import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;

public class RoseJFrame extends JFrame implements ActionListener {
	private RoseCanvas canvas;
	public RoseJFrame() {
		super("四叶玫瑰线");
		Dimension dim = getToolkit().getScreenSize();
		this.setBounds(dim.width/4, dim.height/4, dim.width/2, dim.height/2);
		this.setDefaultCloseOperation(EXIT_ON_CLOSE);
		JPanel jpanel = new JPanel();
		this.getContentPane().add(jpanel, "North");
		JButton button_color = new JButton("选择颜色");
		jpanel.add(button_color);
		button_color.addActionListener(this);
		this.canvas = new RoseCanvas(Color.red);
		this.getContentPane().add(this.canvas, "Center");
		this.setVisible(true);
	}
	@Override
	public void actionPerformed(ActionEvent e) {
		Color c = JColorChooser.showDialog(this, "选择颜色", Color.blue);
		this.canvas.setColor(c);
		this.canvas.repaint();

	}
	public static void main(String args[])
	{
		new RoseJFrame();
	}
	class RoseCanvas extends Canvas {
		private Color color;
		public RoseCanvas(Color color) {
			this.setColor(color);
		}
		public void setColor(Color color) {
			this.color = color;
		}
		public void paint(Graphics g) {
			int x0 = this.getWidth() / 2;
			int y0 = this.getHeight() / 2;
			g.setColor(this.color);
			g.drawLine(x0, 0, x0, y0 * 2);
			g.drawLine(0, y0, x0*2, y0);
			for (int j = 40; j < 100; j += 20)
				for (int i = 0; i < 1024; i++) {
					double angle = i*Math.PI/512;
					double radius = j*Math.sin(8*angle);
					int x = (int)Math.round(radius * Math.cos(angle) * 2);
					int y = (int)Math.round(radius * Math.sin(angle));
					g.fillOval(x0 + x, y0 + y*2, 2, 2);
				}
		}
	}

}