1 /*
2 * Copyright (c) 2015, 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 package java.awt.image;
26
27 import java.awt.Graphics;
28 import java.awt.Image;
29
30 /**
31 * This class provides default implementations of several {@code Image} methods
32 * for classes that want to implement the {@MultiResolutionImage} interface.
33 *
34 * For example,
35 * <pre> {@code
36 * public class CustomMultiResolutionImage extends AbstractMultiResolutionImage {
37 *
38 * final Image[] resolutionVariants;
39 *
40 * public CustomMultiResolutionImage(Image... resolutionVariants) {
41 * this.resolutionVariants = resolutionVariants;
42 * }
43 *
44 * public Image getResolutionVariant(
45 * double destImageWidth, double destImageHeight) {
46 * // return a resolution variant based on the given destination image size
47 * }
48 *
49 * public List<Image> getResolutionVariants() {
50 * return Collections.unmodifiableList(Arrays.asList(resolutionVariants));
51 * }
52 *
53 * protected Image getBaseImage() {
54 * return resolutionVariants[0];
55 * }
56 * }
57 * } </pre>
58 *
59 * @see java.awt.Image
60 * @see java.awt.image.MultiResolutionImage
61 *
62 * @since 9
63 */
64 public abstract class AbstractMultiResolutionImage extends java.awt.Image
65 implements MultiResolutionImage {
66
67 /**
68 * This method simply delegates to the same method on the base image and
69 * it is equivalent to: {@code getBaseImage().getWidth(observer)}.
70 *
71 * @return the width of the base image, or -1 if the width is not yet known
72 * @see #getBaseImage()
73 *
74 * @since 9
75 */
76 @Override
77 public int getWidth(ImageObserver observer) {
78 return getBaseImage().getWidth(observer);
79 }
80
81 /**
82 * This method simply delegates to the same method on the base image and
83 * it is equivalent to: {@code getBaseImage().getHeight(observer)}.
84 *
85 * @return the height of the base image, or -1 if the height is not yet known
86 * @see #getBaseImage()
87 *
88 * @since 9
89 */
90 @Override
91 public int getHeight(ImageObserver observer) {
92 return getBaseImage().getHeight(observer);
93 }
94
95 /**
96 * This method simply delegates to the same method on the base image and
97 * it is equivalent to: {@code getBaseImage().getSource()}.
98 *
99 * @return the image producer that produces the pixels for the base image
100 * @see #getBaseImage()
101 *
102 * @since 9
103 */
104 @Override
105 public ImageProducer getSource() {
106 return getBaseImage().getSource();
107 }
108
109 /**
110 * As per the contract of the base {@code Image#getGraphics()} method,
111 * this implementation will always throw {@code UnsupportedOperationException}
112 * since only off-screen images can return a {@code Graphics} object.
113 *
114 * @return throws {@code UnsupportedOperationException}
115 * @throws UnsupportedOperationException this method is not supported
116 */
117 @Override
118 public Graphics getGraphics() {
119 throw new UnsupportedOperationException("getGraphics() not supported"
120 + " on Multi-Resolution Images");
121 }
122
123 /**
124 * This method simply delegates to the same method on the base image and
125 * it is equivalent to: {@code getBaseImage().getProperty(name, observer)}.
126 *
127 * @return the value of the named property in the base image
128 * @see #getBaseImage()
129 *
130 * @since 9
131 */
132 @Override
133 public Object getProperty(String name, ImageObserver observer) {
134 return getBaseImage().getProperty(name, observer);
135 }
136
137 /**
138 * Return the base image representing the best version of the image for
139 * rendering at the default width and height.
140 *
141 * @return the base image of the set of multi-resolution images
142 *
143 * @since 9
144 */
145 protected abstract Image getBaseImage();
146 }