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

namespace RolloverButton
{
	/// <summary>
	/// Summary description for WebCustomControl1.
	/// </summary>
	[DefaultProperty("ImageUrl"),
		ToolboxData("<{0}:RollOver runat=server></{0}:RollOver>")]
	public class RollOver : System.Web.UI.WebControls.LinkButton
	{
		[Bindable(true),
			Category("Appearance"),
			DefaultValue(""),
			Description("Specifies the image url for the button when in its normal state.")]
		public string ImageUrl
		{
			get
			{
				object o = ViewState["RollOverImageUrl"];
				if (o != null)
					return (string) o;
				else
					return String.Empty;
			}

			set
			{
				ViewState["RollOverImageUrl"] = value;
			}
		}

		[Bindable(true),
		Category("Appearance"),
		DefaultValue(""),
		Description("Specifies the image url for the button when the mouse is hovered above the button.")]
		public string RollOverImageUrl
		{
			get
			{
				object o = ViewState["RollOverRollOverImageUrl"];
				if (o != null)
					return (string) o;
				else
					return String.Empty;
			}

			set
			{
				ViewState["RollOverRollOverImageUrl"] = value;
			}
		}



		protected override void OnPreRender(EventArgs e)
		{
			// Register the client-side script.  See this article for more info on adding client-side
			// script from an ASP.NET server control:
			// http://msdn.microsoft.com/asp.net/using/understanding/aspnet/default.aspx?pull=/library/en-us/dnaspp/html/aspnet-injectclientsidesc.asp

			string imageLoadScriptKey = "rolloverImageBuildingCode" + this.ClientID;
			string script = 
				@"<script language=""JavaScript"">
					<!--
						" + this.ClientID + "_img_out = new Image(); " +
						this.ClientID + @"_img_out.src = """ + this.ImageUrl + @""";
						" + this.ClientID + "_img_over = new Image(); " +
						this.ClientID + @"_img_over.src = """ + this.RollOverImageUrl + @""";
					// -->
				  </script>";
			Page.RegisterClientScriptBlock(imageLoadScriptKey, script);

			this.Attributes["onmouseover"] = "rolloverServerControl_display('" + this.ClientID + "_img'," + this.ClientID + "_img_over);";
			this.Attributes["onmouseout"] = "rolloverServerControl_display('" + this.ClientID + "_img'," + this.ClientID + "_img_out);";

			const string displayScriptKey = "rolloverImageLoadScript";
			if (!Page.IsClientScriptBlockRegistered(displayScriptKey))
			{
				script = @"<script language=""JavaScript"">
				<!--
					function rolloverServerControl_display(imgName, imgUrl) {
						if (document.images && typeof imgUrl != 'undefined')
							document[imgName].src = imgUrl.src;
					}
				// -->
				</script>";

				Page.RegisterClientScriptBlock(displayScriptKey, script);
			}				
			
			base.OnPreRender (e);
		}


		protected override void RenderContents(HtmlTextWriter writer)
		{
			if (this.ImageUrl != String.Empty)
			{
				Image myImage = new Image();
				myImage.Attributes["name"] = this.ClientID + "_img";
				myImage.ImageUrl = this.ImageUrl;
				myImage.AlternateText = this.Text;
				myImage.Height = this.Height;
				myImage.Width = this.Width;
				myImage.ToolTip = this.ToolTip;
				myImage.RenderControl(writer);
			}
			else
				base.RenderContents (writer);
		}


	}
}