Robotを使用してスクリーンショットを取得する

private final transient Robot robot;
private final Rectangle screenRect;
private final Rectangle buf = new Rectangle();
private transient BufferedImage backgroundImage;
private final float[] data = {
    .1f, .1f, .1f,
    .1f, .2f, .1f,
    .1f, .1f, .1f,
};
private Kernel kernel = new Kernel(3, 3, data);
private ConvolveOp op = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
private Color bgc = new Color(255, 255, 255, 100);

@Override protected void paintComponent(Graphics g) {
  super.paintComponent(g);
  Graphics2D g2 = (Graphics2D) g.create();
  Point pt = getLocationOnScreen();
  buf.setBounds(screenRect);
  SwingUtilities.computeIntersection(pt.x, pt.y, getWidth(), getHeight(), buf);
  Image img = backgroundImage.getSubimage(buf.x, buf.y, buf.width, buf.height);
  g2.drawImage(img, -Math.min(pt.x, 0), -Math.min(pt.y, 0), this);
  g2.setPaint(bgc);
  g2.fillRect(0, 0, getWidth(), getHeight());
  g2.dispose();
}

public void updateBackground() {
  backgroundImage = op.filter(robot.createScreenCapture(screenRect), null);
}