// Mandelbrot and Julia Set Fractal Java Applet, 6/9/01

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

// Options: nx, ny, Julia: xc, yc
public class Mandelbrot extends Applet {
 Graphics graphics1;
 boolean julia;
 int nx, ny, imax=50, method=0, fcolor=0;
 double x0=-0.5, y0=0, dpi, power=2, xc=0, yc=0;

 // Initial Layout
 TextField tf1,tf2,tf3,tf4,tf5,tf6,tf7;
 Choice choice1 = new Choice(), choice2 = new Choice(), choice3 = new Choice();
 Button button1 = new Button("Generate Image");
 public TextField editbox(String str, double value, int x, int y, int w) { // use template, overloading
  Label label = new Label(str+":");
  label.setBounds(x,y,w,25);
  add(label);
  TextField tf = new TextField(20);
  tf.setBounds(x+w,y,102-w,25);
  tf.setText(String.valueOf(value));
  add(tf); return tf;
 }
 public void init() {
  setLayout(null);
  nx=size().width-20; ny=size().height-160; dpi=nx/3;
  setSize(nx+20,ny+160); // resize?

  choice1.addItem("Mandelbrot Set");
  choice1.addItem("Julia Set");
  choice1.select(0);
  choice1.setBounds(10,ny+20,102,25);
  add(choice1);
  tf4=editbox("xc",xc,122,ny+20,20);
  tf5=editbox("yc",yc,228,ny+20,20);

  tf1=editbox("dpi",dpi,10,ny+55,50); // max dpi: x=8.93E15, y=1.79E16
  tf6=editbox("x0",x0,122,ny+55,20);
  tf7=editbox("y0",y0,228,ny+55,20);

  tf2=editbox("max iterations",0.0,10,ny+90,72);
  tf2.setText(String.valueOf(imax));
  choice2.addItem("iterations");
  choice2.addItem("magnitude");
  choice2.addItem("real");
  choice2.addItem("imaginary");
  choice2.setBounds(122,ny+90,102,25);
  add(choice2);
  choice3.addItem("red");
  choice3.addItem("green");
  choice3.addItem("blue");
  choice3.addItem("yellow");
  choice3.addItem("cyan");
  choice3.addItem("magenta");
  choice3.addItem("white"); // rainbow
  choice3.setBounds(228,ny+90,102,25);
  add(choice3);

  tf3=editbox("power",power,10,ny+125,50);
  button1.setBounds(228,ny+125,102,25);
  add(button1);
//generate(); // doesn't work
 }

 // Input Actions
 public boolean action(Event event1, Object object1) {
  if (event1.target==button1) {
   String str;
   str=tf1.getText(); if (str!=null&&str.length()!=0) dpi=Double.valueOf(str).doubleValue();
   str=tf2.getText(); if (str!=null&&str.length()!=0) imax=Integer.parseInt(str);
   str=tf3.getText(); if (str!=null&&str.length()!=0) power=Double.valueOf(str).doubleValue();
   str=tf4.getText(); if (str!=null&&str.length()!=0) xc=Double.valueOf(str).doubleValue();
   str=tf5.getText(); if (str!=null&&str.length()!=0) yc=Double.valueOf(str).doubleValue();
   str=tf6.getText(); if (str!=null&&str.length()!=0) x0=Double.valueOf(str).doubleValue();
   str=tf7.getText(); if (str!=null&&str.length()!=0) y0=Double.valueOf(str).doubleValue();
   generate();
  }
  else if (event1.target==choice1) julia=(choice1.getSelectedIndex()==1);
  else if (event1.target==choice2) method=choice2.getSelectedIndex();
  else if (event1.target==choice3) fcolor=choice3.getSelectedIndex();
  return true;
 }
 public boolean mouseUp(Event event1, int x, int y) {
  x-=10; y-=10;
  tf6.setText(String.valueOf(x0+(x-0.5*nx)/dpi));
  tf7.setText(String.valueOf(y0-(y-0.5*ny)/dpi));
  graphics1=getGraphics();
  pixel(x,y,255,255,255);
  return true;
 }

 // Calculations
 public double sinh(double x) {double t1=Math.exp(x); return (t1-1.0/t1)/2.0;}
 public double cosh(double x) {double t1=Math.exp(x); return (t1+1.0/t1)/2.0;}

 // Generate Image
 public void pixel(int x, int y, int r, int g, int b) {
  Color color1 = new Color(r,g,b);
  graphics1.setColor(color1);
  graphics1.fillRect(x+10,y+10,1,1);
 }
 public void generate() {
  graphics1=getGraphics();
  graphics1.setColor(Color.black); // clear previous image
  graphics1.fillRect(10,10,nx,ny);
  boolean unbounded;
  int c1,c2,r=0,g=0,b=0, i, n=(int)power/2-((power%2!=0)?1:0);
  double x=0, y=0, dx=1/dpi, x1=x0-0.5*nx/dpi, x2=x0+0.5*nx/dpi, y1=y0-ny*dx/2, y2=y0+ny*dx/2;
  double t1=Math.max(Math.abs(x1),Math.abs(x2)), t2=Math.max(Math.abs(y1),Math.abs(y2)), zm=Math.sqrt(t1*t1+t2*t2);
  for (int iy=0; iy<=ny; ++iy) {
   if (!julia) yc=y2-iy*dx;
   for (int ix=0; ix<=nx; ++ix) {
    if (julia) {x=x1+ix*dx; y=y2-iy*dx;} else {xc=x1+ix*dx; x=0; y=0;}
    unbounded=false;
    for (i=0; (i<imax)&&(!unbounded); ++i) {
     if (power>=2&&power<=25&&power%1==0) { // faster logic
      for (int j=0; j<n; ++j) {t1=x*x-y*y; y=2*x*y; x=t1;}; // z^2
      if (power%2!=0) {t1=x*(x*x-3*y*y); y=y*(3*x*x-y*y); x=t1;} // z^3
     }
     else {t1=Math.atan2(y,x); t2=Math.pow(x*x+y*y,power/2.0); x=t2*Math.cos(power*t1); y=t2*Math.sin(power*t1);} // z^n
//   t1=x*x+y*y; x=x/t1; y=-y/t1; // z^-1
//   t1=Math.atan(y/x); t2=Math.pow(x*x+y*y,0.25); x=t2*Math.cos(t1/2); y=t2*Math.sin(t1/2); // sqrt(z)
//   t1=Math.sin(x)*cosh(y); y=Math.cos(x)*sinh(y); x=t1; // sin(z)
//   t1=Math.cos(x)*cosh(y); y=-Math.sin(x)*sinh(y); t1=x; // cos(z)
//   t1=Math.cos(2*x)+cosh(2*y); x=Math.sin(2*x)/t1; y=sinh(2*y)/t1; // tan(z)
//   t1=Math.exp(x); x=t1*Math.cos(y); y=t1*Math.sin(y); // e^z
//   t1=Math.log(x*x+y*y)/2; y=Math.atan(y/x); x=t1; // ln(z)
     x+=xc; y+=yc;
     if (x*x+y*y>=4.0) unbounded=true;
    }
    if (unbounded) {
     if (method==0) t1=1.0*i/imax; // iterations
     else if (method==1) t1=Math.min(1,Math.sqrt(x*x+y*y)/zm); // magnitude
     else t1=Math.min(1,Math.abs((method==2)?x:y)/zm); // recenter: don't use abs
     if (fcolor==6) {r=(int)(255*t1); g=r; b=r;}
     else {
      c1=(int)Math.min(255*2*t1,255); c2=(int)Math.max(255*(2*t1-1),0);
      switch(fcolor) {
       case 0: r=c1; g=c2; b=c2; break; // red
       case 1: r=c2; g=c1; b=c2; break; // green
       case 2: r=c2; g=c2; b=c1; break; // blue
       case 3: r=c1; g=c1; b=c2; break; // yellow
       case 4: r=c2; g=c1; b=c1; break; // cyan
       case 5: r=c1; g=c2; b=c1; break; // magenta
      }
     }
     pixel(ix,iy,r,g,b);
    }
   }
  }

  // Label Drawing
  graphics1.setColor(Color.white);
  graphics1.setFont(new Font("Serif", Font.BOLD, 12));
  int sc=9, sc2=9*5/3, ytxt=ny+10-5+sc2;
  if (nx<=1.0*dpi) graphics1.drawString(""+dpi+" dpi, Origin: "+x0+"+"+y0+"i", 15, ytxt-=sc2);
  graphics1.drawString("Max iterations: "+imax, 15, ytxt-=sc2);
  if (julia) graphics1.drawString("Julia Set: z^"+power+"+"+xc+"+"+yc+"i", 15, ytxt-=sc2);
  else graphics1.drawString("Mandelbrot Set: z^"+power+"+zc", 15, ytxt-=sc2);
 }
}