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

public class Mandelbrot extends Applet 
implements Runnable,MouseListener,MouseMotionListener {
    static double RAD=6;
    
    int width,height,length;
    int[] pixels;
    MemoryImageSource mit;
    Image image;
    double[] z_re,z_im;
    double min_re,max_re;
    double min_im,max_im;
    double red_re,green_re,blue_re;
    double red_im,green_im,blue_im;
    int last_x,last_y;
    int dx,dy;
    boolean running;
    
    public void init() {
        width=getSize().width;
        height=getSize().height;
        length=width*height;
        pixels=new int[length];
        mit=new MemoryImageSource(width,height,pixels,0,width);
        mit.setAnimated(true);
        image=getToolkit().createImage(mit);
        z_re=new double[length];
        z_im=new double[length];
        addMouseListener(this);
        addMouseMotionListener(this);
        reset();
    }
    
    void reset() {
        min_re=-2.0;
        max_re=2.0;
        min_im=-2.0*height/width;
        max_im=2.0*height/width;
        red_re=Math.random()*RAD;
        green_re=Math.random()*RAD;
        blue_re=Math.random()*RAD;
        red_im=Math.random()*RAD;
        green_im=Math.random()*RAD;
        blue_im=Math.random()*RAD;
    }
    
    public void start() {
        if (!running) {
            running=true;
            new Thread(this,"Plotter").start();
        }
    }
    
    public void stop() {
        running=false;
    }
    
    public void mousePressed(MouseEvent e) {
        running=false;
        last_x=e.getX();
        last_y=e.getY();
    }
    
    public void mouseReleased(MouseEvent e) {
        if (dx==0 && dy==0) {
            double range_re=max_re-min_re;
            double range_im=max_im-min_im;
            double center_re=min_re+range_re*e.getX()/width;
            double center_im=min_im+range_im*e.getY()/height;
            max_re=center_re+range_re/4;
            min_re=center_re-range_re/4;
            max_im=center_im+range_im/4;
            min_im=center_im-range_im/4;
        } else {
            double d_re=(max_re-min_re)*dx/width;
            double d_im=(max_im-min_im)*dy/height;
            max_re-=d_re;
            min_re-=d_re;
            max_im-=d_im;
            min_im-=d_im;
            dx=dy=0;
        }
        running=false;
        synchronized (this) {
            for (int i=0;i<length;i++) z_re[i]=z_im[i]=0;
            start();
        }
    }
    
    public void mouseClicked(MouseEvent e) {
        if (e.getClickCount()==2) {
            running=false;
            synchronized(this) {
                reset();
                for (int i=0;i<length;i++) z_re[i]=z_im[i]=0;
                start();
            }
        }
    }
    
    public void mouseExited(MouseEvent e) {}
    
    public void mouseEntered(MouseEvent e) {}

    public void mouseDragged(MouseEvent e) {
        dx+=e.getX()-last_x;
        dy+=e.getY()-last_y;
        last_x=e.getX();
        last_y=e.getY();
        repaint();
    }
    
    public void mouseMoved(MouseEvent e) {}
    
    public synchronized void run() {
        int x,y,i;
        double c_re,c_im;
        double d_re=(max_re-min_re)/width;
        double d_im=(max_im-min_im)/height;
        int T=30;
        while (running) {
            for (c_im=min_im,y=0,i=0;y<height && running;c_im+=d_im,y++) 
                for (c_re=min_re,x=0;x<width;c_re+=d_re,x++,i++) {
                    double z_re=this.z_re[i],z_im=this.z_im[i];
                    for (int t=0;t<T;t++) {
                        double z2_re=z_re*z_re-z_im*z_im;
                        double z2_im=2*z_re*z_im;
                        z_re=z2_re+c_re;
                        z_im=z2_im+c_im;
                    }
                    int red=(int)((red_re*z_re+red_im*z_im)*128)+128;
                    int green=(int)((green_re*z_re+green_im*z_im)*128)+128;
                    int blue=(int)((blue_re*z_re+blue_im*z_im)*64)+128;
                    if (red<0) red=0; else if (red>255) red=255;
                    if (green<0) green=0; else if (green>255) green=255;
                    if (blue<0) blue=0; else if (blue>255) blue=255;
                    pixels[i]=0xff000000|red<<16|green<<8|blue;
                    this.z_re[i]=z_re;
                    this.z_im[i]=z_im;
                }
            mit.newPixels();
            if (T<1000) T+=10;
        }
    }
    
    public void update(Graphics g) {
        paint(g);
    }
    
    public void paint(Graphics g) {
        g.drawImage(image,dx,dy,this);
        g.setColor(Color.gray);
        g.fillRect(0,0,dx,height);
        g.fillRect(width+dx,0,width,height);
        g.fillRect(0,0,width,dy);
        g.fillRect(0,height+dy,width,height);
    }
}