BusyIndicator.java

/*******************************************************************************
 * Copyright (c) 2000, 2008, 2012 IBM Corporation, Gerhardt Informatics Kft. 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
 *     Gerhardt Informatics Kft. - GEFGWT port
 *******************************************************************************/
package org.eclipse.swt.custom;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Cursor;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

/**
 * Support for showing a Busy Cursor during a long running process.
 * 
 * @see <a
 *      href="http://www.eclipse.org/swt/snippets/#busyindicator">BusyIndicator
 *      snippets</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further
 *      information</a>
 */
public class BusyIndicator {

	static int nextBusyId = 1;
	static final String BUSYID_NAME = "SWT BusyIndicator"; //$NON-NLS-1$
	static final String BUSY_CURSOR = "SWT BusyIndicator Cursor"; //$NON-NLS-1$

	/**
	 * Runs the given <code>Runnable</code> while providing busy feedback using
	 * this busy indicator.
	 * 
	 * @param display
	 *            the display on which the busy feedback should be displayed. If
	 *            the display is null, the Display for the current thread will
	 *            be used. If there is no Display for the current thread, the
	 *            runnable code will be executed and no busy feedback will be
	 *            displayed.
	 * @param runnable
	 *            the runnable for which busy feedback is to be shown. Must not
	 *            be null.
	 * 
	 * @exception IllegalArgumentException
	 *                <ul>
	 *                <li>ERROR_NULL_ARGUMENT - if the runnable is null</li>
	 *                </ul>
	 */

	public static void showWhile(Display display, Runnable runnable) {
		if (runnable == null)
			SWT.error(SWT.ERROR_NULL_ARGUMENT);
		if (display == null) {
			display = Display.getCurrent();
			if (display == null) {
				runnable.run();
				return;
			}
		}

		Integer busyId = new Integer(nextBusyId);
		nextBusyId++;
		Cursor cursor = display.getSystemCursor(SWT.CURSOR_WAIT);
		Shell[] shells = display.getShells();
		for (int i = 0; i < shells.length; i++) {
			Integer id = (Integer) shells[i].getData(BUSYID_NAME);
			if (id == null) {
				shells[i].setCursor(cursor);
				shells[i].setData(BUSYID_NAME, busyId);
			}
		}

		try {
			runnable.run();
		} finally {
			shells = display.getShells();
			for (int i = 0; i < shells.length; i++) {
				Integer id = (Integer) shells[i].getData(BUSYID_NAME);
				if (id == busyId) {
					shells[i].setCursor(null);
					shells[i].setData(BUSYID_NAME, null);
				}
			}
		}
	}
}