1 /* 2 * Copyright (C) 2015 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 package com.android.tv.util.images; 18 19 import android.support.annotation.VisibleForTesting; 20 import android.util.Log; 21 import android.util.LruCache; 22 import com.android.tv.common.memory.MemoryManageable; 23 import com.android.tv.util.images.BitmapUtils.ScaledBitmapInfo; 24 25 /** A convenience class for caching bitmap. */ 26 public class ImageCache implements MemoryManageable { 27 private static final float MAX_CACHE_SIZE_PERCENT = 0.8f; 28 private static final float MIN_CACHE_SIZE_PERCENT = 0.05f; 29 private static final float DEFAULT_CACHE_SIZE_PERCENT = 0.1f; 30 private static final boolean DEBUG = false; 31 private static final String TAG = "ImageCache"; 32 private static final int MIN_CACHE_SIZE_KBYTES = 1024; 33 34 private final LruCache<String, ScaledBitmapInfo> mMemoryCache; 35 36 /** 37 * Creates a new ImageCache object with a given cache size percent. 38 * 39 * @param memCacheSizePercent The cache size as a percent of available app memory. 40 */ ImageCache(float memCacheSizePercent)41 private ImageCache(float memCacheSizePercent) { 42 int memCacheSize = calculateMemCacheSize(memCacheSizePercent); 43 44 // Set up memory cache 45 if (DEBUG) { 46 Log.d(TAG, "Memory cache created (size = " + memCacheSize + " Kbytes)"); 47 } 48 mMemoryCache = 49 new LruCache<String, ScaledBitmapInfo>(memCacheSize) { 50 /** 51 * Measure item size in kilobytes rather than units which is more practical for 52 * a bitmap cache 53 */ 54 @Override 55 protected int sizeOf(String key, ScaledBitmapInfo bitmapInfo) { 56 return (bitmapInfo.bitmap.getByteCount() + 1023) / 1024; 57 } 58 }; 59 } 60 61 private static ImageCache sImageCache; 62 63 /** 64 * Returns an existing ImageCache, if it doesn't exist, a new one is created using the supplied 65 * param. 66 * 67 * @param memCacheSizePercent The cache size as a percent of available app memory. Should be in 68 * range of MIN_CACHE_SIZE_PERCENT(0.05) ~ MAX_CACHE_SIZE_PERCENT(0.8). 69 * @return An existing retained ImageCache object or a new one if one did not exist 70 */ getInstance(float memCacheSizePercent)71 public static synchronized ImageCache getInstance(float memCacheSizePercent) { 72 if (sImageCache == null) { 73 sImageCache = newInstance(memCacheSizePercent); 74 } 75 return sImageCache; 76 } 77 78 @VisibleForTesting newInstance(float memCacheSizePercent)79 static ImageCache newInstance(float memCacheSizePercent) { 80 return new ImageCache(memCacheSizePercent); 81 } 82 83 /** 84 * Returns an existing ImageCache, if it doesn't exist, a new one is created using 85 * DEFAULT_CACHE_SIZE_PERCENT (0.1). 86 * 87 * @return An existing retained ImageCache object or a new one if one did not exist 88 */ getInstance()89 public static ImageCache getInstance() { 90 return getInstance(DEFAULT_CACHE_SIZE_PERCENT); 91 } 92 93 /** 94 * Adds a bitmap to memory cache. 95 * 96 * <p>If there is an existing bitmap only replace it if {@link 97 * ScaledBitmapInfo#needToReload(ScaledBitmapInfo)} is true. 98 * 99 * @param bitmapInfo The {@link ScaledBitmapInfo} object to store 100 */ putIfNeeded(ScaledBitmapInfo bitmapInfo)101 public void putIfNeeded(ScaledBitmapInfo bitmapInfo) { 102 if (bitmapInfo == null || bitmapInfo.id == null) { 103 throw new IllegalArgumentException("Neither bitmap nor bitmap.id should be null."); 104 } 105 String key = bitmapInfo.id; 106 // Add to memory cache 107 synchronized (mMemoryCache) { 108 ScaledBitmapInfo old = mMemoryCache.put(key, bitmapInfo); 109 if (old != null && !old.needToReload(bitmapInfo)) { 110 mMemoryCache.put(key, old); 111 if (DEBUG) { 112 Log.d( 113 TAG, 114 "Kept original " 115 + old 116 + " in memory cache because it was larger than " 117 + bitmapInfo 118 + "."); 119 } 120 } else { 121 if (DEBUG) { 122 Log.d( 123 TAG, 124 "Add " 125 + bitmapInfo 126 + " to memory cache. Current size is " 127 + mMemoryCache.size() 128 + " / " 129 + mMemoryCache.maxSize() 130 + " Kbytes"); 131 } 132 } 133 } 134 } 135 136 /** 137 * Get from memory cache. 138 * 139 * @param key Unique identifier for which item to get 140 * @return The bitmap if found in cache, null otherwise 141 */ get(String key)142 public ScaledBitmapInfo get(String key) { 143 ScaledBitmapInfo memBitmapInfo = mMemoryCache.get(key); 144 if (DEBUG) { 145 int hit = mMemoryCache.hitCount(); 146 int miss = mMemoryCache.missCount(); 147 String result = memBitmapInfo == null ? "miss" : "hit"; 148 double ratio = ((double) hit) / (hit + miss) * 100; 149 Log.d(TAG, "Memory cache " + result + " for " + key); 150 Log.d(TAG, "Memory cache " + hit + "h:" + miss + "m " + ratio + "%"); 151 } 152 return memBitmapInfo; 153 } 154 155 /** 156 * Remove from memory cache. 157 * 158 * @param key Unique identifier for which item to remove 159 * @return The previous bitmap mapped by key 160 */ remove(String key)161 public ScaledBitmapInfo remove(String key) { 162 return mMemoryCache.remove(key); 163 } 164 165 /** 166 * Calculates the memory cache size based on a percentage of the max available VM memory. Eg. 167 * setting percent to 0.2 would set the memory cache to one fifth of the available memory. 168 * Throws {@link IllegalArgumentException} if percent is < 0.05 or > .8. memCacheSize is stored 169 * in kilobytes instead of bytes as this will eventually be passed to construct a LruCache which 170 * takes an int in its constructor. This value should be chosen carefully based on a number of 171 * factors Refer to the corresponding Android Training class for more discussion: 172 * http://developer.android.com/training/displaying-bitmaps/ 173 * 174 * @param percent Percent of available app memory to use to size memory cache. 175 */ calculateMemCacheSize(float percent)176 public static int calculateMemCacheSize(float percent) { 177 if (percent < MIN_CACHE_SIZE_PERCENT || percent > MAX_CACHE_SIZE_PERCENT) { 178 throw new IllegalArgumentException( 179 "setMemCacheSizePercent - percent must be " 180 + "between 0.05 and 0.8 (inclusive)"); 181 } 182 return Math.max( 183 MIN_CACHE_SIZE_KBYTES, 184 Math.round(percent * Runtime.getRuntime().maxMemory() / 1024)); 185 } 186 187 @Override performTrimMemory(int level)188 public void performTrimMemory(int level) { 189 mMemoryCache.evictAll(); 190 } 191 } 192