/* A simple Double Buffering example by Jayant Mukherjee (courtesy: Complete Reference) */
/* Another way of doing the same is described by Wayne McKenzie on PSC */
import java.awt.*;
import java.applet.*;
import java.awt.image.*;
import java.awt.event.*;
public class DblBuffr extends Applet implements MouseMotionListener
    {
    int ax,ay;
    Dimension dSize;
    Image dblBuffImg; //Off Screen
    Graphics dblBuffer; //Off Screen Graphics
    public void init()
        { 
        dSize = this.getSize();
        dblBuffImg = this.createImage(dSize.width, dSize.height);
        dblBuffer = dblBuffImg.getGraphics();
        addMouseMotionListener(this);
        this.setBackground(Color.yellow);
    }

    public void mouseDragged(MouseEvent em){} //Not used, but required
    public void mouseMoved(MouseEvent em)
        {
        ax = em.getX();
        ay = em.getY();
        this.paint(this.getGraphics()); //Fast repainting
    }

    public void update(){} //Overriding, for Flicker Free Drawing
    public void paint(Graphics g)
        { 
        dblBuffer.clearRect(0, 0, dSize.width, dSize.height); 
        for(int i=0; i<=dSize.width; i=i+10)
            {
            dblBuffer.drawLine(ax,ay,i,0); //Top edge 
            dblBuffer.drawLine(ax,ay,i,dSize.height); //Bottom edge
        }

        for(int i=0; i<=dSize.height; i=i+10)
            {
            dblBuffer.drawLine(ax,ay,0,i); //Left edge
            dblBuffer.drawLine(ax,ay,dSize.width,i); //Right edge
        }

        g.drawImage(dblBuffImg, 0, 0, null);
    }

}