/** Use JWS to modify MyApplet13.java (previously AnimatorApplet5.java) ** so that the scrolling text displayed is phrased correctly, e.g. ** "0th" is not displayed and "1st", "2nd", "3rd" is displayed instead ** of "1th", "2th", "3th", respectively. Make sure to fix all such ** incorrect occurrences. In addition, change scrollDistance and ** scrollPosition so that the text scrolls onto the page incrementally ** from the left, starting with the last character of the scrolling ** text, instead of the complete text jumping onto the page all at once. ** Also, edit MyApplet13.html in the project directory, both to run the ** MyApplet13.class file you create, and so that everything looks nice ** and works properly. **/ /** USE EXISTING JAVA CLASSES **/ import java.awt.*; import java.applet.Applet; /** EXTEND THE JAVA APPLET CLASS AND IMPLEMENT THE RUNNABLE INTERFACE **/ public class MyApplet13 extends Applet implements Runnable {int frameNumber = -1; int delay; Thread animatorThread; boolean frozen = false; Font font=new Font("TimesRoman",Font.BOLD,24); FontMetrics fontm = getFontMetrics(font); String framestr = ""; Dimension preImageDim; // Define preImage variables needed to Image preImage; // create the offscreen copy of the image Graphics preImageGraphics; // we want to paint on the screen. Image gifImage[]; // Define an array of gif images and MediaTracker tracker; // a tracker to preload them. int HiNumber = 1; /** INITIALIZE THE APPLET **/ public void init() {setBackground(Color.blue); String str; int fps = 20; // Define the default fps (frames per second). str = getParameter("fps"); // Possibly, get HTML string specifying the try // fps. {if (str != null) {fps = Integer.parseInt(str);} // If possible, convert HTML fps to an } // integer. catch (Exception e) {} // In case the try caused something strange. delay = (fps > 0) ? (1000/fps): 100; // Convert fps to the milisecond delay // time between frames. gifImage = new Image[10]; tracker = new MediaTracker(this); // Spawn the tracker background thread(s) for (int i = 1; i <= 10; i++) // in order to preload the images. {gifImage[i-1] = getImage(getCodeBase(), "images/T"+i+".gif"); tracker.addImage(gifImage[i-1],0); } } /** CLICK TO START OR STOP THE APPLET **/ public boolean mouseDown(Event e, int x, int y) {if (frozen) {frozen = false; start();} else {frozen = true; animatorThread = null; // Instead of calling stop() here, since } // stop() now nullifies our preImage context, return true; // nullify only the animation thread in case } // we want to build on our current preImage. /** GENERATE AND/OR START THE ANIMATION THREAD **/ public void start() {if (frozen) { } // The animation is supposed to stay frozen. else // Otherwise, generate and/or start the {if (animatorThread == null) // animation thread. Apparently, if run {animatorThread = new Thread(this);} // breaks after catching an exception, animatorThread.start(); // the animatorThread though not null } // will still need to be restarted. } /** CREATE AND DISPLAY FRAMES OF THE ANIMATION THREAD **/ public void run() {try // Start loading the images and {tracker.waitForAll();} // wait until done before starting catch (InterruptedException e) {} // the animation. Thread.currentThread().setPriority(Thread.MIN_PRIORITY); // Set the priority low. long startTime = System.currentTimeMillis(); // Remember start time. while (Thread.currentThread() == animatorThread) // The animation loop. {frameNumber++; // Advance the frame number. repaint(); // Display the frame. try // Sleep for the delay period. {startTime += delay; Thread.sleep(Math.max(0, startTime-System.currentTimeMillis())); } catch (InterruptedException e) {break;} // In case the try caused } // something strange, exit } // the while loop. /** CREATE THE CURRENT FRAME OF THE ANIMATION THREAD **/ public void paint(Graphics g) // This technique of painting by calling {if (!frozen) update(g);} // update, prevents the default (and hidden) // behavior of update, and instead allows public void update(Graphics g) // the creation of an offscreen preImage {Dimension d = size(); // preImage before painting the screen. if (!tracker.checkAll()) // If the images aren't all {g.clearRect(0, 0, d.width, d.height); // loaded, then clear the g.drawString("Please wait...", // background and notify (d.width-20)/2, d.height/2); // the user to wait. } else {if ((preImageGraphics == null) || // When all images are loaded, (d.width != preImageDim.width) || // compare the current applet (d.height != preImageDim.height)) // viewing size to our preImage, {preImageDim = d; // and if different, resize our preImage = createImage(d.width,d.height); // next preImage. preImageGraphics = preImage.getGraphics(); } preImageGraphics.setColor(getBackground()); // Clear the previous preImage preImageGraphics.fillRect(0,0,d.width,d.height); // by filling with the current preImageGraphics.setFont(font); // background color (magenta), preImageGraphics.setColor(Color.black); // and then create the next // offscreen preImage. if ((frameNumber + 5) % 10 == 0) HiNumber++; // Say "Hi" to user, framestr = "Hi StLCOP for the " + HiNumber + "th time !"; // and count times. String frameconstant = framestr; if (HiNumber == 0) HiNumber++; else if ((HiNumber % 10 == 1) && (HiNumber % 100 != 11)) {framestr = "Hi StLCOP for the " + HiNumber + "st time !";} else if ((HiNumber % 10 == 2) && (HiNumber % 100 != 12)) {framestr = "Hi StLCOP for the " + HiNumber + "nd time !";} else if ((HiNumber % 10 == 3) && (HiNumber % 100 != 13)) {framestr = "Hi StLCOP for the " + HiNumber + "rd time !";} else {framestr = "Hi StLCOP for the " + HiNumber + "th time !";} /*if (HiNumber==1) {framestr = "Hi StLCOP for the " + HiNumber + "st time !";} if (HiNumber==2) {framestr = "Hi StLCOP for the " + HiNumber + "nd time !";} if (HiNumber==3) {framestr = "Hi StLCOP for the " + HiNumber + "rd time !";} if ((HiNumber >= 20) && (HiNumber %10 == 1)) {framestr = "Hi StLCOP for the " + HiNumber + "st time !";} if ((HiNumber >= 20) && (HiNumber %10 == 2)) {framestr = "Hi StLCOP for the " + HiNumber + "nd time !";} if ((HiNumber >= 20) && (HiNumber %10 == 3)) {framestr = "Hi StLCOP for the " + HiNumber + "rd time !";}*/ int scrollDistance = d.width + fontm.stringWidth(frameconstant); // Compute scroll position int scrollPosition = -fontm.stringWidth(frameconstant) + (frameNumber % scrollDistance); // of leftmost character preImageGraphics.drawString( // of framestr, and draw framestr,scrollPosition,d.height/2); // framestr above current preImageGraphics.drawImage( // image. gifImage[frameNumber % 10], // Compute current image, scrollPosition + (fontm.stringWidth(framestr))/3, // and draw below framestr. d.height/2,this); // Offscreen preImage completed. g.drawImage(preImage,0,0,this); // Paint preImage on the screen. } } /** STOP THE ANIMATION THREAD **/ public void stop() {animatorThread = null; // The user either clicked to stop or left the page, preImageGraphics = null; // so wipe out the current thread and preImage context. preImage = null; } }