ps no manejo mucho el dubujar pero espero que esto te sirva http://sunsite.dcc.uchile.cl/java/docs/JavaTut/Cap5/grafico.html.

Saludos y suerte.

Interesante... 

La verdad nunca me habia puesto a pensar en hace mi propio protector de pantalla 
Pero es buena idea

Hace tiempo mire esta pagina

http://www.eigelb.at/HP/Links/SpecialEffects/Grappa/BlueRandom/index.html

Está programado en Java

La verdad no se si exista el código libre, pero igual te podria ayudar a darte una idea, habia decompilado las clases  y si mal no recuerdo usaba Graphics

Saludos

este si te ayudaria bastante..

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
import javax.swing.event.*;
 
public class FreeHand extends JPanel
{
    /**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	BufferedImage image;
    Color color;
    Stroke stroke;
 
    public FreeHand()
    {
        color = Color.blue;
        stroke = new BasicStroke(1f, BasicStroke.CAP_BUTT,
                                     BasicStroke.JOIN_MITER);
    }
 
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        if(image == null)
            initImage();
        g.drawImage(image, 0, 0, this);
    }
 
    public void draw(Point start, Point end)
    {
        Graphics2D g2 = image.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(color);
        g2.setStroke(stroke);
        g2.draw(new Line2D.Double(start, end));
        g2.dispose();
        repaint();
    }
 
    private void clearImage()
    {
        Graphics g = image.getGraphics();
        g.setColor(getBackground());
        g.fillRect(0, 0, image.getWidth(), image.getHeight());
        g.dispose();
        repaint();
    }
 
    private void initImage()
    {
        int w = getWidth();
        int h = getHeight();
        image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = image.createGraphics();
        g2.setPaint(getBackground());
        g2.fillRect(0,0,w,h);
        g2.dispose();
    }
 
    private JPanel getColorPanel()
    {
        Color[] colors = {
            Color.red, Color.green.darker(), Color.blue, Color.orange
        };
        ActionListener l = new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                JButton button = (JButton)e.getSource();
                color = button.getBackground();
            }
        };
        JPanel panel = new JPanel(new GridLayout(1,0));
        for(int j = 0; j < colors.length; j++)
        {
            JButton button = new JButton("  ");
            button.setFocusPainted(false);
            button.setBackground(colors[j]);
            button.addActionListener(l);
            panel.add(button);
        }
        return panel;
    }
 
    private JPanel getControlPanel()
    {
        JButton clear = new JButton("clear");
        clear.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                clearImage();
            }
        });
        final JSlider slider = new JSlider(JSlider.HORIZONTAL, 1, 6, 1);
        slider.addChangeListener(new ChangeListener()
        {
            public void stateChanged(ChangeEvent e)
            {
                float value = ((Integer)slider.getValue()).floatValue();
                stroke = new BasicStroke(value, BasicStroke.CAP_BUTT,
                                                BasicStroke.JOIN_MITER);
            }
        });
        JPanel panel = new JPanel();
        panel.add(new JLabel("stroke"));
        panel.add(slider);
        panel.add(clear);
        return panel;
    }
 
    public static void main(String[] args)
    {
        FreeHand freeHand = new FreeHand();
        DrawingListener listener = new DrawingListener(freeHand);
        freeHand.addMouseListener(listener);
        freeHand.addMouseMotionListener(listener);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(freeHand.getColorPanel(), "North");
        f.getContentPane().add(freeHand);
        f.getContentPane().add(freeHand.getControlPanel(), "South");
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}
 
class DrawingListener extends MouseInputAdapter
{
    FreeHand freeHand;
    Point start;
 
    public DrawingListener(FreeHand fh)
    {
        this.freeHand = fh;
    }
 
    public void mousePressed(MouseEvent e)
    {
        start = e.getPoint();
    }
 
    public void mouseDragged(MouseEvent e)
    {
        Point p = e.getPoint();
        freeHand.draw(start, p);
        start = p;
    }
}

import java.net.URL;

import java.awt.Toolkit;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.BasicStroke;

import java.awt.Color;

import java.awt.Image;

import javax.swing.JFrame;

import java.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

import java.util.Random;



import java.awt.Rectangle;

import java.awt.GraphicsEnvironment;

import java.awt.GraphicsDevice;

import java.awt.event.MouseListener;

import java.awt.event.MouseMotionListener;

import java.awt.event.MouseEvent;

import javax.swing.*;



import java.awt.Robot;

import java.awt.Dimension;

import java.awt.Toolkit;

import java.awt.Image;



class Borrado extends JFrame implements MouseListener, MouseMotionListener{

   

   Image img;

   Random r;

   

   GraphicsDevice grafica;   

   int Alto,Ancho;   

   

   int xi=200,yi=200,xf,yf;

   

   Toolkit toolkit;

   Dimension dq;

   Robot rob;                     

//   Image img;

   

   public Borrado(){      

      try{

         toolkit = Toolkit.getDefaultToolkit();

         dq = toolkit.getScreenSize();

         rob = new Robot();                     

         img = rob.createScreenCapture(new Rectangle(dq));

      }

      catch(Exception e){}

      

      Toolkit tk = Toolkit.getDefaultToolkit();

      Dimension d = tk.getScreenSize();

      Alto = d.height;

      Ancho = d.width;



      setUndecorated(false);

      

      addMouseMotionListener(this);

      grafica= GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice();

      grafica.setFullScreenWindow(this);

      

      setTitle("Borrado");



      setVisible(true);

      addWindowListener(wa);

      r=new Random();

      

      refrescar();

   }

   

   public void mouseClicked( MouseEvent evento ){}

   public void mousePressed( MouseEvent evento ){}

   public void mouseReleased( MouseEvent evento ){}

   public void mouseEntered( MouseEvent evento ){}

   public void mouseExited( MouseEvent evento ){}

   public void mouseDragged( MouseEvent evento ){}

   

   public void mouseMoved( MouseEvent evento ){

      System.exit(1);

   }



   

   WindowAdapter wa=new WindowAdapter(){

      public void windowClosing(WindowEvent we){

         System.exit(0);

      }

   };

   

   public void paint(Graphics g){

      setBackground(Color.black);

      g.drawImage(img, 0, 0, this);

   }

   

   public void refrescar(){

      try{

         Thread.sleep(1000); // Pausa de un segundo

         Graphics g=getGraphics();

         int ro=0;

         //while(ro<800){

            Graphics2D g2 = (Graphics2D) g;

            g2.setStroke(new BasicStroke(15.0f));      

            g.setColor( Color.BLACK);         

         

            Thread.sleep(r.nextInt(300));

            //xf=r.nextInt(1000);

            //xf=r.nextInt(1000);

            xf=300;

            yf=100;

            

            System.out.println("xi= "+xi);

            System.out.println("yi= "+yi);

            

            //g.drawArc( xi,yi,xf,yf,r.nextInt(180),r.nextInt(180));   

            g.drawArc( 100,100,300,300,180,180);

            g.drawArc( 380,90,300,400,160,210);

            //g.drawArc( 100,100,300,300,100,100);

            Thread.sleep(300);

            g2.setStroke(new BasicStroke(15.0f));      

            g.setColor( Color.RED);         

            //g.drawArc( xi,yi,xf,yf,90,300);

            //g.drawArc( 100,100,300,300,100,100);

            //g.drawLine( 0,0,300,126);

            g.drawLine( 0,0,250,100);

            

            //xi=xf;

            //yi=yf;

            ro++;

            System.out.println("xf= " +xf);

            System.out.println("yf= "+yf);

         //}

      }

      catch (Exception e){

            System.out.println("MMMM");

      }

      //repaint();

      refrescar();

   }

   public static void main(String arg[]){

      Borrado b=new Borrado();

   }

}