1 files changed, 111 insertions, 0 deletions
diff --git a/gstreamer-sharp/glib-sharp/DelegateWrapper.cs b/gstreamer-sharp/glib-sharp/DelegateWrapper.cs
new file mode 100644
index 0000000..841d554
--- /dev/null
+++ b/gstreamer-sharp/glib-sharp/DelegateWrapper.cs
@@ -0,0 +1,111 @@
+// DelegateWrapper.cs - Delegate wrapper implementation
+//
+// Authors:
+// 	Rachel Hestilow <hestilow@ximian.com>
+// 	Gonzalo Panigua Javier <gonzalo@ximian.com>
+//
+// Copyright (c) 2002 Rachel Hestilow
+// Copyright (c) 2003 Ximian, Inc.
+//
+// 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;
+
+	public class DelegateWrapper
+	{
+		// Keys in the hashtable are instances of classes derived from this one.
+		// Values are each instance's destroy notification delegate
+		static Hashtable instances = new Hashtable ();
+
+		// This list holds references to wrappers for static
+		// methods. These will never expire.
+		static ArrayList static_instances = new ArrayList ();
+
+		static int notify_count = 0;
+		
+		// The object 'o' is the object that creates the instance of the DelegateWrapper
+		// derived class or null if created from a static method.
+		// Note that the instances will never be disposed if they are created in a static
+		// method.
+		[Obsolete ("Callback wrappers should be manually managed for persistence.")]
+		protected DelegateWrapper (object o)
+		{
+			if (o != null) {
+				// If o is a GObject, we can get
+				// destroy notification. Otherwise
+				// no additional references to
+				// the wrapper are kept.
+				// FIXME: This should work because
+				// currently only GObjects store
+				// callbacks over the long-term
+
+				if (o is GLib.Object) {
+					AddDestroyNotify ((GLib.Object) o);
+				}
+			} else {
+				// If o is null, we cannot ask for a destroy
+				// notification, so the wrapper never expires.
+
+				lock (typeof (DelegateWrapper)) {
+					static_instances.Add (this);
+				}
+			}
+		}
+
+		[UnmanagedFunctionPointer (CallingConvention.Cdecl)]
+		private delegate void DestroyNotify (IntPtr data);
+
+		[DllImport("libgobject-2.0-0.dll")]
+		private static extern void g_object_set_data_full (IntPtr obj, IntPtr name, IntPtr data, DestroyNotify destroy);
+		
+		private void AddDestroyNotify (GLib.Object o) {
+			// This is a bit of an ugly hack. There is no
+			// way of getting a destroy notification
+			// explicitly, so we set some data and ask
+			// for notification when it is removed
+
+			IntPtr name = Marshaller.StringToPtrGStrdup (String.Format ("_GtkSharpDelegateWrapper_{0}", notify_count));
+			DestroyNotify destroy = new DestroyNotify (this.OnDestroy);
+
+			g_object_set_data_full (o.Handle, name, IntPtr.Zero, destroy);
+			Marshaller.Free (name);
+			lock (typeof (DelegateWrapper)) {
+				instances[this] = destroy;
+				notify_count++;
+			}
+		}
+
+		// This callback is invoked by GLib to indicate that the
+		// object that owned the native delegate wrapper no longer
+		// exists and the instance of the delegate itself is removed from the hash table.
+		private void OnDestroy (IntPtr data) {
+			try {
+				lock (typeof (DelegateWrapper)) {
+					if (instances.ContainsKey (this)) {
+						instances.Remove (this);
+					}
+				}
+			} catch (Exception e) {
+				ExceptionManager.RaiseUnhandledException (e, false);
+			}
+		}
+	}
+}
+