Java Applet绘制心形曲线

import java.awt.*;
import java.applet.*;

public class CartesianCurve extends Applet{
   int width, height;
   Image image;
   Graphics draw_Curve;
   public void init(){
setBackground(Color.black);
this.setSize(350, 310);
width = getSize().width;
height = getSize().height;
image = createImage(width, height);
draw_Curve = image.getGraphics();
   }
   public void paint(Graphics g){
draw_Curve.clearRect(0, 0, width, height);
draw_Curve.setColor(Color.red);
int i, j;
double x, y, r;
for(i = 0; i <= 90; i++)
for(j = 0; j  <= 90; j++){
r = Math.PI / 45 * i * (1 - Math.sin(Math.PI / 45 * j)) * 18;
x = r * Math.cos(Math.PI / 45 * j) * Math.sin(Math.PI / 45 * i) + width / 2;
y = -r * Math.sin(Math.PI / 45 * j) + height / 4;
draw_Curve.fillOval((int) x, (int)y, 2, 2);
}
g.drawImage(image, 0, 0, this);
   }
   }