C#编程

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RainbowLabel.cs：源码内容

							using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;
using System.Drawing;
namespace PCSCustomWebControls
{
   public class RainbowLabel : System.Web.UI.WebControls.Label
   {
      private Color[] colors = new Color[] {Color.Red, Color.Orange,
                                              Color.Yellow,
                                              Color.GreenYellow,
                                              Color.Blue, Color.Indigo,
                                              Color.Violet};
      private int offset
      {
         get
         {
            object rawOffset = ViewState["_offset"];
            if (rawOffset != null)
            {
               return (int)rawOffset;
            }
            else
            {
               ViewState["_offset"] = 0;
               return 0;
            }
         }
         set
         {
            ViewState["_offset"] = value;
         }
      }
      protected override void Render(HtmlTextWriter output)
      {
         string text = Text;
         for (int pos=0; pos < text.Length; pos++)
         {
            int rgb = colors[(pos + offset) % colors.Length].ToArgb()
               & 0xFFFFFF;
            output.Write("<font color='#" + rgb.ToString("X6") + "'>"
               + text[pos] + "</font>");
         }
      }
      public void Cycle()
      {
         offset = ++offset; 
      }
   }
}

						