drawing a dashed circle

[Alarmmy]

I know I can draw a circle using the codes below

peerGraphComposite.addPaintListener(new PaintListener() {
public void paintControl(PaintEvent event) {
Rectangle rect = peerGraphComposite.getClientArea();
event.gc.drawOval(30, 30, rect.height - 60, rect.height - 60);
}
});

how can I draw a dashed circle using SWT?
Thanks!