import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.applet.*;
import java.awt.image.BufferedImage;

class PlochaF extends JComponent implements MouseListener, MouseMotionListener {
    double x1=-2.0, y1=-2.0, x2=2.0, y2=2.0;     //okno pohľadu
    double cx, cy;                               //konštanty pre Juliovu množinu
    int pX,pY,curX,curY;                         //súradnice stlačenia
    static int sizeX=40,sizeY=40;                //rozmery okna
    int typ = 1;
    BufferedImage bi=null;                        //zapamätaný obrázok
    boolean changed;                              //či treba prepočítať
    
    PlochaF() {
        changed = true;
        addMouseMotionListener(this);
        addMouseListener(this);
    }
    
    public void paint(Graphics g) {
        if(changed) {
            sizeX = this.getWidth();
            sizeY = this.getHeight();
            if(bi==null) bi = new BufferedImage(sizeX,sizeY,BufferedImage.TYPE_INT_RGB);
            double x=x1, y;
            double dx=(x2-x1)/sizeX;
            double dy=(y2-y1)/sizeY;

            for(int xc=0;xc<sizeX;xc++) {
                y=y1;
                for(int yc=0;yc<sizeY;yc++) {
                    bi.setRGB(xc,yc,fract(x,y,cx,cy).getRGB());
                    y=y+dy;
                }
                x=x+dx;
            }
            changed = false;
        }
        g.drawImage((Image) bi, 0, 0, this);
        g.drawRect(pX,pY,curX-pX,curY-pY);
    }

    int col(int c,int m,int n) {                  //farebná škála
        long col = Math.round(200*Math.exp(-0.001*(c-m)*(c-m))
                             + 200*Math.exp(-0.001*(c-n)*(c-n)));
        if(col>255) col=255;                       //hodnoty r,g,b sú 0..255
        if(col<0) col = 0;
        return (int) col;
    }

    Color fract(double x1,double y1,double cx,double cy) {
        double x0;
        
        if(typ==1) {
          //pre Mandelbrotov fraktal
          cx = x1; cy = y1; x1 = 0.0; y1 = 0.0; x0 = 0.0;
        } else {
          //pre Juliovu mnozinu
          x0 = x1; x1 = x0; y1 = y1;
        }
        
        int d;
        for(d=0;d<201;d++) {                     //max. 200 iterácií
            x1=x1*x1-y1*y1+cx;                   //výpočet nového z
            y1=2*x0*y1+cy;
            if(x1*x1+y1*y1>4) break;
            x0=x1;
        }
        return new Color(col(d,20,180),col(d,60,120),col(d,150,140));
    }

    //odpovede na klikanie myšou
    public void mouseExited(MouseEvent e) {}
        
    public void mouseEntered(MouseEvent e) {}

    public void mouseReleased(MouseEvent e) {
        int rX = e.getX();
        int rY = e.getY();
        if((rX-pX>2)&&(rY-pY>2)) {
            if(rX-pX>rY-pY) rY = pY + rX - pX; //aby pohľad bol štvorcový
            if(rY-pY>rX-pX) rX = pX + rY - pY;
            double xs=x1, ys=y1;
            x1=x1+pX*(x2-x1)/sizeX;             //nové okno pohľadu
            y1=y1+pY*(y2-y1)/sizeY;
            x2=xs+rX*(x2-xs)/sizeX;
            y2=ys+rY*(y2-ys)/sizeY;
            pX = 0;
            pY = 0;
            curX = 0;
            curY = 0;
            changed = true;
            repaint();
        }
    }

    public void mousePressed(MouseEvent e) {
        pX = e.getX();
        pY = e.getY();
        }

    public void mouseClicked(MouseEvent e) {
        if(e.getButton()==MouseEvent.BUTTON1) {
            double xs=x1, ys=y1;
            x1=x1-(x2-x1)/2;                   //zoom out
            y1=y1-(y2-y1)/2;
            x2=x2+(x2-xs)/2;
            y2=y2+(y2-ys)/2;
            changed = true;
            repaint();
        }
    }

    //nutné pre MouseMotionListener:

    public void mouseMoved(MouseEvent e) {}
 
    public void mouseDragged(MouseEvent e) { //vyznačovanie okna
        curX = e.getX();
        curY = e.getY();
        repaint();
    }

}   //koniec triedy PlochaF

public class Fractal extends JApplet implements ActionListener {
    protected JButton tlacitko;
    protected JButton tlacitko2;
    protected PlochaF plocha;

    public void init() {
        plocha = new PlochaF();
        plocha.setBounds(0,50,400,400);

        tlacitko = new JButton("Julia");
        tlacitko.setBounds(10,10,110,30);
        tlacitko.addActionListener(this);

        setLayout(null);
        add(tlacitko);
        add(plocha);        
    }

    public void actionPerformed(ActionEvent e) {
        if(e.getActionCommand().equals("Julia")) {    //Juliova mnozina
            tlacitko.setText("Mandelbrot");
            plocha.cx = (plocha.x1 + plocha.x2)/2;
            plocha.cy = (plocha.y1 + plocha.y2)/2;
            plocha.x1 = -2; plocha.x2 = 2; plocha.y1 = -2; plocha.y2 = 2;
            plocha.typ = 2;
            plocha.changed = true;
            plocha.repaint();
        }
        if(e.getActionCommand().equals("Mandelbrot")) { //Mandelbrotova mnozina
            tlacitko.setText("Julia");
            plocha.x1 = -2; plocha.x2 = 2; plocha.y1 = -2; plocha.y2 = 2;
            plocha.typ = 1;
            plocha.changed = true;
            plocha.repaint();
        }
    }
}