绘制饼图
using System.Drawing;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
int[] data = { 100,200,300,460};
Color[] colors = { Color.Green,Color.Blue,Color.Yellow,Color.Tomato};
Bitmap bm = new Bitmap(400, 400);
Graphics g = Graphics.FromImage(bm);
g.Clear(Color.White);
g.DrawString("饼图测试", new Font("Arial", 16), Brushes.Red, new PointF(5, 5));
float totalValue = 0;
foreach (int i in data)
{
totalValue += i;
}
float sweepAngle=0;
float startAngle=0;
int index = 0;
float x=50f;
float y=50f;
float width = 200f;
foreach (int i in data)
{
sweepAngle=i/totalValue*360;
g.FillPie(new SolidBrush(colors[index]), x, y, width, width,startAngle, sweepAngle);
g.DrawPie(Pens.Indigo, x, y, width, width, startAngle, sweepAngle);
index++;
startAngle += sweepAngle;
}

bm.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
g.Dispose();
}
}