Mars Slide Show Applet               Peter Komisar


This slide show is a little primitive in that the thread starts to show the slides whether they are fully
downloaded or not. This is rectified in the Hubble Slide Show which uses MediaTracker. This class
has a method which causes the animation cycle to wait until all the images needed are downloaded
and available. Using a jar file insures all the media files are downloaded at once. Explorer had no
trouble extracting the images from the jar file however Netscape did. Van der Linden says different
code is needed to rebuild the image files from the archive. When I used the alternate code  I had further
complaints that I required different security permissions.  This is an ongoing investigation.


 

The applet code for the Marsian Slide Show

//<applet code=Slider.class width=350 height=250></applet>

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

public class Slider extends Applet implements Runnable {

    Image[] slides=new Image[10];
    Image offScreenImage;
    Graphics offScreenGraphics;
    Font f;
    int index;
    int z=0;

    String slide_files[]=new String[]
    {"msss_icon.jpg","Mars1.jpg",
    "Mars2.gif","Mars3.jpg",
    "Mars4.gif","Mars5.gif",
    "Mars6.gif","Mars7.gif",
    "Mars8.gif","Mars9.jpg"
    };
 

  public void init () {
 

         this.setBackground(Color.darkGray);
         index=0;
 

         for(int i=0; i<slide_files.length;i++)
           slides[i]=getImage(getDocumentBase( ), slide_files[i]);

        offScreenImage=createImage(getSize().width,getSize().height);
        offScreenGraphics=offScreenImage.getGraphics();

        }
 /* Because the images were different sizes their overlaps would become visible.
    A work around was too include resizing the pictures relative to the container */
 

    public void paint (Graphics g) {
        g.setColor(Color.pink);
        g.setFont(new Font("Monosapced", Font.PLAIN, 22));
        g.drawString("Mars Slide Show",10,20);
        g.setColor(Color.white);
        g.setFont( new Font("Helvitica", Font.ITALIC, 11));
        g.drawString(" photos by NASA (also do weddings) ",20,30);
        g.drawImage (slides[index],80,60,getSize().width/2,getSize().height/2,this);

        }

/* overriding update and leaving out it's clear to background reduces the associated
   flicker but only works for images of the same size overlapping or full screen.
   on the other hand, Overlapping panelling could be used to your advantage artistically. */

public void update(Graphics g){
paint(offScreenGraphics);
g.drawImage(offScreenImage,0,0,this);

}
 

       public void run() {
       while (true) {
            try{Thread.sleep(3000 );
               int temp = index;
               temp = ++ temp % slides.length;
               index = temp;

       //      j++;
       //      if(j==slides.length)
       //      j=0;
             }
            catch(InterruptedException ie){}
            repaint();
           }
       }

       Thread t;

       public void start() {
           t = new Thread(this);
           t.start();
       }

       public void stop( ) {
           t.interrupt();       // Here the outlawed Thread stop( ) method is avoided
           t = null;
       }
}