint32_t mSize;
133    uint32_t mMaxSize;
134}; // class LayerCache
135
136}; // namespace uirenderer
137}; // namespace android
138
139#endif // ANDROID_UI_LAYER_CACHE_H
140