org.eclipse.swt.snippets.Snippet294.java Source code

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Here is the source code for org.eclipse.swt.snippets.Snippet294.java

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/*******************************************************************************
 * Copyright (c) 2000, 2016 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.layout.*;
import org.eclipse.swt.widgets.*;

/*
 * Region on a control: create a non-rectangular button
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 *
 * @since 3.4
 */

public class Snippet294 {

    static int[] circle(int r, int offsetX, int offsetY) {
        int[] polygon = new int[8 * r + 4];
        // x^2 + y^2 = r^2
        for (int i = 0; i < 2 * r + 1; i++) {
            int x = i - r;
            int y = (int) Math.sqrt(r * r - x * x);
            polygon[2 * i] = offsetX + x;
            polygon[2 * i + 1] = offsetY + y;
            polygon[8 * r - 2 * i - 2] = offsetX + x;
            polygon[8 * r - 2 * i - 1] = offsetY - y;
        }
        return polygon;
    }

    public static void main(String[] args) {
        final Display display = new Display();

        final Shell shell = new Shell(display);
        shell.setText("Regions on a Control");
        shell.setLayout(new FillLayout());
        shell.setBackground(display.getSystemColor(SWT.COLOR_DARK_RED));

        Button b2 = new Button(shell, SWT.PUSH);
        b2.setText("Button with Regions");

        // define a region that looks like a circle with two holes in ot
        Region region = new Region();
        region.add(circle(67, 87, 77));
        region.subtract(circle(20, 87, 47));
        region.subtract(circle(20, 87, 113));

        // define the shape of the button using setRegion
        b2.setRegion(region);
        b2.setLocation(100, 50);

        b2.addListener(SWT.Selection, e -> shell.close());

        shell.setSize(200, 200);
        shell.open();

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

}