/*******************************************************************************
 * Copyright (c) 2000, 2010 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.gef;

import org.eclipse.jface.action.IMenuListener;
import org.eclipse.jface.action.IMenuManager;
import org.eclipse.jface.action.MenuManager;

/**
 * Extends MenuManager to allow populating the menu directly from the manager
 * itself. Using this class is no different than using a standalone
 * <code>MenuManager</code>, and adding a menuAboutToShow listener.
 * 
 * @author hudsonr
 */
public abstract class ContextMenuProvider extends MenuManager implements
		IMenuListener {

	private EditPartViewer viewer;

	/**
	 * Constructs a context menu for the specified EditPartViewer.
	 * 
	 * @param viewer
	 *            the editpart viewer
	 */
	public ContextMenuProvider(EditPartViewer viewer) {
		setViewer(viewer);
		addMenuListener(this);
		setRemoveAllWhenShown(true);
	}

	/**
	 * Called when the menu is about to show. Subclasses must implement this
	 * method to populate the menu each time it is shown.
	 * 
	 * @param menu
	 *            this parameter is actually <code>this</code> object
	 */
	public abstract void buildContextMenu(IMenuManager menu);

	/**
	 * Returns the EditPartViewer
	 * 
	 * @return the viewer
	 */
	protected EditPartViewer getViewer() {
		return viewer;
	}

	/**
	 * @see IMenuListener#menuAboutToShow(IMenuManager)
	 */
	public void menuAboutToShow(IMenuManager menu) {
		buildContextMenu(menu);
	}

	/**
	 * Sets the editpart viewer. Called during construction.
	 * 
	 * @param viewer
	 *            the viewer
	 */
	protected void setViewer(EditPartViewer viewer) {
		this.viewer = viewer;
	}

}
