Universität Tübingen - 1997/1998 Winter/Universität Tübingen - Wintersemester 1997-98 - Uni-Informationssystem und Stadt-Informationssystem.iso/ajs/imageloo.jav

Text File | 1997-08-14 | 5KB | 194 lines

/*
 * @(#)ImageLoopItem.java    1.22f 95/03/28 James Gosling
 *
 * Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies. Please refer to the file "copyright.html"
 * for further important copyright and licensing information.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */

import java.io.InputStream;
import java.awt.*;
import java.net.*;

/**
 * ImageLoop class. This is a container for a list
 * of images that can be animated.
 *
 * @author     James Gosling
 * @version     1.22f, 28 Mar 1995
 */
class ImageLoop {
    /**
     * The images.
     */
    Image imgs[];

    /**
     * The number of images actually loaded.
     */
    int nimgs = 0;

    /**
     * Load the images, from dir. The images are assumed to be
     * named T1.gif, T2.gif...
     * Once all images are loaded the applet is resized to the
     * maximum size().width and size().height.
     */
    ImageLoop(URL context, String dir, ImageLoopItem parent, int nimgs) {
    this.nimgs = nimgs;
    imgs = new Image[nimgs];
    for (int i = 0; i < nimgs; i++) {
        imgs[i] = parent.getImage(parent.getCodeBase(), dir + "/T" + (i + 1) + ".gif");
    }
    }
}

/**
 * A simple Item class to play an image loop.  The "img" tag parameter
 * indicates what image loop to play.
 *
 * @author     James Gosling
 * @version     1.22f, 28 Mar 1995
 */
public class ImageLoopItem extends java.applet.Applet implements Runnable {
    /**
     * The current loop slot.
     */
    int loopslot = 0;

    /**
     * The directory or URL from which the images are loaded
     */
    String dir;

    /**
     * The image loop.
     */
    ImageLoop loop;

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

    /**
     * The length of the pause between revs.
     */
    int pause;

    /**
     * Whether or not the thread has been paused by the user.
     */
    boolean threadSuspended = false;

    /**
     * The offscreen image.
     */
    Image    im;

    /**
     * The number of images.
     */
    int nimgs;

    /**
     * The offscreen graphics context
     */
    Graphics    offscreen;

    /**
     * Initialize the applet. Get attributes.
     */
    public void init() {
    String at = getParameter("img");
    dir = (at != null) ? at : "doc:/demo/images/duke";
    at = getParameter("pause");
    pause = (at == null) ? 0 : Integer.valueOf(at).intValue();
    nimgs = Integer.valueOf(getParameter("nimgs")).intValue();
    }

    /**
     * Run the image loop. This methods is called by class Thread.
     * @see java.lang.Thread
     */
    public void run() {
    Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
    loop = new ImageLoop(getDocumentBase(), dir, this, nimgs);

    if (loop.nimgs > 1) {
        while (size().width > 0 && size().height > 0 && kicker != null) {
        if (++loopslot >= loop.nimgs) {
            loopslot = 0;
        }
        repaint();
        try {
            Thread.sleep(100 + ((loopslot == 0) ? pause : 0));
        } catch (InterruptedException e) {
            return;
        }
        }
    }
    }

    /**
     * Paint the current frame.
     */
    public void paint(Graphics g) {
    update(g);
    }
    public void update(Graphics g) {
    if ((loop != null) && (loop.imgs != null) &&
        (loopslot < loop.nimgs) && (loop.imgs[loopslot] != null)) {
        if (im == null) {
        im = createImage(size().width, size().height);
        offscreen = im.getGraphics();
        offscreen.setColor(Color.lightGray);
        }
        offscreen.fillRect(0, 0, size().width, size().height);
        offscreen.drawImage(loop.imgs[loopslot], 0, 0, this);
        g.drawImage(im, 0, 0, this);
    }
    }

    /**
     * Start the applet by forking an animation thread.
     */
    public void start() {
    if (kicker == null) {
        kicker = new Thread(this);
        kicker.start();
    }
    }

    /**
     * Stop the applet. The thread will exit because kicker is set to null.
     */
    public void stop() {
    kicker = null;
    }

    /**
     * Pause the thread when the user clicks the mouse in the applet.
     */
    public boolean mouseDown(java.awt.Event evt, int x, int y) {
        if (threadSuspended)
            kicker.resume();
    else
            kicker.suspend();
        threadSuspended = !threadSuspended;
    return true;
    }

}