/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal.decorators;


import java.util.*;

import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.swt.graphics.*;

/**
 * The OverlayCache is a helper class used by the DecoratorManger
 * to manage the lifecycle of overlaid images.
 */
class OverlayCache {
	private Map cache = new HashMap(); /*from OverlayIcon to Image*/

	/**
	 * Returns and caches an image corresponding to the specified icon.
	 * @param icon the icon
	 * @return the image
	 */
	Image getImageFor(DecoratorOverlayIcon icon) {
		Image image = (Image) cache.get(icon);
		if (image == null) {
			image = icon.createImage();
			cache.put(icon, image);
		}
		return image;
	}

	/**
	 * Disposes of all images in the cache.
	 */
	void disposeAll() {
		for (Iterator it = cache.values().iterator(); it.hasNext();) {
			Image image = (Image) it.next();
			image.dispose();
		}
		cache.clear();
	}

	/**
	 * 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);
		DecoratorOverlayIcon icon =
			new DecoratorOverlayIcon(source, descriptors, size);
		return getImageFor(icon);
	}

}