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Diffstat (limited to 'src/com/android/photos/data/GalleryBitmapPool.java')
-rw-r--r-- | src/com/android/photos/data/GalleryBitmapPool.java | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/src/com/android/photos/data/GalleryBitmapPool.java b/src/com/android/photos/data/GalleryBitmapPool.java new file mode 100644 index 000000000..390a0d42f --- /dev/null +++ b/src/com/android/photos/data/GalleryBitmapPool.java @@ -0,0 +1,161 @@ +/* + * Copyright (C) 2013 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package com.android.photos.data; + +import android.graphics.Bitmap; +import android.graphics.Point; +import android.util.Pools.Pool; +import android.util.Pools.SynchronizedPool; + +import com.android.photos.data.SparseArrayBitmapPool.Node; + +/** + * Pool allowing the efficient reuse of bitmaps in order to avoid long + * garbage collection pauses. + */ +public class GalleryBitmapPool { + + private static final int CAPACITY_BYTES = 20971520; + + // We found that Gallery uses bitmaps that are either square (for example, + // tiles of large images or square thumbnails), match one of the common + // photo aspect ratios (4x3, 3x2, or 16x9), or, less commonly, are of some + // other aspect ratio. Taking advantage of this information, we use 3 + // SparseArrayBitmapPool instances to back the GalleryBitmapPool, which affords + // O(1) lookups for square bitmaps, and average-case - but *not* asymptotically - + // O(1) lookups for common photo aspect ratios and other miscellaneous aspect + // ratios. Beware of the pathological case where there are many bitmaps added + // to the pool with different non-square aspect ratios but the same width, as + // performance will degrade and the average case lookup will approach + // O(# of different aspect ratios). + private static final int POOL_INDEX_NONE = -1; + private static final int POOL_INDEX_SQUARE = 0; + private static final int POOL_INDEX_PHOTO = 1; + private static final int POOL_INDEX_MISC = 2; + + private static final Point[] COMMON_PHOTO_ASPECT_RATIOS = + { new Point(4, 3), new Point(3, 2), new Point(16, 9) }; + + private int mCapacityBytes; + private SparseArrayBitmapPool [] mPools; + private Pool<Node> mSharedNodePool = new SynchronizedPool<Node>(128); + + private GalleryBitmapPool(int capacityBytes) { + mPools = new SparseArrayBitmapPool[3]; + mPools[POOL_INDEX_SQUARE] = new SparseArrayBitmapPool(capacityBytes / 3, mSharedNodePool); + mPools[POOL_INDEX_PHOTO] = new SparseArrayBitmapPool(capacityBytes / 3, mSharedNodePool); + mPools[POOL_INDEX_MISC] = new SparseArrayBitmapPool(capacityBytes / 3, mSharedNodePool); + mCapacityBytes = capacityBytes; + } + + private static GalleryBitmapPool sInstance = new GalleryBitmapPool(CAPACITY_BYTES); + + public static GalleryBitmapPool getInstance() { + return sInstance; + } + + private SparseArrayBitmapPool getPoolForDimensions(int width, int height) { + int index = getPoolIndexForDimensions(width, height); + if (index == POOL_INDEX_NONE) { + return null; + } else { + return mPools[index]; + } + } + + private int getPoolIndexForDimensions(int width, int height) { + if (width <= 0 || height <= 0) { + return POOL_INDEX_NONE; + } + if (width == height) { + return POOL_INDEX_SQUARE; + } + int min, max; + if (width > height) { + min = height; + max = width; + } else { + min = width; + max = height; + } + for (Point ar : COMMON_PHOTO_ASPECT_RATIOS) { + if (min * ar.x == max * ar.y) { + return POOL_INDEX_PHOTO; + } + } + return POOL_INDEX_MISC; + } + + /** + * @return Capacity of the pool in bytes. + */ + public synchronized int getCapacity() { + return mCapacityBytes; + } + + /** + * @return Approximate total size in bytes of the bitmaps stored in the pool. + */ + public int getSize() { + // Note that this only returns an approximate size, since multiple threads + // might be getting and putting Bitmaps from the pool and we lock at the + // sub-pool level to avoid unnecessary blocking. + int total = 0; + for (SparseArrayBitmapPool p : mPools) { + total += p.getSize(); + } + return total; + } + + /** + * @return Bitmap from the pool with the desired height/width or null if none available. + */ + public Bitmap get(int width, int height) { + SparseArrayBitmapPool pool = getPoolForDimensions(width, height); + if (pool == null) { + return null; + } else { + return pool.get(width, height); + } + } + + /** + * Adds the given bitmap to the pool. + * @return Whether the bitmap was added to the pool. + */ + public boolean put(Bitmap b) { + if (b == null || b.getConfig() != Bitmap.Config.ARGB_8888) { + return false; + } + SparseArrayBitmapPool pool = getPoolForDimensions(b.getWidth(), b.getHeight()); + if (pool == null) { + b.recycle(); + return false; + } else { + return pool.put(b); + } + } + + /** + * Empty the pool, recycling all the bitmaps currently in it. + */ + public void clear() { + for (SparseArrayBitmapPool p : mPools) { + p.clear(); + } + } +} |