//CaughtUp Applet, version 1 Last updated 2/27/99
//M.Dubson, Feb. 1999, ENVD 3252

import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;
import java.lang.*;

public class CaughtUp extends Applet implements MouseListener, Runnable
{ 
 int nbrSpaces;  //number of pixels between gridlines
 int maxGridlines; //Maximum number of gridlines = array size
 int increment;  //increment of nbrSpaces
 int w, h; // width and height of applet frame
 int radius;
 Thread theThread;
 Image offscreen;
 int[][] xyGreen; //xy-coords of green circle
 
 
 public void init()
 {  
    addMouseListener(this);
    w = getSize().width;
    h = getSize().height;
    //nbrSpaces = 30;
    nbrSpaces = Integer.parseInt( getParameter( "nbrSpaces"));
    increment = 1;
    maxGridlines = w/nbrSpaces+2;
    xyGreen = new int[maxGridlines][maxGridlines];
    
    
    radius = nbrSpaces/3;
    System.out.println("Variable nbrSpaces is " + nbrSpaces + ".");
    for (int xline = 0; xline < maxGridlines; xline++)
    {
      for (int yline = 0; yline < maxGridlines; yline++)
      {
        xyGreen[xline][yline] = -1;  //-1 means circle not green
      }
    }
    
 }
 
 public void step()
 {
       nbrSpaces += increment;
       radius = nbrSpaces/3;
       if (nbrSpaces > 150 || nbrSpaces < 30)  //Breath in ... breath out
       {
         increment *= -1;
       }
       //System.out.println("Spacing is " + nbrSpaces + ".");
       repaint();
 
 }//end of step method     
       
      
  public void paint(Graphics g)
  {
      g.setColor(Color.white);
      g.fillRect(0,0,w,h);
      for (int x = 0; x < w; x += nbrSpaces) //Draw vertical lines
      {
        int blueValue = x*255/w;
        g.setColor(new Color(0,0,blueValue));
        g.drawLine(x, 0, x, h);
      }
      for (int y = 0; y < h;  y += nbrSpaces)//Draw horizontal lines
      {
        int redValue = y*255/h;
        g.setColor(new Color(redValue,0,0));
        g.drawLine(0, y, w, y);
      }


      for (int x = 0; x < w+nbrSpaces; x += nbrSpaces) //Draw disks at intersections
      {
        //int radius = nbrSpaces/3;
        int blueValue = x*255/(w+nbrSpaces);
        for (int y = 0; y < h+nbrSpaces;  y += nbrSpaces)
        {
          int redValue = y*255/(h+nbrSpaces);
          g.setColor(new Color(redValue,0,blueValue));
          g.fillOval(x - radius, y - radius, 2*radius, 2*radius);
        }
      }// end of disk drawing loops
      
      for (int xline = 0; xline <= w/nbrSpaces + 1; xline++) //Draw green disks 
      {
        for (int yline = 0; yline <= h/nbrSpaces + 1;  yline++)
        {
          if (xyGreen[xline][yline] == 1 )
          {
            g.setColor(Color.green);
            int x = xline*nbrSpaces;
            int y = yline*nbrSpaces;
            g.fillOval(x - radius, y - radius, 2*radius, 2*radius);
          }
        }
      }// end of green disk drawing 
      //System.out.println("xGreen[1] is " + xGreen[1] + ".   "+"yGreen[1] is " + yGreen[1]);
                  
      //System.out.println("xGreen[3] is " + xGreen[3] + ".   "+"yGreen[3] is " + yGreen[3]);
                  
    }//end of paint method      

 public void mousePressed( MouseEvent e)
 {
    int x = e.getX();
    int y = e.getY();
    int x_near = ((x+nbrSpaces/2)/nbrSpaces)*nbrSpaces;
    int y_near = ((y+nbrSpaces/2)/nbrSpaces)*nbrSpaces;
    int xline = x_near/nbrSpaces;
    int yline = y_near/nbrSpaces;
    if (xyGreen[xline][yline] == -1)
    {
      xyGreen[xline][yline] = 1;
    }
    else xyGreen[xline][yline] = -1;
    
    Graphics g = getGraphics();
    
    g.setColor(Color.green);
    g.fillOval(x_near - radius,y_near - radius, 2*radius, 2*radius); 
 
 }
 
 public void update (Graphics g)
 {
    if (offscreen == null || offscreen.getWidth(this) != w 
        || offscreen.getHeight(this) != h)
    {
        offscreen = createImage (w, h );
    }
    Graphics g2 = offscreen.getGraphics();
    paint(g2);
    g.drawImage(offscreen, 0, 0, this);
 }//end of update method
 
 public void mouseReleased( MouseEvent e){;}
 public void mouseClicked( MouseEvent e){;}
 public void mouseEntered( MouseEvent e){;}
 public void mouseExited( MouseEvent e){;}
 
   public void start()
  {
     if( theThread == null ){theThread = new Thread( this );}
     theThread.start();
  }
             
  public void run()
  {
    while( true )
      {
        step();
        try
        {
          theThread.sleep( 100 );
        }
        catch( Exception e ) {;}

      }
  }//end of run method
             
  public void stop()
  {
    if( theThread != null && theThread.isAlive() )
    {
      theThread.stop();
    }
      theThread = null;
  }


} // end of class CaughtUp