org.whole.lang.ui.WholeImageDescriptorRegistry.java Source code

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Here is the source code for org.whole.lang.ui.WholeImageDescriptorRegistry.java

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/**
 * Copyright 2004-2014 Riccardo Solmi. All rights reserved.
 * This file is part of the Whole Platform.
 *
 * The Whole Platform 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 3 of the License, or
 * (at your option) any later version.
 *
 * The Whole Platform 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 the Whole Platform. If not, see <http://www.gnu.org/licenses/>.
 */
package org.whole.lang.ui;

import java.util.HashMap;
import java.util.Iterator;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;

/**
 * A registry that maps <code>ImageDescriptors</code> to <code>Image</code>.
 * @see org.eclipse.jdt.internal.ui.viewsupport.ImageDescriptorRegistry
 */
public class WholeImageDescriptorRegistry {
    private HashMap<ImageDescriptor, Image> registryMap = new HashMap<ImageDescriptor, Image>(10);
    private Display display;

    /**
     * Creates a new image descriptor registry for the current or default display,
     * respectively.
     */
    public WholeImageDescriptorRegistry() {
        this(getStandardDisplay());
    }

    /**
     * Creates a new image descriptor registry for the given display. All images
     * managed by this registry will be disposed when the display gets disposed.
     * 
     * @param display the display the images managed by this registry are allocated for 
     */
    public WholeImageDescriptorRegistry(Display display) {
        this.display = display;
        Assert.isNotNull(display);
        hookDisplay();
    }

    /**
     * Returns the image associated with the given image descriptor.
     * 
     * @param descriptor the image descriptor for which the registry manages an image
     * @return the image associated with the image descriptor or <code>null</code>
     *  if the image descriptor can't create the requested image.
     */
    public Image get(ImageDescriptor descriptor) {
        if (descriptor == null)
            descriptor = ImageDescriptor.getMissingImageDescriptor();

        Image result = registryMap.get(descriptor);
        if (result != null)
            return result;

        Assert.isTrue(display == getStandardDisplay(), "Allocating image for wrong display."); //$NON-NLS-1$
        result = descriptor.createImage();
        if (result != null)
            registryMap.put(descriptor, result);
        return result;
    }

    /**
     * Disposes all images managed by this registry.
     */
    public void dispose() {
        for (Iterator<Image> iter = registryMap.values().iterator(); iter.hasNext();) {
            Image image = iter.next();
            image.dispose();
        }
        registryMap.clear();
    }

    private void hookDisplay() {
        display.disposeExec(new Runnable() {
            public void run() {
                dispose();
            }
        });
    }

    private static Display getStandardDisplay() {
        Display display;
        display = Display.getCurrent();
        if (display == null)
            display = Display.getDefault();
        return display;
    }
}