funscroll.java

java编程的一些Applets例子。值得深入研究一下。

/*
 * Copyright (c) 1995 by Jan Andersson, Torpa Konsult AB.
 *
 * Permission to use, copy, and distribute this software for
 * NON-COMMERCIAL purposes and without fee is hereby granted
 * provided that this copyright notice appears in all copies.
 */
import java.applet.*;
import java.awt.*;
import java.awt.image.*;
import java.util.*;

/**
 * FunScroll - A Funnier (?) scrolling text applet.
 *
 * @version 1.9 96/02/10
 * @author  Jan Andersson ([e-mail])
 * 
 */
public class FunScroll extends Applet implements Runnable 
{
   Thread thread = null;	// animation thread
   boolean suspended = false;	// animation thread suspended
   int threadDelay = 100;	// animation thread delay 
   Vector animatedTexts = null;	// animated texts
   int noOfTexts = 0;		// number of texts
   int currentTextIndex = 0;	// current text index
   FunScrollAnimatedText currentText;	// current text instance
   int lastWidth = 0;		// last know width
   int lastHeight = 0;		// last know height
   static boolean debug = false;// debug flag
   				// updates done "off-screen"...
   private Image osImage;	// ... image
   private Graphics osGraphics;	// ... graphics
   private Dimension osSize;	// ... size

   /**
    * Init applet
    */
   public void init()
   {
      String lines[] = initLineParameters();
      
      // get color parameters
      Color fg = readColor(getParameter("fgColor"), Color.black);
      Color bg = readColor(getParameter("bgColor"), getBackground());
      setBackground(bg);
      setForeground(fg);

      // get font parameters
      String fontName = getParameter("font");
      if (fontName == null)
	 fontName = "TimesRoman";
      String fontSize = getParameter("size");
      if (fontSize == null)
	 fontSize = "22";
      int size = Integer.valueOf(fontSize).intValue();
      Font font = new Font(fontName, Font.BOLD, size);

      // get animation thread delay time
      String par = getParameter("delay");
      if (par != null) 
	 threadDelay = Integer.valueOf(par).intValue();

      // get dx/dy movement
      int dx = 3;
      int dy = 2;
      par = getParameter("dx");
      if (par != null) 
	 dx = Integer.valueOf(par).intValue();
      par = getParameter("dy");
      if (par != null) 
	 dy = Integer.valueOf(par).intValue();

      // get delimiters string
      String delim = getParameter("delim");

      // create animated texts
      createAnimatedTexts(lines, font, fg, bg, dx, dy, delim);
   }

   /**
    * Init unparsed line parameters
    */
   protected String[] initLineParameters()
   {
      String par;
      // get unparsed line parameters
      dbg("get line parameters...");
      String lines[] = new String[10];
      for (int i=0; i<10; i++) {
	 String parName = "line" + i;
	 par = getParameter(parName);
	 lines[i] = par;
	 dbg("  " + parName + ":" + par);
      }
      if (lines[0] == null) {
	 // assume no line parameter provided; use default
	 lines[0] = "<20>" + getAppletInfo();
	 lines[1] = "<Text can be displayed as normal text";
	 lines[2] = "<nervous><20>or as this - nervous";
	 lines[3] = "<sine-wave><25>or as this - sine-wave";
	 lines[4] = "<up>We can scroll up, down, left and right<up>";
	 lines[5] = "We can start like this, and move down<down>";
	 lines[6] = "<up>We can also use more than one line\\nlike this.<up>";
	 lines[7] = "<down><20>Another feature -" +
	    "\"exploding\" chacters...<explode>";
	 lines[8] = "<left><10><sine-wave>Fun? I think so..." +
	    " at least a little bit.";
      }
      return lines;
   }

   /**
    * Gets a parameter of the applet.
    *
    * Use this function to overload java.applet.Applet.getParameter
    * to handle ISO Latin 1 characters correctly in Netscape 2.0.
    * Following a suggestion from Peter Sylvester,
    * [e-mail].
    *
    * Note: this is a work-a-round for a bug in Netscape and should
    *       be removed!
    */
   public String getParameter(String s) {
      String tmp = super.getParameter(s);
      if (tmp == null)
	 return null;
      char ec[] = tmp.toCharArray();
      for (int i=0; i < ec.length; i++) {
	 if (ec[i] >= 0xff00) 
	    ec[i] &= 0x00ff ;
      }
      return(new String(ec)) ;
   }

   /**
    * Applet Info.
    */
   public String getAppletInfo() {
      return "FunScroll.java 1.9 96/02/10, by [e-mail].";
   }   

   /**
    * Parameter Info.
    */
   public String[][] getParameterInfo() {
      // More should be added...
      String[][] info = {
	 {"line0",   "string", "Message line 0" },
	 {"linen",   "string", "Message line <n>" },
	 {"line9",   "string", "Message line 9" },
	 {"delim",   "string", "Delimiter string (<>)" },
	 {"font",    "string", "Message font (TimesRoman)" },
	 {"size",    "int",    "Message font size (22)" },
	 {"delay",   "int",    "Animation delay time in millisec. (100)" },
	 {"dx",      "int",
	        "No of pixels to move horizontally for each animation (2)" },
	 {"dy",      "int",
	        "No of pixels to move vertically for each animation (1)" },
	 {"fgColor", "hex",    "Foreground Color" },
	 {"bgColor", "hex",    "Background Color" },
      };
      return info;
   }
   
   /**
    * Convert a Hexadecimal String with RGB-Values to Color
    * Uses aDefault, if no or not enough RGB-Values
    */
   public Color readColor(String aColor, Color aDefault) {
      if ((aColor == null) ||
	  (aColor.charAt(0) != '#') ||
	  (aColor.length() != 7 )) {
	 return aDefault;
      }
      
      try {
	 Integer rgbValue = new Integer(0);
	 rgbValue = Integer.valueOf(aColor.substring(1, 7), 16);
	 return new Color(rgbValue.intValue());
      }
      catch (Exception e) {
	 return aDefault;
      }
   }
   
   /**
    * Create animated texts
    */
   public void createAnimatedTexts(String lines[], Font font,
				   Color fg, Color bg,
				   int dx, int dy,
				   String delim)
   {
      noOfTexts = 0;
      animatedTexts = new Vector(10);
      dbg("Creating Animated Text...");
      for (int i=0; i<10; i++) {
	 if (lines[i] == null)
	    break;
	 dbg("  " + lines[i]);
         animatedTexts.addElement(
            new FunScrollAnimatedText(
	       this, lines[i], font, fg, bg, dx, dy, delim));
	 noOfTexts++;
      }
      currentTextIndex = 0;
      currentText = (FunScrollAnimatedText)
	 animatedTexts.elementAt(currentTextIndex);
   }
   

   /**
    * Animate the texts
    */
   public void animate(Graphics g) {
      // update current text
      if (currentText.update(g)) {
	 // done; get next text
	 currentTextIndex++;
	 if (currentTextIndex >= noOfTexts)
	    currentTextIndex = 0;
	 currentText = (FunScrollAnimatedText)
	    animatedTexts.elementAt(currentTextIndex);
	 currentText.reset(lastWidth, lastHeight);
      }
   }

   /**
    * Paint the graphics
    */
   public void paint(Graphics g) {
      if (lastWidth != size().width || lastHeight != size().height) {
	 lastWidth = size().width;
	 lastHeight = size().height;
	 // reset Animated Text item
	 currentText.reset(lastWidth, lastHeight);
      }
      animate(g);
   }

   /**
    * Update off-screen graphics
    *
    * From NoFlickerApplet, by Matthew Gray
    */
    public final synchronized void update (Graphics theG)
    {
      Dimension d = size();
      if((osImage == null) || (d.width != osSize.width) ||
	 (d.height != osSize.height)) {
	 osImage = createImage(d.width, d.height);
	 osSize = d;
	 osGraphics = osImage.getGraphics();
	 osGraphics.setFont(getFont());
      }
      osGraphics.setColor(getBackground());
      osGraphics.fillRect(0,0,d.width, d.height);
      paint(osGraphics);
      theG.drawImage(osImage, 0, 0, null);
    }

   /**
    * Run the loop. This method is called by class Thread.
    */
   public void run() {
      Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
      while (thread != null) {
	 repaint();
	 try {Thread.sleep(threadDelay);}
	 catch (InterruptedException e){}
      }
   }
   
   /**
    * Start the applet by forking an animation thread.
    */
   public void start() {
      if (thread == null) {
	 thread = new Thread(this);
	 thread.start();
      }
   }
   
   /**
    * Stop the applet. The thread will exit because run() exits.
    */
   public void stop() {
      thread = null;
   }
   
   /**
    * Suspend/Resume
    */
   public boolean mouseDown(Event evt, int x, int y) {
      // handle Suspend/Resume
      if (suspended) {
	 thread.resume();
      }
      else {
	 thread.suspend();
      }
      suspended = !suspended;
      // show version
      if (suspended)
	 showStatus(getAppletInfo());
      return true;
   }

   /**
    * Simple debug...
    */
   static public void dbg(String str) {
      if (debug) {
	 System.out.println("Debug: " + str);
	 System.out.flush();
      }
   }  
}

/**
 * Attributes of FunScroll Animated Text
 */
class FunScrollTextAttr
{
				// scroll styles:
   static final int NONE = 0;	// no scrolling (default)
   static final int LEFT = 1;	// scroll left
   static final int RIGHT = 2;	// ... right
   static final int UP = 3;	// ... up
   static final int DOWN = 4;	// ... down
   static final int EXPLODE = 5;// explode (only for endScroll)
				  // text styles:
   static final int NORMAL = 0;	  // normal (default)
   static final int NERVOUS = 1;  // "nervous" text
   static final int SINEWAVE = 2; // sine-wave text

   String msg = "";		// message line
   String delimiters = "<>";	// used delimiters (default is "<>")
   int startScroll = NONE;	// start scroll style
   int endScroll = NONE;	// end scroll style
   int showDelay = 10;		// start delay
   int endDelay = -1;		// end delay
   int style = NORMAL;		// text style
   
   public FunScrollTextAttr(String line, String delim)
   {
      if (delim != null) {
	 // used specified delimiter
	 delimiters = delim;
      }
      parse(line);
   }

   public String msg()
   {
      return msg;
   }
   
   public int startScroll()
   {
      return startScroll;
   }
   
   public int endScroll()
   {
      return endScroll;
   }
   
   public int showDelay()
   {
      return showDelay;
   }
   
   public int endDelay()
   {
      return endDelay;
   }

   public int style()
   {
      return style;
   }
   
   void parse(String line)
   {
      StringTokenizer st = new StringTokenizer(line, delimiters);
      boolean gotText = false;
      while (st.hasMoreTokens()) {
	 int scroll = -1;
	 String token = st.nextToken();
	 // parse scroll style
	 if (token.equalsIgnoreCase("left")) 
	    scroll = LEFT;
	 else if (token.equalsIgnoreCase("right")) 
	    scroll = RIGHT;
	 else if (token.equalsIgnoreCase("up")) 
	    scroll = UP;
	 else if (token.equalsIgnoreCase("down")) 
	    scroll = DOWN;
	 else if (gotText && token.equalsIgnoreCase("explode")) 
	    scroll = EXPLODE;
	 if (scroll >= 0) {
	    if (!gotText)
	       startScroll = scroll;
	    else
	       endScroll = scroll;
	    continue;
	 }

	 // parse text style
	 if (token.equalsIgnoreCase("nervous")) {
	    style = NERVOUS;
	    continue;
	 }
	 if (token.equalsIgnoreCase("sine-wave")) {
	    style = SINEWAVE;
	    continue;
	 }

	 // check if integer, if so assume delay value
	 boolean isInt = true;
	 for (int i=0; i<token.length(); i++) {
	    int digit = Character.digit(token.charAt(i), 10);
	    if (digit < 0) {
	       // not a digit
	       isInt = false;
	       break;
	    }
	 }
	 if (isInt) {
	    try {
	       if (!gotText)
		  showDelay = Integer.parseInt(token);
	       else
		  endDelay = Integer.parseInt(token);
	    } catch (NumberFormatException ne) {}
	    continue;
	 }
	 else {
	    // assume text string parsed
	    if (!gotText) {
	       msg = token;
	       gotText = true;
	    }
	 }
      }