Excel-DNA#124 Unhook from LOCATIONCHANGE upon MOVESIZESTART and hook again upon MOVESIZEEND

Author: sshukurov

Source/ExcelDna.IntelliSense/UIMonitor/WindowWatcher.cs

@@ -117,7 +117,11 @@ internal WindowChangedEventArgs(IntPtr windowHandle, WinEventHook.WinEvent winEv
         const string _nuiDialogClass = "NUIDialog";
         const string _selectDataSourceTitle = "Select Data Source";     // TODO: How does localization work?
 
+        private readonly SynchronizationContext _syncContextAuto;
+        private readonly SynchronizationContext _syncContextMain;
+
         List<WinEventHook> _windowStateChangeHooks = new List<WinEventHook>();
+        private WinEventHook _locationChangeEventHook;
 
         // These track keyboard focus for Windows in the Excel process
         // Used to synthesize the 'Unfocus' change events
@@ -138,6 +142,9 @@ internal WindowChangedEventArgs(IntPtr windowHandle, WinEventHook.WinEvent winEv
 
         public WindowWatcher(SynchronizationContext syncContextAuto, SynchronizationContext syncContextMain)
         {
+            _syncContextAuto = syncContextAuto;
+            _syncContextMain = syncContextMain;
+
 #pragma warning disable CS0618 // Type or member is obsolete (GetCurrentThreadId) - But for debugging we want to monitor this anyway
             // Debug.Print($"### WindowWatcher created on thread: Managed {Thread.CurrentThread.ManagedThreadId}, Native {AppDomain.GetCurrentThreadId()}");
 #pragma warning restore CS0618 // Type or member is obsolete
@@ -164,6 +171,14 @@ public WindowWatcher(SynchronizationContext syncContextAuto, SynchronizationCont
             {
                 windowStateChangeHook.WinEventReceived += _windowStateChangeHook_WinEventReceived;
             }
+
+            SetUpLocationChangeEventListener();
+        }
+
+        private void SetUpLocationChangeEventListener()
+        {
+            _locationChangeEventHook = new WinEventHook(WinEventHook.WinEvent.EVENT_OBJECT_LOCATIONCHANGE, WinEventHook.WinEvent.EVENT_OBJECT_LOCATIONCHANGE, _syncContextAuto, _syncContextMain, IntPtr.Zero);
+            _locationChangeEventHook.WinEventReceived += _windowStateChangeHook_WinEventReceived;
         }
 
         // Runs on the Automation thread (before syncContextAuto starts pumping)
@@ -224,6 +239,17 @@ void _windowStateChangeHook_WinEventReceived(object sender, WinEventHook.WinEven
             {
                 Debug.Fail("WinEvent with window 0!?");
             }
+
+            if (e.EventType == WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZESTART)
+            {
+                _syncContextMain.Post(_ => _locationChangeEventHook.Dispose(), null);
+            }
+
+            if (e.EventType == WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZEEND)
+            {
+                _syncContextMain.Post(_ => SetUpLocationChangeEventListener(), null);
+            }
+
             if (e.EventType == WinEventHook.WinEvent.EVENT_OBJECT_FOCUS)
             {
                 // Might raise change event for Unfocus
@@ -322,6 +348,7 @@ public void Dispose()
             }
 
             _windowStateChangeHooks = new List<WinEventHook>();
+            _locationChangeEventHook.Dispose();
         }
     }