animator.java

java applet动画演示源码

            }
	}
    }

    public void mouseClicked(MouseEvent event) {
	if ((hrefURL != null) &&
	        ((event.getModifiers() & InputEvent.SHIFT_MASK) == 0)) {
	    getAppletContext().showDocument(hrefURL, hrefTarget);
	}
    }

    public void mouseReleased(MouseEvent event) {
    }

    public void mouseEntered(MouseEvent event) {
	showStatus(getAppletInfo()+" -- "+userInstructions);
    }

    public void mouseExited(MouseEvent event) {
        showStatus("");
    }    
}

/**
 * A class that represents an animation to be displayed by the applet
 */
class Animation extends Object {
    static final int STARTUP_ID    = 0;
    static final int BACKGROUND_ID = 1;
    static final int ANIMATION_ID  = 2;
    static final String imageLabel = "image";
    static final String soundLabel = "sound";

    int globalPause = 1300;        // global pause in milleseconds
    List frames = null;            // List holding frames of animation
    int currentFrame;              // Index into images for current position
    Image startUpImage = null;     // The startup image if any
    Image backgroundImage = null;  // The background image if any
    AudioClip soundTrack = null;   // The soundtrack for this animation
    Color backgroundColor = null;  // Background color if any
    URL backgroundImageURL = null; // URL of background image if any
    URL startUpImageURL = null;    // URL of startup image if any 
    URL soundTrackURL = null;      // URL of soundtrack
    URL imageSource = null;        // Directory or URL for images
    URL soundSource = null;        // Directory or URL for sounds
    boolean repeat;                // Repeat the animation if true
    Image offScrImage;             // Offscreen image
    Graphics offScrGC;             // Offscreen graphics context
    MediaTracker tracker;          // MediaTracker used to load images
    Animator owner;                // Applet that contains this animation

    Animation(Animator container) {
        super();
        owner = container;
    }

    void init() {
        tracker = new MediaTracker(owner);
	currentFrame = 0;
        loadAnimationMedia();
	startPlaying();
    }

    void setGlobalPause(int pause) {
        globalPause = pause;
    }

    /**
     * Loads the images and sounds involved with this animation
     */
    void loadAnimationMedia() {
        URL badURL;
        boolean error;
        try {
            if (startUpImageURL != null) {
                owner.tellLoadingMsg(startUpImageURL, imageLabel);
                startUpImage = fetchImageAndWait(startUpImageURL, STARTUP_ID);
                if (tracker.isErrorID(STARTUP_ID)) {
                    owner.loadError(startUpImageURL, "start-up image");
                }
                owner.repaint();
            }
	    
	    if (backgroundImageURL != null) {
	         owner.tellLoadingMsg(backgroundImageURL, imageLabel);
	        backgroundImage = fetchImageAndWait(backgroundImageURL, 
                                                    BACKGROUND_ID);
	        if (tracker.isErrorID(BACKGROUND_ID))
                    owner.loadError(backgroundImageURL, 
                                        "background image");
		owner.repaint();
            }

	    // Fetch the animation frame images
            Iterator iterator = frames.iterator();
            while(iterator.hasNext()) {
                AnimationFrame frame = (AnimationFrame) iterator.next();
                owner.tellLoadingMsg(frame.imageLocation, imageLabel);
                frame.image = owner.getImage(frame.imageLocation);
                tracker.addImage(frame.image, ANIMATION_ID);
                try {
                    tracker.waitForID(ANIMATION_ID);
                } catch (InterruptedException e) {}
	    }

	    if (soundTrackURL != null && soundTrack == null) {
		owner.tellLoadingMsg(soundTrackURL, imageLabel);
		soundTrack = owner.getAudioClip(soundTrackURL);
		if (soundTrack == null) {
		    owner.loadError(soundTrackURL, "soundtrack");
		    return;
		}
	    }

            // Load the sounds into their frames
            iterator = frames.iterator();
            while(iterator.hasNext()) {
                AnimationFrame frame = (AnimationFrame) iterator.next();
                if (frame.soundLocation != null) {
                    owner.tellLoadingMsg(frame.soundLocation, soundLabel);
                    try {
                        frame.sound = owner.getAudioClip(frame.soundLocation);
                    } catch (Exception ex) {
                        owner.loadError(frame.soundLocation, soundLabel);
                    }
                }
	    }

	    owner.clearLoadingMessage();
	    offScrImage = owner.createImage(owner.appWidth, owner.appHeight);
	    offScrGC = offScrImage.getGraphics();
	    offScrGC.setColor(Color.lightGray);
            owner.loaded = true;
	    error = false;
	} catch (Exception e) {
	    error = true;
	    e.printStackTrace();
	}
    }

    /**
     * Fetch an image and wait for it to come in.  Used to enforce a load
     * order for background and startup images.
     */
    Image fetchImageAndWait(URL imageURL, int trackerClass) 
                              throws InterruptedException {
	Image image = owner.getImage(imageURL);
	tracker.addImage(image, trackerClass);
	tracker.waitForID(trackerClass);
	return image;
    }

    /**
     * Stuff a range of image names into a List
     * @return a List of image URLs.
     */
    void prepareImageRange(int startImage, int endImage, String pattern)
    throws MalformedURLException {
	frames = new ArrayList(Math.abs(endImage - startImage) + 1);
	if (pattern == null)
	    pattern = "T%N.gif";
	if (startImage > endImage) {
	    for (int i = startImage; i >= endImage; i--) {
                AnimationFrame frame = new AnimationFrame();
		frames.add(frame);
                frame.duration = globalPause;
                frame.imageLocation = new URL(imageSource, 
                                              doSubst(pattern, i+""));
	    }
	} else {
	    for (int i = startImage; i <= endImage; i++) {
                AnimationFrame frame = new AnimationFrame();
		frames.add(frame);
                frame.duration = globalPause;
                frame.imageLocation = new URL(imageSource,
                                              doSubst(pattern, i+""));
	    }
	}
    }

    /**
     * Parse the SOUNDS parameter.  It looks like
     * train.au||hello.au||stop.au, etc., where each item refers to a
     * source image.  Empty items mean that the corresponding image
     * has no associated sound.
     */
    void parseSounds(String attr) throws MalformedURLException {
	int frameIndex = 0;
	int numFrames = frames.size();
	for (int i = 0; (i < attr.length()) && (frameIndex < numFrames); ) {
	    int next = attr.indexOf('|', i);
	    if (next == -1) next = attr.length();
	    String sound = attr.substring(i, next);
	    if (sound.length() != 0) {
                AnimationFrame frame = (AnimationFrame) frames.get(frameIndex);
		frame.soundLocation = new URL(soundSource, sound);
	    }
	    i = next + 1;
	    frameIndex++;
        }
    }

    /**
     * Parse the IMAGES parameter.  It looks like
     * 1|2|3|4|5, etc., where each number (item) names a source image.
     */
    void parseImages(String attr, String pattern) 
                           throws MalformedURLException {
        frames = new ArrayList();
	if (pattern == null)
	    pattern = "T%N.gif";
	for (int i = 0; i < attr.length(); ) {
	    int next = attr.indexOf('|', i);
	    if (next == -1) next = attr.length();
	    String file = attr.substring(i, next);
            AnimationFrame frame = new AnimationFrame();
            frames.add(frame);
            frame.imageLocation = new URL(imageSource, doSubst(pattern, file));
            frame.duration = globalPause;
	    i = next + 1;
	}
    }

    /**
     * Parse the PAUSES parameter.  It looks like
     * 1000|500|||750, etc., where each item corresponds to a
     * source image.  Empty items mean that the corresponding image
     * has no special duration, and should use the global one.
     *
     * @return a Hashtable of Integer pauses keyed to Integer
     * frame numbers.
     */
    void parseDurations(String attr) {
	int imageNum = 0;
	int numImages = frames.size();
	for (int i = 0; (i < attr.length()) && (imageNum < numImages); ) {
	    int next = attr.indexOf('|', i);
	    if (next == -1) next = attr.length();
            AnimationFrame aFrame = (AnimationFrame) frames.get(imageNum);
	    if (i != next) {
		int duration = Integer.parseInt(attr.substring(i, next));
                aFrame.duration = duration;
	    }
	    i = next + 1;
	    imageNum++;
	}
    }

    /**
     * Parse a String of form xxx@yyy and return a Point.
     */
    Point parsePoint(String s) throws ParseException {
	int atPos = s.indexOf('@');
	if (atPos == -1) throw new ParseException("Illegal position: "+s);
	return new Point(Integer.parseInt(s.substring(0, atPos)),
			 Integer.parseInt(s.substring(atPos + 1)));
    }

    /**
     * Parse the POSITIONS parameter.  It looks like
     * 10@30|11@31|||12@20, etc., where each item is an X@Y coordinate
     * corresponding to a source image.  Empty items mean that the
     * corresponding image has the same position as the preceding one.
     *
     * @return a Hashtable of Points keyed to Integer frame numbers.
     */
    void parsePositions(String param)
    throws ParseException {
	int imageNum = 0;
	int numImages = frames.size();
	for (int i = 0; (i < param.length()) && (imageNum < numImages); ) {
	    int next = param.indexOf('|', i);
	    if (next == -1) 
                next = param.length();
	    if (i != next) {
                AnimationFrame frame = (AnimationFrame) frames.get(imageNum);
                frame.position = parsePoint(param.substring(i, next));
            }
	    i = next + 1;
	    imageNum++;
	}
    }

    /**
     * Substitute an integer some number of times in a string, subject to
     * parameter strings embedded in the string.
     * Parameter strings:
     *   %N - substitute the integer as is, with no padding.
     *   %<digit>, for example %5 - substitute the integer left-padded with
     *        zeros to <digits> digits wide.
     *   %% - substitute a '%' here.
     * @param inStr the String to substitute within
     * @param theInt the int to substitute, as a String.
     */
    String doSubst(String inStr, String theInt) {
	String padStr = "0000000000";
	int length = inStr.length();
	StringBuffer result = new StringBuffer(length);
	
	for (int i = 0; i < length;) {
	    char ch = inStr.charAt(i);
	    if (ch == '%') {
		i++;
		if (i == length) {
		    result.append(ch);
		} else {
		    ch = inStr.charAt(i);
		    if (ch == 'N' || ch == 'n') {
			// just stick in the number, unmolested
			result.append(theInt);
			i++;
		    } else {
			int pad;
			if ((pad = Character.digit(ch, 10)) != -1) {
			    // we've got a width value
			    String numStr = theInt;
			    String scr = padStr+numStr;
			    result.append(scr.substring(scr.length() - pad));
			    i++;
			} else {
			    result.append(ch);
			    i++;
			}
		    }
		}
	    } else {
		result.append(ch);
		i++;
	    }
	}
	return result.toString();
    }	

    void startPlaying() {
	if (soundTrack != null)
	    soundTrack.loop();
    }

    void stopPlaying() {
	if (soundTrack != null)
	    soundTrack.stop();
    }

    public void paint(Graphics g) {
        int xPos = 0;
        int yPos = 0;
        if ((frames.size() > 0) && tracker.checkID(ANIMATION_ID) && 
                                                          (offScrGC != null)) {
            AnimationFrame frame = (AnimationFrame) frames.get(currentFrame);
            Image image = frame.image;
            if (backgroundImage == null) {
                offScrGC.clearRect(0, 0, owner.appWidth, owner.appHeight);
            }
            else
                offScrGC.drawImage(backgroundImage, 0, 0, owner);
            Point pos = null;
            if (frame.position != null) {
                xPos = frame.position.x;
                yPos = frame.position.y;
            }
            if (backgroundColor != null) {
                offScrGC.setColor(backgroundColor);
                offScrGC.fillRect(0, 0, owner.appWidth, owner.appHeight);
                offScrGC.drawImage(image, xPos, yPos, backgroundColor, owner);
            } else {
                offScrGC.drawImage(image, xPos, yPos, owner);
            }
            if (offScrImage != null)
                g.drawImage(offScrImage, 0, 0, owner);
        }
    }
}

/**
 * Instances of this class represent a single frame of an animation
 * There can be an image, sound, and position associated with each frame
 */
class AnimationFrame extends Object {
    static final String imageLabel = "image";
    static final String soundLabel = "sound";

    URL imageLocation = null; // Directory or URL of this frames image
    URL soundLocation = null; // Directory or URL of this frames sound
    int duration;             // Duration time for this frame in milliseconds
    AudioClip sound;          // Sound associated with this frame object
    Image image;              // Image associated with this frame
    Point position;           // Position of this frame

}

/**
 * ParseException: signals a parameter parsing problem.
 */
class ParseException extends Exception {
    ParseException(String s) {
	super(s);
    }
}

/**
 * DescriptionFrame: implements a pop-up "About" box.
 */
class DescriptionFrame extends Frame implements ActionListener {
    static final int rows = 27;
    static final int cols = 70;
    TextArea info;
    Button cancel;

    DescriptionFrame() {
	super("Animator v1.10");
	add("Center", info = new TextArea(rows, cols));
	info.setEditable(false);
	info.setBackground(Color.white);
	Panel buttons = new Panel();
	add("South", buttons);
	buttons.add(cancel = new Button("Cancel"));
	cancel.addActionListener(this);
	pack();
    }

    public void show() {
	info.select(0,0);
	super.show();
    }

    void tell(String s) {
	info.append(s);
    }

    public void actionPerformed(ActionEvent e) {
	setVisible(false);
    }
}