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

public class c04_staircase extends java.applet.Applet {
  double r = (double)1/3;
  int n = 7;
  boolean devil = true;
  static final int left = 30;
  static final int w = 300;
  Graph graph;
  Controls controls;

  class Graph extends Canvas {
    public void paint(Graphics g)
    {
      cantor(g, 1, left, left+(1+(devil?1:0))*w/2, left+w, left+(1-(devil?1:0))*w/2);
      double d = r < 1 ? Math.log(2)/Math.log(2/(1-r)) : 0;
      g.drawString("Dimension of Cantor set: "+d, 10, 20);
    }

    private void cantor(Graphics g, int level, double x1, double y1, double x2, double y2)
    {
      if (level < n) {
        double x = ((1+r)*x1+(1-r)*x2)/2;
        double y = (y1+y2)/2;
        cantor(g, level+1, x1, y1, x, y);
        double xx = ((1-r)*x1+(1+r)*x2)/2;
        if (devil) {
          g.drawLine((int)x, (int)y, (int)xx, (int)y);
        }
        cantor(g, level+1, xx, y, x2, y2);
      } else {
        g.drawLine((int)x1, (int)y1, (int)x2, (int)y2);
      }
    }
  }

  class Controls extends Container {
    private TextField tr;
    private TextField tn;
    private Checkbox td;
    private Button redraw;

    public Controls()
    {
      setLayout(new FlowLayout());
      add(new Label("r =", Label.RIGHT));
      add(tr = new TextField(""+r, 6));
      add(new Label("n =", Label.RIGHT));
      add(tn = new TextField(""+n, 6));
      add(td = new Checkbox("Staircase", devil));
      add(redraw = new Button("Redraw"));
      redraw.addActionListener(
        new ActionListener() {
          public void actionPerformed(ActionEvent e) {
            try {
              r = Double.valueOf(tr.getText()).doubleValue();
              n = Integer.parseInt(tn.getText());
              devil = td.getState();
            } catch (NumberFormatException nfx) {
            }
            c04_staircase.this.graph.repaint();
          }
        }
      );
    }
  }

  public void init()
  {
    setLayout(new BorderLayout());
    add(controls = new Controls(), BorderLayout.SOUTH);
    add(graph = new Graph(), BorderLayout.CENTER);
  }
}