谁能帮我看看代码？C#代码，缩略图控件。帮我解释解释代码。谢谢啦！

[yunfeng6380]

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Design;
using System.ComponentModel;
using System.IO;
using System.Text;

#endregion

namespace Bright.WebControls
{
/// <summary>
/// Thumbnail Image Viewer Control缩略图

Viewer控件
/// </summary>
[ToolboxData("<{0}:ThumbViewer

runat=\"server\" ImageUrl=\"\" Title=\"\"

Width=\"100\" Height=\"100\" />")]
[ToolboxBitmap(typeof

(System.Web.UI.WebControls.Image))]
public class ThumbViewer :

System.Web.UI.WebControls.Image
{
#region Properties & Fields

#region Urls

private string _srcImageUrl;

[
Category("Appearance"),
Description("The URL of the image."),
DefaultValue(""),
Bindable(true)
]
public override string ImageUrl
{
get
{
return ViewState["ImageUrl"] ==

null ?
string.Empty : ViewState

["ImageUrl"].ToString();
}
set
{
ViewState["ImageUrl"] = value;
}
......