WaitingImageObserver.java Source code

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Here is the source code for WaitingImageObserver.java

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/* 
 * 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 1.8 2008/09/10 09:24:41 mungady 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.
 */

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 <code>ImageObserver<code> for the given <code>Image<code>.
     * The observer has to be started by an external thread.
     *
     * @param image  the image to observe (<code>null</code> 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:  <code>WIDTH</code>, <code>HEIGHT</code>,
     *               <code>PROPERTIES</code>, <code>SOMEBITS</code>,
     *               <code>FRAMEBITS</code>, <code>ALLBITS</code>,
     *               <code>ERROR</code>, <code>ABORT</code>.
     * @param     x   the <i>x</i> coordinate.
     * @param     y   the <i>y</i> coordinate.
     * @param     width    the width.
     * @param     height   the height.
     *
     * @return    <code>false</code> if the infoflags indicate that the
     *            image is completely loaded; <code>true</code> 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) {
                System.out.println("WaitingImageObserver.waitImageLoaded(): InterruptedException thrown" + e);
            }
        }
    }

    /**
     * Returns <code>true</code> if loading is complete, and <code>false</code>
     * otherwise.
     *
     * @return A boolean.
     */
    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;
    }
}