SWT Mouse Cursor Auto Hide

MouseCursorAutoHider.java

/**
 * Copyright (c) 2012 Gunnar Wagenknecht 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:
 *     Gunnar Wagenknecht - initial API and implementation
 */
package net.ageto.labs.dashboard.ui;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Cursor;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.PaletteData;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.ui.progress.UIJob;

/**
 * A job which runs periodically and hides the mouse cursor if it hasn't been
 * moved for a while.
 * <p>
 * Can be used as follows:
 * 
 * <pre>
 * final Display display = PlatformUI.createDisplay();
 * try {
 * 	final MouseCursorAutoHider cursorHider = new MouseCursorAutoHider(display, 5000L);
 * 	try {
 * 		final int returnCode = PlatformUI.createAndRunWorkbench(display, new DashboardWorkbenchAdvisor());
 * 		if (returnCode == PlatformUI.RETURN_RESTART) {
 * 			return IApplication.EXIT_RESTART;
 * 		}
 * 		return IApplication.EXIT_OK;
 * 	} finally {
 * 		cursorHider.dispose();
 * 	}
 * } finally {
 * 	display.dispose();
 * }
 * </pre>
 * 
 * </p>
 */
public final class MouseCursorAutoHider extends UIJob {

	private final long timeout;

	private long lastMouseActivity;
	private Cursor transparentMouseCursor;
	private boolean hidden;

	private final Listener listener = new Listener() {
		@Override
		public void handleEvent(final Event event) {
			mouseMovement();
		}
	};

	public MouseCursorAutoHider(final Display display, final long timeout) {
		super(display, "Mouse Cursor Auto Hide");
		this.timeout = Math.max(timeout, 5000L);
		setSystem(true);
		setPriority(Job.INTERACTIVE);
		activate();
	}

	private void activate() {
		// get display
		final Display display = getDisplay();

		// create transparent cursor
		final PaletteData palette = new PaletteData(new RGB[] { display.getSystemColor(SWT.COLOR_WHITE).getRGB(), display.getSystemColor(SWT.COLOR_BLACK).getRGB() });
		final ImageData sourceData = new ImageData(16, 16, 1, palette);
		sourceData.transparentPixel = 0;
		transparentMouseCursor = new Cursor(display, sourceData, 0, 0);

		display.addFilter(SWT.MouseMove, listener);

		schedule(timeout);
	}

	public void dispose() {
		try {
			if (null != transparentMouseCursor) {
				transparentMouseCursor.dispose();
			}
		} finally {
			transparentMouseCursor = null;
			getDisplay().removeFilter(SWT.MouseMove, listener);
		}
	}

	void hideCursor() {
		if (hidden) {
			return;
		}

		final Shell shell = getDisplay().getActiveShell();
		if (shell == null) {
			return;
		}

		final Cursor cursor = transparentMouseCursor;
		if ((null != cursor) && !cursor.isDisposed()) {
			shell.setCursor(cursor);
			hidden = true;
		}
	}

	void mouseMovement() {
		lastMouseActivity = System.currentTimeMillis();

		// show cursor if hidden
		if (!hidden) {
			return;
		}

		final Shell shell = getDisplay().getActiveShell();
		if (null != shell.getCursor()) {
			shell.setCursor(null);
			hidden = false;
		}
	}

	@Override
	public IStatus runInUIThread(final IProgressMonitor monitor) {
		if (null == transparentMouseCursor) {
			return Status.CANCEL_STATUS;
		}

		final long timeWithoutMovement = System.currentTimeMillis() - lastMouseActivity;

		if (timeWithoutMovement > timeout) {
			hideCursor();
		}

		schedule(Math.max(1000L, timeout - timeWithoutMovement));
		return Status.OK_STATUS;
	}
}