Applet Code -- Mixing Two Scenes

import java.awt.*;
import java.awt.image.*;
import java.applet.*;
import java.lang.*;

public class Fade extends Applet
{
       Graphics    sG;

       Graphics    bG;
       Image       bI;
       Image       lincoln, memorial, display;

       int         lincoln_array[] = new int[48000];
       int         memorial_array[] = new int[48000];
       int         display_array[] = new int[48000];

       int         red, green, blue;

       int         sw = 0;

       Color       back   = new Color(247, 243, 234);
       Color       black  = new Color(0, 0, 0);
       Color       slider = new Color(255, 128, 128);

       PixelGrabber        getmemorial, getlincoln;

       double      t = 1.0;

       int         mx, my;


       public void init()
       {
              bI = createImage(this.size().width, this.size().height);
              bG = bI.getGraphics();
              lincoln = getImage(getCodeBase(), "lincoln.gif");
              memorial = getImage(getCodeBase(), "memorial.gif");
              display = getImage(getCodeBase(), "memorial.gif");
              mx = 215;
              drawscreen();
       }

       public void paint(Graphics g)
       {
              bG.drawImage(memorial, 0, 0, this);
              bG.drawImage(lincoln, 430, 0, this);
              bG.drawImage(display, 215, 0, this);
              g.drawImage(bI, 0, 0, this);
              sG = getGraphics();
       }

       public void update(Graphics g)
       {
              drawscreen();
              paint(g);
       }

       public void drawscreen()
       {
              bG.setColor(back);
              bG.fillRect(0, 0, 631, 271);
              bG.setColor(slider);
              bG.fillRect(mx - 3, 250, 7, 17);
              bG.setColor(black);
              bG.drawLine(215, 258, 415, 258);
              for(int x = 215; x < 416; x = x + 20)
              {
                   bG.drawLine(x, 253, x, 263);
              } 
       }

       public boolean mouseDown(Event evt, int px, int py)
       {
              if(py > 250)
              {
                    mx = java.lang.Math.min(px, 415);
                    mx = java.lang.Math.max(mx, 215);
                    t = 1.0 - (mx - 215.0)/200.0;
                    if (sw == 0)
                    {
                         sw = 1;
                         getmemorial = 
                         new PixelGrabber(
                           memorial, 0, 0, 200, 240, memorial_array, 0, 200);
                         getlincoln = 
                         new PixelGrabber(
                           lincoln, 0, 0, 200, 240, lincoln_array, 0, 200);

                         try {getmemorial.grabPixels();}
                             catch(Exception e) {return true;}
                         try {getlincoln.grabPixels();}
                             catch(Exception e) {return true;}

                    }
                    drawscreen();
                    for(int i = 0; i < 48000; i = i + 1)
                    {
                        blue = (int) java.lang.Math.round(
                               t * (0xFF & memorial_array[i]) +
                               (1 - t) * (0xFF & lincoln_array[i]));
                        green = (int) java.lang.Math.round(
                               t * (0xFF00 & memorial_array[i]) +
                               (1 - t) * (0xFF00 & lincoln_array[i]));
                        green = green & 0xFF00;
                        red = (int) java.lang.Math.round(
                               t * (0xFF0000 & memorial_array[i]) +
                               (1 - t) * (0xFF0000 & lincoln_array[i]));
                        red = red & 0xFF0000;
                        display_array[i] = 0xFF000000 | blue | red | green; 
                     }
                    display =
                      createImage(
                        new MemoryImageSource(200, 240, display_array, 0, 200));
 
                    bG.drawImage(memorial, 0, 0, this);
                    bG.drawImage(lincoln, 430, 0, this);
                    bG.drawImage(display, 215, 0, this);
                    sG.drawImage(bI, 0, 0, this);
              }
              return true;
       }

}