org.eclipse.swt.snippets.Snippet352.java Source code

Introduction

Here is the source code for org.eclipse.swt.snippets.Snippet352.java

Source

/*******************************************************************************
 * 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 (int i = 0; i < touches.length; i++) {
                Touch currTouch = touches[i];

                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();
    }
}