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();

}

}