使用System.Drawing绘制圆圈

using System;
using System.Drawing;
using System.Windows.Forms;

public class MyForm : Form
{
    public MyForm()
    {
        this.Size = new Size(300, 300);
        this.Paint += new PaintEventHandler(MyForm_Paint);
    }

    private void MyForm_Paint(object sender, PaintEventArgs e)
    {
        Graphics g = e.Graphics;
        Pen p = new Pen(Color.Red, 2);
        g.DrawEllipse(p, 50, 50, 200, 200);
    }

    [STAThread]
    static void Main()
    {
        Application.Run(new MyForm());
    }
}