页面范例2 - 定时更新多个统计图

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
this.Image1.ImageUrl = "DrawLine1.ashx";
this.Image2.ImageUrl = "DrawLine2.ashx";
this.Image3.ImageUrl = "DrawLine3.ashx";
this.Image4.ImageUrl = "DrawLine4.ashx";
this.Image5.ImageUrl = "DrawLine5.ashx";
this.Image6.ImageUrl = "DrawLine6.ashx";
}
}

protected void Timer1_Tick(object sender, EventArgs e)
{
this.Image1.ImageUrl = "DrawLine1.ashx";
this.Image2.ImageUrl = "DrawLine2.ashx";
this.Image3.ImageUrl = "DrawLine3.ashx";
this.Image4.ImageUrl = "DrawLine4.ashx";
this.Image5.ImageUrl = "DrawLine5.ashx";
this.Image6.ImageUrl = "DrawLine6.ashx";
}

<%@ WebHandler Language="C#" Class="DrawLine1" %>
 
using System;
using System.Web;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Drawing.Imaging;
 
public class DrawLine1 : IHttpHandler 
{    
 public void ProcessRequest (HttpContext context) 
 {
  List<Point> points = GetPointArray1();
 
  using (Bitmap ChartingImage = new Bitmap(320, 240))
 
 {
   using (Graphics g = Graphics.FromImage(ChartingImage))
   {
    // 指定使用平滑化处理（又称为反锯齿功能）。
    g.SmoothingMode = SmoothingMode.AntiAlias;
    g.FillRectangle(new LinearGradientBrush(new Rectangle(0, 0, 320, 240), 
      Color.DeepPink, Color.YellowGreen, LinearGradientMode.Vertical), 
      new Rectangle(0, 0, 320, 240));
 
    using (Pen p = new Pen(Color.Yellow, 2))
    {
     if (points.Count > 1)
     {
      int startX = points[0].X;
      int startY = points[0].Y;
 
     for (int i = 1; i < points.Count; i++)
      {
       g.DrawLine(p, startX, startY, points[i].X, points[i].Y);
       startX = points[i].X;
       startY = points[i].Y;
      }
      g.DrawString("深圳A股：" + 
        Convert.ToString(240 - points[points.Count - 1].Y), 
        new Font("标楷体", 20), Brushes.Yellow, 0, 0);
     }
    }
    context.Response.ContentType = "Image/png";
    context.Response.Cache.SetNoStore();
    context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
    context.Response.Cache.SetExpires(DateTime.Now);
    context.Response.Cache.SetValidUntilExpires(false);
    using (MemoryStream ms = new MemoryStream())
    {
        ChartingImage.Save(ms, ImageFormat.Png);
        ms.Flush();
        context.Response.BinaryWrite(ms.GetBuffer());
    }
   }
  }
 }
 private List<Point> GetPointArray1()
 {
  List<Point> Points = (List<Point>)(HttpContext.Current.Cache["PointArray1"]);
  if (Points == null)
  {
   Points = new List<Point>();
   Points.Add(new Point(0, 120));  // 添加第一个坐标点 (0, 120)。
   HttpContext.Current.Cache["X1"] = 0;
   HttpContext.Current.Cache["Y1"] = 120;
  }
  Random r = new Random();
  int x = Convert.ToInt32(HttpContext.Current.Cache["X1"]) + 10;
  int y = Convert.ToInt32(HttpContext.Current.Cache["Y1"]);
  if (x == 320)
  {
   x = 0;
   y = 120;
   Points.Clear();
  }
  if (y % 2 == 0)
  {
   y += r.Next(0, 11);
  }
  else
  {
   y -= r.Next(0, 11);
  }
  Points.Add(new Point(x, y));
  HttpContext.Current.Cache["PointArray1"] = Points;
  HttpContext.Current.Cache["X1"] = x;
  HttpContext.Current.Cache["Y1"] = y;
  return Points;
 }
 
 ...
}