1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Web;
 5 using System.Web.UI;
 6 using System.Web.UI.WebControls;
 7 
 8 using System.Drawing;
 9 
10 public partial class _Default : System.Web.UI.Page
11 {
12     /// <summary>
13     /// 画饼图
14     /// </summary>
15     /// <param name="sender"></param>
16     /// <param name="e"></param>
17     protected void Page_Load(object sender, EventArgs e)
18     {
19         //在一张图片上写“饼图显示”，并把图片显示出来
20         Bitmap bm = new Bitmap(400, 400); 
21         Graphics g = Graphics.FromImage(bm); 
22         g.Clear(Color.White);                            //先清理一下图形的背景色
23         g.DrawString("饼图显示",new Font("宋体",23),new SolidBrush(Color.Red),new PointF(5,5));
24 
25 
26         //画饼图
27         int[] Num = { 100, 200, 300, 460 };              //饼图上各部分所占的比例
28         Color[] colors = { Color.Red, Color.Green, Color.Blue, Color.Yellow }; //饼图各部分的颜色
29 
30         //计算各部分数字的和
31         float TotalValue = 0;   
32         for (int i = 0; i < Num.Length; i++)
33         {
34             TotalValue = TotalValue + Num[i];
35         }
36 

38         float sweepAngle = 0;                          //扇形经过的角度
39         float startAngle = 0;                          //扇形起始的角度，不断的累加
40         float x = 50f;
41         float y = 50f;                                 //全部都用float型，
42         float width = 200;
43         int index = 0;                                 //指示器，指示用哪一个颜色
44         Color Singlecolor = new Color();               //有更简便的方法
45         foreach (int i in Num)
46         {
47             sweepAngle = i / TotalValue * 360;         //旋转的角度
48             Singlecolor = colors[index];               //颜色
49             g.FillPie(new SolidBrush(Singlecolor), x, y, width, width, startAngle, sweepAngle); //填充扇形区域，从正右边开始，顺时针往下画，x,y的意思是？？
50 
51             g.DrawPie(Pens.Black , x, y, width, width, startAngle, sweepAngle);                    //画边
52             startAngle = startAngle + sweepAngle;                                                  //起始角度不断的累加
53             index++;
54         }
55         bm.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);      //保存图片
56         g.Dispose();
57     }
58 }