// Henon attractor,  Evgeny Demidov,  27 June 2004

import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import java.util.StringTokenizer;

public class @file extends java.applet.Applet implements MouseListener,
   MouseMotionListener{
double Ymid, Xmid, DelX=3., A=-1,B=0, Xo=0,Yo=0;
int MaxIt = 1000, N=0,  w,h,w2,h2,  pixArr[];
boolean showXY = true;
long generTime;
Image img;             IndexColorModel iColor;
TextField tfXY;

public void init() {
  String s=getParameter("XYmidDel"); if (s != null) {
    StringTokenizer st = new StringTokenizer(s);
    Xmid = Double.valueOf(st.nextToken()).doubleValue();
    Ymid = Double.valueOf(st.nextToken()).doubleValue();
    DelX = Double.valueOf(st.nextToken()).doubleValue();
    A = Double.valueOf(st.nextToken()).doubleValue();
    B = Double.valueOf(st.nextToken()).doubleValue();}
  s=getParameter("MaxIt"); if (s != null) MaxIt=Integer.parseInt(s);
  s=getParameter("N"); if (s != null) N=Integer.parseInt(s);
  byte rColor[] = new byte[2], bColor[] = new byte[2],
       gColor[] = new byte[2];
  rColor[0] = gColor[0] = bColor[0] = (byte)255;
  rColor[1] = gColor[1] = bColor[1] = 0;
  iColor = new IndexColorModel( 8, 2, rColor,gColor,bColor);
  w = getSize().width;   h = getSize().height;
  s=getParameter("showXY");
  if ( (s != null) && (s.equalsIgnoreCase("N")) ) showXY = false;
  else{
    setLayout(new BorderLayout());
    tfXY = new TextField( ""+Xmid+", "+Ymid+"; "+(float)DelX );
    add("South",  tfXY);
    h -= tfXY.getPreferredSize().height;}
  h2 = h/2;  w2 = w/2;
  pixArr = new int[w*h];
  addMouseListener(this);
  addMouseMotionListener(this);
  Draw();
}

public void destroy() {
  removeMouseListener(this); 
  removeMouseMotionListener(this); }
public void mouseClicked(MouseEvent e) {}      //1.1 event handling
public void mousePressed(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent  e) {}

public void mouseReleased(MouseEvent e) {
  Xmid = Xmid+(e.getX()-w/2)*DelX/w;
  Ymid = Ymid-(e.getY()-h/2)*DelX/w;
  if ( e.isControlDown() ) {
    if ( e.isShiftDown() )  DelX *=4.;  else  DelX *=2.;}
  else {
    if ( e.isShiftDown() )  DelX /=4.;  else  DelX /=2.;}
  if (showXY)
    tfXY.setText( ""+(float)Xmid+", "+(float)Ymid+"; "+(float)DelX);
  Draw();
  repaint();
}
public void mouseMoved(MouseEvent e){}  //1.1 event handling
public void mouseDragged(MouseEvent e) {}

public void paint(Graphics g) {
  g.drawImage(img, 0, 0, this);
  drawLabel(g);
  showStatus( "T=" + generTime + " msec");
}

public void drawLabel(Graphics gra) {
 double  StZ=DelX/w;
 gra.setColor(Color.blue);
 int ix,iy;
 String s=getParameter("sqrRID"); if (s != null) {
   StringTokenizer st = new StringTokenizer(s);
   double sqrRmid = Double.valueOf(st.nextToken()).doubleValue(),
   sqrImid = Double.valueOf(st.nextToken()).doubleValue();
   int sqr = (int)(Double.valueOf(st.nextToken()).doubleValue()/StZ);
   if (sqr < 3000){
     ix = (w - sqr)/2 + (int)((sqrRmid-Xmid)/StZ);
     iy = (h - sqr)/2 + (int)((Ymid - sqrImid) /StZ);
     gra.drawRect(ix,iy, sqr,sqr);}}
 gra.setColor(Color.black);
 gra.setFont(
   new Font( gra.getFont().getName(), Font.BOLD, 15 ) );
 int maxLabel=0;
 while (true) {
   s=getParameter("lb"+maxLabel);
   if (s == null) break;
   StringTokenizer st = new StringTokenizer(s);
   double x=(Double.valueOf(st.nextToken()).doubleValue()-Xmid)/StZ,
   y=(Ymid-Double.valueOf(st.nextToken()).doubleValue())/StZ;
   if ( (Math.abs(x)<w)&&(Math.abs(y)<h) ){
     ix = w/2+(int)x;  iy = h/2+(int)y;
     gra.drawString(st.nextToken(), ix,iy);}
   maxLabel++; }
}

public void Draw(){
  for (int it=0; it < w*h; it++) pixArr[it] = 0;
  double X=Xo, X2=X*X, X1, Y=Yo, St = DelX/w;
  int ix,iy;
  generTime = System.currentTimeMillis();
  for (int it=0; it <= MaxIt; it++){
    X1 = A + X2 + B*Y;  Y = X;  X = X1;  X2 = X*X;
    ix = (int)((X - Xmid)/St) + w2;
    iy = -(int)((Y - Ymid)/St) + h2;
//System.out.println(""+X +"  "+Y+"  "+it);
    if ((ix >= 0)&&(ix < w)&&(iy >= 0)&&(iy < h)) pixArr[ix+iy*w] = 1;
  }
  img = createImage(new MemoryImageSource(w, h, iColor, pixArr, 0, w));
  generTime = System.currentTimeMillis()-generTime;
}

}