bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/framelist/FrameAction.java

package org.eclipse.ui.views.framelist;

/**********************************************************************
Copyright (c) 2000, 2001, 2002, International Business Machines Corp and others.
All rights reserved.   This program and the accompanying materials
are made available under the terms of the Common Public License v0.5
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/cpl-v05.html
 
Contributors:
**********************************************************************/

import java.net.MalformedURLException;
import java.net.URL;

import org.eclipse.core.runtime.Platform;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.plugin.AbstractUIPlugin;

/**
 * Abstract superclass for actions dealing with frames or a frame list.
 * This listens for changes to the frame list and updates itself
 * accordingly.
 */
public abstract class FrameAction extends Action {
	private FrameList frameList;

	private IPropertyChangeListener propertyChangeListener = new IPropertyChangeListener() {
		public void propertyChange(PropertyChangeEvent event) {
			FrameAction.this.handlePropertyChange(event);
		}
	};

	/**
	 * Constructs a new action for the specified frame list.
	 * and adds a property change listener on it.
	 * 
	 * @param frameList the frame list
	 */
	protected FrameAction(FrameList frameList) {
		this.frameList = frameList;
		frameList.addPropertyChangeListener(propertyChangeListener);
	}

	/**
	 * Disposes this frame action.
	 * This implementation removes the property change listener from the frame list.
	 */
	public void dispose() {
		frameList.removePropertyChangeListener(propertyChangeListener);
	}

	/**
	 * Returns the frame list.
	 */
	public FrameList getFrameList() {
		return frameList;
	}

	/**
	 * Returns the image descriptor with the given relative path.
	 */
	static ImageDescriptor getImageDescriptor(String relativePath) {
		String iconPath = "icons/full/"; //$NON-NLS-1$
		try {
			AbstractUIPlugin plugin = (AbstractUIPlugin) Platform.getPlugin(PlatformUI.PLUGIN_ID);
			URL installURL = plugin.getDescriptor().getInstallURL();
			URL url = new URL(installURL, iconPath + relativePath);
			return ImageDescriptor.createFromURL(url);
		} catch (MalformedURLException e) {
			// should not happen
			return ImageDescriptor.getMissingImageDescriptor();
		}
	}

	/**
	 * Handles a property change event from the frame list.
	 * This implementation calls <code>update()</code>.
	 */
	protected void handlePropertyChange(PropertyChangeEvent event) {
		update();
	}

	/**
	 * Updates this action.  This implementation does nothing.
	 * Most implementations will override this method.
	 */
	public void update() {
	}

}