SWT 2D Graphics Java Tutorial

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
public class DrawOval {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setText("Canvas Example");
    shell.setLayout(new FillLayout());
    Canvas canvas = new Canvas(shell, SWT.NONE);
    canvas.addPaintListener(new PaintListener() {
      public void paintControl(PaintEvent e) {
        e.gc.drawOval(200, 100, 500, 400);
      }
    });
    
    canvas.redraw();
    
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
    display.dispose();
  }
}