animator.java

北大Java 语言程序设计 ppt课件及源码

     * @return the image's dimensions.
     */
    Dimension getImageDimensions(Image im) {
	return new Dimension(im.getWidth(null), im.getHeight(null));
    }

    /**
     * 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.
     */
    String doSubst(String inStr, int 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') {
			// 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();
    }	

    /**
     * Stuff a range of image names into a Vector.
     * @return a Vector of image URLs.
     */
    Vector prepareImageRange(int startImage, int endImage, String pattern)
    throws MalformedURLException {
	Vector result = new Vector(Math.abs(endImage - startImage) + 1);
	if (pattern == null) {
	    pattern = "T%N.gif";
	}
	if (startImage > endImage) {
	    for (int i = startImage; i >= endImage; i--) {
		result.addElement(new URL(imageSource, doSubst(pattern, i)));
	    }
	} else {
	    for (int i = startImage; i <= endImage; i++) {
		result.addElement(new URL(imageSource, doSubst(pattern, i)));
	    }
	}
	return result;
    }

    
    /**
     * Initialize the applet.  Get parameters.
     */
    public void init() {

	tracker = new MediaTracker(this);
	
	try {
	    String param = getParameter("IMAGESOURCE");	
	    imageSource = (param == null) ? getDocumentBase() : new URL(getDocumentBase(), param + "/");
	
	    param = getParameter("PAUSE");
	    globalPause =
		(param != null) ? Integer.parseInt(param) : defaultPause;

	    param = getParameter("REPEAT");
	    repeat = (param == null) ? true : (param.equalsIgnoreCase("yes") ||
					       param.equalsIgnoreCase("true"));

	    int startImage = 1;
	    int endImage = 1;
	    param = getParameter("ENDIMAGE");
	    if (param != null) {
		endImage = Integer.parseInt(param);
		param = getParameter("STARTIMAGE");
		if (param != null) {
		    startImage = Integer.parseInt(param);
		}
		param = getParameter("NAMEPATTERN");
		images = prepareImageRange(startImage, endImage, param);
	    } else {
		param = getParameter("STARTIMAGE");
		if (param != null) {
		    startImage = Integer.parseInt(param);
		    param = getParameter("NAMEPATTERN");
		    images = prepareImageRange(startImage, endImage, param);
		} else {
		    param = getParameter("IMAGES");
		    if (param == null) {
			showStatus("No legal IMAGES, STARTIMAGE, or ENDIMAGE "+
				   "specified.");
			return;
		    } else {
			images = parseImages(param);
		    }
		}
	    }

	    param = getParameter("BACKGROUND");
	    if (param != null) {
		backgroundImageURL = new URL(imageSource, param);
	    }

	    param = getParameter("STARTUP");
	    if (param != null) {
		startUpImageURL = new URL(imageSource, param);
	    }

	    param = getParameter("SOUNDSOURCE");
	    soundSource = (param == null) ? imageSource : new URL(getDocumentBase(), param + "/");
	
	    param = getParameter("SOUNDS");
	    if (param != null) {
		sounds = parseSounds(param, images);
	    }

	    param = getParameter("PAUSES");
	    if (param != null) {
		durations = parseDurations(param, images);
	    }

	    param = getParameter("POSITIONS");
	    if (param != null) {
		positions = parsePositions(param, images);
	    }

	    param = getParameter("SOUNDTRACK");
	    if (param != null) {
		soundtrackURL = new URL(soundSource, param);
	    }
	} catch (MalformedURLException e) {
	    showParseError(e);
	} catch (ParseException e) {
	    showParseError(e);
	}
	


	setFrameNum(0);
    }

    void tellLoadingMsg(String file, String fileType) {
	showStatus("Animator: loading "+fileType+" "+file);
    }

    void tellLoadingMsg(URL url, String fileType) {
	tellLoadingMsg(url.toExternalForm(), fileType);
    }

    void clearLoadingMessage() {
	showStatus("");
    }
    
    void loadError(String fileName, String fileType) {
	String errorMsg = "Animator: Couldn't load "+fileType+" "+
	    fileName;
	showStatus(errorMsg);
	System.err.println(errorMsg);
	error = true;
	repaint();
    }

    void loadError(URL badURL, String fileType) {
	loadError(badURL.toExternalForm(), fileType);
    }

    void showParseError(Exception e) {
	String errorMsg = "Animator: Parse error: "+e;
	showStatus(errorMsg);
	System.err.println(errorMsg);
	error = true;
	repaint();
    }

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

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

    /**
     * Run the animation. This method is called by class Thread.
     * @see java.lang.Thread
     */
    public void run() {
	Thread me = Thread.currentThread();
	URL badURL;
	
	me.setPriority(Thread.MIN_PRIORITY);

	if (! loaded) {
	    try {
		// ... to do a bunch of loading.
		if (startUpImageURL != null) {
		    tellLoadingMsg(startUpImageURL, imageLabel);
		    startUpImage = getImage(startUpImageURL);
		    tracker.addImage(startUpImage, STARTUP_ID);
		    tracker.waitForID(STARTUP_ID);
		    if (tracker.isErrorID(STARTUP_ID)) {
			loadError(startUpImageURL, "start-up image");
		    }
		    Dimension size = getImageDimensions(startUpImage);
		    resize(size.width, size.height);
		    repaint();
		}
	    
		if (backgroundImageURL != null) {
		    tellLoadingMsg(backgroundImageURL, imageLabel);
		    backgroundImage = getImage(backgroundImageURL);
		    tracker.addImage(backgroundImage, BACKGROUND_ID);
		    tracker.waitForID(BACKGROUND_ID);
		    if (tracker.isErrorID(BACKGROUND_ID)) {
			loadError(backgroundImageURL, "background image");
		    }
		    updateMaxDims(getImageDimensions(backgroundImage));
		    repaint();
		}

		// Fetch the animation frames
		if (!fetchImages(images)) {
		    // Need to add method to MediaTracker to return
		    // files that caused errors during loading.
		    loadError("an image", imageLabel);
		    return;
		}

		if (soundtrackURL != null && soundtrack == null) {
		    tellLoadingMsg(soundtrackURL, imageLabel);
		    soundtrack = getAudioClip(soundtrackURL);
		    if (soundtrack == null) {
			loadError(soundtrackURL, "soundtrack");
			return;
		    }
		}

		if (sounds != null) {
		    badURL = fetchSounds(sounds);
		    if (badURL != null) {
			loadError(badURL, soundLabel);
			return;
		    }
		}

		clearLoadingMessage();

		offScrImage = createImage(maxWidth, maxHeight);
		offScrGC = offScrImage.getGraphics();
		offScrGC.setColor(Color.white);

		resize(maxWidth, maxHeight);
		loaded = true;
		error = false;
	    } catch (Exception e) {
		error = true;
		e.printStackTrace();
	    }
	}

	if (userPause) {
	    return;
	}

	if (repeat || frameNum < images.size()) {
	    startPlaying();
	}

	try {
	    if (images.size() > 1) {
		while (maxWidth > 0 && maxHeight > 0 && engine == me) {
		    if (frameNum >= images.size()) {
			if (!repeat) {
			    return;
			}
			setFrameNum(0);
		    }
		    repaint();

		    if (sounds != null) {
			AudioClip clip =
			    (AudioClip)sounds.get(frameNumKey);
			if (clip != null) {
			    clip.play();
			}
		    }

		    try {
			Integer pause = null;
			if (durations != null) {
			    pause = (Integer)durations.get(frameNumKey);
			}
			if (pause == null) {
			    Thread.sleep(globalPause);
			} else {
			    Thread.sleep(pause.intValue());
			}
		    } catch (InterruptedException e) {
			// Should we do anything?
		    }
		    setFrameNum(frameNum+1);
		}
	    }
	} finally {
	    stopPlaying();
	}
    }

    /**
     * No need to clear anything; just paint.
     */
    public void update(Graphics g) {
	paint(g);
    }

    /**
     * Paint the current frame.
     */
    public void paint(Graphics g) {
	if (error || !loaded) {
	    if (startUpImage != null) {
		if (tracker.checkID(STARTUP_ID)) {
		    g.drawImage(startUpImage, 0, 0, this);
		}
	    } else {
		if (backgroundImage != null) {
		    if (tracker.checkID(BACKGROUND_ID)) {
			g.drawImage(backgroundImage, 0, 0, this);
		    }
		} else {
		    g.clearRect(0, 0, maxWidth, maxHeight);
		}
	    }
	} else {
	    if ((images != null) && (images.size() > 0)) {
		if (frameNum < images.size()) {
		    if (backgroundImage == null) {
			offScrGC.fillRect(0, 0, maxWidth, maxHeight);
		    } else {
			offScrGC.drawImage(backgroundImage, 0, 0, this);
		    }

		    Image image = (Image)images.elementAt(frameNum);
		    Point pos = null;
		    if (positions != null) {
			pos = (Point)positions.get(frameNumKey);
		    }
		    if (pos != null) {
			xPos = pos.x;
			yPos = pos.y;
		    }
		    offScrGC.drawImage(image, xPos, yPos, this);
		    g.drawImage(offScrImage, 0, 0, this);
		} else {
		    // no more animation, but need to draw something
		    dbg("No more animation; drawing last image.");
		    if (backgroundImage == null) {
			g.fillRect(0, 0, maxWidth, maxHeight);
		    } else {
			g.drawImage(backgroundImage, 0, 0, this);
		    }
		    g.drawImage((Image)images.lastElement(), 0, 0, this);
		}
	    }
	}
    }

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

    /**
     * Stop the insanity, um, applet.
     */
    public void stop() {
	if (engine != null && engine.isAlive()) {
	    engine.stop();
	}
	engine = null;
    }

    /**
     * Pause the thread when the user clicks the mouse in the applet.
     * If the thread has stopped (as in a non-repeat performance),
     * restart it.
     */
    public boolean handleEvent(Event evt) {
	if (evt.id == Event.MOUSE_DOWN) {
	    if (loaded) {
		if (engine != null && engine.isAlive()) {
		    if (userPause) {
			engine.resume();
			startPlaying();
		    } else {
			engine.suspend();
			stopPlaying();
		    }
		    userPause = !userPause;
		} else {
		    userPause = false;
		    setFrameNum(0);
		    engine = new Thread(this);
		    engine.start();
		}
	    }
	    return true;
	} else {	    
	    return super.handleEvent(evt);
	}
    }
    
}


class ParseException extends Exception {
    ParseException(String s) {
	super(s);
    }
}

class ImageNotFoundException extends Exception {
    ImageNotFoundException(ImageProducer source) {
	super(source+"");
    }
}