bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/decorators/OverlayCache.java

/*******************************************************************************
 * Copyright (c) 2000, 2007 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
 *******************************************************************************/
package org.eclipse.ui.internal.decorators;

import java.util.HashSet;
import java.util.Set;

import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.jface.resource.LocalResourceManager;
import org.eclipse.jface.viewers.DecorationOverlayIcon;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.ui.PlatformUI;

/**
 * The OverlayCache is a helper class used by the DecoratorManger to manage the
 * life cycle of overlaid images.
 */
class OverlayCache {

	/**
	 * The CacheEntry
	 * 
	 * @since 3.3
	 * 
	 */

	private Set keys = new HashSet(); // Hold onto the cache entries we
	// created
	// Use a resource manager to hold onto any images we have to create
	private LocalResourceManager resourceManager;

	/**
	 * 
	 */
	public OverlayCache() {
		super();
		//As we are not in the UI Thread lookup the Display
		resourceManager = new LocalResourceManager(JFaceResources
				.getResources(PlatformUI.getWorkbench().getDisplay()));
	}

	/**
	 * Returns and caches an image corresponding to the specified icon.
	 * 
	 * @param icon
	 *            the icon
	 * @return the image
	 */
	private Image getImageFor(DecorationOverlayIcon icon) {
		keys.add(icon);// Cache the keys so there is a reference somewhere
		return resourceManager.createImage(icon);
	}

	/**
	 * Disposes of all images in the cache.
	 */
	void disposeAll() {
		keys.clear();
		resourceManager.dispose();
	}

	/**
	 * Apply the descriptors for the receiver to the supplied image.
	 * 
	 * @param source
	 * @param descriptors
	 * @return Image
	 */

	Image applyDescriptors(Image source, ImageDescriptor[] descriptors) {
		Rectangle bounds = source.getBounds();
		Point size = new Point(bounds.width, bounds.height);
		DecorationOverlayIcon icon = new DecorationOverlayIcon(source, descriptors, size);
		return getImageFor(icon);
	}

}