Asp.NET生成饼状图

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using System.IO;

public partial class Admin_Drawing_Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        
        Response.ContentType = "image/jpeg";
        const int width = 180, height = 150;
        int x = 30, y = 50;

        int pieWidth = 120, pieHeight = 50, pieShadow = 20;
        int[] arrVote = { 100, 50, 100,60,50};
        Random oRan = new Random();

        Bitmap objBitmap = new Bitmap(width, height);
        Graphics objGraphics = Graphics.FromImage(objBitmap);
        objGraphics.DrawRectangle(new Pen(Color.Black), 0, 0, width, height);
        objGraphics.FillRectangle(new SolidBrush(Color.White), 1, 1, width - 2, height - 2);
        SolidBrush objBrush = new SolidBrush(Color.Blue);
        objGraphics.SmoothingMode = SmoothingMode.AntiAlias;

        int iCurrentPos = 0;

        Color[] arrColor = { Color.Red, Color.Red, Color.Red, Color.Red, Color.Red, Color.Red };

        for (int i = arrVote.Length - 1; i >= 0; i--)
        {
            arrColor[i] = Color.FromArgb(oRan.Next(255), oRan.Next(255), oRan.Next(255));
        }

        for (int i = arrVote.Length - 1; i >= 0; i--)
        {
            objBrush.Color = arrColor[i];
            for (int iLoop2 = 0; iLoop2 < pieShadow; iLoop2++)
                objGraphics.FillPie(new HatchBrush(HatchStyle.Percent50, objBrush.Color), x, y + iLoop2, pieWidth, pieHeight, iCurrentPos, arrVote[i]);
            iCurrentPos += arrVote[i];
        }

        iCurrentPos = 0;
        for (int i = arrVote.Length - 1; i >= 0; i--)
        {
            objBrush.Color = arrColor[i];
            objGraphics.FillPie(objBrush, x, y, pieWidth, pieHeight, iCurrentPos, arrVote[i]);
            iCurrentPos += arrVote[i];
        }

        objBitmap.Save(Response.OutputStream, ImageFormat.Jpeg);        
        objGraphics.Dispose();
        objBitmap.Dispose();

    }
}