/*
   This code is, for the moment, totally uncommented.  Sorry.
   
   David Eck
   Department of Mathematics and Computer Science
   Hobart and William Smith Colleges
   Geneva, NY   14456
   E-mail:  eck@hws.edu
   WWW:     http://www.hws.edu/~eck
   
   June 18, 1996
   
   NOTE:  YOU CAN DO ANYTHING YOU WANT WITH THIS CODE, EXCEPT COPYRIGHT IT,
          PATENT IT, OR OTHERWISE TRY TO CLAIM CREDIT FOR IT.
          
*/

import java.awt.*;

class CACanvas extends Canvas {

   private boolean backedUp = true;
   private Image OSC = null;
   private int[] rule = null;
   private int ruleCt = 8;
   private int states = 2;
   private int neighbors = 3;
   private int halfNeighborCt = 1;
   private int[] startWorld = null;
   private int[] world = null;
   private int[] newWorld = null;
   private Color[] stateColor = null;
   private int width = 0;
   private int height = 0;
   private int lineCt = 0;
      
   synchronized void properties(int stateCt, int neighborCt, 
                                int[] theRules, Color[] theColors, 
                                boolean useOffScreenCanvas) {
      backedUp = useOffScreenCanvas;
      states = stateCt;
      if (states < 2)
         states = 2;
      neighbors = neighborCt;
      if (neighbors % 2 == 0)
        neighbors++;
      if (neighborCt < 3)
         neighborCt = 3;
      ruleCt = 1;
      for (int i=0; i<neighbors; i++) {
         if (ruleCt > 32768) {
            states = 2;
            neighbors = 3;
            ruleCt = 8;
            break;
         }
         ruleCt = ruleCt*states;
      }
      halfNeighborCt = neighbors / 2;
      if (theRules != null && theRules.length >= ruleCt)
         rule = theRules;
      else 
         rule = null;
      if (theColors != null && theColors.length >= states)
         stateColor = theColors;
      else
         theColors = null;
   }
   
   int getWidth() {
     return (width == 0)? size().width : width;
   }
   
   void disposeOSC() {
      OSC = null;
   }
      
   synchronized void set(int[] theWorld) {
       if ((width != size().width || height != size().height))
          OSC = null;
       width = size().width;
       height = size().height;
       if (world == null || world.length < width)
          world = new int[width];
       if (newWorld == null || newWorld.length < width)
          newWorld = new int[width];
       if (rule == null || rule.length < ruleCt) {
          rule = new int[ruleCt];
          for (int i = 0; i < ruleCt; i++)
             rule[i] = 1;
          rule[0] = 0;
          rule[ruleCt-1] = 0;
       }
       if (stateColor == null || stateColor.length < states) {
          stateColor = new Color[states];
          stateColor[0] = Color.white;
          stateColor[1] = Color.black;
          if (states>2) {
             float hue = 0.0F;
             for (int i = 2; i < states; i++) {
                 stateColor[i] = Color.getHSBColor(hue,1.0F,1.0F); 
                 hue = hue + (1.0F / (states - 2));
             }
          }
       }
       if (theWorld == null) {
          for (int i=0; i<width; i++)
             world[i] = 0;
          world[width/2] = 1;
       }
       else {
          for (int i=0; i<width; i++)
             if (i < theWorld.length && theWorld[i] >= 0 && theWorld[i] < states)
                world[i] = theWorld[i];
             else
               world[i] = 0;
       }
       if (startWorld == null || startWorld.length < width)
          startWorld = new int[width];
       for (int i = 0; i<width; i++)
          startWorld[i] = world[i];
       if (backedUp && OSC == null)
           OSC = createImage(width,height);
       clear();
   }
   
   void reset() {
      if (startWorld != null) {
          if (world == null || world.length < width)
             world = new int[width];
          for (int i=0; i<width; i++)
             if (i < startWorld.length && startWorld[i] >= 0 && startWorld[i] < states)
                world[i] = startWorld[i];
             else
               world[i] = 0;
         clear();
      }
   }
   
   void setStart() {
      if (world != null) {
         if (startWorld == null || startWorld.length < world.length)
            startWorld = new int[world.length];
         for (int i=0; i<world.length; i++)
            startWorld[i] = world[i];
      }
   }
   
   synchronized void setCell(int cellNum, int state) {
       if (world != null && cellNum >= 0 && cellNum < world.length && state >= 0 && state < states)
            world[cellNum] = state;
   }
   
   synchronized void clear() {
      if (OSC != null) {
         Graphics g = OSC.getGraphics();
         if (stateColor != null)
            g.setColor(stateColor[0]);
         else
            g.setColor(Color.black);
         g.fillRect(0,0,width,height);
         g.dispose();
         repaint();
      }
      else {
         Graphics g = getGraphics();
         if (stateColor != null)
            g.setColor(stateColor[0]);
         else
            g.setColor(Color.black);
         g.fillRect(0,0,width,height);
         g.dispose();
      }
      lineCt = 0;
   }
   
   synchronized void  setRules(int[] theRules) {
      if (theRules.length >= ruleCt)
         rule = theRules;
   }
   
   synchronized void  setRule(int ruleNum, int value) {
      if ((rule != null) && (value >= 0) && (value < states) && (ruleNum >= 0) && (ruleNum < rule.length))
         rule[ruleNum] = value;
   }
   
   synchronized void  setColors(Color[] theColors) {
      if (theColors.length >= states)
         stateColor = theColors;
   }

   synchronized void  setColor(int colorNum, Color value) {
      if ((stateColor != null) && (value != null) && (colorNum >= 0) && (colorNum < stateColor.length))
         stateColor[colorNum] = value;
   }
   
   public void update(Graphics g) {
      paint(g);
   }
   
   public void paint(Graphics g) {
      if (OSC != null)
         g.drawImage(OSC,0,0,this);
   }
   
   synchronized void putWorld() {
      Graphics g=null;
      if (OSC == null)
         g = getGraphics();
      else
         g = OSC.getGraphics();
      if (lineCt >= height && g != null) {
         g.copyArea(0,0,width,height,0,-1);
         lineCt = height-1;
      }
      if (g != null) {
         for (int i=0; i< width; i++) {
            g.setColor(stateColor[world[i]]);
            g.fillRect(i,lineCt,1,1);
         }
         lineCt++;
         g.dispose();
      }
      if (OSC != null) {
         g = getGraphics();
         if (g != null && OSC != null) {
            g.drawImage(OSC,0,0,this);
            g.dispose();
         }
      }
   }
   
   synchronized void next() {
      if (width > 0) {
        for (int i=0; i < width; i++) {
           int left = i - halfNeighborCt;
           if (left<0)
              left = width+left;
           int right = i + halfNeighborCt;
           if (right>=width)
              right = right-width;
           int k = 0;
           if (left < right) {
              for (int j=left; j<=right; j++)
                 k = states*k + world[j];
           }
           else {
              for (int j=left; j<width; j++)
                k = states*k + world[j];
              for (int j=0; j<=right; j++)
                k = states*k + world[j];
           }
           newWorld[i] = rule[k];
         }
         putWorld();
         for (int i = 0; i < width; i++)
            world[i] = newWorld[i];
      }
   }   // next()
   
}  // class CACanvas