org.kalypso.ogc.gml.wms.provider.images.ImageCacheThread.java Source code

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Here is the source code for org.kalypso.ogc.gml.wms.provider.images.ImageCacheThread.java

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/*----------------    FILE HEADER KALYPSO ------------------------------------------
 *
 *  This file is part of kalypso.
 *  Copyright (C) 2004 by:
 *
 *  Technical University Hamburg-Harburg (TUHH)
 *  Institute of River and coastal engineering
 *  Denickestrae 22
 *  21073 Hamburg, Germany
 *  http://www.tuhh.de/wb
 *
 *  and
 *
 *  Bjoernsen Consulting Engineers (BCE)
 *  Maria Trost 3
 *  56070 Koblenz, Germany
 *  http://www.bjoernsen.de
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Contact:
 *
 *  E-Mail:
 *  belger@bjoernsen.de
 *  schlienger@bjoernsen.de
 *  v.doemming@tuhh.de
 *
 *  ---------------------------------------------------------------------------*/
package org.kalypso.ogc.gml.wms.provider.images;

import java.net.URL;
import java.util.LinkedList;
import java.util.Queue;

import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;

/**
 * @author Gernot Belger
 */
public class ImageCacheThread extends Thread {
    private final Queue<URL> m_queue = new LinkedList<>();

    private boolean m_isCanceled = false;

    private final ImageCache m_cache;

    public ImageCacheThread(final ImageCache cache) {
        m_cache = cache;
    }

    public synchronized void addImage(final URL onlineResource) {
        synchronized (m_queue) {
            m_queue.add(onlineResource);
        }

        this.notify();
    }

    public synchronized void cancel() {
        if (m_isCanceled)
            return;

        m_isCanceled = true;

        notify();
    }

    @Override
    public void run() {
        while (!m_isCanceled) {
            final boolean isEmpty = loadNextImage();
            if (!isEmpty)
                continue;

            synchronized (this) {
                try {
                    wait();
                } catch (final InterruptedException e) {
                    // proceed with next image
                }
            }
        }
    }

    private boolean loadNextImage() {
        final URL onlineResource;
        synchronized (m_queue) {
            onlineResource = m_queue.poll();
        }

        if (onlineResource == null)
            return true;

        final ImageDescriptor onlineImage = ImageDescriptor.createFromURL(onlineResource);

        final Image image = onlineImage.createImage();

        final ImageDescriptor scaledImage = createScaledImage(image);

        image.dispose();

        m_cache.imageLoaded(onlineResource, scaledImage);

        return false;
    }

    private ImageDescriptor createScaledImage(final Image image) {
        final ImageData data = image.getImageData();

        if (data.width <= 16 && data.height <= 16)
            return ImageDescriptor.createFromImageData(data);

        final ImageData scaledData = data.scaledTo(16, 16);
        return ImageDescriptor.createFromImageData(scaledData);
    }
}