asp.net GDI+绘制五边形

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Drawing2D;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Bitmap bitmap = new Bitmap(240, 200);
        Graphics g = Graphics.FromImage(bitmap);
        g.Clear(Color.White);
        Pen pen = new Pen(Color.Green, 3);
        Point[] pts = new Point[] { new Point(10, 120), new Point(120, 100), new Point(180, 120), new Point(240, 200), new Point(60, 200) };
        g.DrawPolygon(pen, pts);
        System.IO.MemoryStream ms = new System.IO.MemoryStream(); ;
        bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        Response.ClearContent();
        Response.ContentType = "image/Jpeg";
        Response.BinaryWrite(ms.ToArray());
    }
}