/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */
package net.sourceforge.phpdt.internal.ui.viewsupport;

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

import net.sourceforge.phpdt.internal.ui.util.SWTUtil;

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>.
 */
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 diaplay
	 *            the display the images managed by this registry are allocated
	 *            for
	 */
	public ImageDescriptorRegistry(Display display) {
		fDisplay = display;
		Assert.isNotNull(fDisplay);
		hookDisplay();
	}

	/**
	 * Returns the image assiciated 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 == 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();
			}
		});
	}
}
