Magic AJAX: Applying AJAX to your existing Web Pages

#region LGPL License
/*
MagicAjax.NET Framework
Copyright (C) 2005  MagicAjax Project Team

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#endregion

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

namespace MagicAjax.UI
{
	/// <summary>
	///	The base control for controls to get notified for AjaxCall events from the client.
	/// </summary>
	public abstract class AjaxControl : System.Web.UI.WebControls.WebControl, IAjaxCallEventHandler, IPreWriteScriptEventHandler
	{
		private MagicAjaxContext _magicAjaxContext;
		private bool _isAjaxCall;
		private bool _isPageNoStoreMode;
		private bool _isInAjaxScope;

		/// <summary>
		/// Raised by the MagicAjaxModule and at Load event during an AjaxCall.
		/// </summary>
		public event EventHandler AjaxCallStart;

		/// <summary>
		/// Raised by the MagicAjaxModule and at PreRender event during an AjaxCall.
		/// </summary>
		public event EventHandler PreWriteScript;

		/// <summary>
		/// Raised by the MagicAjaxModule and at Unload event during an AjaxCall.
		/// </summary>
		public event EventHandler AjaxCallEnd;

		/// <summary>
		/// Implements the IAjaxCallEventHandler interface. It is called by the MagicAjaxModule.
		/// </summary>
		public void RaiseAjaxCallStartEvent()
		{
			SetAjaxIntrinsics();
			OnAjaxCallStart(EventArgs.Empty);
		}

		/// <summary>
		/// Implements the IPreWriteScriptEventHandler interface. It is called by the MagicAjaxModule.
		/// </summary>
		public void RaisePreWriteScriptEvent()
		{
			OnPreWriteScript (EventArgs.Empty);
		}

		/// <summary>
		/// Implements the IAjaxCallEventHandler interface. It is called by the MagicAjaxModule.
		/// </summary>
		public void RaiseAjaxCallEndEvent()
		{
			OnAjaxCallEnd(EventArgs.Empty);
		}

		[Browsable(false),DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
		public bool IsPageNoStoreMode
		{
			get { return _isPageNoStoreMode; }
		}

		/// <summary>
		/// Determines if the control is being processed during an AjaxCall.
		/// </summary>
		[Browsable(false),DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
		public bool IsAjaxCall
		{
			get { return _isAjaxCall; } 
		}

		[Browsable(false),DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
		public bool IsInAjaxScope
		{
			get { return _isInAjaxScope; }
		}

		public AjaxControl()
		{
		}
		public AjaxControl(HtmlTextWriterTag tag) : base(tag)
		{
		}

		protected MagicAjaxContext MagicAjaxContext
		{
			get { return _magicAjaxContext; }
		}

		protected override void OnLoad(EventArgs e)
		{
			SetAjaxIntrinsics();

			base.OnLoad (e);
			if ( IsAjaxCall )
				OnAjaxCallStart (e);
		}

		protected override void OnPreRender(EventArgs e)
		{
			// Register 'AjaxCallObject.js' script
			MagicAjaxModule.EnableAjaxOnPage(this.Page);

#if NET_2_0
			// add WebPartManager script (AddWebPartClientFunctions will check if this page is a WebPartPage)
			MagicAjaxModule.AddWebPartClientFunctions(this.Page);
#endif

			base.OnPreRender (e);
			if ( IsAjaxCall )
				OnPreWriteScript (e);
		}

		protected override void AddAttributesToRender(HtmlTextWriter writer)
		{
			base.AddAttributesToRender (writer);
			AddAjaxAttributesToRender (writer);
		}

		protected override void OnUnload(EventArgs e)
		{
			base.OnUnload (e);
			if ( IsAjaxCall )
				OnAjaxCallEnd (e);
		}

		protected virtual void OnAjaxCallStart(EventArgs e)
		{
			if (AjaxCallStart != null)
				AjaxCallStart(this, e);
		}
		
		protected virtual void OnPreWriteScript(EventArgs e)
		{
			if (PreWriteScript != null)
				PreWriteScript(this, e);
		}

		protected virtual void OnAjaxCallEnd(EventArgs e)
		{
			_magicAjaxContext = null;

			if (AjaxCallEnd != null)
				AjaxCallEnd(this, e);
		}

		protected virtual void SetAjaxIntrinsics()
		{
			_magicAjaxContext = MagicAjaxContext.Current;
			_isAjaxCall = ( HttpContext.Current != null && this.Page != null && MagicAjaxContext.Current.IsAjaxCallForPage(this.Page) );
			_isPageNoStoreMode = ( HttpContext.Current != null && MagicAjaxContext.Current.IsPageNoStoreMode );

			string ajaxScopeID = Context.Request.Form["__AJAXSCOPE"];
			_isInAjaxScope = ( ajaxScopeID == null || IsInAjaxScopeRecursive(this, ajaxScopeID) );
		}

		/// <summary>
		/// It is empty for the AjaxControl class. It is meant to be overriden
		/// by subclasses so that they render their MagicAjax attributes.
		/// </summary>
		protected virtual void AddAjaxAttributesToRender (HtmlTextWriter writer)
		{
		}

		private bool IsInAjaxScopeRecursive (Control control, string ajaxScopeID)
		{
			if (control.ClientID == ajaxScopeID)
				return true;

			if (control.Parent == null || control.Parent == control.Page)
				return false;

			return IsInAjaxScopeRecursive(control.Parent, ajaxScopeID);
		}
	}
}