/*
 * Copyright (c) 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 sun.swing;

import java.awt.GraphicsConfiguration;
import java.awt.Image;
import java.lang.ref.SoftReference;
import java.util.Iterator;
import java.util.LinkedList;

/**
 * Cache is used to cache an image based on a set of arguments.
 */
public class ImageCache {
 // Maximum number of entries to cache
 private int maxCount;
 // The entries.
 private final LinkedList<SoftReference<Entry>> entries;

 public ImageCache(int maxCount) {
 this.maxCount = maxCount;
 entries = new LinkedList<SoftReference<Entry>>();
 }

 void setMaxCount(int maxCount) {
 this.maxCount = maxCount;
 }

 public void flush() {
 entries.clear();
 }

 private Entry getEntry(Object key, GraphicsConfiguration config,
 int w, int h, Object[] args) {
 Entry entry;
 Iterator<SoftReference<Entry>> iter = entries.listIterator();
 while (iter.hasNext()) {
 SoftReference<Entry> ref = iter.next();
 entry = ref.get();
 if (entry == null) {
 // SoftReference was invalidated, remove the entry
 iter.remove();
 }
 else if (entry.equals(config, w, h, args)) {
 // Put most recently used entries at the head
 iter.remove();
 entries.addFirst(ref);
 return entry;
 }
 }
 // Entry doesn't exist
 entry = new Entry(config, w, h, args);
 if (entries.size() >= maxCount) {
 entries.removeLast();
 }
 entries.addFirst(new SoftReference<Entry>(entry));
 return entry;
 }

 /**
 * Returns the cached Image, or null, for the specified arguments.
 */
 public Image getImage(Object key, GraphicsConfiguration config,
 int w, int h, Object[] args) {
 Entry entry = getEntry(key, config, w, h, args);
 return entry.getImage();
 }

 /**
 * Sets the cached image for the specified constraints.
 */
 public void setImage(Object key, GraphicsConfiguration config,
 int w, int h, Object[] args, Image image) {
 Entry entry = getEntry(key, config, w, h, args);
 entry.setImage(image);
 }


 /**
 * Caches set of arguments and Image.
 */
 private static class Entry {
 private final GraphicsConfiguration config;
 private final int w;
 private final int h;
 private final Object[] args;
 private Image image;

 Entry(GraphicsConfiguration config, int w, int h, Object[] args) {
 this.config = config;
 this.args = args;
 this.w = w;
 this.h = h;
 }

 public void setImage(Image image) {
 this.image = image;
 }

 public Image getImage() {
 return image;
 }

 public String toString() {
 String value = super.toString() +
 "[ graphicsConfig=" + config +
 ", image=" + image +
 ", w=" + w + ", h=" + h;
 if (args != null) {
 for (int counter = 0; counter < args.length; counter++) {
 value += ", " + args[counter];
 }
 }
 value += "]";
 return value;
 }

 public boolean equals(GraphicsConfiguration config,
 int w, int h, Object[] args) {
 if (this.w == w && this.h == h &&
 ((this.config != null && this.config.equals(config)) ||
 (this.config == null && config == null))) {
 if (this.args == null && args == null) {
 return true;
 }
 if (this.args != null && args != null &&
 this.args.length == args.length) {
 for (int counter = args.length - 1; counter >= 0;
 counter--) {
 Object a1 = this.args[counter];
 Object a2 = args[counter];
 if ((a1 == null && a2 != null) ||
 (a1 != null && !a1.equals(a2))) {
 return false;
 }
 }
 return true;
 }
 }
 return false;
 }
 }
}