Java画心形线

画出心形线，同时在左上角显示步长值和画图所用时间

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.Random;
import java.math.BigDecimal;
import static java.lang.Math.*;

public class Test{
	long start = System.currentTimeMillis();
	private Frame f = new Frame("心形线");
	//画布大小
	private final int SIZE=600;
	//重写paint()
	private MyCanvas area = new MyCanvas();
	
	private BufferedImage image = new BufferedImage(SIZE,SIZE,BufferedImage.TYPE_INT_RGB);
	private Graphics g = image.getGraphics();
	
	//循环步长
	private final double STEP = 0.00001;
	
	private void init(){
		area.setPreferredSize(new Dimension(SIZE,SIZE));
		// 画白色背景
		g.setColor(Color.white);
		g.fillRect(0, 0, SIZE, SIZE);
		// 画两条坐标轴
		g.setColor(Color.black);
		g.drawLine(0,SIZE/2,SIZE,SIZE/2);
		g.drawLine(SIZE/2,0,SIZE/2,SIZE);
		
		//计算坐标
		//新坐标
		int x1, y1,x2, y2;
		for (double t = -Math.PI; t < Math.PI; t = t + STEP){
			g.setColor(Color.black);
			x1 = axisSystem(axisX(t));
			y1 = axisSystem(axisY(t));
			x2 = axisSystem(axisX(t+STEP));
			y2 = axisSystem(axisY(t+STEP));
			//原曲线是横向的，为求美观调整了输出把它画成纵向，若画其他函数须修改
			//g.drawLine(x1, y1, x2, y2);
			g.drawLine(y1, SIZE-x1, y2, SIZE-x2);
				
		}
		
		
		//关闭窗口
		f.addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent e){
				System.exit(0);
			}
		});	
		
		long end = System.currentTimeMillis();
		g.setColor(Color.red); 
		g.setFont(new Font("Times", Font.BOLD,15));
		
		g.drawString("步长值：" + BigDecimal.valueOf(STEP) , 20, 30);
		g.drawString("画图所用时间：" + (end - start) + "毫秒", 20, 50);
		
		area.repaint();	
		f.add(area);
		f.pack();
		f.setVisible(true);
	}
	
	//根据t算出对应的心形线新坐标X值，若画其他函数须修改
	private double axisX(double t){
		return 2*cos(t) - cos(2*t);
	}
	
	//根据t算出对应的心形线新坐标Y值，若画其他函数须修改
	private double axisY(double t){
		return 2*sin(t) - sin(2*t);
	}
	
	//把新坐标换算成系统坐标，若画其他函数须修改
	private int axisSystem(double d){
		return (int)((0.5+d/8)*SIZE);
	}
	
	private class MyCanvas extends Canvas{
		public void paint(Graphics g){
			g.drawImage(image, 0, 0, null);
		}
	}

	public static void main(String[] args){
		new Test().init();
	}
}