ASP.net中access饼图的实现代码

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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 = "我的投票系统";
         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);
           objgraphics.Dispose();
           objbitmap.Dispose();