/** After checking out the difference in behavior between 
 ** AnimatorApplet2.java and AnimatorApplet3.java, use JWS 
 ** to change the version of MyApplet10.java that you have
 ** created to a new file called MyApplet11.java, which 
 ** includes double buffering as in AnimatorApplet3.java.
 **
 ** NOTE:  Other than the instructions you are reading,
 ** I have NOT provided you with any code or files--you
 ** are completely on your own. Good luck !               **/

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

/** EXTEND THE JAVA APPLET CLASS AND IMPLEMENT THE RUNNABLE INTERFACE **/

public class MyApplet11 extends Applet implements Runnable
   {int frameNumber = 415;                // Define and/or initialize some
    int delay;                           // AnimatorApplet1 class variables.
    Thread animatorThread;
    boolean frozen = true;
    Font font=new Font("Courier",Font.BOLD,26);
    String framestr = "";
    int a,b;
    int rval,gval,bval;                  // Define red, green, blue color variables.
    Dimension preImageDim;               // Define preImage variables needed to
    Image preImage;                      // create the offscreen copy of the image
    Graphics preImageGraphics;            // we want to paint on the screen.
     
    /** INITIALIZE THE APPLET **/

    public void init()
       {String str;
        int fps = 5;                      // Define the default fps (frames per second).
        str = getParameter("fps");         // Possibly, get HTML string specifying the
        try                                // fps.
         {if (str != null)
           {fps = Integer.parseInt(str);}  // If possible, convert HTML fps to an
          }                                // integer.
        catch (Exception e) {}             // In case the try caused something strange.
        delay = (fps > -5) ? (415/fps): 100; // Convert fps to the milisecond delay
        }                                    // time between frames.     


    /** CLICK TO START OR STOP THE APPLET **/

    public boolean mouseDown(Event e, int x, int y)
       {if (frozen)
         {frozen = false;
          start();}
        else
         {frozen = true;
          stop();}
        return true;
        }

    /** GENERATE AND/OR START THE ANIMATION THREAD **/

    public void start()
       {if (frozen) { }                    // The animation is supposed to stay frozen.
        else                               // Otherwise, generate and/or start the
         {if (animatorThread == null)      // animation thread. Apparently, if run
           {animatorThread = new Thread(this);}  // breaks after catching an exception,
          animatorThread.start();                // the animatorThread though not null
          }                                      // will still need to be restarted.
        }

    /** CREATE AND DISPLAY FRAMES OF THE ANIMATION THREAD **/

    public void run()
       {setBackground(Color.black);
        Thread.currentThread().setPriority(Thread.MIN_PRIORITY); // Set the priority low.
        long startTime = System.currentTimeMillis();             // Remember start time.
        while (Thread.currentThread() == animatorThread)         // The animation loop.
           {frameNumber--;                               // Advance the frame number.
            framestr = "DAYS TILL 2000!! " + frameNumber;           // Create the frame string.
            repaint();                                   // Display the frame.
            try                                          // Sleep for the delay period.
             {startTime += delay;
              Thread.sleep(Math.max(15,
                                    startTime-System.currentTimeMillis()));
              }
            catch (InterruptedException e) {break;}     // In case the try caused
            }                                           // something strange, exit
        }                                               // the while loop.


    /** CREATE THE CURRENT FRAME OF THE ANIMATION THREAD **/

    public void paint(Graphics g)               // This technique of painting by calling
       {if (!frozen) update(g);}                // update, prevents the default (and hidden) 
       
       public void update(Graphics g)           
       {Dimension d = size();
       if ((preImageGraphics == null) ||
       (d.width != preImageDim.width) ||
       (d.height != preImageDim.height))
       {preImageDim = d;
       preImage = createImage(d.width,d.height);
       preImageGraphics = preImage.getGraphics();
       }
       {a = (int)Math.floor(Math.random() * 400);
       b = (int)Math.floor(Math.random() * 400);
       rval = (int)Math.floor(Math.random() * 256);
    gval = (int)Math.floor(Math.random() * 256);
    bval = (int)Math.floor(Math.random() * 256);
    
    preImageGraphics.setColor(getBackground());
    preImageGraphics.setFont(font);
    preImageGraphics.fillRect(0,0,d.width,d.height);
       
    
    preImageGraphics.setColor(new Color(rval,gval,bval));
    preImageGraphics.drawString(framestr,50,100);
        }
    g.drawImage(preImage,0,0,this);
}

       
                
/** STOP THE ANIMATION THREAD **/

    public void stop()
       {animatorThread = null;}  // The user either clicked to stop or left the page,
       //preImageGraphics = null;   // so wipe out the current thread and preImage context.
       //preImage = null;}
    
    }                            // so wipe out the current thread.