examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet219.java

/*******************************************************************************
 * Copyright (c) 2000, 2014 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.snippets;

import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

/**
 * Region snippet: Create non-rectangular shell from an image with transparency
 * (ESC to close shell)
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 *
 * @since 3.2
 */
public class Snippet219 {
	public static void main(String[] args) {
		final Display display = new Display ();
		final Image image = display.getSystemImage(SWT.ICON_INFORMATION);
		final Shell shell = new Shell (display, SWT.NO_TRIM);
		shell.setText("Snippet 219");
		Region region = new Region();
		final ImageData imageData = image.getImageData();
		if (imageData.alphaData != null) {
			Rectangle pixel = new Rectangle(0, 0, 1, 1);
			for (int y = 0; y < imageData.height; y++) {
				for (int x = 0; x < imageData.width; x++) {
					if (imageData.getAlpha(x, y) == 255) {
						pixel.x = imageData.x + x;
						pixel.y = imageData.y + y;
						region.add(pixel);
					}
				}
			}
		} else {
			ImageData mask = imageData.getTransparencyMask();
			Rectangle pixel = new Rectangle(0, 0, 1, 1);
			for (int y = 0; y < mask.height; y++) {
				for (int x = 0; x < mask.width; x++) {
					if (mask.getPixel(x, y) != 0) {
						pixel.x = imageData.x + x;
						pixel.y = imageData.y + y;
						region.add(pixel);
					}
				}
			}
		}
		shell.setRegion(region);

		Listener l = new Listener() {
			/** The x/y of the MouseDown, relative to top-left of the shell. */
			int startX, startY;
			@Override
			public void handleEvent(Event e)  {
				if (e.type == SWT.KeyDown && e.character == SWT.ESC) {
					shell.dispose();
				}
				if (e.type == SWT.MouseDown && e.button == 1) {
					Point p = shell.toDisplay(e.x, e.y);
					Point loc = shell.getLocation();
					startX = p.x - loc.x;
					startY = p.y - loc.y;
				}
				if (e.type == SWT.MouseMove && (e.stateMask & SWT.BUTTON1) != 0) {
					Point p = shell.toDisplay(e.x, e.y);
					p.x -= startX;
					p.y -= startY;
					shell.setLocation(p);
				}
				if (e.type == SWT.Paint) {
					e.gc.drawImage(image, imageData.x, imageData.y);
				}
			}
		};
		shell.addListener(SWT.KeyDown, l);
		shell.addListener(SWT.MouseDown, l);
		shell.addListener(SWT.MouseMove, l);
		shell.addListener(SWT.Paint, l);

		shell.open ();
		while (!shell.isDisposed ()) {
			if (!display.readAndDispatch ()) display.sleep ();
		}
		region.dispose();
		image.dispose ();
		display.dispose ();
	}
}