001/* FilteredImageSource.java -- Java class for providing image data
002   Copyright (C) 1999 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.awt.image;
040
041import java.util.Hashtable;
042
043/**
044 *
045 * @see ImageConsumer
046 * @author C. Brian Jones (cbj@gnu.org)
047 */
048public class FilteredImageSource implements ImageProducer
049{
050    ImageProducer ip;
051    ImageFilter filter;
052    Hashtable consumers = new Hashtable();
053
054    /**
055     * The given filter is applied to the given image producer
056     * to create a new image producer.
057     */
058    public FilteredImageSource(ImageProducer ip, ImageFilter filter) {
059        this.ip = ip;
060        this.filter = filter;
061    }
062
063    /**
064     * Used to register an <code>ImageConsumer</code> with this
065     * <code>ImageProducer</code>.
066     */
067    public synchronized void addConsumer(ImageConsumer ic) {
068        if (consumers.containsKey(ic))
069            return;
070
071        ImageFilter f = filter.getFilterInstance(ic);
072        consumers.put(ic, f);
073        ip.addConsumer(f);
074    }
075
076    /**
077     * Used to determine if the given <code>ImageConsumer</code> is
078     * already registered with this <code>ImageProducer</code>.
079     */
080    public synchronized boolean isConsumer(ImageConsumer ic) {
081        ImageFilter f = (ImageFilter)consumers.get(ic);
082        if (f != null)
083            return ip.isConsumer(f);
084        return false;
085    }
086
087    /**
088     * Used to remove an <code>ImageConsumer</code> from the list of
089     * registered consumers for this <code>ImageProducer</code>.
090     */
091    public synchronized void removeConsumer(ImageConsumer ic) {
092        ImageFilter f = (ImageFilter)consumers.remove(ic);
093        if (f != null)
094            ip.removeConsumer(f);
095    }
096
097    /**
098     * Used to register an <code>ImageConsumer</code> with this
099     * <code>ImageProducer</code> and then immediately start
100     * reconstruction of the image data to be delivered to all
101     * registered consumers.
102     */
103    public void startProduction(ImageConsumer ic) {
104        ImageFilter f;
105        if (!(consumers.containsKey(ic))) {
106            f = filter.getFilterInstance(ic);
107            consumers.put(ic, f);
108            ip.addConsumer(f);
109        } else {
110            f = (ImageFilter)consumers.get( ic );
111        }
112        ip.startProduction(f);
113    }
114
115    /**
116     * Used to register an <code>ImageConsumer</code> with this
117     * <code>ImageProducer</code> and then request that this producer
118     * resend the image data in the order top-down, left-right.
119     */
120    public void requestTopDownLeftRightResend(ImageConsumer ic) {
121        ImageFilter f = (ImageFilter)consumers.get(ic);
122        ip.requestTopDownLeftRightResend(f);
123    }
124}