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