import java.applet.Applet;
import java.awt.*;

public class BufferedEyes extends Applet{

  double lx=150, ly=150, rx=260, ry=150;

  // Buffering to avoid flickering
  Dimension offDimension;
  Image offImage;
  Graphics offGraphics;
  
  public void update(Graphics g) {
    Dimension d = size(); // Size of the applet as it now is.

    // Create the offscreen graphics context, if no good one exists.
    if ( (offGraphics == null)
	 || (d.width != offDimension.width)
	 || (d.height != offDimension.height) ) {
      offDimension = d;
      offImage = createImage(d.width, d.height);
      offGraphics = offImage.getGraphics();
    }

    //Erase the previous image.
    offGraphics.setColor(getBackground());
    offGraphics.fillRect(0, 0, d.width, d.height);

    // Paint as we would do without buffering
    offGraphics.setColor(Color.white);
    offGraphics.fillOval(100, 100, 100, 100);
    offGraphics.fillOval(210, 100, 100, 100);
    offGraphics.setColor(Color.black);
    offGraphics.fillOval((int)(lx-8), (int)(ly-8), 16, 16);
    offGraphics.fillOval((int)(rx-8), (int)(ry-8), 16, 16);
    
    // Map the image onto the screen.
    g.drawImage(offImage, 0, 0, this);
  }
  
  // Adapt paint by refering to update.
  public void paint (Graphics g) {
    update(g);
  }

  public boolean mouseMove (Event evt, int x, int y){
    double X=x, Y=y;
    double k = scale(X-150, Y-150);
    lx = k*(X-150)+150;
    ly = k*(Y-150)+150;
    k  = scale(X-260, Y-150);
    rx = k*(X-260)+260;
    ry = k*(Y-150)+150;
    repaint();
    return true;
  }
  
  public double scale (double x, double y){
    return 42 / 
      Math.sqrt(x*x+y*y+1764);
  }
}