/** 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 !               **/
 
 /** USE EXISTING JAVA CLASSES **/

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 = -1;                // Define and/or initialize some
    int delay;                           // AnimatorApplet1 class variables.
    Thread animatorThread;
    boolean frozen = true;
    Font font=new Font("TimesRoman",Font.BOLD,36);
    FontMetrics fontm = getFontMetrics(font);
    int fontH = fontm.getHeight();
    int rval,gval,bval;
    String framestr = "";
    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.
    Color currentColor;
    int xval = 5;
    int yval = 30;


    /** INITIALIZE THE APPLET **/

    public void init()
       {String str;
        int fps = 8;                      // 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 > 0) ? (1000/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.white);
	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 = "Frame " + frameNumber;           // Create the frame string.
            repaint();                                   // Display the frame.
            try                                          // Sleep for the delay period.
             {startTime += delay;
              Thread.sleep(Math.max(0,
                                    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)  
					  // behavior of update, and instead allows
    public void update(Graphics g)        // the creation of an offscreen preImage 
     {Dimension d = size();               // preImage before painting the screen.           
      if ((preImageGraphics == null) ||              
	  (d.width != preImageDim.width) ||         // Compare the current applet
	  (d.height != preImageDim.height))         // viewing size to our preImage,
	   {preImageDim = d;                        // and if different, resize our 
	    preImage = createImage(d.width,d.height); // next preImage.
	    preImageGraphics = preImage.getGraphics();
	    }                                
       preImageGraphics.setColor(getBackground());      // Clear the previous preImage
       preImageGraphics.fillRect(0,0,d.width,d.height); // by filling with the current
       preImageGraphics.setFont(font);                  // background color (white),
       rval = (int) Math.floor(Math.random()*256);
       gval = (int) Math.floor(Math.random()*256);
       bval = (int) Math.floor(Math.random()*256);
       if (frameNumber % 2 == 0)
	{currentColor = new Color(rval,gval,bval);}
       if (xval >= d.width - fontm.stringWidth(framestr) - 20)
	{yval+=10;
	 xval = 10;}
       if (yval >= d.height)
	 {xval = 5;
	  yval = 30;}
       xval+=10;
       preImageGraphics.setColor(currentColor); // and then create the next
       preImageGraphics.drawString(framestr,xval,yval); // offscreen preImage.
       
	
	/*       for (int j = 40; j < (size().height - 25); j += 30) // Set up vertical spacing.
	 {for (int i = 5; i < (size().width - 25); i += 30)// Set up horizontal spacing.
	  {rval =(int) Math.floor(Math.random()*256);      // Generate a random color
	   gval =(int) Math.floor(Math.random()*256);      // red, green, blue mix.
	   bval =(int) Math.floor(Math.random()*256);      // Note the "casting" here.				       
	   preImageGraphics.setColor(new Color(rval,gval,bval));// Draw a small box with
	   preImageGraphics.fillRect(i,j,25,25);           // the current random color.
	   preImageGraphics.setColor(Color.black);         // Draw a black border around 
	   preImageGraphics.drawRect(i-1,j-1,26,26);       // the edge of the small box.
	   }
	  }  */                                          // Offscreen preImage completed.                                          
       g.drawImage(preImage,0,0,this);	               // Paint preImage on the screen.
       } 

/** 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;
    }}