Scrolling Images in Java

import java.awt.*;
import java.applet.*;
import java.net.*;

public class ScrollingImages extends java.applet.Applet implements Runnable
{
	Image imgs[];
	int nimgs;
	int imgwidth;
	int x, newx;
	int dist = 5;
	int timeout = 50;
	Thread scroller;

    public void init()
	{

		newx = x = size().width;

		nimgs = 12;
		imgs = new Image[nimgs];

		for (int i = 0; i < nimgs; i++)
		{
		    imgs[i] = getImage (getCodeBase(), "graphics/P" + (i+1) + ".jpg");
		}

    }

    public void start ()
	{
		if (scroller == null)
		{
		    scroller = new Thread (this);
		    scroller.start ();
		}
    }

    public void stop ()
	{
		if (scroller != null)
		{
		    scroller.stop ();
		    scroller = null;
		}
    }

    public void run()
	{
		while (true)
		{
			try
			{
				Thread.currentThread().sleep(timeout);
			}
			catch (InterruptedException e)
			{
			}
			scroll (dist);
			
		}
    }

    synchronized void scroll (int dist)
	{
		newx += dist;
		repaint ();
    }

    public void update (Graphics g)
	{
		g.setColor (Color.lightGray);

		if (newx != x)
		{
		    int dist = newx - x;
		    if (dist > 0)
			{
				g.copyArea (1, 1, (size().width-2) - dist, size().height-2, dist, 0);
				for (x = newx ; x > size().width ; x -= Math.max(size().width - 2, imgwidth));
				paint (g, 1, dist + 1);
		    }
			else
			{
				g.copyArea (1 - dist, 1, (size().width-2) + dist, size().height-2, 1, 1);
				for (x = newx ; x < 0 ; x += Math.max(size().width - 2, imgwidth));
				paint (g, (size().width-1) + dist, size().width-1);
		    }
		}
		else
		{
		    paint (g);
		}
    }

    public boolean imageUpdate (Image img, int flags, int x, int y, int w, int h)
	{
		if ((flags & WIDTH) != 0)
		{
			imgwidth += img.getWidth(this);
		}
		return super.imageUpdate (img, flags, x, y, w, h);
    }

    public void paint (Graphics g, int fromx, int tox)
	{
		int x = this.x;
		newx = x;

		g.setColor(Color.lightGray);
		g.fillRect(fromx, 1, tox - fromx, size().height-2);
		g.clipRect(fromx, 1, tox - fromx, size().height-2);
		g.setColor(Color.black);

		for (int i = 0 ; i < nimgs ; i++)
		{
			if (imgs[i] == null)
			{
				continue;
			}

		    int w = imgs[i].getWidth(this);
		    int h = imgs[i].getHeight(this);
		    if ((w > 0) && (h > 0))
			{
				if ((x + w > fromx) && (x < tox))
				{
				    g.drawImage (imgs[i], x, size().height - (h+1), this);
				}
				if ((x + w) > size().width)
				{
				    x -= Math.max(size().width - 2, imgwidth);
				    if ((x + w > fromx) && (x < tox))
					{
						g.drawImage (imgs[i], x, size().height - (h + 1), this);
				    }
				}
				x += w;
		    }
		}
    }

    public void paint (Graphics g)
	{
		g.draw3DRect (0, 0, size().width, size().height, true);
		paint(g, 1, size().width-1);
    }

}