/*
 *(c) Copyright QNX Software Systems Ltd. 2002.
 * All Rights Reserved.
 * 
 */
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.jface.resource.ImageDescriptor;
import org.eclipse.jface.util.Assert;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;

/**
 * 
 * A registry that maps <code>ImageDescriptors</code> to <code>Image</code>.
 * 
 * @since Aug 30, 2002
 */
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(), CDebugUIPlugin.getResourceString("internal.ui.CDebugImageDescriptorRegistry.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.asyncExec(new Runnable() {
			public void run() {
				getDisplay().disposeExec( new Runnable() {
					public void run()	{
						dispose();
					}
				} );
			}
		} );
	}

	protected Display getDisplay() {
		return fDisplay;
	}
}