examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet352.java

/*******************************************************************************
 * Copyright (c) 2011, 2017 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;

/*
 * Touch example: create a shell and listen for TouchEvents. Paint
 * circles where the user touched.
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 *
 * @since 3.7
 */
import java.util.*;

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

public class Snippet352 {

	private static class CircleInfo {

		public CircleInfo(Point inCenter, Color inColor) {
			this.center = inCenter;
			this.color = inColor;
		}

		Point center;
		Color color;
	}

	static Map<Long, CircleInfo> touchLocations = new HashMap<>();
	static int colorIndex = 0;
	static final int PAINTABLE_COLORS = 15;
	static final int CIRCLE_RADIUS = 40;

	public static void main (String [] args) {
		final Display display = new Display ();
		final Shell shell = new Shell (display);
		shell.setText("Snippet 352");
		shell.setLayout(new FillLayout(SWT.HORIZONTAL));
		shell.setText ("Touch demonstration");

		TouchListener tl = e -> {

			Touch touches[] = e.touches;

			for (Touch currTouch : touches) {
				if ((currTouch.state & (SWT.TOUCHSTATE_UP)) != 0) {
					touchLocations.remove(currTouch.id);
				} else {
					CircleInfo info = touchLocations.get(currTouch.id);
					Point newPoint = Display.getCurrent().map(null, (Control)e.widget, new Point(currTouch.x, currTouch.y));

					if (info == null) {
						info = new CircleInfo(newPoint, display.getSystemColor((colorIndex + 2) % PAINTABLE_COLORS));
						colorIndex++;
					}

					info.center = newPoint;
					touchLocations.put(currTouch.id, info);
				}
			}

			Control c = (Control)e.widget;
			c.redraw();
		};

		PaintListener pl = e -> {
			for (CircleInfo ci : touchLocations.values()) {
				e.gc.setBackground(ci.color);
				e.gc.fillOval(ci.center.x - CIRCLE_RADIUS, ci.center.y - CIRCLE_RADIUS, CIRCLE_RADIUS * 2, CIRCLE_RADIUS * 2);
			}
		};

		Canvas c = new Canvas(shell, SWT.NONE);
		c.setTouchEnabled(true);
		c.setSize(800, 800);
		c.addTouchListener(tl);
		c.addPaintListener(pl);

		shell.setSize (800, 800);
		shell.open ();
		while (!shell.isDisposed ()) {
			if (!display.readAndDispatch ()) display.sleep ();
		}
		display.dispose ();
	}
}