Associated Icons Image Control

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;

namespace AssociatedIcons.Controls
{
	[ToolboxData("<{0}:AssociatedIcon runat=server></{0}:AssociatedIcon>")]
	public class AssociatedIcon : Image
	{
		/*****
		 * This control accepts a file name or file extension,
		 * determines the associated icon, and displays it on the page
		 * ***/
	
		/// <summary>
		/// Gets or sets a file name or extension (including the dot)
		/// to display the associated icon
		/// </summary>
		public string ExtensionOrFile
		{
			get
			{
				string s = (string)ViewState["ExtensionOrFile"];
				if(s == null) return "";
				return s;
			} 
			set{ ViewState["ExtensionOrFile"] = value; } 
		}

		/// <summary>
		/// Determines if the icon size will be 16x16 or 32x32 pixels
		/// </summary>
		public bool LargeIcon
		{
			get
			{
				object obj = ViewState["LargeIcon"];
				if(obj == null) return false;
				return (bool)obj;
			} 
			set
			{
				ViewState["LargeIcon"] = value;
			}
		}

		public override string ImageUrl
		{
			get{ return base.ImageUrl;}
			set{ throw new InvalidOperationException("The ImageUrl cannot be set.");}
		}

		protected override void OnLoad(EventArgs e)
		{
			if(!Page.IsPostBack)
				base.ImageUrl = IconExtractor.GetUrlToIcon(ExtensionOrFile, LargeIcon);
		}


	}
}