/*
 * Copyright (c) 1995, 2014, 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.applet;

import java.awt.Toolkit;
import java.awt.Image;
import java.lang.ref.SoftReference;
import sun.awt.image.URLImageSource;
import java.net.URL;

@Deprecated(since = "9")
class AppletImageRef {
    private SoftReference<Image> soft = null;

    URL url;

    
Returns a pointer to the object referenced by this Ref.  If the object
has been thrown away by the garbage collector, it will be
reconstituted. This method does everything necessary to ensure that the garbage
collector throws things away in Least Recently Used(LRU) order.  Applications should
never override this method. The get() method effectively caches calls to
reconstitute().
/**
     * Returns a pointer to the object referenced by this Ref.  If the object
     * has been thrown away by the garbage collector, it will be
     * reconstituted. This method does everything necessary to ensure that the garbage
     * collector throws things away in Least Recently Used(LRU) order.  Applications should
     * never override this method. The get() method effectively caches calls to
     * reconstitute().
     */
    public synchronized Image get() {
        Image t = check();
        if (t == null) {
            t = reconstitute();
            setThing(t);
        }
        return t;
    }

    
Create the Ref
/**
     * Create the Ref
     */
    AppletImageRef(URL url) {
        this.url = url;
    }

    
Flushes the cached object.  Forces the next invocation of get() to
invoke reconstitute().
/**
     * Flushes the cached object.  Forces the next invocation of get() to
     * invoke reconstitute().
     */
    public synchronized void flush() {
        SoftReference<Image> s = soft;
        if (s != null) s.clear();
        soft = null;
    }

    
Sets the thing to the specified object.
Params:
thing – the specified object/**
     * Sets the thing to the specified object.
     * @param thing the specified object
     */
    public synchronized void setThing(Image thing) {
        flush();
        soft = new SoftReference<>(thing);
    }

    
Checks to see what object is being pointed at by this Ref and returns it.
/**
     * Checks to see what object is being pointed at by this Ref and returns it.
     */
    public synchronized Image check() {
        SoftReference<Image> s = soft;
        if (s == null) return null;
        return s.get();
    }

    
Reconsitute the image.  Only called when the ref has been flushed.
/**
     * Reconsitute the image.  Only called when the ref has been flushed.
     */
    public Image reconstitute() {
        Image img = Toolkit.getDefaultToolkit().createImage(new URLImageSource(url));
        return img;
    }
}