GtkSharp/glib/ManagedValue.cs

// GLib.ManagedValue.cs : Managed types boxer
//
// Author: Rachel Hestilow <hestilow@ximian.com>
//
// Copyright (c) 2002 Rachel Hestilow
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of version 2 of the Lesser GNU General 
// Public License as published by the Free Software Foundation.
//
// This program 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 program; if not, write to the
// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.


namespace GLib {
	using System;
	using System.Collections;
	using System.Runtime.InteropServices;
	using GLib;
	
	internal class ManagedValue {
		
		[CDeclCallback]
		delegate IntPtr CopyFunc (IntPtr gch);
		[CDeclCallback]
		delegate void FreeFunc (IntPtr gch);
		
		static CopyFunc copy;
		static FreeFunc free;
		static GType boxed_type = GType.Invalid;

		[DllImport("libgobject-2.0-0.dll")]
		static extern IntPtr g_boxed_type_register_static (IntPtr typename, CopyFunc copy_func, FreeFunc free_func);
		
		public static GType GType {
			get {
				if (boxed_type == GType.Invalid) {
					copy = new CopyFunc (Copy);
					free = new FreeFunc (Free);
				
					IntPtr name = Marshaller.StringToPtrGStrdup ("GtkSharpValue");
					boxed_type = new GLib.GType (g_boxed_type_register_static (name, copy, free));
					Marshaller.Free (name);
				}

				return boxed_type;
			}
		}
		
		static IntPtr Copy (IntPtr ptr)
		{
			try {
				if (ptr == IntPtr.Zero)
					return ptr;
				GCHandle gch = (GCHandle) ptr;
				return (IntPtr) GCHandle.Alloc (gch.Target);
			} catch (Exception e) {
				ExceptionManager.RaiseUnhandledException (e, false);
			}

			return IntPtr.Zero;
		}

		static void Free (IntPtr ptr)
		{
			try {
				if (ptr == IntPtr.Zero)
					return;
				GCHandle gch = (GCHandle) ptr;
				gch.Free ();
			} catch (Exception e) {
				ExceptionManager.RaiseUnhandledException (e, false);
			}
		}

		public static IntPtr WrapObject (object obj)
		{
			if (obj == null)
				return IntPtr.Zero;
			return (IntPtr) GCHandle.Alloc (obj);
		}

		public static object ObjectForWrapper (IntPtr ptr)
		{
			if (ptr == IntPtr.Zero)
				return null;
			return ((GCHandle)ptr).Target;
		}

		public static void ReleaseWrapper (IntPtr ptr)
		{
			if (ptr == IntPtr.Zero)
				return;

			((GCHandle)ptr).Free ();
		}
	}
}