Simplify IME integration a bit

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

@@ -22,7 +22,6 @@ namespace ICSharpCode.AvalonEdit.Editing
 	{
 		readonly TextArea textArea;
 		readonly TextView textView;
-		readonly ImeSupport ime;
 		readonly CaretLayer caretAdorner;
 		bool visible;
 		
@@ -31,7 +30,6 @@ namespace ICSharpCode.AvalonEdit.Editing
 			this.textArea = textArea;
 			this.textView = textArea.TextView;
 			position = new TextViewPosition(1, 1, 0);
-			ime = new ImeSupport(textArea);
 			
 			caretAdorner = new CaretLayer(textView);
 			textView.InsertLayer(caretAdorner, KnownLayer.Caret, LayerInsertionPosition.Replace);
@@ -436,7 +434,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 				} else {
 					caretAdorner.Hide();
 				}
-				ime.UpdateCompositionWindow();
+				textArea.ime.UpdateCompositionWindow();
 			}
 		}
 		

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

@@ -76,16 +76,23 @@ 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")]
+		[return: MarshalAs(UnmanagedType.Bool)]
+		public static extern bool ImmDestroyContext(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")]
 		[return: MarshalAs(UnmanagedType.Bool)]
-		static extern bool ImmNotifyIME(IntPtr hIMC, int dwAction, int dwIndex, int dwValue = 0);
+		static extern bool ImmReleaseContext(IntPtr hWnd, IntPtr hIMC);
 		[DllImport("imm32.dll")]
 		[return: MarshalAs(UnmanagedType.Bool)]
-		static extern bool ImmReleaseContext(IntPtr hWnd, IntPtr hIMC);
+		static extern bool ImmNotifyIME(IntPtr hIMC, int dwAction, int dwIndex, int dwValue = 0);
 		[DllImport("imm32.dll")]
 		[return: MarshalAs(UnmanagedType.Bool)]
 		static extern bool ImmSetCompositionWindow(IntPtr hIMC, ref CompositionForm form);

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

@@ -19,11 +19,10 @@ using ICSharpCode.AvalonEdit.Rendering;
 
 namespace ICSharpCode.AvalonEdit.Editing
 {
-	class ImeSupport : IDisposable
+	class ImeSupport
 	{
-		TextArea textArea;
+		readonly TextArea textArea;
 		IntPtr currentContext;
-		IntPtr previousContext;
 		HwndSource hwndSource;
 		
 		public ImeSupport(TextArea textArea)
@@ -32,47 +31,29 @@ namespace ICSharpCode.AvalonEdit.Editing
 				throw new ArgumentNullException("textArea");
 			this.textArea = textArea;
 			InputMethod.SetIsInputMethodSuspended(this.textArea, true);
-			textArea.GotKeyboardFocus += TextAreaGotKeyboardFocus;
-			textArea.LostKeyboardFocus += TextAreaLostKeyboardFocus;
 			textArea.OptionChanged += TextAreaOptionChanged;
 			currentContext = IntPtr.Zero;
-			previousContext = IntPtr.Zero;
 		}
 
 		void TextAreaOptionChanged(object sender, PropertyChangedEventArgs e)
 		{
-			if (e.PropertyName == "EnableImeSupport" && textArea.IsKeyboardFocusWithin) {
+			if (e.PropertyName == "EnableImeSupport" && textArea.IsKeyboardFocused) {
 				CreateContext();
 			}
 		}
-		
-		public void Dispose()
-		{
-			if (textArea != null) {
-				textArea.GotKeyboardFocus -= TextAreaGotKeyboardFocus;
-				textArea.LostKeyboardFocus -= TextAreaLostKeyboardFocus;
-				textArea.OptionChanged -= TextAreaOptionChanged;
-				textArea = null;
-			}
-			ClearContext();
-		}
 
 		void ClearContext()
 		{
 			if (hwndSource != null) {
-				hwndSource.RemoveHook(WndProc);
-				ImeNativeWrapper.AssociateContext(hwndSource, previousContext);
-				previousContext = IntPtr.Zero;
 				ImeNativeWrapper.ReleaseContext(hwndSource, currentContext);
-				hwndSource = null;
 				currentContext = IntPtr.Zero;
+				hwndSource.RemoveHook(WndProc);
+				hwndSource = null;
 			}
 		}
 		
-		void TextAreaGotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
+		public void OnGotFocus(KeyboardFocusChangedEventArgs e)
 		{
-			if (e.OriginalSource != this.textArea)
-				return;
 			CreateContext();
 		}
 
@@ -84,17 +65,15 @@ namespace ICSharpCode.AvalonEdit.Editing
 			hwndSource = (HwndSource)PresentationSource.FromVisual(this.textArea);
 			if (hwndSource != null) {
 				currentContext = ImeNativeWrapper.GetContext(hwndSource);
-				previousContext = ImeNativeWrapper.AssociateContext(hwndSource, currentContext);
 //				ImeNativeWrapper.SetCompositionFont(hwndSource, currentContext, textArea);
 				hwndSource.AddHook(WndProc);
+				// UpdateCompositionWindow() will be called by the caret becoming visible
 			}
 		}
 		
-		void TextAreaLostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
+		public void OnLostFocus(KeyboardFocusChangedEventArgs e)
 		{
-			if (e.OriginalSource != this.textArea)
-				return;
-			if (currentContext != IntPtr.Zero)
+			if (e.OldFocus == textArea && currentContext != IntPtr.Zero)
 				ImeNativeWrapper.NotifyIme(currentContext);
 			ClearContext();
 		}
@@ -103,6 +82,8 @@ namespace ICSharpCode.AvalonEdit.Editing
 		{
 			switch (msg) {
 				case ImeNativeWrapper.WM_INPUTLANGCHANGE:
+					// Don't mark the message as handled; other windows
+					// might want to handle it as well.
 					ClearContext();
 					CreateContext();
 					break;
@@ -115,7 +96,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 		
 		public void UpdateCompositionWindow()
 		{
-			if (currentContext != IntPtr.Zero && textArea != null) {
+			if (currentContext != IntPtr.Zero) {
 				ImeNativeWrapper.SetCompositionWindow(hwndSource, currentContext, textArea);
 			}
 		}

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

@@ -29,6 +29,8 @@ namespace ICSharpCode.AvalonEdit.Editing
 	/// </summary>
 	public class TextArea : Control, IScrollInfo, IWeakEventListener, ITextEditorComponent, IServiceProvider
 	{
+		internal readonly ImeSupport ime;
+		
 		#region Constructor
 		static TextArea()
 		{
@@ -68,6 +70,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 			
 			caret = new Caret(this);
 			caret.PositionChanged += (sender, e) => RequestSelectionValidation();
+			ime = new ImeSupport(this);
 			
 			leftMargins.CollectionChanged += leftMargins_CollectionChanged;
 			
@@ -754,6 +757,8 @@ namespace ICSharpCode.AvalonEdit.Editing
 		protected override void OnGotKeyboardFocus(KeyboardFocusChangedEventArgs e)
 		{
 			base.OnGotKeyboardFocus(e);
+			// First activate IME, then show caret
+			ime.OnGotFocus(e);
 			caret.Show();
 		}
 		
@@ -762,6 +767,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 		{
 			base.OnLostKeyboardFocus(e);
 			caret.Hide();
+			ime.OnLostFocus(e);
 		}
 		#endregion