Ring Shell : Shell « SWT « Java Tutorial

You can create an irregular-shaped shell with the setRegion method:

Ring Shell
public void setRegion(Region region)

This shell must be created with the style NO_TRIM in order to specify a region.

Ring Shell
 * Copyright (c) 1998, 2004 Jackwind Li Guojie
 * All right reserved. 
 * Created on Jan 25, 2004 7:58:06 PM by JACK
 * $Id$
 * visit: http://www.asprise.com/swt

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseListener;
import org.eclipse.swt.events.MouseMoveListener;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.graphics.Region;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class RingShell {
  static int[] createCircle(int radius, int centerX, int centerY) {
    int[] points = new int[360 * 2];
    for(int i=0; i<360; i++) {
      points[i*2] = centerX + (int)(radius * Math.cos(Math.toRadians(i)));
      points[i*2+1] = centerY + (int)(radius * Math.sin(Math.toRadians(i)));
    return points;
  static Point originalPosition = null;
  public static void main(String[] args) {
    final Display display = new Display();
    final Shell shell = new Shell(display, SWT.NO_TRIM | SWT.ON_TOP);
    Region region = new Region();
    region.add(createCircle(100, 100, 100));
    region.subtract(createCircle(50, 100, 100));
    // Make the shell movable by using the mouse pointer. 
    shell.addMouseListener(new MouseListener() {
      public void mouseDoubleClick(MouseEvent e) {
        shell.dispose(); // Double click to dispose the shell.

      public void mouseDown(MouseEvent e) {
        originalPosition = new Point(e.x, e.y);

      public void mouseUp(MouseEvent e) {
        originalPosition = null;
    shell.addMouseMoveListener(new MouseMoveListener() {
      public void mouseMove(MouseEvent e) {
        if(originalPosition == null)
        Point point = display.map(shell, null, e.x, e.y);
        shell.setLocation(point.x - originalPosition.x, point.y - originalPosition.y);
        System.out.println("Moved from: " + originalPosition + " to " + point);
    Rectangle regionBounds = region.getBounds();
    shell.setSize(regionBounds.width, regionBounds.height);

    // Set up the event loop.
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        // If no more entries in event queue


17.4.1.Understanding the Shell Object
17.4.2.Creating Shells
17.4.3.Open a shell minimized (iconified)
17.4.4.Open a shell maximized (full screen)
17.4.5.Center a shell on the primary monitorCenter a shell on the primary monitor
17.4.6.Set icons with different resolutions
17.4.7.Create a non-rectangular windowCreate a non-rectangular window
17.4.8.Create a non-rectangular shell to simulate transparencyCreate a non-rectangular shell to simulate transparency
17.4.9.Create non-rectangular shell from an image with transparencyCreate non-rectangular shell from an image with transparency
17.4.10.Allow escape to close a shellAllow escape to close a shell
17.4.11.Prevent a shell from closing (prompt the user)Prevent a shell from closing (prompt the user)
17.4.12.Create GC from Shell and paint on windowCreate GC from Shell and paint on window
17.4.13.Getting Controls on a shellGetting Controls on a shell
17.4.14.Set default Button for ShellSet default Button for Shell
17.4.15.Get Default ButtonGet Default Button
17.4.16.Shell with SWT.SHELL_TRIM|SWT.TOOL styleShell with SWT.SHELL_TRIM|SWT.TOOL style
17.4.17.Ring ShellRing Shell
17.4.18.Set left upper corner imageSet left upper corner image
17.4.19.Shell without Title bar
17.4.20.ON_TOP: This style bit causes the shell to always float on the top of the desktop.
17.4.21.SHELL_TRIM = (CLOSE | TITLE | MIN | MAX | RESIZE): top-level shells.SHELL_TRIM = (CLOSE | TITLE | MIN | MAX | RESIZE): top-level shells.
17.4.22.DIALOG_TRIM = (CLOSE | TITLE | BORDER): dialog shells.
17.4.24.TOOL: the shell is a tool window(floating toolbars)
17.4.25.Shell States
17.4.26.Setting the Title