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JCommon is a free general purpose Java class library that is used in several projects at www.jfree.org, including JFreeChart and JFreeReport.
/* ========================================================================
* JCommon : a free general purpose class library for the Java(tm) platform
* ========================================================================
*
* (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jcommon/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* -------------------------
* WaitingImageObserver.java
* -------------------------
* (C)opyright 2000-2004, by Thomas Morgner and Contributors.
*
* Original Author: Thomas Morgner
* Contributor(s): Stefan Prange;
*
* $Id: WaitingImageObserver.java,v 1.7 2007/10/15 10:03:35 taqua Exp $
*
* Changes (from 8-Feb-2002)
* -------------------------
* 15-Apr-2002 : first version used by ImageElement.
* 16-May-2002 : Line delimiters adjusted
* 04-Jun-2002 : Documentation and added a NullPointerCheck for the constructor.
* 14-Jul-2002 : BugFixed: WaitingImageObserver dead-locked (bugfix by Stefan
* Prange)
* 18-Mar-2003 : Updated header and made minor Javadoc changes (DG);
* 21-Sep-2003 : Moved from JFreeReport.
*/
package org.jfree.util;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.ImageObserver;
import java.io.Serializable;
/**
* This image observer blocks until the image is completely loaded. AWT
* defers the loading of images until they are painted on a graphic.
*
* While printing reports it is not very nice, not to know whether a image
* was completely loaded, so this observer forces the loading of the image
* until a final state (either ALLBITS, ABORT or ERROR) is reached.
*
* @author Thomas Morgner
*/
public class WaitingImageObserver implements ImageObserver, Serializable,
Cloneable
{
/** For serialization. */
static final long serialVersionUID = -807204410581383550L;
/** The lock. */
private boolean lock;
/** The image. */
private Image image;
/** A flag that signals an error. */
private boolean error;
/**
* Creates a new ImageObserver for the given Image.
* The observer has to be started by an external thread.
*
* @param image the image to observe (null not permitted).
*/
public WaitingImageObserver(final Image image) {
if (image == null) {
throw new NullPointerException();
}
this.image = image;
this.lock = true;
}
/**
* Callback function used by AWT to inform that more data is available. The
* observer waits until either all data is loaded or AWT signals that the
* image cannot be loaded.
*
* @param img the image being observed.
* @param infoflags the bitwise inclusive OR of the following
* flags: WIDTH, HEIGHT,
* PROPERTIES, SOMEBITS,
* FRAMEBITS, ALLBITS,
* ERROR, ABORT.
* @param x the x coordinate.
* @param y the y coordinate.
* @param width the width.
* @param height the height.
*
* @return false if the infoflags indicate that the
* image is completely loaded; true otherwise.
*/
public synchronized boolean imageUpdate(
final Image img,
final int infoflags,
final int x,
final int y,
final int width,
final int height) {
if ((infoflags & ImageObserver.ALLBITS) == ImageObserver.ALLBITS) {
this.lock = false;
this.error = false;
notifyAll();
return false;
}
else if ((infoflags & ImageObserver.ABORT) == ImageObserver.ABORT
|| (infoflags & ImageObserver.ERROR) == ImageObserver.ERROR) {
this.lock = false;
this.error = true;
notifyAll();
return false;
}
//notifyAll();
return true;
}
/**
* The workerthread. Simply draws the image to a BufferedImage's
* Graphics-Object and waits for the AWT to load the image.
*/
public synchronized void waitImageLoaded() {
if (this.lock == false)
{
return;
}
final BufferedImage img = new BufferedImage(
1, 1, BufferedImage.TYPE_INT_RGB
);
final Graphics g = img.getGraphics();
while (this.lock) {
if (g.drawImage(this.image, 0, 0, img.getWidth(this),
img.getHeight(this), this)) {
return;
}
try {
wait(500);
}
catch (InterruptedException e) {
Log.info(
"WaitingImageObserver.waitImageLoaded(): InterruptedException thrown",
e
);
}
}
}
/**
* Clones this WaitingImageObserver.
*
* @return a clone.
*
* @throws CloneNotSupportedException this should never happen.
* @deprecated cloning may lock down the observer
*/
public Object clone() throws CloneNotSupportedException {
return (WaitingImageObserver) super.clone();
}
public boolean isLoadingComplete() {
return this.lock == false;
}
/**
* Returns true if there is an error condition, and false otherwise.
*
* @return A boolean.
*/
public boolean isError() {
return this.error;
}
}