ASP.NET實現折線圖的繪制

用到.Net中繪圖類，實現折線圖的繪制，生成圖片，在頁面的顯示，代碼如下：

 /// <summary>
    /// 獲取數據 
    /// strChartName：圖名稱；
    /// yName：縱坐標名稱；
    /// xName：橫坐標名稱；
    /// iyMaxValue:縱坐標最大值；
    /// dyAveValue:縱坐標單位值=（縱坐標最大值/標量30）
    /// ----100   30    :3
    /// ----200   30    :1.5；
    /// xdbColumnName:橫坐標綁定顯示數據表值的列名；
    /// ydbColumnName:縱坐標綁定顯示數據表值得列名；
    /// </summary>
    public void Get_CurveData(string strSql,string strChartName,string yName,string xName,int iyMaxValue, double dyAveValue,string xdbColumnName,string ydbColumnName)
    {
        try
        {
            DataSet ds = sqlAccess.ReadFromDB(strSql);
            draw(ds.Tables[0], strChartName, yName, xName, iyMaxValue, dyAveValue, xdbColumnName, ydbColumnName);
        }
        catch (Exception exp)
        {
            Response.Write(sqlAccess.ExceptionMessage);
        }
    }

    public void draw(DataTable dt, string strChartName, string yName, string xName, int iyMaxValue, double dyAveValue, string xdbColumnName, string ydbColumnName)
    {
        //取得記錄數量 
        int count = dt.Rows.Count;
        //記算圖表寬度 
        int wd = 80 + 20 * (count - 1);
        //設置最小寬度為800 
        if (wd < 600) wd = 600;
        //生成Bitmap對像 
        Bitmap img = new Bitmap(wd, 400);
        //生成繪圖對像 
        Graphics g = Graphics.FromImage(img);
        //定義黑色畫筆 
        Pen Bp = new Pen(Color.Black);
        //定義紅色畫筆 
        Pen Rp = new Pen(Color.Red);
        //定義銀灰色畫筆 
        Pen Sp = new Pen(Color.Silver);
        //定義藍色畫筆
        Pen Blp = new Pen(Color.Blue);
        //定義大標題字體 
        Font Bfont = new Font("Arial", 12, FontStyle.Bold);
        //定義一般字體 
        Font font = new Font("Arial", 9);
        //定義大點的字體 
        Font Tfont = new Font("Arial", 9);
        //定義橫坐標間隔，(最佳值是總寬度-留空寬度[左右側都需要])/(記錄數量-1) 
        int xSpace = (wd - 100) / (count - 1);
        //定義縱坐標間隔,不能隨便修改，跟高度和橫坐標線的條數有關，最佳值=(繪圖的高度-上面留空-下面留空) 
        int ySpace = 30;
        //縱坐標最大值和間隔值 
        int yMaxValue = iyMaxValue;
        //繪制底色 
        g.DrawRectangle(new Pen(Color.White, 400), 0, 0, img.Width, img.Height);
        //定義黑色過渡型筆刷 
        LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, img.Width, img.Height), Color.Black, Color.Black, 1.2F, true);
        //定義藍色過渡型筆刷 
        LinearGradientBrush Bluebrush = new LinearGradientBrush(new Rectangle(0, 0, img.Width, img.Height), Color.Blue, Color.Blue, 1.2F, true);
        //繪制大標題 
        g.DrawString(strChartName, Bfont, brush, 40, 5);
        //繪制信息簡報 
        //string info = " 曲線圖生成時間：" + DateTime.Now.ToString();
        //g.DrawString(info, Tfont, Bluebrush, 40, 25);
        //繪制圖片邊框 
        g.DrawRectangle(Bp, 0, 0, img.Width - 1, img.Height - 1);
        //繪制豎坐標軸 
        g.DrawLine(Bp, 40, 55, 40, 360);
        //繪制橫坐標軸 x2的60是右側空出部分 
        g.DrawLine(Bp, 40, 360, 60 + xSpace * (count - 1), 360);
        //繪制豎坐標標題 
        g.DrawString(yName, Tfont, brush, 5, 40);
        //繪制橫坐標標題 
        g.DrawString(xName, Tfont, brush, 40, 385);
        //繪制豎坐標線 
        for (int i = 0; i < count; i++)
        {
            g.DrawLine(Sp, 40 + xSpace * i, 60, 40 + xSpace * i, 360);
        }
        //繪制時間軸坐標標簽 
        for (int i = 0; i < count; i++)
        {
            //string st = Convert.ToDateTime(dt.Rows[i]["testdate"]).ToString("MM:dd");
            //string st = "第" + dt.Rows[i]["testdate"].ToString() + "周";
            string st = dt.Rows[i][xdbColumnName].ToString();
            g.DrawString(st, font, brush, 30 + xSpace * i, 370);
        }
        //繪制橫坐標線 
        for (int i = 0; i < 10; i++)
        {
            g.DrawLine(Sp, 40, 60 + ySpace * i, 40 + xSpace * (count - 1), 60 + ySpace * i);
            //橫坐標軸的值間隔是最大值除以間隔數 
            int s = yMaxValue - i * (yMaxValue / 10);
            //繪制發送量軸坐標標簽 
            g.DrawString(s.ToString(), font, brush, 10, 60 + ySpace * i);
        }

        //處理39.6%形式的數據
        string[] strArr = new string[dt.Rows.Count];
        for (int i = 0; i < count; i++)
        {
            string strValue = dt.Rows[i][ydbColumnName].ToString();
            if (strValue.Contains("%"))
            {
                strArr[i] = strValue.Split('%')[0];
            }
            else
            {
                strArr[i] = strValue;
            }
        }
        //200/30
        //定義縱坐標單位數值=縱坐標最大值/標量最大值
        double yAveValue = dyAveValue;
        //定義曲線轉折點 
        Point[] p = new Point[count];
        for (int i = 0; i < count; i++)
        {
            p[i].X = 40 + xSpace * i;
            p[i].Y = 360 - Convert.ToInt32(Convert.ToDouble(strArr[i]) * yAveValue);
        }

        //繪制折線圖 
        //g.DrawLines(Rp, p); 
        //繪制曲線圖 
        //g.DrawCurve(Rp, p); 
        //繪制自定義張力的曲線圖（0.5F是張力值，默認就是這個值） 
        g.DrawCurve(Rp, p, 0.5F);
        //g.DrawLines(Rp, p); 
        //當需要在一個圖里繪制多條曲線的時候，就多定義個point數組，然后畫出來就可以了。 
        for (int i = 0; i < count; i++)
        {
            //繪制發送記錄點的發送量 
            g.DrawString(strArr[i], font, Bluebrush, p[i].X, p[i].Y - 10);
            //繪制發送記錄點 
            g.DrawRectangle(Rp, p[i].X - 1, p[i].Y - 1, 2, 2);
        }

        ///*******************畫中值線///
        //for (int i = 0; i < count; i++)
        //{
        //    p[i].X = 40 + xSpace * i;
        //    p[i].Y = 360 - Convert.ToInt32("50") * yAveValue;
        //}
        //for (int i = 0; i < count; i++)
        //{
        //    //繪制發送記錄點的發送量 
        //    g.DrawString("", font, Bluebrush, p[i].X, p[i].Y - 10);
        //    //繪制發送記錄點 
        //    g.DrawRectangle(Rp, p[i].X - 1, p[i].Y - 1, 2, 2);
        //}
        //g.DrawLine(Blp, 40, 360 - Convert.ToInt32("50") * yAveValue, 60 + xSpace * (count - 1), 360 - Convert.ToInt32("50") * yAveValue);
        ///**************************///

        //保存繪制的圖片 
        MemoryStream stream = new MemoryStream();
        img.Save(stream, ImageFormat.Jpeg);
        //圖片輸出 
        Response.Clear();
        Response.ContentType = "image/jpeg";
        Response.BinaryWrite(stream.ToArray());
    } 
}