asp.net画曲线图(折线图)代码 详细注释

using System; 
using System.Collections; 
using System.Configuration; 
using System.Data; 
using System.Web; 
using System.Web.Security; 
using System.Web.UI; 
using System.Web.UI.HtmlControls; 
using System.Web.UI.WebControls; 
using System.Web.UI.WebControls.WebParts; 
//添加画图类 
using System.Drawing.Drawing2D; 
using System.Drawing.Imaging; 
using System.Drawing; 
using System.IO; 
using System.Data.SqlClient; 
public partial class Curve_Default : System.Web.UI.Page 
{ 
protected void Page_Load(object sender, EventArgs e) 
{ 
if (!IsPostBack) 
{ 
Get_CurveData(); 
} 
} 
//获取数据 
public void Get_CurveData() 
{ 
SqlConnection conn = null; 
try 
{ 
conn = CommonFunction.CreateDBTest(); 
conn.Open(); 
SqlCommand cmd = conn.CreateCommand(); 
string sqlStr = "SELECT * FROM CURVE ORDER BY TESTDATE"; 
DataTable dt = CommonFunction.ExecuteDatable(conn, cmd, CommandType.Text, sqlStr, null); 
draw(dt); 
} 
catch (Exception exp) 
{ 
Response.Write(exp.Message); 
} 
finally 
{ 
if (conn != null) 
conn.Close(); 
} 
} 
public void draw(DataTable dt) 
{ 
//取得记录数量 
int count = dt.Rows.Count; 
//记算图表宽度 
int wd = 80 + 20 * (count - 1); 
//设置最小宽度为800 
if (wd < 600) wd = 600; 
//生成Bitmap对像 
Bitmap img = new Bitmap(wd, 400); 
//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); 
//定义大标题字体 
Font Bfont = new Font("Arial", 12, FontStyle.Bold); 
//定义一般字体 
Font font = new Font("Arial", 6); 
//定义大点的字体 
Font Tfont = new Font("Arial", 9); 
//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 - 100) / (count - 1); 
//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 = 30; 
//纵坐标最大值和间隔值 
int yMaxValue = 30; 
//绘制底色 
g.DrawRectangle(new Pen(Color.White, 400), 0, 0, img.Width, img.Height); 
//定义黑色过渡型笔刷 
LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, 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(0, 0, img.Width, img.Height), Color.Blue, Color.Blue, 1.2F, true); 
//绘制大标题 
g.DrawString("测试曲线图", Bfont, brush, 40, 5); 
//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, 0, 0, img.Width - 1, img.Height - 1); 
//绘制竖坐标轴 
g.DrawLine(Bp, 40, 55, 40, 360); 
//绘制横坐标轴 x2的60是右侧空出部分 
g.DrawLine(Bp, 40, 360, 60 + xSpace * (count - 1), 360); 
//绘制竖坐标标题 
g.DrawString("测试值", Tfont, brush, 5, 40); 
//绘制横坐标标题 
g.DrawString("测试时间", Tfont, brush, 40, 385); 
//绘制竖坐标线 
for (int i = 0; i < count; i++) 
{ 
g.DrawLine(Sp, 40 + xSpace * i, 60, 40 + xSpace * i, 360); 
} 
//绘制时间轴坐标标签 
for (int i = 0; i < count; i++) 
{ 
string st = Convert.ToDateTime(dt.Rows[i]["testdate"]).ToString("MM:dd"); 
g.DrawString(st, font, brush, 30 + xSpace * i, 370); 
} 
//绘制横坐标线 
for (int i = 0; i < 10; i++) 
{ 
g.DrawLine(Sp, 40, 60 + ySpace * i, 40 + xSpace * (count - 1), 60 + ySpace * i); 
//横坐标轴的值间隔是最大值除以间隔数 
int s = yMaxValue - i * (yMaxValue / 10); 
//绘制发送量轴坐标标签 
g.DrawString(s.ToString(), font, brush, 10, 60 + ySpace * i); 
} 
//定义纵坐标单位数值=纵坐标最大值/标量最大值（300/30） 
int yAveValue = 10; 
//定义曲线转折点 
Point[] p = new Point[count]; 
for (int i = 0; i < count; i++) 
{ 
p[i].X = 40 + xSpace * i; 
p[i].Y = 360 - Convert.ToInt32(dt.Rows[i]["testvalue"]) * 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); 
//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 = 0; i < count; i++) 
{ 
//绘制发送记录点的发送量 
g.DrawString(dt.Rows[i]["testvalue"].ToString(), 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); 
} 
//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()); 
} 
} 
数据表的内容很简单，就两个字段：testValue和testDate，由于图的纵坐标有最大值，所以testValue的值不能超过30，当然，你可以调整坐标轴的单位或者高度。 
12 2008-12-1 0:00:00 
9 2008-12-5 0:00:00 
20 2008-12-10 0:00:00 
18 2008-12-15 0:00:00 
27 2008-12-20 0:00:00 
8 2008-12-25 0:00:00 
15 2008-12-30 0:00:00 
25 2009-1-1 0:00:00 
23 2009-1-5 0:00:00