import java.awt.*;
import java.applet.*;
/*Modified by
  Carlos E. Yaguna
  Dept. Fisica
  Universidad de Antioquia
  Medellin-COLOMBIA */
public class Dla2 extends Applet{

 private Dla2Canva theCanvas;
 private Button b1,b2,b3,b4,b5,b6;
 private Panel p1,p2,p3,p4;
 private Scrollbar s1,s2;
 private TextField t1,t2;

 public void init()
 {
  theCanvas=new Dla2Canva();
  theCanvas.resize(300,300);
  theCanvas.setBackground(Color.black);
  s1=new Scrollbar(Scrollbar.VERTICAL,20,0,0,100);
  s2=new Scrollbar(Scrollbar.HORIZONTAL,10,0,0,38);
  t1=new TextField("  Num = 4");
  t1.setEditable(false);
  t2=new TextField(" m=1");
  t2.setEditable(false);
  b1=new Button(" Start ");
  b2=new Button(" Pause ");
  b3=new Button(" Stop ");
  b6=new Button(" Reset ");
  b4=new Button( "Num +");
  b5=new Button( "Num -");
  p1=new Panel();
  p2=new Panel();
  p3=new Panel();
  p4=new Panel();
  p1.setLayout(new GridLayout(6,1));
  p2.setLayout(new BorderLayout());
  p4.setLayout(new GridLayout(3,1));
  p3.setLayout(new BorderLayout());
  p1.add(b1);
  p1.add(b2);
  p1.add(b3);
  p1.add(b6);
  p4.add(b4);
  p4.add(b5);
  p4.add(t1);
  p3.add("North",p1);
  p3.add("South",p4);
  p2.add("Center",theCanvas);
  p2.add("East",p3);
  add("Center",p2);
  theCanvas.bb=0;
  theCanvas.jj=0;
  theCanvas.init();
  theCanvas.start();
 }

  public boolean handleEvent(Event e)
  {
    if(e.target instanceof Scrollbar){
     if(e.target==s1){

      }
    if(e.target==s2){

      }
    theCanvas.jj=1;
    theCanvas.repaint();
    return true;
    }
   return super.handleEvent(e);
  }

 public boolean action(Event e, Object o)
 {
  if(e.target instanceof Button){
  if(e.target==b1){theCanvas.bb=1;theCanvas.jj=1;}

  if(e.target==b2){theCanvas.bb=0;theCanvas.jj=0;}

  if(e.target==b3){theCanvas.bb=0;theCanvas.jj=0;theCanvas.Limpiar();theCanvas.Poner();}
  
  if(e.target==b6){theCanvas.bb=0;theCanvas.jj=0;theCanvas.pmax=1;
                     theCanvas.Limpiar();theCanvas.Poner();}

  if(e.target==b4){
  if(theCanvas.num<=20){theCanvas.num+=1;theCanvas.bb=0;theCanvas.jj=0;
   t1.setText("  Num = "+Integer.toString(theCanvas.num-1));}}

  if(e.target==b5){
  if(theCanvas.num>1){theCanvas.num-=1;theCanvas.bb=0;theCanvas.jj=0;
   t1.setText("  Num = "+Integer.toString(theCanvas.num-1));}}


  theCanvas.repaint();
  return true;
  }
 return true;
 }

 public boolean mouseDown(Event e,int x,int y){
   theCanvas.Mouse(x,y);
   theCanvas.repaint();
   //t2.setText(" num = "+Integer.toString(theCanvas.pmax));
   return true;
  }

}

class Dla2Canva extends Canvas implements Runnable {
  Thread runstring;
  private Image offScreenImage;
  int max,size,seed,jj,num;
  double PI;
  double mxx,myy,bxx,byy;
  int grid[][], hit,mem,bb,pmax,px[],py[];


 public void init()
 {
    int i,j;
    pmax=1;
    px=new int[10];
    py=new int[10];
    px[0]=150;
    py[0]=150;
    num=5;
    max= 40000;
    size= 101;                         /* size of grid array  */
    PI= 3.1415926535897932385;
    seed= 68111;                       /* seed for number generator */
    offScreenImage=createImage(size().width,size().height);
    grid=new int[size][size];
  offScreenImage=createImage(size().width,size().height);
    for(i=0; i<size; i++)                /* clear grid */
       for(j=0;j<size;j++) grid[i][j]=0;
 }

   public void start()
  {
    if(runstring==null);
    {
     runstring=new Thread(this);
     runstring.start();
    }
  }
  public void stop()
  {
     if(runstring != null){
       runstring.stop();
       runstring=null;
     }
  }
  public void run()
  {
    while(true){if(bb==1)
      repaint();
      try{ Thread.sleep(300);
      }
      catch(InterruptedException e){ }
    }
  }
public void update(Graphics g)
{ //To avoid flicker
    Graphics offScreenGraphics=offScreenImage.getGraphics();
    offScreenGraphics.setColor(getBackground());
    offScreenGraphics.fillRect(0,0,size().width,size().height);
    offScreenGraphics.setColor(g.getColor());
    paint(offScreenGraphics);
    g.drawImage(offScreenImage,0,0,this);
}
  void coormundo(double xiz,double ysu,double xde,double yinf)
  {
    double maxx,maxy,xxfin,xxcom,yyin,yysu;
    maxx=600;
    maxy=350;
    xxcom=0.15*maxx;
    xxfin=0.75*maxx;
    yyin=0.8*maxy;
    yysu=0.2*maxy;
    mxx=(xxfin-xxcom)/(xde-xiz);
    bxx=0.5*(xxcom+xxfin-mxx*(xiz+xde));
    myy=(yyin-yysu)/(yinf-ysu);
    byy=0.5*(yysu+yyin-myy*(yinf+ysu));
  }

  public int gauss_ran()
 {
    double fac, rr, r1, r2;
    int old=0;            /* have to be static so information */
    if (old==0)                  /* no random number left from */
    {                            /* previous function call */
      do
      {
        r1= 2.0*Math.random()-1.0;      /* choose random point in */
        r2= 2.0*Math.random()-1.0;      /* the unit circle */
        rr= r1*r1+r2*r2;
       }while ((rr>=1)||(rr==0));
     fac=Math.sqrt(-2*Math.log(rr)/rr);
     mem=(int)(5000*r1*fac);               /* save for next call */
     old=1;                         /* set flag */
     return((int)(5000*r2*fac));
   }
   else                              /* return second number */
   {				     /* from last call */
      old=0;			     /* unset flag */
      return mem;   		     /* return number from last call */
   }
 }


  public void Dlaplot(Graphics g,int jj)
 {
    double angle, rad;
    int i,j, x, y, dist, dir, step, trav;
    int xol,yol;
    rad=45.0;
    g.setColor(Color.blue);
    g.drawOval(60,60,180,180);
    /* if(jj==1){                             
      for(i=0; i<size; i++)                
      {
       for(j=0;j<size;j++) grid[i][j]=0;
      }
      grid[50][50] = 1;                  

    }*/
     grid[50][50] = 1; 
    g.setColor(Color.red);
    for(i=0;i<pmax;i++){
    g.drawOval(px[i],py[i],1,1);        //circle center
    }
    for(i=0;i<size;i++)             /*  print resulting grid  */
    {
      for(j=0; j<size; j++)
      {
         if(grid[i][j]==1) g.drawOval(2*i+50,2*j+50,1,1);
      }
   }

    if(jj==1||jj==10)for(i=1;i<num;i++)                 /* choose starting point  */
    {
      hit= 0;
      angle=(2*PI*Math.random());         /* random angle */
      x=(int)(50+rad*Math.cos(angle));     /* coordinates */
      y=(int)(50+rad*Math.sin(angle));
      xol=x;
      yol=y;
      dist = gauss_ran();       /* random number gaussian dist. */
      // if (dist<0) step=-1;      /* move forwards or backwards */
      // else step=1;    CHANGE THIS IN BOOK PROGRAM
      trav=0;
      g.setColor(Color.yellow);
      while((x<99)&&(x>1)&&(y<99)&&(y>1)&&(hit==0)&&(trav<Math.abs(dist)))
      {
         if(Math.random() <0.5)step=1;
         else step=-1;
         if(grid[x+1][y]+grid[x-1][y]+grid[x][y+1]+grid[x][y-1]>=1)
         {
            hit=1;               /* one neighbor is occupied */
            grid[x][y]=1;
            g.drawOval(2*x+50,2*y+50,1,1);        /* particle sticks, walk is over */
            //play(getCodeBase(),"9.au");
         }

         else if(Math.random() < 0.5) x+=step;      /* move horizontally */
         else y+=step;      /* move vertically */
         g.drawLine(2*xol+50,2*yol+50,2*x+50,2*y+50);
         xol=x;
         yol=y;
         trav++;

      }//while
      //play(getCodeBase(),"drip.au");
   }  //for i
   } //rutine

   public void Limpiar()
   {
    int i,j;
    for(i=0;i<size;i++)
     for(j=0;j<size;j++)grid[i][j]=0;
   }
   
   public void Poner()
   {
    int i,n,m;
    for(i=0;i<pmax;i++){
     n=(int)((px[i]-50)/2);
        m=(int)((py[i]-50)/2);
        grid[n][m]=1;
    } 
   }
   public void Mouse(int x,int y){
        int n,m; 
        if(pmax<9 && x>60 && x<240 && y>60 && y<240) {
        px[pmax]=x;py[pmax]=y;
        pmax+=1;
        n=(int)((x-50)/2);
        m=(int)((y-50)/2);
        grid[n][m]=1;
      }

   }
 public void paint(Graphics g){
   int i;
   Dlaplot(g,jj);
     if(bb==1) jj=10;
   g.setColor(Color.green);
   for(i=0;i<5;i++)
   g.drawRect(0+i,0+i,298-2*i,294-2*i);
 }


}//class