de.walware.ecommons.ui.util.ImageDescriptorRegistry.java Source code

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Here is the source code for de.walware.ecommons.ui.util.ImageDescriptorRegistry.java

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/*=============================================================================#
 # Copyright (c) 2000-2015 IBM Corporation and others.
 # All rights reserved. This program and the accompanying materials
 # are made available under the terms of the Eclipse Public License v1.0
 # which accompanies this distribution, and is available at
 # http://www.eclipse.org/legal/epl-v10.html
 # 
 # Contributors:
 #     IBM Corporation - initial API and implementation
 #     Patrick Chuong (Texas Instruments) - Bug 292411
 #     Stephan Wahlbrink - sync, IDisposable
 #=============================================================================*/

package de.walware.ecommons.ui.util;

import java.util.HashMap;
import java.util.Map;

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

import de.walware.ecommons.IDisposable;

/**
 * A registry that maps <code>ImageDescriptors</code> to <code>Image</code>.
 */
public class ImageDescriptorRegistry implements IDisposable {

    private final Map<ImageDescriptor, Image> fRegistry = new HashMap<ImageDescriptor, Image>();

    private final Display fDisplay;

    private boolean fDisposed;

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

    /**
     * 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 ImageDescriptorRegistry(final Display display) {
        if (display == null) {
            throw new NullPointerException("display");
        }
        fDisplay = 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();
        }
        synchronized (fRegistry) {
            Image result = fRegistry.get(descriptor);
            if (result == null && !fDisposed) {
                result = descriptor.createImage();
                if (result != null) {
                    fRegistry.put(descriptor, result);
                }
            }
            return result;
        }
    }

    private void hookDisplay() {
        fDisplay.asyncExec(new Runnable() {
            @Override
            public void run() {
                fDisplay.disposeExec(new Runnable() {
                    @Override
                    public void run() {
                        dispose();
                    }
                });
            }
        });
    }

    /**
     * Disposes all images managed by this registry.
     */
    @Override
    public void dispose() {
        synchronized (fRegistry) {
            fDisposed = true;
            for (final Image image : fRegistry.values()) {
                image.dispose();
            }
            fRegistry.clear();
        }
    }

}