ASP.NET实现折线图的绘制

用到.Net中绘图类，实现折线图的绘制，生成图片，在页面的显示，代码如下：

  /// <summary>
     /// 获取数据
     /// strChartName：图名称；
     /// yName：纵坐标名称；
     /// xName：横坐标名称；
     /// iyMaxValue:纵坐标最大值；
     /// dyAveValue:纵坐标单位值=（纵坐标最大值/标量30）
     /// ----100   30    :3
     /// ----200   30    :1.5；
     /// xdbColumnName:横坐标绑定显示数据表值的列名；
     /// ydbColumnName:纵坐标绑定显示数据表值得列名；
     /// </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[], 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)
     {
         //取得记录数量
         int count = dt.Rows.Count;
         //记算图表宽度
         int wd =  +  * (count - );
         //设置最小宽度为800
         if (wd < ) wd = ;
         //生成Bitmap对像
         Bitmap img = new Bitmap(wd, );
         //生成绘图对像
         Graphics g = Graphics.FromImage(img);
         //定义黑色画笔
         Pen Bp = new Pen(Color.Black);
         //定义红色画笔
         Pen Rp = new Pen(Color.Red);
         //定义银灰色画笔
         Pen Sp = new Pen(Color.Silver);
         //定义蓝色画笔
         Pen Blp = new Pen(Color.Blue);
         //定义大标题字体
         Font Bfont = new Font("Arial", , FontStyle.Bold);
         //定义一般字体
         Font font = new Font("Arial", );
         //定义大点的字体
         Font Tfont = new Font("Arial", );
         //定义横坐标间隔，(最佳值是总宽度-留空宽度[左右侧都需要])/(记录数量-1)
         int xSpace = (wd - ) / (count - );
         //定义纵坐标间隔,不能随便修改，跟高度和横坐标线的条数有关，最佳值=(绘图的高度-上面留空-下面留空)
         int ySpace = ;
         //纵坐标最大值和间隔值
         int yMaxValue = iyMaxValue;
         //绘制底色
         g.DrawRectangle(new Pen(Color.White, ), , , img.Width, img.Height);
         //定义黑色过渡型笔刷
         LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(, , img.Width, img.Height), Color.Black, Color.Black, 1.2F, true);
         //定义蓝色过渡型笔刷
         LinearGradientBrush Bluebrush = new LinearGradientBrush(new Rectangle(, , img.Width, img.Height), Color.Blue, Color.Blue, 1.2F, true);
         //绘制大标题
         g.DrawString(strChartName, Bfont, brush, , );
         //绘制信息简报
         //string info = " 曲线图生成时间：" + DateTime.Now.ToString();
         //g.DrawString(info, Tfont, Bluebrush, 40, 25);
         //绘制图片边框
         g.DrawRectangle(Bp, , , img.Width - , img.Height - );
         //绘制竖坐标轴
         g.DrawLine(Bp, , , , );
         //绘制横坐标轴 x2的60是右侧空出部分
         g.DrawLine(Bp, , ,  + xSpace * (count - ), );
         //绘制竖坐标标题
         g.DrawString(yName, Tfont, brush, , );
         //绘制横坐标标题
         g.DrawString(xName, Tfont, brush, , );
         //绘制竖坐标线
         for (int i = ; i < count; i++)
         {
             g.DrawLine(Sp,  + xSpace * i, ,  + xSpace * i, );
         }
         //绘制时间轴坐标标签
         for (int i = ; 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,  + xSpace * i, );
         }
         //绘制横坐标线
         for (int i = ; i < ; i++)
         {
             g.DrawLine(Sp, ,  + ySpace * i,  + xSpace * (count - ),  + ySpace * i);
             //横坐标轴的值间隔是最大值除以间隔数
             int s = yMaxValue - i * (yMaxValue / );
             //绘制发送量轴坐标标签
             g.DrawString(s.ToString(), font, brush, ,  + ySpace * i);
         }

         //处理39.6%形式的数据
         string[] strArr = new string[dt.Rows.Count];
         for (int i = ; i < count; i++)
         {
             string strValue = dt.Rows[i][ydbColumnName].ToString();
             if (strValue.Contains("%"))
             {
                 strArr[i] = strValue.Split('%')[];
             }
             else
             {
                 strArr[i] = strValue;
             }
         }
         //200/30
         //定义纵坐标单位数值=纵坐标最大值/标量最大值
         double yAveValue = dyAveValue;
         //定义曲线转折点
         Point[] p = new Point[count];
         for (int i = ; i < count; i++)
         {
             p[i].X =  + xSpace * i;
             p[i].Y =  - Convert.ToInt32(Convert.ToDouble(strArr[i]) * yAveValue);
         }

         //绘制折线图
         //g.DrawLines(Rp, p);
         //绘制曲线图
         //g.DrawCurve(Rp, p);
         //绘制自定义张力的曲线图（0.5F是张力值，默认就是这个值）
         g.DrawCurve(Rp, p, 0.5F);
         //g.DrawLines(Rp, p);
         //当需要在一个图里绘制多条曲线的时候，就多定义个point数组，然后画出来就可以了。
         for (int i = ; i < count; i++)
         {
             //绘制发送记录点的发送量
             g.DrawString(strArr[i], font, Bluebrush, p[i].X, p[i].Y - );
             //绘制发送记录点
             g.DrawRectangle(Rp, p[i].X - , p[i].Y - , , );
         }

         ///*******************画中值线///
         //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++)
         //{
         //    //绘制发送记录点的发送量
         //    g.DrawString("", font, Bluebrush, p[i].X, p[i].Y - 10);
         //    //绘制发送记录点
         //    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);
         ///**************************///

         //保存绘制的图片
         MemoryStream stream = new MemoryStream();
         img.Save(stream, ImageFormat.Jpeg);
         //图片输出
         Response.Clear();
         Response.ContentType = "image/jpeg";
         Response.BinaryWrite(stream.ToArray());
     }
 }