Drawing the "Lo feather fractal" using recursion

Description

Demo Code

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;

import javax.swing.JButton;
import javax.swing.JColorChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

class FractalJPanel extends JPanel {
  private Color color; // stores color used to draw fractal
  private int level; // stores current level of fractal

  private static final int WIDTH = 400; // defines width of JPanel
  private static final int HEIGHT = 400; // defines height of JPanel

  public FractalJPanel(int currentLevel) {
    color = Color.BLUE;//from ww  w .  java 2 s.c o  m
    level = currentLevel; // set initial fractal level
    setBackground(Color.WHITE);
    setPreferredSize(new Dimension(WIDTH, HEIGHT));
  }

  public void drawFractal(int level, int xA, int yA, int xB, int yB, Graphics g) {
    if (level == 0)
      g.drawLine(xA, yA, xB, yB);
    else {
      // calculate midpoint between (xA, yA) and (xB, yB)
      int xC = (xA + xB) / 2;
      int yC = (yA + yB) / 2;

      // calculate the fourth point (xD, yD) which forms an
      // isosceles right triangle between (xA, yA) and (xC, yC)
      // where the right angle is at (xD, yD)
      int xD = xA + (xC - xA) / 2 - (yC - yA) / 2;
      int yD = yA + (yC - yA) / 2 + (xC - xA) / 2;

      // recursively draw the Fractal
      drawFractal(level - 1, xD, yD, xA, yA, g);
      drawFractal(level - 1, xD, yD, xC, yC, g);
      drawFractal(level - 1, xD, yD, xB, yB, g);
    }
  }

  // start the drawing of fractal
  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.setColor(color);
    drawFractal(level, 100, 90, 290, 200, g);
  }

  public void setColor(Color c) {
    color = c;
  }

  public void setLevel(int currentLevel) {
    level = currentLevel;
  }

  public int getLevel() {
    return level;
  }
}

public class Main extends JFrame {
  private static final int WIDTH = 400; // define width of GUI
  private static final int HEIGHT = 480; // define height of GUI
  private static final int MIN_LEVEL = 0, MAX_LEVEL = 15;

  private JButton changeColorJButton, increaseLevelJButton,
      decreaseLevelJButton;
  private JLabel levelJLabel;
  private FractalJPanel drawSpace;
  private JPanel mainJPanel, controlJPanel;

  public Main() {
    controlJPanel = new JPanel();
    controlJPanel.setLayout(new FlowLayout());

    changeColorJButton = new JButton("Color");
    controlJPanel.add(changeColorJButton);
    changeColorJButton.addActionListener(e -> {
      Color color = JColorChooser.showDialog(Main.this, "Choose a color",
          Color.BLUE);

      // set default color, if no color is returned
        if (color == null)
          color = Color.BLUE;

        drawSpace.setColor(color);
      });

    // set up decrease level button to add to control panel and
    // register listener
    decreaseLevelJButton = new JButton("Decrease Level");
    controlJPanel.add(decreaseLevelJButton);
    decreaseLevelJButton.addActionListener(e -> {
      int level = drawSpace.getLevel();
      --level;

      // modify level if possible
        if ((level >= MIN_LEVEL) && (level <= MAX_LEVEL)) {
          levelJLabel.setText("Level: " + level);
          drawSpace.setLevel(level);
          repaint();
        }
      }

      );

    // set up increase level button to add to control panel
    // and register listener
    increaseLevelJButton = new JButton("Increase Level");
    controlJPanel.add(increaseLevelJButton);
    increaseLevelJButton.addActionListener(e -> {
      int level = drawSpace.getLevel();
      ++level;

      // modify level if possible
        if ((level >= MIN_LEVEL) && (level <= MAX_LEVEL)) {
          levelJLabel.setText("Level: " + level);
          drawSpace.setLevel(level);
          repaint();

        }
      });

    // set up levelJLabel to add to controlJPanel
    levelJLabel = new JLabel("Level: 0");
    controlJPanel.add(levelJLabel);

    drawSpace = new FractalJPanel(0);

    // create mainJPanel to contain controlJPanel and drawSpace
    mainJPanel = new JPanel();
    mainJPanel.add(controlJPanel);
    mainJPanel.add(drawSpace);

    add(mainJPanel); // add JPanel to JFrame

    setSize(WIDTH, HEIGHT); // set size of JFrame
    setVisible(true); // display JFrame
  }

  public static void main(String[] args) {
    Main demo = new Main();
    demo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
}
Drawing the "Lo feather fractal" using recursion - Java Object Oriented Design

Description

Demo Code

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