// JavaProject HilbertCurve
// HilbertCurve.java
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
class Canvas extends JPanel {
// Die Hilbert-Kurve ist die Grenzkurve der unendlichen
// Folge speziell definierter Polygonzüge. Sie füllt die
// Fläche eines beliebig großen Quadrats vollständig aus.
// Die Zeichenfläche canvas dient zur Darstellung der
// ersten sieben Glieder dieser Polygonzug-Folge.
private static final long serialVersionUID = 0L;
int n = 0; // Rekursionstiefe
Graphics2D g2d;
Rectangle2D.Float rectangle = new Rectangle2D.Float(1f, 1f, 254f, 254f);
BasicStroke stroke = new BasicStroke(0.5f);
private Turtle turtle;
public Canvas() {
setBounds(3, 3, 256, 256);
setBackground(Color.WHITE);
}
private void defineRendering(Graphics2D g) {
RenderingHints rh;
rh = new RenderingHints (
RenderingHints.KEY_DITHERING,
RenderingHints.VALUE_ANTIALIAS_ON
);
g.setRenderingHints(rh);
}
private void drawHilbertCurve(int n) {
// unter Verwendung zweier rekursiver Methoden
// von Robert Sedgewick und Kevin Wayne
// introcs.cs.princeton.edu/java/32class/Hilbert.java.html
double sc = 1/Math.pow(2, n);
g2d.scale(sc, sc);
turtle = new Turtle(this, 65, 65, 0);
moveTurtle(n);
}
private void moveTurtle(int n) {
if (n == -1) return;
turtle.turn(90);
evomTurtle(n-1);
turtle.goForward(128d);
turtle.turn(-90);
moveTurtle(n-1);
turtle.goForward(128d);
moveTurtle(n-1);
turtle.turn(-90);
turtle.goForward(128d);
evomTurtle(n-1);
turtle.turn(90);
}
private void evomTurtle(int n) {
if (n == -1) return;
turtle.turn(-90);
moveTurtle(n-1);
turtle.goForward(128d);
turtle.turn(90);
evomTurtle(n-1);
turtle.goForward(128d);
evomTurtle(n-1);
turtle.turn(90);
turtle.goForward(128d);
moveTurtle(n-1);
turtle.turn(-90);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g2d = (Graphics2D) g.create();
defineRendering(g2d);
g2d.setPaint(Color.GRAY);
g2d.setStroke(stroke);
g2d.draw(rectangle);
g2d.setPaint(Color.DARK_GRAY);
drawHilbertCurve(n);
g2d.dispose();
}
}
class CFrame extends JFrame {
private static final long serialVersionUID = 0L;
Image icon;
Canvas canvas;
BContainer container;
public CFrame() {
setTitle("Hilbert\u02BCsche Polygonzüge");
icon = Toolkit.getDefaultToolkit().getImage("dh.png");
setIconImage(icon);
setSize(349, 301);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setLayout(null);
canvas = new Canvas();
add(canvas);
container = new BContainer(canvas);
add(container);
setVisible(true);
}
}
public class HilbertCurve {
public static void main(String[] args) {
new CFrame();
}
}
// Turtle.java
import java.awt.geom.*;
public class Turtle {
private double x, y, angle;
private Canvas canvas;
public Turtle(Canvas canvas, double x, double y, double angle) {
this.canvas = canvas;
this.x = x;
this.y = y;
this.angle = angle;
}
public void turn(double d) {
angle += d;
}
public void goForward(double step) {
double xold = x;
double yold = y;
x += step * Math.cos(Math.toRadians(angle));
y += step * Math.sin(Math.toRadians(angle));
Line2D.Double line = new Line2D.Double(xold, yold, x, y);
canvas.g2d.draw(line);
}
}
// BContainer.java
import java.awt.*;
import java.awt.event.*;
import java.awt.Container;
import java.awt.event.ActionEvent;
import javax.swing.*;
class Button extends JButton {
private static final long serialVersionUID = 0L;
public Button(String txt) {
setText(txt);
}
}
public class BContainer extends Container implements ActionListener {
private static final long serialVersionUID = 0L;
Canvas canvas;
Button b0 = new Button("n = 0");
Button b1 = new Button("n = 1");
Button b2 = new Button("n = 2");
Button b3 = new Button("n = 3");
Button b4 = new Button("n = 4");
Button b5 = new Button("n = 5");
Button b6 = new Button("n = 6");
Button b7 = new Button("n = 7");
Button[] b = {b0, b1, b2, b3, b4, b5, b6, b7};
public BContainer(Canvas canvas) {
this.canvas = canvas;
setBounds(262, 4, 68, 256);
setLayout(new GridLayout(8, 1, 4, 4));
for (int i=0; i<8; i++) {
b[i].addActionListener(this);
add(b[i]);
}
}
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == b0) canvas.n = 0;
if (e.getSource() == b1) canvas.n = 1;
if (e.getSource() == b2) canvas.n = 2;
if (e.getSource() == b3) canvas.n = 3;
if (e.getSource() == b4) canvas.n = 4;
if (e.getSource() == b5) canvas.n = 5;
if (e.getSource() == b6) canvas.n = 6;
if (e.getSource() == b7) canvas.n = 7;
canvas.repaint();
}
}
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