// Julia set dynamics,  Evgeny Demidov,  12 January 2006

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

public class @file extends java.applet.Applet implements KeyListener,
   MouseMotionListener{
double maxIZI2=10., Ymid=.0, Xmid=-.5, DelX=3.,  Cr,Ci, Xm=1, Ym=0, Rm=.1, Step;
int maxIt = 256, maxColor = 96, w, h, w2,h2,  ix,iy, ixo,iyo, ir,ir2,
  lbSize,   px[],py[], pxo[],pyo[],  pixArr[];
Image img;             IndexColorModel RainbowColor;
boolean   bXOR=false;
Label  lbZ, lbCr, lbCi, lbR, lbD;    TextField tfZ, tfCr, tfCi, tfR, tfD;

public void init() {
  String s=getParameter("XYmidDelCD"); 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();
    Cr = Double.valueOf(st.nextToken()).doubleValue();
    Ci = Double.valueOf(st.nextToken()).doubleValue();}
  s=getParameter("MaxIt"); if (s != null) maxIt=Integer.parseInt(s);
  s=getParameter("MaxIZI2");
  if (s != null) maxIZI2 = Double.valueOf(s).doubleValue();
  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+2], bColor[] = new byte[maxColor+2],
       gColor[] = new byte[maxColor+2];
  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+1] = gColor[maxColor+1] = bColor[maxColor+1] = (byte)200;
  RainbowColor = new IndexColorModel( 8, maxColor+2, rColor,gColor,bColor);
  s=getParameter("XYR"); if (s != null) {
    StringTokenizer st = new StringTokenizer(s);
    Xm = Double.valueOf(st.nextToken()).doubleValue();
    Ym = Double.valueOf(st.nextToken()).doubleValue();
    Rm = Double.valueOf(st.nextToken()).doubleValue();}
  this.setLayout( new FlowLayout(FlowLayout.LEFT, 0, 0) );
  lbZ = new Label("Z", Label.RIGHT);  add(lbZ);
  if (Ym < 0.) s = ""+Xm+" "+Ym+" i";  else s = ""+Xm+" +"+Ym+" i";
  tfZ = new TextField(s, 20);    add(tfZ);
  lbCr = new Label("Cr", Label.RIGHT);  add(lbCr);
  tfCr = new TextField(""+Cr, 8);    add(tfCr);
  lbCi = new Label("Ci", Label.RIGHT);  add(lbCi);
  tfCi = new TextField(""+Ci, 8);    add(tfCi);
  lbR = new Label("R", Label.RIGHT);  add(lbR);
  tfR = new TextField(""+Rm, 3);    add(tfR);
  lbD = new Label("dz", Label.RIGHT);  add(lbD);
  tfD = new TextField(""+DelX, 3);    add(tfD);
  tfCr.addKeyListener(this);  tfCi.addKeyListener(this);
  tfD.addKeyListener(this);   tfR.addKeyListener(this);
  w = getSize().width;   h = getSize().height;
  lbSize = tfZ.getPreferredSize().height;
  h -= lbSize;
  w2 = w/2;  h2 = h/2;
  Step=DelX/w;
  pixArr = new int[w*(h+2)];
  px = new int[9];  pxo = new int[9];  py = new int[9];  pyo = new int[9];
  addMouseMotionListener(this);
  Draw();
}

public void Draw(){
  Step=DelX/w;
  ix = ixo = w2 + (int)((Xm - Xmid)*w/DelX);
  iy = iyo = h2 - (int)((Ym - Ymid)*w/DelX);
  ir = (int)(Rm*w/DelX);   ir2 = 2*ir;
  Polygon();
  System.arraycopy(px,0,pxo,0,9);
  System.arraycopy(py,0,pyo,0,9);
  double X,Y;
  int pix=w, ix,iy;
  for (iy=0, Y=Ymid+Step*h2; iy < h; iy++, Y-=Step) {
   for (ix=0, X=Xmid-Step*(w2-1); ix < w; ix++, X+=Step, pix++) {
      pixArr[pix] =iterateDE(X,Y);
   }
  }
  img = createImage(new MemoryImageSource(w, h, RainbowColor, pixArr, w, w));
}

public void Polygon(){
  double R=Xm-Rm, I=Ym-Rm;  st(R, I, 0);
  R=Xm;     st(R,I,1);
  R=Xm+Rm;  st(R,I,2);
  I=Ym;     st(R,I,3);
  I=Ym+Rm;  st(R,I,4);
  R=Xm;     st(R,I,5);
  R=Xm-Rm;  st(R,I,6);
  I=Ym;     st(R,I,7);
  px[8]=px[0]; py[8]=py[0];
}

public void st(double R, double I, int k){
  px[k] = w2 + (int)((R*R-I*I+Cr - Xmid)*w/DelX);
  py[k] = h2 - (int)((2*R*I+Ci - Ymid)*w/DelX) + lbSize;
}

public void destroy(){ removeMouseMotionListener(this); }
public void mouseMoved(MouseEvent e){}  //1.1 event handling

public void mouseDragged(MouseEvent e) {
  ix = e.getX(); iy = e.getY() - lbSize;
  Xm = Xmid+(ix-w2)*Step;  Ym = Ymid-(iy-h2)*Step;
    if (Ym < 0.) tfZ.setText( ""+(float)Xm+" "+(float)Ym+" i");
       else  tfZ.setText( ""+(float)Xm+" +"+(float)Ym+" i");
  Polygon();
  bXOR = true;
  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{
      Cr = Double.valueOf(tfCr.getText()).doubleValue();
      Ci = Double.valueOf(tfCi.getText()).doubleValue();
      Rm = Double.valueOf(tfR.getText()).doubleValue();
      DelX = Double.valueOf(tfD.getText()).doubleValue();
    }catch(NumberFormatException ne){}
    Draw();
    repaint();
  }
}

public void update(Graphics g){ paint(g); }

public void paint(Graphics g) {
  if(!bXOR){
   g.drawImage(img, 0, lbSize, this);
   drawLabel(g);
   int r = (int)(w/DelX);
   g.setColor(Color.white);
   g.drawOval(w2-r,h2-r+lbSize,r+r,r+r);
   g.drawLine(w2-5,h2+lbSize, w2+5,h2+lbSize);
   g.drawLine(w2,h2-5+lbSize, w2,h2+5+lbSize);
   g.setXORMode(Color.black);
   g.fillPolygon(px,py,9);
   g.drawRect(ix-ir,iy-ir+lbSize,ir2,ir2);
   g.setPaintMode();}
  else{
   g.setXORMode(Color.black);
   g.setColor(Color.white);
   g.fillPolygon(pxo,pyo,9);
   g.drawRect(ixo-ir,iyo-ir+lbSize,ir2,ir2);
   System.arraycopy(px,0,pxo,0,9);   System.arraycopy(py,0,pyo,0,9);
   ixo = ix; iyo = iy;
   g.fillPolygon(px,py,9);
   g.drawRect(ix-ir,iy-ir+lbSize,ir2,ir2);
   g.setPaintMode();
   bXOR=false;}
//   showStatus( "Cr="+Cr+"  Ci="+Ci);
}

public void drawLabel(Graphics gra) {
 double  R=0.,I=0.;
 gra.setColor(Color.white);
 int x,y;
 gra.setFont(
   new Font( gra.getFont().getName(), Font.BOLD, 15 ) );
 int maxLabel=0;
 while (true) {
   String s=getParameter("lb"+maxLabel);
   if (s == null) break;
   StringTokenizer st = new StringTokenizer(s);
   x=w2+(int)((Double.valueOf(st.nextToken()).doubleValue()-Xmid)/Step);
   y=h2+(int)((Ymid-Double.valueOf(st.nextToken()).doubleValue())/Step);
   gra.drawString(st.nextToken(), x,y);
   maxLabel++; }
}

int iterateDE(double X, double Y){
    double I=Y, R=X,  I2=I*I, R2=R*R, Dr=.7,Di=.7,D, K=5;   int n=0;
    do  {
      D = (R*Dr - I*Di);  Di = (R*Di + I*Dr);  Dr = D;
      I=(R+R)*I+Ci;  R=R2-I2+Cr;  R2=R*R;  I2=I*I;  n++;
    } while ((R2+I2 < 100.) && (n < maxIt) );
    if (n == maxIt) return maxColor;
    else{
     R = -K*(Math.log(Math.log(R2+I2)*Math.sqrt((R2+I2)/(Dr*Dr+Di*Di)))-n*.693);
     if (R < 0) R=0;
     return (int)R % maxColor; };
}

}