Special Effects and Game Development in Java(TM) - The Applet SlideShow II

import java.applet.*;

import java.awt.*;



public class slideshow2 extends Applet implements Runnable {



public Thread animationthread = null;

int maxitems=0;

int sleeptime=0;

Image images[];

int currentimage=0;

int nextimage = 0;

int nextimagexposition = 0;

int nextimageyposition = 0;



//"bufferimage" is used as the buffer and

//"bufferg" is used to draw on this buffer.

Image bufferimage;

Graphics bufferg;



//"delay" will be used instead of "sleeptime" to

//delay the each animation. "sleeptime" will be used to

//add a configurable delay between each image instead.

int delay=0;



public void init()
{
    maxitems=getIntegerParameter("maxitems",10);
    sleeptime=getIntegerParameter("sleeptime",10);
    images=new Image[maxitems];
    MediaTracker tracker=new MediaTracker(this);
    for (int i=0; i<maxitems; i++)
    {
        images[i]=getImage(getDocumentBase()
            ,getParameter("image"+i));
        tracker.addImage(images[i],i);
    }
    try {tracker.waitForAll();}
    catch(InterruptedException e)
    {
        System.out.println("Something happened while reading images...");
    }
    //Fetch the size for the applet
    Dimension d=size();



    //createImage() creates an empty image

    //that has the same dimensions as the

    //applet screen

    bufferimage=createImage(d.width,d.height);



    //"bufferg" is now associated with the

    //buffer image.

    bufferg=bufferimage.getGraphics();

    delay=getIntegerParameter("delay",10);

}



public int getIntegerParameter(String name, int base)

{

    String value=getParameter(name);

    int intvalue;

    try {intvalue=Integer.parseInt(value,base);}

    catch (NumberFormatException e) {return 0;}

    return intvalue;

}



public void start()

{

    if (animationthread == null)

    {

         animationthread = new Thread(this,"animationthread");

         animationthread.start();

    }

}



public void stop()

{

    if ((animationthread != null) && animationthread.isAlive())

        animationthread.stop();

    animationthread = null;

}



public synchronized void paint(Graphics g)

{

    //First we should check that "bufferg"

    //is initialized, it is not always sure that it

    //is.

    if (bufferg!=null)

    {

        //We draw the two images into the buffer first.

        bufferg.drawImage(images[currentimage],0,0,this);

        bufferg.drawImage(images[nextimage]

             ,nextimagexposition,nextimageyposition,this);



        //Now we draw the buffer image into the applet

        //screen.

        g.drawImage(bufferimage,0,0,this);

    }

}



public void update(Graphics g)

{

    paint(g);

}



public void run()
{
    Dimension d=size();
    int displacementx=0;
    int displacementy=0;
    int pathsize=0;
    currentimage=0;
    nextimage=1;
    while (true)
    {
        int directionx=(int) (Math.random()*3.0)-1;
        int directiony=(int) (Math.random()*3.0)-1;
        if (directionx==0 && directiony==0) directiony=1;
        if (d.width<d.height) pathsize=d.width;
        else pathsize=d.height;
        displacementx=directionx*d.width;
        displacementy=directiony*d.height;
        if (nextimage>maxitems-1) nextimage=0;
        for (int i=0; i<=pathsize; i++)
        {
            nextimagexposition=displacementx
                -directionx*(i*d.width)/pathsize;
            nextimageyposition=displacementy
                -directiony*(i*d.height)/pathsize;
            update(getGraphics());



            //Now "delay" is the delay in the loop.

            try {Thread.sleep(delay);}

            catch(InterruptedException e) {}

        }

        //"sleeptime" is used outside the loop.

        try {Thread.sleep(sleeptime);}

        catch(InterruptedException e) {}

        currentimage=nextimage;

        nextimage++;

        if (nextimage>maxitems-1) nextimage=0;

    }

}



}