AvalonEdit IME support: use the default input context, and fix issues with IME not activating in some cases using ITfThreadMgr.SetFocus(null).

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Editing/ImeNativeWrapper.cs

@@ -76,15 +76,16 @@ namespace ICSharpCode.AvalonEdit.Editing
 		public const int WM_IME_SETCONTEXT = 0x281;
 		public const int WM_INPUTLANGCHANGE = 0x51;
 		
-		[DllImport("imm32.dll")]
-		public static extern IntPtr ImmCreateContext();
+//		[DllImport("imm32.dll")]
+//		public static extern IntPtr ImmCreateContext();
+//
+//		[DllImport("imm32.dll")]
+//		[return: MarshalAs(UnmanagedType.Bool)]
+//		public static extern bool ImmDestroyContext(IntPtr hIMC);
 		
-		[DllImport("imm32.dll")]
-		[return: MarshalAs(UnmanagedType.Bool)]
-		public static extern bool ImmDestroyContext(IntPtr hIMC);
+//		[DllImport("imm32.dll")]
+//		public static extern IntPtr ImmAssociateContext(IntPtr hWnd, IntPtr hIMC);
 		
-		[DllImport("imm32.dll")]
-		static extern IntPtr ImmAssociateContext(IntPtr hWnd, IntPtr hIMC);
 		[DllImport("imm32.dll")]
 		static extern IntPtr ImmGetContext(IntPtr hWnd);
 		[DllImport("imm32.dll")]
@@ -103,11 +104,19 @@ namespace ICSharpCode.AvalonEdit.Editing
 		[return: MarshalAs(UnmanagedType.Bool)]
 		static extern bool ImmGetCompositionFont(IntPtr hIMC, out LOGFONT font);
 		
-		public static IntPtr AssociateContext(HwndSource source, IntPtr hIMC)
+		[DllImport("msctf.dll")]
+		static extern int TF_CreateThreadMgr(out ITfThreadMgr threadMgr);
+		
+		[ThreadStatic] static bool textFrameworkThreadMgrInitialized;
+		[ThreadStatic] static ITfThreadMgr textFrameworkThreadMgr;
+		
+		public static ITfThreadMgr GetTextFrameworkThreadManager()
 		{
-			if (source == null)
-				throw new ArgumentNullException("source");
-			return ImmAssociateContext(source.Handle, hIMC);
+			if (!textFrameworkThreadMgrInitialized) {
+				textFrameworkThreadMgrInitialized = true;
+				TF_CreateThreadMgr(out textFrameworkThreadMgr);
+			}
+			return textFrameworkThreadMgr;
 		}
 		
 		public static bool NotifyIme(IntPtr hIMC)
@@ -194,4 +203,20 @@ namespace ICSharpCode.AvalonEdit.Editing
 				.TransformToDevice(source.RootVisual); // rect on HWND
 		}
 	}
+	
+	[ComImport, Guid("aa80e801-2021-11d2-93e0-0060b067b86e"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+	interface ITfThreadMgr
+	{
+		void Activate(out int clientId);
+		void Deactivate();
+		void CreateDocumentMgr(out object docMgr);
+		void EnumDocumentMgrs(out object enumDocMgrs);
+		void GetFocus(out object docMgr);
+		void SetFocus(object docMgr);
+		void AssociateFocus(IntPtr hwnd, object newDocMgr, out object prevDocMgr);
+		void IsThreadFocus([MarshalAs(UnmanagedType.Bool)] out bool isFocus);
+		void GetFunctionProvider(ref Guid classId, out object funcProvider);
+		void EnumFunctionProviders(out object enumProviders);
+		void GetGlobalCompartment(out object compartmentMgr);
+	}
 }

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Editing/ImeSupport.cs

@@ -23,7 +23,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 	{
 		readonly TextArea textArea;
 		IntPtr currentContext;
-		IntPtr previousContext;
+		//IntPtr previousContext;
 		HwndSource hwndSource;
 		
 		public ImeSupport(TextArea textArea)
@@ -46,8 +46,9 @@ namespace ICSharpCode.AvalonEdit.Editing
 		void ClearContext()
 		{
 			if (hwndSource != null) {
-				ImeNativeWrapper.AssociateContext(hwndSource, previousContext);
-				ImeNativeWrapper.ImmDestroyContext(currentContext);
+				//ImeNativeWrapper.AssociateContext(hwndSource, previousContext);
+				//ImeNativeWrapper.ImmDestroyContext(currentContext);
+				ImeNativeWrapper.ReleaseContext(hwndSource, currentContext);
 				currentContext = IntPtr.Zero;
 				hwndSource.RemoveHook(WndProc);
 				hwndSource = null;
@@ -66,11 +67,19 @@ namespace ICSharpCode.AvalonEdit.Editing
 				return;
 			hwndSource = (HwndSource)PresentationSource.FromVisual(this.textArea);
 			if (hwndSource != null) {
-				currentContext = ImeNativeWrapper.ImmCreateContext();
-				previousContext = ImeNativeWrapper.AssociateContext(hwndSource, currentContext);
+				//currentContext = ImeNativeWrapper.ImmCreateContext();
+				//previousContext = ImeNativeWrapper.AssociateContext(hwndSource, currentContext);
+				currentContext = ImeNativeWrapper.GetContext(hwndSource);
 //				ImeNativeWrapper.SetCompositionFont(hwndSource, currentContext, textArea);
 				hwndSource.AddHook(WndProc);
 				// UpdateCompositionWindow() will be called by the caret becoming visible
+				
+				var threadMgr = ImeNativeWrapper.GetTextFrameworkThreadManager();
+				if (threadMgr != null) {
+					// Even though the docu says passing null is invalid, this seems to help
+					// activating the IME on the default input context that is shared with WPF
+					threadMgr.SetFocus(null);
+				}
 			}
 		}