/*******************************************************************************
 * Copyright (c) 2004, 2007 QNX Software Systems 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:
 * QNX Software Systems - Initial API and implementation
 *******************************************************************************/
package org.eclipse.cdt.debug.internal.ui;

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

import org.eclipse.cdt.debug.ui.CDebugUIPlugin;
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>.
 */
public class CDebugImageDescriptorRegistry {

	private HashMap fRegistry = new HashMap( 10 );

	private Display fDisplay;

	/**
	 * Creates a new image descriptor registry for the current or default display, respectively.
	 */
	public CDebugImageDescriptorRegistry() {
		this( CDebugUIPlugin.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 diaplay
	 *            the display the images managed by this registry are allocated for
	 */
	public CDebugImageDescriptorRegistry( 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
	 * @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 == CDebugUIPlugin.getStandardDisplay(), CDebugUIMessages.getString( "CDebugImageDescriptorRegistry.0" ) ); //$NON-NLS-1$
		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.asyncExec( new Runnable() {

			public void run() {
				getDisplay().disposeExec( new Runnable() {

					public void run() {
						dispose();
					}
				} );
			}
		} );
	}

	protected Display getDisplay() {
		return fDisplay;
	}
}
