content: /*******************************************************************************
   * 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.wst.jsdt.internal.ui.viewsupport;
  
  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;
  import org.eclipse.wst.jsdt.internal.ui.util.SWTUtil;
  
  /**
   * A registry that maps <code>ImageDescriptors</code> to <code>Image</code>.
   */
  public class ImageDescriptorRegistry {
  
  	private HashMap fRegistry= new HashMap(10);
  	private Display fDisplay;
  	
  	/**
  	 * Creates a new image descriptor registry for the current or default display,
  	 * respectively.
  	 */
  	public ImageDescriptorRegistry() {
  		this(SWTUtil.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 ImageDescriptorRegistry(Display display) {
  		fDisplay= display;
  		Assert.isNotNull(fDisplay);
  		hookDisplay();
  	}
  	
  	/**
  	 * Returns the image associated with the given image descriptor.
  	 * 
  	 * @param descriptor the image descriptor for which the registry manages an image,
  	 *  or <code>null</code> for a missing image descriptor
  	 * @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= (Image)fRegistry.get(descriptor);
  		if (result != null)
  			return result;
  	
  		Assert.isTrue(fDisplay == SWTUtil.getStandardDisplay(), "Allocating image for wrong display."); //$NON-NLS-1$
  		result= descriptor.createImage();
  		if (result != null)
  			fRegistry.put(descriptor, result);
  		return result;
  	}
  
  	/**
  	 * Disposes all images managed by this registry.
  	 */	
  	public void dispose() {
  		for (Iterator iter= fRegistry.values().iterator(); iter.hasNext(); ) {
  			Image image= (Image)iter.next();
  			image.dispose();
  		}
  		fRegistry.clear();
  	}
  	
  	private void hookDisplay() {
  		fDisplay.disposeExec(new Runnable() {
  			public void run() {
  				dispose();
  			}	
  		});
  	}
  }