/*
* 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.
*
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package com.sun.java.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<Image>();
// 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<Integer, PixelCountSoftReference>> mapIter = map.entrySet().iterator();
while ((currentPixelCount > maxPixelCount) && mapIter.hasNext()) {
Map.Entry<Integer, PixelCountSoftReference> entry = mapIter.next();
mapIter.remove();
Image img = entry.getValue().get();
if (img != null) img.flush();
currentPixelCount -= entry.getValue().pixelCount;
}
}
// finaly put new in map
map.put(hash, new PixelCountSoftReference(image, referenceQueue, newPixelCount,hash, config, w, h, args));
return true;
} finally {
lock.writeLock().unlock();
}
}
/** Create a unique hash from all the input */
private int hash(GraphicsConfiguration config, int w, int h, Object ... args) {
int hash;
hash = (config != null ? config.hashCode() : 0);
hash = 31 * hash + w;
hash = 31 * hash + h;
hash = 31 * hash + Arrays.deepHashCode(args);
return hash;
}
/** Extended SoftReference that stores the pixel count even after the image is lost */
private static class PixelCountSoftReference extends SoftReference<Image> {
private final int pixelCount;
private final int hash;
// key parts
private final GraphicsConfiguration config;
private final int w;
private final int h;
private final Object[] args;
public PixelCountSoftReference(Image referent, ReferenceQueue<? super Image> q, int pixelCount, int hash,
GraphicsConfiguration config, int w, int h, Object[] args) {
super(referent, q);
this.pixelCount = pixelCount;
this.hash = hash;
this.config = config;
this.w = w;
this.h = h;
this.args = args;
}
public boolean equals (GraphicsConfiguration config, int w, int h, Object[] args){
return config == this.config &&
w == this.w &&
h == this.h &&
Arrays.equals(args, this.args);
}
}
}