/*

File: TumbleItem.java

Abstract: Panel displaying an animation of Duke

Version: 1.2

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*/

package duke;

import java.awt.*;

import java.io.*;

/**

 * Based on the TumbleItem Applet by James Gosling.

 */

public class TumbleItem extends Panel implements Runnable {

//_______________________ CLASS METHODS

    public TumbleItem(String dir) throws Exception {

        super();

        // used to monitor the image importing process

        MediaTracker tracker = new MediaTracker(this);

        // import gif images

        File fDir = new File(dir);

        if (fDir.isDirectory() == false)

            throw new FileNotFoundException (dir);

        if (dir.charAt (dir.length() - 1) != File.separatorChar)

            dir += File.separatorChar;

        for (int i=0; i < nimgs; i++) {     

            images[i] = Toolkit.getDefaultToolkit().getImage(dir + "T" + i + ".gif");

            tracker.addImage(images[i], i);

        }

        // wait for them all to finish importing

        try { tracker.waitForAll(); }

        catch (InterruptedException e) { }

        // we do nothing about no duke images

        if (tracker.isErrorAny()) throw new Exception ("Duke:Error in Media Tracker");

   }

//_______________________ INSTANCE VARIABLES

    private int      loopslot   = -1;   // The current loop slot.

    private Thread   kicker     = null; // The thread animating the images.

    private int      pause      = 100;  // The length of the pause between revs.

    private int      offset     = -57;

    private int      xOffset;

    private int      speed      = 100;

    private int      nimgs      = 17;

    private int      maxWidth   = 120;

    private Image    images[] = new Image[nimgs];

    private Image    offscreenImage;

    private Graphics offscreenGraphics;

    private boolean kickerStop = false;

//_______________________ INSTANCE METHODS

    /** Run the image loop. This method is called by class Thread. */

    public void run() {

        Thread.currentThread().setPriority(Thread.NORM_PRIORITY-1);

        // create offscreen image and graphics objects

        offscreenImage    = createImage(images[0].getWidth(this), images[0].getHeight(this));

        offscreenGraphics = offscreenImage.getGraphics();

        // take care of positioning the images across the screen

        Dimension d = getSize();

        if (nimgs > 1) {

            if (offset < 0) xOffset = d.width - maxWidth;

            while (kicker != null) {

                d = getSize();

                if (++loopslot >= nimgs) {

                    loopslot = 0;

                    xOffset += offset;

                    if (xOffset < 0) xOffset = d.width - maxWidth;

                    else if (xOffset + maxWidth > d.width) xOffset = 0;

                }

                repaint();

                if (kickerStop)

                    break;

                try { Thread.sleep(speed + ((loopslot == nimgs - 1) ? pause : 0)); }

                catch (InterruptedException e) { break; }

            }

        }

    }

    /** Should not get called because we are using MediaTracker.waitForAll(). */

    public boolean imageUpdate(Image img, int flags, int x, int y, int w, int h) {

        if ((flags & (SOMEBITS|FRAMEBITS|ALLBITS)) != 0) {

            if ((images != null) && (loopslot < nimgs) && (images[loopslot] == img)) {

                repaint();

            }

        }

        return (flags & (ALLBITS|ERROR)) == 0;

    }

    /** Paint the current frame using our offscreen graphics to reduce flicker. */

    public void paint(Graphics g) {

        if (loopslot < 0) return;

        if ((images != null) && (loopslot < nimgs) && (images[loopslot] != null)) {

            offscreenGraphics.drawImage(images[loopslot], 0, 0, this);

            g.drawImage(offscreenImage, xOffset, 0, this);

        }

    }

    /** Start the animation by forking an animation thread. */

    public void start() {

        if (kicker == null) {

            kicker = new Thread(this);

            kicker.start();

        }

    }

    /** Stop the animation. The thread will exit because kicker is set to null. */

    public void stop() {

        if (kicker != null) {

            kickerStop = true;

            kicker = null;

        }

    }

    /** So the layout manager respects our preferred size. */

    public Dimension getPreferredSize() { return new Dimension(5, 80); }

}