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();
    }
}