Saturday, October 24, 2009

Flicker-free rendering with double buffering in Java

If you draw graphics directly using the paint(Graphics) method in an AWT component such as Canvas, Frame or Panel your rendering will suffer greatly from flickering. The general solution to this is double buffering.

There are many ways to implement double buffering. One way is to not do it and instead use Swing components, such as JFrame and JPanel, that already does double buffering. Use paintComponent(Graphics) and override it the same way as you would with paint(Graphics).

class JPanelWithSmileyFace extends JPanel  {
 public Dimension getPreferredSize() {
  return new Dimension(200, 200);

 public void paintComponent(Graphics g) {
  g.fillOval(10, 10, 180, 180);
  g.fillOval(90-30, 50, 20, 30);
  g.fillOval(90+30, 50, 20, 30);
  g.drawArc(40, 40, 200-2*40, 200-2*40, -10, -160);
Example paintComponent.

public class SmileyFaceDemo {
 public static void main(String[] args) {
  JFrame window = new JFrame();
  window.getContentPane().add(new JPanelWithOval());
Example main.

1 comment:

Anonymous said...

thanks sooo much!