class/System.Windows/Mono/ToggleRef.cs

   1 //
   2 // ToggleRef.cs
   3 //
   4 // Contact:
   5 //   Moonlight List (moonlight-list@lists.ximian.com)
   6 //
   7 // Copyright 2009 Novell, Inc.
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System;
  30 using System.Runtime.InteropServices;
  31 using System.Collections.Generic;
  32
  33 namespace Mono
  34 {
  35         internal sealed class ToggleRef
  36         {
  37                 IntPtr handle;
  38                 object reference;
  39                 GCHandle gch;
  40
  41                 public ToggleRef (INativeEventObjectWrapper target)
  42                 {
  43                         handle = target.NativeHandle;
  44                         gch = GCHandle.Alloc (this);
  45                         reference = target;
  46                 }
  47
  48                 public void Initialize () {
  49                         NativeMethods.event_object_add_toggle_ref_notifier (handle, ToggleNotifyCallback);
  50                 }
  51
  52                 public bool IsAlive {
  53                         get {
  54                                 if (reference is WeakReference) {
  55                                         WeakReference weak = reference as WeakReference;
  56                                         return weak.IsAlive;
  57                                 } else if (reference == null)
  58                                         return false;
  59                                 return true;
  60                         }
  61                 }
  62
  63                 public IntPtr Handle {
  64                         get {
  65                                 return handle;
  66                         }
  67                 }
  68
  69                 public INativeEventObjectWrapper Target {
  70                         get {
  71                                 if (reference == null)
  72                                         return null;
  73                                 else if (reference is INativeEventObjectWrapper)
  74                                         return reference as INativeEventObjectWrapper;
  75
  76                                 WeakReference weak = reference as WeakReference;
  77                                 return weak.Target as INativeEventObjectWrapper;
  78                         }
  79                 }
  80
  81                 public void Free ()
  82                 {
  83                         NativeMethods.event_object_remove_toggle_ref_notifier (handle);
  84                         reference = null;
  85                         gch.Free ();
  86                 }
  87
  88                 void Toggle (bool isLastRef)
  89                 {
  90                         if (isLastRef && reference is INativeEventObjectWrapper)
  91                                 reference = new WeakReference (reference);
  92                         else if (!isLastRef && reference is WeakReference) {
  93                                 WeakReference weak = reference as WeakReference;
  94                                 if (weak.IsAlive)
  95                                         reference = weak.Target;
  96                         }
  97                 }
  98
  99                 internal delegate void ToggleNotifyHandler (IntPtr obj, bool isLastref);
 100
 101                 static void RefToggled (IntPtr obj, bool isLastRef)
 102                 {
 103                         try {
 104                                 ToggleRef tref = null;
 105                                 NativeDependencyObjectHelper.objects.TryGetValue (obj, out tref);
 106                                 if (tref != null)
 107                                         tref.Toggle (isLastRef);
 108                         } catch (Exception e) {
 109                                 //ExceptionManager.RaiseUnhandledException (e, false);
 110                                 Console.WriteLine (e);
 111                         }
 112                 }
 113
 114                 static ToggleNotifyHandler toggle_notify_callback;
 115                 static ToggleNotifyHandler ToggleNotifyCallback {
 116                         get {
 117                                 if (toggle_notify_callback == null)
 118                                         toggle_notify_callback = new ToggleNotifyHandler (RefToggled);
 119                                 return toggle_notify_callback;
 120                         }
 121                 }
 122         }
 123 }