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());
}
}