asp.net画饼图

<%@ Page Language=C# %>
<%@import namespace=System.Data %>
<%@import namespace=System.Data.OleDb %>
<%@import namespace=System.Drawing %>
<%@import namespace=System.Drawing.Imaging %>
<script language=c# runat=server >
  public void page_load(Object obj,EventArgs e)
 {
//把连接字串指定为一个常量
const String strconn = Provider=Microsoft.Jet.OLEDB.4.0; +
                             Data Source=c:/mess.mdb ;
OleDbConnection conn=new OleDbConnection(strconn);
conn.Open();
string sql=select *  from title ;
OleDbCommand cmd=new OleDbCommand(sql,conn);
DataSet ds=new DataSet();
OleDbDataAdapter adapter1=new OleDbDataAdapter(cmd);
adapter1.Fill(ds);
conn.Close();
float total=0.0f,tmp;
int iloop;
    for(iloop=0;iloop<ds.Tables[0].Rows.Count;iloop++)
     {
        tmp=Convert.ToSingle(ds.Tables[0].Rows[iloop][ point ]);//转换成单精度,投票不可能投半票。也可写成Convert.ToInt32
        total+=tmp;
        }
//Response.Write(Convert.ToString(total));

Font fontlegend=new Font( verdana ,9),fonttitle=new Font( verdana ,10,FontStyle.Bold);//设置字体
//fonttitle为主标题的字体

int width=230;//白色背景宽
const int bufferspace=15;
int legendheight=fontlegend.Height*(ds.Tables[0].Rows.Count+1)+bufferspace;
 int titleheight = fonttitle.Height + bufferspace;
 int height = width + legendheight + titleheight + bufferspace;//白色背景高
 int pieheight = width;
Rectangle pierect=new Rectangle(0,titleheight,width,pieheight);

//加上各种随机色
 ArrayList colors = new ArrayList();
 Random rnd = new Random();
 for (iloop = 0; iloop < ds.Tables[0].Rows.Count; iloop++)
  colors.Add(new SolidBrush(Color.FromArgb(rnd.Next(255), rnd.Next(255), rnd.Next(255))));

Bitmap objbitmap=new Bitmap(width,height);//创建一个bitmap实例
//Bitmap objbitmap=new Bitmap(230,500);//创建一个bitmap实例
Graphics objgraphics=Graphics.FromImage(objbitmap);

objgraphics.FillRectangle(new SolidBrush(Color.White), 0, 0, width, height);//画一个白色背景
objgraphics.FillRectangle(new SolidBrush(Color.LightYellow), pierect);//画一个亮黄色背景
//以下为画饼图(有几行row画几个)
float currentdegree=0.0f;
 for (iloop = 0; iloop < ds.Tables[0].Rows.Count; iloop++)
 {
  objgraphics.FillPie((SolidBrush) colors[iloop], pierect, currentdegree,
    Convert.ToSingle(ds.Tables[0].Rows[iloop][ point ]) / total * 360);
  currentdegree += Convert.ToSingle(ds.Tables[0].Rows[iloop][ point ]) / total * 360;
 }
//---以下为生成主标题
SolidBrush blackbrush=new SolidBrush(Color.Black);
string title=本次《程序员大本营》推出了配套的专刊，您对专刊满意吗？ ;
 StringFormat stringFormat = new StringFormat();
 stringFormat.Alignment = StringAlignment.Center;
 stringFormat.LineAlignment = StringAlignment.Center;

 objgraphics.DrawString(title, fonttitle, blackbrush,
     new Rectangle(0, 0, width, titleheight), stringFormat);
//列出各字段与得票数
objgraphics.DrawRectangle(new Pen(Color.Black, 2), 0, height - legendheight, width, legendheight);
  for (iloop = 0; iloop < ds.Tables[0].Rows.Count; iloop++)
    {
      objgraphics.FillRectangle((SolidBrush) colors[iloop], 5, height - legendheight + fontlegend.Height * iloop + 5, 10, 10);
      objgraphics.DrawString(((String) ds.Tables[0].Rows[iloop][ title ]) + - + Convert.ToString(ds.Tables[0].Rows[iloop][ point ]), fontlegend, blackbrush,
   20, height - legendheight + fontlegend.Height * iloop + 1);
        }
//
objgraphics.DrawString( 总票数是: +Convert.ToString(total),fontlegend,blackbrush, 5, height - fontlegend.Height );
//图像总的高度-一行字体的高度，即是最底行的一行字体高度(height - fontlegend.Height )
Response.ContentType=image/jpeg ;
objbitmap.Save(Response.OutputStream,ImageFormat.Jpeg);
//objbitmap.Save( myyyyyyyyyyy.jpg , ImageFormat.Jpeg);//输出到文件

objgraphics.Dispose();
objbitmap.Dispose();
  }
</script>