// Henon Mixing,  Evgeny Demidov,  25 June 2007

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

public class @file extends java.applet.Applet implements MouseListener,
  KeyListener, ActionListener {
double Yc=.0, Xc=.0, dx=4, dy=dx, R=.3,  a=-1.5, b=.5;
int maxColor=96, N=1, w, h, w2, h2,  pixArr[];
Image img;             IndexColorModel RainbowColor;
Label     lbA, lbB, lbN;
TextField tfXY, tfA, tfB, tfN;
Button    btPl, btMn;

public void init() {
  String s=getParameter("XYmidDelCD"); if (s != null) {
    StringTokenizer st = new StringTokenizer(s);
    Xc = Double.valueOf(st.nextToken()).doubleValue();
    Yc = Double.valueOf(st.nextToken()).doubleValue();
    dx = Double.valueOf(st.nextToken()).doubleValue();
    dy = Double.valueOf(st.nextToken()).doubleValue();}
  s=getParameter("ab"); if (s != null) {
    StringTokenizer st = new StringTokenizer(s);
    a = Double.valueOf(st.nextToken()).doubleValue();
    b = Double.valueOf(st.nextToken()).doubleValue();}
  s=getParameter("R"); if (s != null) R = Double.valueOf(s).doubleValue();
  s=getParameter("N"); if (s != null) N=Integer.parseInt(s);
  s=getParameter("MaxColor"); if (s != null) maxColor=Integer.parseInt(s);
  int M=maxColor/3,  M2=2*M;  maxColor = 3*M;     // maxColor is 3*int
  long M4 = (long)M*M*M*M;
  byte rColor[] = new byte[maxColor+1], bColor[] = new byte[maxColor+1],
       gColor[] = new byte[maxColor+1];
  for (int i = 1; i < M2; i++){                   // set Color Map
    long dum = M - i;  dum *=dum;  dum *=dum;
    gColor[i] =  bColor[(i+M) % maxColor] = rColor[(i+M2) % maxColor] =
        (byte)(255 - (255*dum)/M4);}
  rColor[maxColor] = gColor[maxColor] = bColor[maxColor] = (byte)255;
  RainbowColor = new IndexColorModel( 8, maxColor+1, rColor,gColor,bColor);
  w = getSize().width;   h = getSize().height;
  w2 = w/2;  h2 = h/2;
  pixArr = new int[w*h];
  this.setLayout( new FlowLayout(FlowLayout.LEFT, 0, 0) );
  tfXY = new TextField( ""+(float)Xc+" "+(float)Yc+"; "+(float)dx+
    " "+(float)dy, 25);   add(tfXY);
  lbA = new Label("A", Label.RIGHT); add(lbA);
  tfA = new TextField( "" + a, 3);   add(tfA);
  tfA.addKeyListener(this);
  lbB = new Label("B", Label.RIGHT); add(lbB);
  tfB = new TextField( "" + b, 3);   add(tfB);
  tfB.addKeyListener(this);
  lbN = new Label("N", Label.RIGHT); add(lbN);
  tfN = new TextField( "" + N, 2);   add(tfN);
  tfN.addKeyListener(this);
  btPl = new Button("+"); btPl.addActionListener(this); add(btPl);
  btMn = new Button("-"); btMn.addActionListener(this); add(btMn);
  Draw();
  addMouseListener(this);
}

public void destroy() {  removeMouseListener(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) {
  Xc = Xc+(e.getX()-w2)*dx/w;
  Yc = Yc-(e.getY()-h2)*dx/w;
  if (e.isControlDown()){
    dy *= 2.; if (!e.isShiftDown()) dx *= 2.;}
  else {
    dy /= 2.; if (!e.isShiftDown()) dx /= 2.;}
  tfXY.setText( ""+(float)Xc+" "+(float)Yc+"; "+(float)dx+" "+(float)dy);
  Draw();
  repaint();
}
public void actionPerformed(ActionEvent e){
  if ( e.getActionCommand().equals("+") ) N++;
    else N--;
  tfN.setText(""+N);
  Draw();
  repaint();
}
public void keyTyped(KeyEvent e) {}
public void keyPressed(KeyEvent e) {}
public void keyReleased(KeyEvent e) {
  final int keyEnter = 10;
  if (e.getKeyCode() == keyEnter) {
    try{
      a = Double.valueOf(tfA.getText()).doubleValue();
      b = Double.valueOf(tfB.getText()).doubleValue();
      N = Integer.parseInt(tfN.getText());
      Draw();
      repaint();
    }catch ( NumberFormatException ne) {}
  }
  e.consume();
}

public void paint(Graphics g) {
  g.drawImage(img, 0, 0, this);
  double X, b1 = (1-b)*.5, d=b1*b1-a;
  if (d > 0){
    g.setColor(Color.white);
    X = b1 - Math.sqrt(d);
    int ix = w2 + (int)((X - Xc)*w/dx);
    int iy = h2 - (int)((X - Yc)*h/dy);
    g.drawLine(ix-3,iy, ix+3,iy); g.drawLine(ix,iy-3, ix,iy+3);
    X = b1 + Math.sqrt(d);
    ix = w2 + (int)((X - Xc)*w/dx);
    iy = h2 - (int)((X - Yc)*h/dy);
    g.drawLine(ix-3,iy, ix+3,iy); g.drawLine(ix,iy-3, ix,iy+3);}
}

public void Draw(){
  for (int p = h*w; p > 0;) pixArr[--p] = maxColor;
  int pix, ix,iy;
  pix = 0;
  double X,Y, Xo,Yo, t;
  for (iy=0; iy < h; iy++) {
   Yo = Yc + (h2-iy)*dy/h;
   for (ix=0; ix < w; ix++){
    Xo = X = Xc + (ix-w2)*dx/w;  Y = Yo;
    if (N >=0){
     for(int i=N; i>0; i--){
       t = (X-Y*Y-a)/b;
       X = Y;  Y = t; }}
    else{
     for(int i=-N; i>0; i--){
       t = a + X*X +b*Y;
       Y = X;   X = t; }}
    if((Math.abs(Xo) < R)&&(Math.abs(Yo) < R))
       pixArr[pix] = (int)(maxColor*0.35*(Xo/R+1.));
    if((Math.abs(X) < R)&&(Math.abs(Y) < R))
       pixArr[pix] = (int)(maxColor*0.35*(X/R+1.));
    pix++;}
  }
//System.out.println(""+Xc +"  "+Yc);
  img = createImage(new MemoryImageSource(w, h, RainbowColor, pixArr, 0, w));
}

}