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Java > Open Source Codes > org > jfree > util > WaitingImageObserver


1 /* ========================================================================
2  * JCommon : a free general purpose class library for the Java(tm) platform
3  * ========================================================================
4  *
5  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6  *
7  * Project Info: http://www.jfree.org/jcommon/index.html
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * -------------------------
28  * WaitingImageObserver.java
29  * -------------------------
30  * (C)opyright 2000-2004, by Thomas Morgner and Contributors.
31  *
32  * Original Author: Thomas Morgner
33  * Contributor(s): Stefan Prange;
34  *
35  * $Id: WaitingImageObserver.java,v 1.6 2006/06/28 17:15:14 taqua Exp $
36  *
37  * Changes (from 8-Feb-2002)
38  * -------------------------
39  * 15-Apr-2002 : first version used by ImageElement.
40  * 16-May-2002 : Line delimiters adjusted
41  * 04-Jun-2002 : Documentation and added a NullPointerCheck for the constructor.
42  * 14-Jul-2002 : BugFixed: WaitingImageObserver dead-locked (bugfix by Stefan
43  * Prange)
44  * 18-Mar-2003 : Updated header and made minor Javadoc changes (DG);
45  * 21-Sep-2003 : Moved from JFreeReport.
46  */
47
48 package org.jfree.util;
49
50 import java.awt.Graphics JavaDoc;
51 import java.awt.Image JavaDoc;
52 import java.awt.image.BufferedImage JavaDoc;
53 import java.awt.image.ImageObserver JavaDoc;
54 import java.io.Serializable JavaDoc;
55
56 /**
57  * This image observer blocks until the image is completely loaded. AWT
58  * defers the loading of images until they are painted on a graphic.
59  *
60  * While printing reports it is not very nice, not to know whether a image
61  * was completely loaded, so this observer forces the loading of the image
62  * until a final state (either ALLBITS, ABORT or ERROR) is reached.
63  *
64  * @author Thomas Morgner
65  */
66 public class WaitingImageObserver implements ImageObserver JavaDoc, Serializable JavaDoc,
67                                              Cloneable JavaDoc
68 {
69   /** For serialization. */
70   static final long serialVersionUID = -807204410581383550L;
71     
72   /** The lock. */
73   private boolean lock;
74
75   /** The image. */
76   private Image JavaDoc image;
77
78   /** A flag that signals an error. */
79   private boolean error;
80
81   /**
82    * Creates a new <code>ImageObserver<code> for the given <code>Image<code>.
83    * The observer has to be started by an external thread.
84    *
85    * @param image the image to observe (<code>null</code> not permitted).
86    */
87   public WaitingImageObserver(final Image JavaDoc image) {
88     if (image == null) {
89       throw new NullPointerException JavaDoc();
90     }
91     this.image = image;
92     this.lock = true;
93   }
94
95   /**
96    * Callback function used by AWT to inform that more data is available. The
97    * observer waits until either all data is loaded or AWT signals that the
98    * image cannot be loaded.
99    *
100    * @param img the image being observed.
101    * @param infoflags the bitwise inclusive OR of the following
102    * flags: <code>WIDTH</code>, <code>HEIGHT</code>,
103    * <code>PROPERTIES</code>, <code>SOMEBITS</code>,
104    * <code>FRAMEBITS</code>, <code>ALLBITS</code>,
105    * <code>ERROR</code>, <code>ABORT</code>.
106    * @param x the <i>x</i> coordinate.
107    * @param y the <i>y</i> coordinate.
108    * @param width the width.
109    * @param height the height.
110    *
111    * @return <code>false</code> if the infoflags indicate that the
112    * image is completely loaded; <code>true</code> otherwise.
113    */
114   public synchronized boolean imageUpdate(
115       final Image JavaDoc img,
116       final int infoflags,
117       final int x,
118       final int y,
119       final int width,
120       final int height) {
121     if ((infoflags & ImageObserver.ALLBITS) == ImageObserver.ALLBITS) {
122         this.lock = false;
123         this.error = false;
124         notifyAll();
125         return false;
126     }
127     else if ((infoflags & ImageObserver.ABORT) == ImageObserver.ABORT
128         || (infoflags & ImageObserver.ERROR) == ImageObserver.ERROR) {
129         this.lock = false;
130         this.error = true;
131         notifyAll();
132         return false;
133     }
134     //notifyAll();
135 return true;
136   }
137
138   /**
139    * The workerthread. Simply draws the image to a BufferedImage's
140    * Graphics-Object and waits for the AWT to load the image.
141    */
142   public synchronized void waitImageLoaded() {
143
144     if (this.lock == false)
145     {
146       return;
147     }
148
149     final BufferedImage JavaDoc img = new BufferedImage JavaDoc(
150         1, 1, BufferedImage.TYPE_INT_RGB
151     );
152     final Graphics JavaDoc g = img.getGraphics();
153
154     while (this.lock) {
155       if (g.drawImage(this.image, 0, 0, img.getWidth(this),
156             img.getHeight(this), this)) {
157         return;
158       }
159
160       try {
161         wait(500);
162       }
163       catch (InterruptedException JavaDoc e) {
164         Log.info(
165           "WaitingImageObserver.waitImageLoaded(): InterruptedException thrown",
166           e
167         );
168       }
169     }
170   }
171
172   /**
173    * Clones this WaitingImageObserver.
174    *
175    * @return a clone.
176    *
177    * @throws CloneNotSupportedException this should never happen.
178    * @deprecated cloning may lock down the observer
179    */
180   public Object JavaDoc clone() throws CloneNotSupportedException JavaDoc {
181     return (WaitingImageObserver) super.clone();
182   }
183
184   public boolean isLoadingComplete() {
185     return this.lock == false;
186   }
187
188   /**
189    * Returns true if there is an error condition, and false otherwise.
190    *
191    * @return A boolean.
192    */
193   public boolean isError() {
194     return this.error;
195   }
196 }
197
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