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

public class Fraktal_Applet extends Applet {
    
    final    int ITERATIONEN = 10000;
    final    double FAKTOR   = 5;
    final    double OFFSET_X = 200;
    final    double OFFSET_Y = 380;
    final    int    BREITE   = 400;

    private  double faktor   = FAKTOR;
    private  double offset_x = OFFSET_X;
    private  double offset_y = OFFSET_Y;
    private  int    delta    = BREITE;
    int iterationen;
    
    private  int start_x;
    private  int ende_x; 
    private  int start_y;
    private  int ende_y;
    int dev_x, dev_y;
    boolean neues_fenster;

    private  int regel_system = 0;
    private Graphics g;
    private Rectangle r;
    Punkt p = new Punkt ();

    private Color current_color = Color.black;
    private Button clear_button;
    private Button start_button;
    private Choice regel_choices;
   
    void reset_graphics(){
        g = this.getGraphics();
        r = this.bounds();
        g.setColor(Color.black);
        g.fillRect(r.x, r.y, r.width, r.height);
        g.setColor(Color.green);
    }   
    
    void reset_parameters() {
        faktor        = FAKTOR;
        offset_x      = OFFSET_X;
        offset_y      = OFFSET_Y;
        delta         = BREITE;
        neues_fenster = false;
    } 

    public void init() {                                   // initialisiere Applet
        setBackground(Color.black);                        // setze Hintergrundfarbe
        regel_choices = new Choice();                      // Menu fuer Regeln
        regel_choices.addItem("Farn");
        regel_choices.addItem("Sierpinski");
        regel_choices.addItem("Blatt");
        regel_choices.addItem("Wuerfel");
        regel_choices.setBackground(Color.lightGray);
        regel_choices.setForeground(Color.black);
        this.add(regel_choices);
        
        start_button = new Button("Start");                // lege Pushbutton an
        start_button.setForeground(Color.black);
        start_button.setBackground(Color.lightGray);
        this.add(start_button);
        
        clear_button = new Button("Reset");                // lege Pushbutton an
        clear_button.setForeground(Color.black);
        clear_button.setBackground(Color.lightGray);
        this.add(clear_button);
        reset_parameters();
    }
    
    public boolean mouseDown(Event e, int x, int y)        // aufgerufen 
    {                                                      // bei Mausdruck
        start_x = x; 
        start_y = y;
        ende_x  = start_x + 1;
        ende_y  = start_y + 1;
        g=this.getGraphics();
        g.setXORMode(Color.red);
        return true;
    }
    
    public boolean mouseDrag(Event e, int x, int y)         // beim Mausziehen
    {
        g.drawLine(start_x, start_y, ende_x, start_y);      // altes Zoomrechteck
        g.drawLine(start_x, start_y, start_x, ende_y);      // entfernen
        g.drawLine(start_x, ende_y,  ende_x,  ende_y);
        g.drawLine(ende_x,  start_y, ende_x,  ende_y);
        
        int dis_x = x - start_x;                            // kleinere Distanz
        int dis_y = y - start_y;                            // bzgl. x oder y
        delta = dis_x < dis_y ? dis_x : dis_y ;             // legt Quadrat fest
        ende_x = start_x + delta;
        ende_y = start_y + delta;


        g.drawLine(start_x, start_y, ende_x, start_y);      // neues Zoomrechteck
        g.drawLine(start_x, start_y, start_x, ende_y);      // malen
        g.drawLine(start_x, ende_y,  ende_x,  ende_y);
        g.drawLine(ende_x,  start_y, ende_x,  ende_y);

        return true;
    }

    public boolean mouseUp(Event e, int x, int y)           // aufgerufen bei 
    {                                                       // Maustaste loslassen
        faktor   = BREITE * faktor / delta;
        offset_x = BREITE * (offset_x-start_x) / delta;
        offset_y = BREITE * (offset_y-start_y) / delta;
        g.setPaintMode();
        neues_fenster = true;
        return true;
    }
    
    public boolean action(Event event, Object arg) {        // bei Button-Druck
        int i, j;

        if (event.target == clear_button) {                 // bei Clear-Button
            reset_parameters();
            reset_graphics();
            return true;
        }

        else if (event.target == regel_choices) {           // bei Regel-Menu
            String colorname = (String) arg;
            if (arg.equals("Farn"))            regel_system = 0;
            else if (arg.equals("Sierpinski")) regel_system = 1;
            else if (arg.equals("Blatt"))      regel_system = 2;
            else if (arg.equals("Wuerfel"))    regel_system = 3;
            reset_parameters();
            reset_graphics();
            return true;
        }

        else if (event.target == start_button) {            // bei Start-Button

            g = this.getGraphics();
            g.setColor(Color.green);
            if (neues_fenster) {
                reset_graphics();
                neues_fenster = false;
            }

            iterationen = ITERATIONEN;    
            while (iterationen-- > 0) { 

                IFS.transform (p);                
                dev_x = (int) (faktor * p.x + offset_x); 
                dev_y = (int) (offset_y - faktor * p.y);
                g.drawLine(dev_x, dev_y, dev_x, dev_y);
            }

            return true;
        }

        else return super.action(event, arg);                // sonst: Superklasse
    }

}