A Raw Serializer

/*
Copyright (c) 2005, Marc Clifton
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this list
  of conditions and the following disclaimer. 

* Redistributions in binary form must reproduce the above copyright notice, this 
  list of conditions and the following disclaimer in the documentation and/or other
  materials provided with the distribution. 
 
* Neither the name of MyXaml nor the names of its contributors may be
  used to endorse or promote products derived from this software without specific
  prior written permission. 

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

using System;
using System.ComponentModel;
using System.Reflection;
using System.Windows.Forms;

namespace Clifton.Tools.Data
{
	public class BindHelper : ISupportInitialize
	{
		protected bool immediateMode;
		protected object src;
		protected string srcProp;
		protected object dest;
		protected string destProp;

		protected PropertyInfo srcPropInfo;
		protected PropertyInfo destPropInfo;

		public bool ImmediateMode
		{
			get {return immediateMode;}
			set {immediateMode=value;}
		}

		public object Source
		{
			get {return src;}
			set {src=value;}
		}

		public string SourceProperty
		{
			get {return srcProp;}
			set {srcProp=value;}
		}

		public object Destination
		{
			get {return dest;}
			set {dest=value;}
		}

		public string DestinationProperty
		{
			get {return destProp;}
			set {destProp=value;}
		}

		public BindHelper()
		{
			immediateMode=false;
		}

		public void BeginInit()
		{
		}

		public void EndInit()
		{
			Type t1=src.GetType();
			Type t2=dest.GetType();

			// Get the PropertyInfo now rather than in the event handler.
			srcPropInfo=t1.GetProperty(srcProp);
			destPropInfo=t2.GetProperty(destProp);

			Bind(src, srcProp, dest, destProp);
		}

		protected void Bind(object obj1, string prop1, object obj2, string prop2)
		{
			string event1=prop1+"Changed";
			string event2=prop2+"Changed";

			Type t1=obj1.GetType();
			Type t2=obj2.GetType();

			EventInfo ei1=t1.GetEvent(event1);
			EventInfo ei2=t2.GetEvent(event2);

			// The signature of the event delegate must be of the form (object, EventArgs).
			// Although events don't have to be of this signature, this is a good reason
			// to comply with the .NET guidelines.

			// Unfortunately, .NET 1.1 does not handle event signatures that are derived from
			// EventArgs when programatically adding a generic handler.  This "bug"
			// is corrected in .NET 2.0!

			ei1.AddEventHandler(obj1, new EventHandler(SourceChanged));
			ei2.AddEventHandler(obj2, new EventHandler(DestinationChanged));

			DestinationChanged(this, EventArgs.Empty);

			// don't update the data until the user leaves the control.
			if (obj1 is Control)
			{
				((Control)obj1).Leave+=new EventHandler(OnLeave);
			}
		}

		private void SourceChanged(object sender, EventArgs e)
		{
			// Don't update the data until the user leaves the control.
			if ( (src is Control) && (!immediateMode) )
			{
				if (((Control)src).Focused)
				{
					// As long as the control has focus, don't update the container.
					// However, if the control does not have focus but the control value
					// changes, then we DO want to update the container.  This fixes
					// a bug in the .NET implementation of data binding, if something
					// programatically changes the control value that we're bound to.
					return;
				}
			}

			object val=srcPropInfo.GetValue(src, null);
			val=Converter.Convert(val, destPropInfo.PropertyType);
			destPropInfo.SetValue(dest, val, null);
		}

		private void DestinationChanged(object sender, EventArgs e)
		{
			object val=destPropInfo.GetValue(dest, null);
			val=Converter.Convert(val, srcPropInfo.PropertyType);
			srcPropInfo.SetValue(src, val, null);
		}

		private void OnLeave(object sender, EventArgs e)
		{
			if (!immediateMode)
			{
				object val=srcPropInfo.GetValue(src, null);
				val=Converter.Convert(val, destPropInfo.PropertyType);
				destPropInfo.SetValue(dest, val, null);
			}
		}
	}
}