#124 Move location change hook registration to WindowLocationWatcher

Author: sshukurov

Source/ExcelDna.IntelliSense/UIMonitor/WindowLocationWatcher.cs

@@ -9,7 +9,8 @@ public class WindowLocationWatcher : IDisposable
         IntPtr _hWnd;
         SynchronizationContext _syncContextAuto;
         SynchronizationContext _syncContextMain;
-        WinEventHook _windowLocationChangeHook;
+        WinEventHook _windowMoveSizeHook;
+        WinEventHook _locationChangeEventHook;
 
         public event EventHandler LocationChanged;
 
@@ -22,26 +23,63 @@ public WindowLocationWatcher(IntPtr hWnd, SynchronizationContext syncContextAuto
             _hWnd = hWnd;
             _syncContextAuto = syncContextAuto;
             _syncContextMain = syncContextMain;
-            _windowLocationChangeHook = new WinEventHook(WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZESTART, WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZEEND, _syncContextAuto, syncContextMain, _hWnd);
-            _windowLocationChangeHook.WinEventReceived += _windowLocationChangeHook_WinEventReceived;
+            _windowMoveSizeHook = new WinEventHook(WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZESTART, WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZEEND, _syncContextAuto, syncContextMain, _hWnd);
+            _windowMoveSizeHook.WinEventReceived += _windowMoveSizeHook_WinEventReceived;
+
+            SetUpLocationChangeEventListener();
         }
 
-        void _windowLocationChangeHook_WinEventReceived(object sender, WinEventHook.WinEventArgs winEventArgs)
+        void SetUpLocationChangeEventListener()
+        {
+            // NB: Including the next event 'EVENT_OBJECT_LOCATIONCHANGE (0x800B = 32779)' will cause the Excel main window to lag when dragging.
+            // This drag issue seems to have been introduced with an Office update around November 2022.
+            // To workaround this, we unhook from this event upon encountering EVENT_SYSTEM_MOVESIZESTART and then hook again upon encountering
+            // EVENT_SYSTEM_MOVESIZEEND (see UnhookFromLocationChangeUponDraggingExcelMainWindow).
+            _locationChangeEventHook = new WinEventHook(WinEventHook.WinEvent.EVENT_OBJECT_LOCATIONCHANGE, WinEventHook.WinEvent.EVENT_OBJECT_LOCATIONCHANGE, _syncContextAuto, _syncContextMain, IntPtr.Zero);
+            _locationChangeEventHook.WinEventReceived += _windowMoveSizeHook_WinEventReceived;
+        }
+
+        // This allows us to temporarily stop listening to EVENT_OBJECT_LOCATIONCHANGE events when the user is dragging the Excel main window.
+        // Otherwise we are going to bump into https://github.com/Excel-DNA/IntelliSense/issues/123. The rest of the time we need to stay
+        // hooked to EVENT_OBJECT_LOCATIONCHANGE for IntelliSense to work correctly (see https://github.com/Excel-DNA/IntelliSense/issues/124).
+        void UnhookFromLocationChangeUponDraggingExcelMainWindow(WinEventHook.WinEventArgs e)
+        {
+            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);
+            }
+        }
+
+        void _windowMoveSizeHook_WinEventReceived(object sender, WinEventHook.WinEventArgs winEventArgs)
         {
 #if DEBUG
             Logger.WinEvents.Verbose($"{winEventArgs.EventType} - Window {winEventArgs.WindowHandle:X} ({Win32Helper.GetClassName(winEventArgs.WindowHandle)} - Object/Child {winEventArgs.ObjectId} / {winEventArgs.ChildId} - Thread {winEventArgs.EventThreadId} at {winEventArgs.EventTimeMs}");
 #endif
+
+            UnhookFromLocationChangeUponDraggingExcelMainWindow(winEventArgs);
+
             LocationChanged?.Invoke(this, EventArgs.Empty);
         }
 
         // Runs on the Main thread, perhaps during shutdown
         public void Dispose()
         {
             Debug.Assert(Thread.CurrentThread.ManagedThreadId == 1);
-            if (_windowLocationChangeHook != null)
+            if (_windowMoveSizeHook != null)
+            {
+                _windowMoveSizeHook.Dispose();
+                _windowMoveSizeHook = null;
+            }
+
+            if (_locationChangeEventHook != null)
             {
-                _windowLocationChangeHook.Dispose();
-                _windowLocationChangeHook = null;
+                _locationChangeEventHook.Dispose();
+                _locationChangeEventHook = null;
             }
         }
     }

Source/ExcelDna.IntelliSense/UIMonitor/WindowWatcher.cs

@@ -121,7 +121,6 @@ internal WindowChangedEventArgs(IntPtr windowHandle, WinEventHook.WinEvent winEv
         readonly SynchronizationContext _syncContextMain;
 
         List<WinEventHook> _windowStateChangeHooks = new List<WinEventHook>();
-        WinEventHook _locationChangeEventHook;
 
         // These track keyboard focus for Windows in the Excel process
         // Used to synthesize the 'Unfocus' change events
@@ -169,18 +168,6 @@ public WindowWatcher(SynchronizationContext syncContextAuto, SynchronizationCont
             {
                 windowStateChangeHook.WinEventReceived += _windowStateChangeHook_WinEventReceived;
             }
-
-            SetUpLocationChangeEventListener();
-        }
-
-        void SetUpLocationChangeEventListener()
-        {
-            // NB: Including the next event 'EVENT_OBJECT_LOCATIONCHANGE (0x800B = 32779)' will cause the Excel main window to lag when dragging.
-            // This drag issue seems to have been introduced with an Office update around November 2022.
-            // To workaround this, we unhook from this event upon encountering EVENT_SYSTEM_MOVESIZESTART and then hook again upon encountering
-            // EVENT_SYSTEM_MOVESIZEEND (see UnhookFromLocationChangeUponDraggingExcelMainWindow).
-            _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)
@@ -230,22 +217,6 @@ bool UpdateFocus(IntPtr windowHandle, string windowClassName)
             return true;
         }
 
-        // This allows us to temporarily stop listening to EVENT_OBJECT_LOCATIONCHANGE events when the user is dragging the Excel main window.
-        // Otherwise we are going to bump into https://github.com/Excel-DNA/IntelliSense/issues/123. The rest of the time we need to stay
-        // hooked to EVENT_OBJECT_LOCATIONCHANGE for IntelliSense to work correctly (see https://github.com/Excel-DNA/IntelliSense/issues/124).
-        void UnhookFromLocationChangeUponDraggingExcelMainWindow(WinEventHook.WinEventArgs e)
-        {
-            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);
-            }
-        }
-
         // This runs on the Automation thread, via SyncContextAuto passed in to WinEventHook when we created this WindowWatcher
         // CONSIDER: We would be able to run all the watcher updates from WinEvents, including Location and Selection changes,
         //           but since WinEvents have no hwnd filter, UIAutomation events might be more efficient.
@@ -258,8 +229,6 @@ void _windowStateChangeHook_WinEventReceived(object sender, WinEventHook.WinEven
                 Debug.Fail("WinEvent with window 0!?");
             }
 
-            UnhookFromLocationChangeUponDraggingExcelMainWindow(e);
-
             if (e.EventType == WinEventHook.WinEvent.EVENT_OBJECT_FOCUS)
             {
                 // Might raise change event for Unfocus
@@ -358,7 +327,6 @@ public void Dispose()
             }
 
             _windowStateChangeHooks = new List<WinEventHook>();
-            _locationChangeEventHook.Dispose();
         }
     }