DHTML Tree View of Arbitrary Depth using AJAX

// Copyright (c)2005 Rewritten Software.  http://www.rewrittensoftware.com
// This script is supplied "as is" without any form of warranty. Rewritten Software 
// shall not be liable for any loss or damage to person or property as a result of using this script.
// Use this script at your own risk!
// You are licensed to use this script free of charge for commercial or non-commercial use providing you do not remove 
// the copyright notice or disclaimer.

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace WebApplication1
{
	/// <summary>
	/// Responder for child nodes
	/// </summary>
	public class TreeFill : System.Web.UI.Page
	{
		private void Page_Load(object sender, System.EventArgs e)
		{
			// Put user code to initialize the page here
		}

		/// <summary>
		/// Render the nodes attached to a node at a specific level in the tree
		/// </summary>
		/// <param name="writer"></param>
		protected override void Render(HtmlTextWriter writer)
		{
			string treeID = Request["tree"];
			if (treeID == null)
				throw new HttpException("Tree identifier not found in request during delay load.");

			Tree tree = (Tree)Session["tree" + treeID];
			if (tree == null)
				throw new HttpException("Tree was not found in session during delay load.");

			string nodeID = Request["id"];
			if (nodeID == null)
				throw new HttpException("Node id null in delay load.");
        
			// Locate and output the requested node
			bool found = false;
			OutputTreeNode(nodeID, treeID, writer, tree.Root, ref found);
		}
    
		/// <summary>
		/// Recursive: Search the tree for the relevant node and output its children
		/// </summary>
		/// <param name="nodeID">parent node id</param>
		/// <param name="treeID">id of this tree</param>
		/// <param name="writer">output writer</param>
		/// <param name="node">starting node</param>
		/// <param name="found">found yet or not</param>
		void OutputTreeNode(string nodeID, string treeID, HtmlTextWriter writer, TreeNode node, ref bool found)
		{
			// We found the node, output its children, and stop.
			if (nodeID == node.ID)
			{
				foreach (TreeNode child in node.Children)
					child.WriteNode(writer, treeID, true);
				found = true;
				return;
			}

			// Not found yet, search children for the node.
			if (!found)
				foreach (TreeNode child in node.Children)
					OutputTreeNode(nodeID, treeID, writer, child, ref found);
		}

		#region Web Form Designer generated code
		override protected void OnInit(EventArgs e)
		{
			//
			// CODEGEN: This call is required by the ASP.NET Web Form Designer.
			//
			InitializeComponent();
			base.OnInit(e);
		}
		
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{    
			this.Load += new System.EventHandler(this.Page_Load);
		}
		#endregion
	}
}