1 /*
2 * Copyright (c) 2015, 2020, 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 {@code MultiResolutionImage}
33 * interface.
34 *
35 * For example,
36 * <pre> {@code
37 * public class CustomMultiResolutionImage extends AbstractMultiResolutionImage {
38 *
39 * final Image[] resolutionVariants;
40 *
41 * public CustomMultiResolutionImage(Image... resolutionVariants) {
42 * this.resolutionVariants = resolutionVariants;
43 * }
44 *
45 * public Image getResolutionVariant(
46 * double destImageWidth, double destImageHeight) {
47 * // return a resolution variant based on the given destination image size
48 * }
49 *
50 * public List<Image> getResolutionVariants() {
51 * return Collections.unmodifiableList(Arrays.asList(resolutionVariants));
52 * }
53 *
54 * protected Image getBaseImage() {
55 * return resolutionVariants[0];
56 * }
57 * }
58 * } </pre>
59 *
60 * @see java.awt.Image
61 * @see java.awt.image.MultiResolutionImage
62 *
63 * @since 9
64 */
65 public abstract class AbstractMultiResolutionImage extends java.awt.Image
66 implements MultiResolutionImage {
67
68 /**
69 * Constructor for subclasses to call.
70 */
71 public AbstractMultiResolutionImage() {}
72
73 /**
74 * This method simply delegates to the same method on the base image and
75 * it is equivalent to: {@code getBaseImage().getWidth(observer)}.
76 *
77 * @return the width of the base image, or -1 if the width is not yet known
78 * @see #getBaseImage()
79 *
80 * @since 9
81 */
82 @Override
83 public int getWidth(ImageObserver observer) {
84 return getBaseImage().getWidth(observer);
85 }
86
87 /**
88 * This method simply delegates to the same method on the base image and
89 * it is equivalent to: {@code getBaseImage().getHeight(observer)}.
90 *
91 * @return the height of the base image, or -1 if the height is not yet known
92 * @see #getBaseImage()
93 *
94 * @since 9
95 */
96 @Override
97 public int getHeight(ImageObserver observer) {
98 return getBaseImage().getHeight(observer);
99 }
100
101 /**
102 * This method simply delegates to the same method on the base image and
103 * it is equivalent to: {@code getBaseImage().getSource()}.
104 *
105 * @return the image producer that produces the pixels for the base image
106 * @see #getBaseImage()
107 *
108 * @since 9
109 */
110 @Override
111 public ImageProducer getSource() {
112 return getBaseImage().getSource();
113 }
114
115 /**
116 * As per the contract of the base {@code Image#getGraphics()} method,
117 * this implementation will always throw {@code UnsupportedOperationException}
118 * since only off-screen images can return a {@code Graphics} object.
119 *
120 * @return throws {@code UnsupportedOperationException}
121 * @throws UnsupportedOperationException this method is not supported
122 */
123 @Override
124 public Graphics getGraphics() {
125 throw new UnsupportedOperationException("getGraphics() not supported"
126 + " on Multi-Resolution Images");
127 }
128
129 /**
130 * This method simply delegates to the same method on the base image and
131 * it is equivalent to: {@code getBaseImage().getProperty(name, observer)}.
132 *
133 * @return the value of the named property in the base image
134 * @see #getBaseImage()
135 *
136 * @since 9
137 */
138 @Override
139 public Object getProperty(String name, ImageObserver observer) {
140 return getBaseImage().getProperty(name, observer);
141 }
142
143 /**
144 * Return the base image representing the best version of the image for
145 * rendering at the default width and height.
146 *
147 * @return the base image of the set of multi-resolution images
148 *
149 * @since 9
150 */
151 protected abstract Image getBaseImage();
152 }