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111 lines
3.6 KiB
C#
111 lines
3.6 KiB
C#
// DelegateWrapper.cs - Delegate wrapper implementation
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//
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// Authors:
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// Rachel Hestilow <hestilow@ximian.com>
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// Gonzalo Panigua Javier <gonzalo@ximian.com>
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//
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// Copyright (c) 2002 Rachel Hestilow
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// Copyright (c) 2003 Ximian, Inc.
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of version 2 of the Lesser GNU General
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// Public License as published by the Free Software Foundation.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this program; if not, write to the
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// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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// Boston, MA 02111-1307, USA.
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namespace Gst.GLib {
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using System;
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using System.Collections;
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using System.Runtime.InteropServices;
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public class DelegateWrapper
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{
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// Keys in the hashtable are instances of classes derived from this one.
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// Values are each instance's destroy notification delegate
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static Hashtable instances = new Hashtable ();
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// This list holds references to wrappers for static
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// methods. These will never expire.
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static ArrayList static_instances = new ArrayList ();
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static int notify_count = 0;
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// The object 'o' is the object that creates the instance of the DelegateWrapper
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// derived class or null if created from a static method.
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// Note that the instances will never be disposed if they are created in a static
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// method.
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[Obsolete ("Callback wrappers should be manually managed for persistence.")]
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protected DelegateWrapper (object o)
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{
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if (o != null) {
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// If o is a GObject, we can get
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// destroy notification. Otherwise
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// no additional references to
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// the wrapper are kept.
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// FIXME: This should work because
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// currently only GObjects store
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// callbacks over the long-term
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if (o is Gst.GLib.Object) {
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AddDestroyNotify ((Gst.GLib.Object) o);
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}
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} else {
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// If o is null, we cannot ask for a destroy
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// notification, so the wrapper never expires.
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lock (typeof (DelegateWrapper)) {
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static_instances.Add (this);
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}
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}
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}
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[UnmanagedFunctionPointer (CallingConvention.Cdecl)]
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private delegate void DestroyNotify (IntPtr data);
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[DllImport("libgobject-2.0-0.dll")]
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private static extern void g_object_set_data_full (IntPtr obj, IntPtr name, IntPtr data, DestroyNotify destroy);
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private void AddDestroyNotify (Gst.GLib.Object o) {
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// This is a bit of an ugly hack. There is no
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// way of getting a destroy notification
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// explicitly, so we set some data and ask
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// for notification when it is removed
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IntPtr name = Marshaller.StringToPtrGStrdup (String.Format ("_GtkSharpDelegateWrapper_{0}", notify_count));
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DestroyNotify destroy = new DestroyNotify (this.OnDestroy);
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g_object_set_data_full (o.Handle, name, IntPtr.Zero, destroy);
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Marshaller.Free (name);
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lock (typeof (DelegateWrapper)) {
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instances[this] = destroy;
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notify_count++;
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}
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}
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// This callback is invoked by GLib to indicate that the
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// object that owned the native delegate wrapper no longer
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// exists and the instance of the delegate itself is removed from the hash table.
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private void OnDestroy (IntPtr data) {
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try {
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lock (typeof (DelegateWrapper)) {
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if (instances.ContainsKey (this)) {
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instances.Remove (this);
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}
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}
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} catch (Exception e) {
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ExceptionManager.RaiseUnhandledException (e, false);
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}
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}
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}
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}
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