1 /*
2 * Copyright (c) 1995, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.awt.image;
27
28 import java.awt.Image;
29 import java.awt.image.ImageFilter;
30 import java.awt.image.ImageConsumer;
31 import java.awt.image.ImageProducer;
32 import java.util.Hashtable;
33 import java.awt.image.ColorModel;
34
35 /**
36 * This class is an implementation of the ImageProducer interface which
37 * takes an existing image and a filter object and uses them to produce
38 * image data for a new filtered version of the original image.
39 * Here is an example which filters an image by swapping the red and
40 * blue components:
41 * <pre>
42 *
43 * Image src = getImage("doc:///demo/images/duke/T1.gif");
44 * ImageFilter colorfilter = new RedBlueSwapFilter();
45 * Image img = createImage(new FilteredImageSource(src.getSource(),
46 * colorfilter));
47 *
48 * </pre>
49 *
50 * @see ImageProducer
51 *
52 * @author Jim Graham
53 */
54 public class FilteredImageSource implements ImageProducer {
55 ImageProducer src;
56 ImageFilter filter;
57
58 /**
59 * Constructs an ImageProducer object from an existing ImageProducer
60 * and a filter object.
61 * @param orig the specified {@code ImageProducer}
62 * @param imgf the specified {@code ImageFilter}
63 * @see ImageFilter
64 * @see java.awt.Component#createImage
65 */
66 public FilteredImageSource(ImageProducer orig, ImageFilter imgf) {
67 src = orig;
68 filter = imgf;
69 }
70
71 private Hashtable<ImageConsumer, ImageFilter> proxies;
72
73 /**
74 * Adds the specified {@code ImageConsumer}
75 * to the list of consumers interested in data for the filtered image.
76 * An instance of the original {@code ImageFilter}
77 * is created
78 * (using the filter's {@code getFilterInstance} method)
79 * to manipulate the image data
80 * for the specified {@code ImageConsumer}.
81 * The newly created filter instance
82 * is then passed to the {@code addConsumer} method
83 * of the original {@code ImageProducer}.
84 *
85 * <p>
86 * This method is public as a side effect
87 * of this class implementing
88 * the {@code ImageProducer} interface.
89 * It should not be called from user code,
90 * and its behavior if called from user code is unspecified.
91 *
92 * @param ic the consumer for the filtered image
93 * @see ImageConsumer
94 */
95 public synchronized void addConsumer(ImageConsumer ic) {
96 if (proxies == null) {
97 proxies = new Hashtable<>();
98 }
99 if (!proxies.containsKey(ic)) {
100 ImageFilter imgf = filter.getFilterInstance(ic);
101 proxies.put(ic, imgf);
102 src.addConsumer(imgf);
103 }
104 }
105
106 /**
107 * Determines whether an ImageConsumer is on the list of consumers
108 * currently interested in data for this image.
109 *
110 * <p>
111 * This method is public as a side effect
112 * of this class implementing
113 * the {@code ImageProducer} interface.
114 * It should not be called from user code,
115 * and its behavior if called from user code is unspecified.
116 *
117 * @param ic the specified {@code ImageConsumer}
118 * @return true if the ImageConsumer is on the list; false otherwise
119 * @see ImageConsumer
120 */
121 public synchronized boolean isConsumer(ImageConsumer ic) {
122 return (proxies != null && proxies.containsKey(ic));
123 }
124
125 /**
126 * Removes an ImageConsumer from the list of consumers interested in
127 * data for this image.
128 *
129 * <p>
130 * This method is public as a side effect
131 * of this class implementing
132 * the {@code ImageProducer} interface.
133 * It should not be called from user code,
134 * and its behavior if called from user code is unspecified.
135 *
136 * @see ImageConsumer
137 */
138 public synchronized void removeConsumer(ImageConsumer ic) {
139 if (proxies != null) {
140 ImageFilter imgf = proxies.get(ic);
141 if (imgf != null) {
142 src.removeConsumer(imgf);
143 proxies.remove(ic);
144 if (proxies.isEmpty()) {
145 proxies = null;
146 }
147 }
148 }
149 }
150
151 /**
152 * Starts production of the filtered image.
153 * If the specified {@code ImageConsumer}
154 * isn't already a consumer of the filtered image,
155 * an instance of the original {@code ImageFilter}
156 * is created
157 * (using the filter's {@code getFilterInstance} method)
158 * to manipulate the image data
159 * for the {@code ImageConsumer}.
160 * The filter instance for the {@code ImageConsumer}
161 * is then passed to the {@code startProduction} method
162 * of the original {@code ImageProducer}.
163 *
164 * <p>
165 * This method is public as a side effect
166 * of this class implementing
167 * the {@code ImageProducer} interface.
168 * It should not be called from user code,
169 * and its behavior if called from user code is unspecified.
170 *
171 * @param ic the consumer for the filtered image
172 * @see ImageConsumer
173 */
174 public void startProduction(ImageConsumer ic) {
175 if (proxies == null) {
176 proxies = new Hashtable<>();
177 }
178 ImageFilter imgf = proxies.get(ic);
179 if (imgf == null) {
180 imgf = filter.getFilterInstance(ic);
181 proxies.put(ic, imgf);
182 }
183 src.startProduction(imgf);
184 }
185
186 /**
187 * Requests that a given ImageConsumer have the image data delivered
188 * one more time in top-down, left-right order. The request is
189 * handed to the ImageFilter for further processing, since the
190 * ability to preserve the pixel ordering depends on the filter.
191 *
192 * <p>
193 * This method is public as a side effect
194 * of this class implementing
195 * the {@code ImageProducer} interface.
196 * It should not be called from user code,
197 * and its behavior if called from user code is unspecified.
198 *
199 * @see ImageConsumer
200 */
201 public void requestTopDownLeftRightResend(ImageConsumer ic) {
202 if (proxies != null) {
203 ImageFilter imgf = proxies.get(ic);
204 if (imgf != null) {
205 imgf.resendTopDownLeftRight(src);
206 }
207 }
208 }
209 }