AbstractUiHandler.java

/*******************************************************************************
 * Copyright (c) 2011 Tasktop Technologies.
 * 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:
 *     Tasktop Technologies - initial API and implementation
 *******************************************************************************/

package org.eclipse.mylyn.internal.sandbox.search.ui;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.handlers.HandlerUtil;

/**
 * @author David Green
 */
public abstract class AbstractUiHandler extends AbstractHandler {

	public Object execute(ExecutionEvent event) throws ExecutionException {
		Display display = computeDisplay(event);
		display.asyncExec(computeUiRunnable(event));
		return null;
	}

	protected abstract Runnable computeUiRunnable(ExecutionEvent event);

	protected IWorkbenchWindow computeWorkbenchWindow(ExecutionEvent event) {
		IWorkbenchWindow window = HandlerUtil.getActiveWorkbenchWindow(event);
		if (window == null) {
			window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
			if (window == null) {
				window = PlatformUI.getWorkbench().getWorkbenchWindows()[0];
			}
		}
		return window;
	}

	protected Display computeDisplay(ExecutionEvent event) {
		Display display = null;
		final IWorkbenchWindow workbenchWindow = computeWorkbenchWindow(event);
		if (workbenchWindow != null) {
			display = workbenchWindow.getShell().getDisplay();
		}
		if (display == null) {
			display = Display.getDefault();
		}
		return display;
	}
}