1 /*
2 * Copyright 1995-1999 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.awt.image;
27
28 import java.awt.Image;
29
30 /**
31 * An asynchronous update interface for receiving notifications about
32 * Image information as the Image is constructed.
33 *
34 * @author Jim Graham
35 */
36 public interface ImageObserver {
37 /**
38 * This method is called when information about an image which was
39 * previously requested using an asynchronous interface becomes
40 * available. Asynchronous interfaces are method calls such as
41 * getWidth(ImageObserver) and drawImage(img, x, y, ImageObserver)
42 * which take an ImageObserver object as an argument. Those methods
43 * register the caller as interested either in information about
44 * the overall image itself (in the case of getWidth(ImageObserver))
45 * or about an output version of an image (in the case of the
46 * drawImage(img, x, y, [w, h,] ImageObserver) call).
47 *
48 * <p>This method
49 * should return true if further updates are needed or false if the
50 * required information has been acquired. The image which was being
51 * tracked is passed in using the img argument. Various constants
52 * are combined to form the infoflags argument which indicates what
53 * information about the image is now available. The interpretation
54 * of the x, y, width, and height arguments depends on the contents
55 * of the infoflags argument.
56 * <p>
57 * The <code>infoflags</code> argument should be the bitwise inclusive
58 * <b>OR</b> of the following flags: <code>WIDTH</code>,
59 * <code>HEIGHT</code>, <code>PROPERTIES</code>, <code>SOMEBITS</code>,
60 * <code>FRAMEBITS</code>, <code>ALLBITS</code>, <code>ERROR</code>,
61 * <code>ABORT</code>.
62 *
63 * @param img the image being observed.
64 * @param infoflags the bitwise inclusive OR of the following
65 * flags: <code>WIDTH</code>, <code>HEIGHT</code>,
66 * <code>PROPERTIES</code>, <code>SOMEBITS</code>,
67 * <code>FRAMEBITS</code>, <code>ALLBITS</code>,
68 * <code>ERROR</code>, <code>ABORT</code>.
69 * @param x the <i>x</i> coordinate.
70 * @param y the <i>y</i> coordinate.
71 * @param width the width.
72 * @param height the height.
73 * @return <code>false</code> if the infoflags indicate that the
74 * image is completely loaded; <code>true</code> otherwise.
75 *
76 * @see #WIDTH
77 * @see #HEIGHT
78 * @see #PROPERTIES
79 * @see #SOMEBITS
80 * @see #FRAMEBITS
81 * @see #ALLBITS
82 * @see #ERROR
83 * @see #ABORT
84 * @see Image#getWidth
85 * @see Image#getHeight
86 * @see java.awt.Graphics#drawImage
87 */
88 public boolean imageUpdate(Image img, int infoflags,
89 int x, int y, int width, int height);
90
91 /**
92 * This flag in the infoflags argument to imageUpdate indicates that
93 * the width of the base image is now available and can be taken
94 * from the width argument to the imageUpdate callback method.
95 * @see Image#getWidth
96 * @see #imageUpdate
97 */
98 public static final int WIDTH = 1;
99
100 /**
101 * This flag in the infoflags argument to imageUpdate indicates that
102 * the height of the base image is now available and can be taken
103 * from the height argument to the imageUpdate callback method.
104 * @see Image#getHeight
105 * @see #imageUpdate
106 */
107 public static final int HEIGHT = 2;
108
109 /**
110 * This flag in the infoflags argument to imageUpdate indicates that
111 * the properties of the image are now available.
112 * @see Image#getProperty
113 * @see #imageUpdate
114 */
115 public static final int PROPERTIES = 4;
116
117 /**
118 * This flag in the infoflags argument to imageUpdate indicates that
119 * more pixels needed for drawing a scaled variation of the image
120 * are available. The bounding box of the new pixels can be taken
121 * from the x, y, width, and height arguments to the imageUpdate
122 * callback method.
123 * @see java.awt.Graphics#drawImage
124 * @see #imageUpdate
125 */
126 public static final int SOMEBITS = 8;
127
128 /**
129 * This flag in the infoflags argument to imageUpdate indicates that
130 * another complete frame of a multi-frame image which was previously
131 * drawn is now available to be drawn again. The x, y, width, and height
132 * arguments to the imageUpdate callback method should be ignored.
133 * @see java.awt.Graphics#drawImage
134 * @see #imageUpdate
135 */
136 public static final int FRAMEBITS = 16;
137
138 /**
139 * This flag in the infoflags argument to imageUpdate indicates that
140 * a static image which was previously drawn is now complete and can
141 * be drawn again in its final form. The x, y, width, and height
142 * arguments to the imageUpdate callback method should be ignored.
143 * @see java.awt.Graphics#drawImage
144 * @see #imageUpdate
145 */
146 public static final int ALLBITS = 32;
147
148 /**
149 * This flag in the infoflags argument to imageUpdate indicates that
150 * an image which was being tracked asynchronously has encountered
151 * an error. No further information will become available and
152 * drawing the image will fail.
153 * As a convenience, the ABORT flag will be indicated at the same
154 * time to indicate that the image production was aborted.
155 * @see #imageUpdate
156 */
157 public static final int ERROR = 64;
158
159 /**
160 * This flag in the infoflags argument to imageUpdate indicates that
161 * an image which was being tracked asynchronously was aborted before
162 * production was complete. No more information will become available
163 * without further action to trigger another image production sequence.
164 * If the ERROR flag was not also set in this image update, then
165 * accessing any of the data in the image will restart the production
166 * again, probably from the beginning.
167 * @see #imageUpdate
168 */
169 public static final int ABORT = 128;
170 }
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