bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/keys/OutOfOrderListener.java

/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Common Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors: IBM Corporation - initial API and implementation
 ******************************************************************************/

package org.eclipse.ui.internal.keys;

import java.util.List;

import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Widget;

/**
 * A listener that makes sure that global key bindings are processed if no
 * other listeners do any useful work.
 * 
 * @since 3.0
 */
public class OutOfOrderListener implements Listener {

	/**
	 * The keyboard interface to which the event should be passed if it is not
	 * eaten.
	 */
	private final WorkbenchKeyboard keyboard;

	/**
	 * Constructs a new instance of <code>OutOfOrderListener</code> with a
	 * reference to the keyboard interface which should be allowed to process
	 * uneaten events.
	 * 
	 * @param workbenchKeyboard
	 *            The keyboard interface for the workbench capable of
	 *            processing key bindings; must not be <code>null</code>.
	 */
	public OutOfOrderListener(WorkbenchKeyboard workbenchKeyboard) {
		keyboard = workbenchKeyboard;
	}

	/**
	 * Handles the key down event on a widget by passing uneaten events to the
	 * key binding architecture. This is used to allow special keys to reach
	 * the widget first -- before being processed by the key binding
	 * architecture.
	 * 
	 * @param event
	 *            The event to process; must not be <code>null</code>
	 */
	public void handleEvent(Event event) {
		// Always remove myself as a listener.
	    Widget widget = event.widget;
	    if ((widget != null) && (!widget.isDisposed())) { 
	        widget.removeListener(event.type, this);
	    }

		/*
		 * If the event is still up for grabs, then re-route through the global
		 * key filter.
		 */
		if (event.doit) {
			List keyStrokes = WorkbenchKeyboard.generatePossibleKeyStrokes(event);
			keyboard.processKeyEvent(keyStrokes, event);
		}
	}
}