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Java example source code file (ImageCache.java)
The ImageCache.java Java example source code/* * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing.plaf.nimbus; import java.awt.GraphicsConfiguration; import java.awt.Image; import java.lang.ref.ReferenceQueue; import java.lang.ref.SoftReference; import java.util.Arrays; import java.util.Iterator; import java.util.LinkedHashMap; import java.util.Map; import java.util.concurrent.locks.ReadWriteLock; import java.util.concurrent.locks.ReentrantReadWriteLock; /** * ImageCache - A fixed pixel count sized cache of Images keyed by arbitrary set of arguments. All images are held with * SoftReferences so they will be dropped by the GC if heap memory gets tight. When our size hits max pixel count least * recently requested images are removed first. * * @author Created by Jasper Potts (Aug 7, 2007) */ class ImageCache { // Ordered Map keyed by args hash, ordered by most recent accessed entry. private final LinkedHashMap<Integer, PixelCountSoftReference> map = new LinkedHashMap<Integer, PixelCountSoftReference>(16, 0.75f, true); // Maximum number of pixels to cache, this is used if maxCount private final int maxPixelCount; // Maximum cached image size in pxiels private final int maxSingleImagePixelSize; // The current number of pixels stored in the cache private int currentPixelCount = 0; // Lock for concurrent access to map private ReadWriteLock lock = new ReentrantReadWriteLock(); // Reference queue for tracking lost softreferences to images in the cache private ReferenceQueue<Image> referenceQueue = new ReferenceQueue(); // Singleton Instance private static final ImageCache instance = new ImageCache(); /** Get static singleton instance */ static ImageCache getInstance() { return instance; } public ImageCache() { this.maxPixelCount = (8 * 1024 * 1024) / 4; // 8Mb of pixels this.maxSingleImagePixelSize = 300 * 300; } public ImageCache(int maxPixelCount, int maxSingleImagePixelSize) { this.maxPixelCount = maxPixelCount; this.maxSingleImagePixelSize = maxSingleImagePixelSize; } /** Clear the cache */ public void flush() { lock.readLock().lock(); try { map.clear(); } finally { lock.readLock().unlock(); } } /** * Check if the image size is to big to be stored in the cache * * @param w The image width * @param h The image height * @return True if the image size is less than max */ public boolean isImageCachable(int w, int h) { return (w * h) < maxSingleImagePixelSize; } /** * Get the cached image for given keys * * @param config The graphics configuration, needed if cached image is a Volatile Image. Used as part of cache key * @param w The image width, used as part of cache key * @param h The image height, used as part of cache key * @param args Other arguments to use as part of the cache key * @return Returns the cached Image, or null there is no cached image for key */ public Image getImage(GraphicsConfiguration config, int w, int h, Object... args) { lock.readLock().lock(); try { PixelCountSoftReference ref = map.get(hash(config, w, h, args)); // check reference has not been lost and the key truly matches, in case of false positive hash match if (ref != null && ref.equals(config,w, h, args)) { return ref.get(); } else { return null; } } finally { lock.readLock().unlock(); } } /** * Sets the cached image for the specified constraints. * * @param image The image to store in cache * @param config The graphics configuration, needed if cached image is a Volatile Image. Used as part of cache key * @param w The image width, used as part of cache key * @param h The image height, used as part of cache key * @param args Other arguments to use as part of the cache key * @return true if the image could be cached or false if the image is too big */ public boolean setImage(Image image, GraphicsConfiguration config, int w, int h, Object... args) { if (!isImageCachable(w, h)) return false; int hash = hash(config, w, h, args); lock.writeLock().lock(); try { PixelCountSoftReference ref = map.get(hash); // check if currently in map if (ref != null && ref.get() == image) { return true; } // clear out old if (ref != null) { currentPixelCount -= ref.pixelCount; map.remove(hash); } // add new image to pixel count int newPixelCount = image.getWidth(null) * image.getHeight(null); currentPixelCount += newPixelCount; // clean out lost references if not enough space if (currentPixelCount > maxPixelCount) { while ((ref = (PixelCountSoftReference)referenceQueue.poll()) != null){ //reference lost map.remove(ref.hash); currentPixelCount -= ref.pixelCount; } } // remove old items till there is enough free space if (currentPixelCount > maxPixelCount) { Iterator<Map.Entry Other Java examples (source code examples)Here is a short list of links related to this Java ImageCache.java source code file: |
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