asp.net GDI+绘制矩形渐变

 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(, );
         Graphics graphics = Graphics.FromImage(bitmap);
         graphics.Clear(Color.White);
         Rectangle rectangle = new Rectangle(, , , );
         LinearGradientBrush mylineargradientbrush = new LinearGradientBrush(rectangle, Color.White, Color.Green, LinearGradientMode.ForwardDiagonal);
         graphics.FillRectangle(mylineargradientbrush, , , , );
         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());
     }
 }