Fix GetTextLineText

src/Android/Avalonia.Android/AndroidInputMethod.cs

@@ -100,12 +100,13 @@ namespace Avalonia.Android
             {
                 var surroundingText = Client.SurroundingText;
 
-                _imm.UpdateSelection(_host, surroundingText.AnchorOffset, surroundingText.CursorOffset, _inputConnection.ComposingRegion.Start, _inputConnection.ComposingRegion.End);
+                _imm.UpdateSelection(_host, surroundingText.AnchorOffset, surroundingText.CursorOffset, surroundingText.AnchorOffset, surroundingText.CursorOffset);
             }
         }
 
         public void SetCursorRect(Rect rect)
         {
+            
         }
 
         public void SetOptions(TextInputOptions options)
@@ -114,7 +115,7 @@ namespace Avalonia.Android
 
             _host.InitEditorInfo((_host, outAttrs) =>
             {          
-                _inputConnection?.FinishComposingText();
+                //_inputConnection?.FinishComposingText();
 
                 outAttrs.InputType = options.ContentType switch
                 {

src/Android/Avalonia.Android/Platform/SkiaPlatform/TopLevelImpl.cs

@@ -276,7 +276,7 @@ namespace Avalonia.Android.Platform.SkiaPlatform
 
         public View View { get; }
 
-        public ComposingRegion ComposingRegion { get; private set; }
+        public ComposingRegion ComposingRegion { get; internal set; }
 
         public string CompositionText { get; private set; }
 
@@ -365,14 +365,18 @@ namespace Avalonia.Android.Platform.SkiaPlatform
             {
                 _inputMethod.Client.SetPreeditText(null);
 
-                var textLength = text.Length();
-
-                if (string.IsNullOrEmpty(CompositionText) && ComposingRegion.End > 0)
+                if (string.IsNullOrEmpty(CompositionText))
                 {
-                    _inputMethod.Client.SelectInSurroundingText(ComposingRegion.Start, ComposingRegion.Start + textLength);
+                    var surroundingText = _inputMethod.Client.SurroundingText;
+
+                    var composingRegionLength = ComposingRegion.End - ComposingRegion.Start;
+
+                    var composingRegionText = surroundingText.Text?.Substring(ComposingRegion.Start, composingRegionLength);
+
+                    _inputMethod.Client.SelectInSurroundingText(ComposingRegion.Start, ComposingRegion.End);
                 }
 
-                ComposingRegion = new ComposingRegion(ComposingRegion.Start, ComposingRegion.Start + textLength);
+                ComposingRegion = new ComposingRegion(ComposingRegion.End, ComposingRegion.End);
             }
 
             return base.CommitText(text, newCursorPosition);

src/Avalonia.Base/Input/TextInput/ITextInputMethodClient.cs

@@ -42,13 +42,6 @@ namespace Avalonia.Input.TextInput
         /// </summary>
         event EventHandler? SurroundingTextChanged;
 
-        /// <summary>
-        /// Deletes specified length before and after current selection.
-        /// </summary>
-        /// <param name="beforeLength">The length before current selection.</param>
-        /// <param name="afterLength">The length after current selection.</param>
-        void DeleteSurroundingText(int beforeLength, int afterLength);
-
         void SelectInSurroundingText(int start, int end);
     }
 

src/Avalonia.Controls/Presenters/TextPresenter.cs

@@ -847,12 +847,21 @@ namespace Avalonia.Controls.Presenters
             _caretTimer.Tick -= CaretTimerTick;
         }
 
-        protected void OnPreeditTextChanged(string? preeditText)
+        protected void OnPreeditTextChanged(string? oldValue, string? newValue)
         {
             InvalidateTextLayout();
 
-            if (preeditText is null)
+            if (string.IsNullOrEmpty(newValue))
             {
+                if (!string.IsNullOrEmpty(oldValue))
+                {
+                    var textPosition = _compositionStartHit.FirstCharacterIndex + _compositionStartHit.TrailingLength + newValue?.Length ?? 0;
+
+                    var characterHit = GetCharacterHitFromTextPosition(textPosition);
+
+                    UpdateCaret(characterHit, true);
+                }
+
                 _compositionStartHit = new CharacterHit(-1);
             }
             else
@@ -865,18 +874,25 @@ namespace Avalonia.Controls.Presenters
 
             if (_compositionStartHit.FirstCharacterIndex != -1)
             {
-                var textPosition = _compositionStartHit.FirstCharacterIndex + _compositionStartHit.TrailingLength + preeditText?.Length ?? 0;
-
-                var lineIndex = TextLayout.GetLineIndexFromCharacterIndex(textPosition, true);
-
-                var textLine = TextLayout.TextLines[lineIndex];
+                var textPosition = _compositionStartHit.FirstCharacterIndex + _compositionStartHit.TrailingLength + newValue?.Length ?? 0;
 
-                var characterHit = textLine.GetNextCaretCharacterHit(new CharacterHit(textPosition - 1));
+                var characterHit = GetCharacterHitFromTextPosition(textPosition);
 
                 UpdateCaret(characterHit, false);
             }
         }
 
+        private CharacterHit GetCharacterHitFromTextPosition(int textPosition)
+        {
+            var lineIndex = TextLayout.GetLineIndexFromCharacterIndex(textPosition, true);
+
+            var textLine = TextLayout.TextLines[lineIndex];
+
+            var characterHit = textLine.GetNextCaretCharacterHit(new CharacterHit(textPosition - 1));
+
+            return characterHit;
+        }
+
         protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
         {
             base.OnPropertyChanged(change);
@@ -885,7 +901,7 @@ namespace Avalonia.Controls.Presenters
             {
                 case nameof(PreeditText):
                     {
-                        OnPreeditTextChanged(change.NewValue as string);
+                        OnPreeditTextChanged(change.OldValue as string, change.NewValue as string);
                         break;
                     }
 

src/Avalonia.Controls/TextBox.cs

@@ -831,6 +831,11 @@ namespace Avalonia.Controls
                 return;
             }
 
+            if (!string.IsNullOrEmpty(_presenter.PreeditText))
+            {
+                return;
+            }
+
             var text = Text ?? string.Empty;
             var caretIndex = CaretIndex;
             var movement = false;

src/Avalonia.Controls/TextBoxTextInputMethodClient.cs

@@ -1,7 +1,9 @@
 using System;
 using Avalonia.Controls.Presenters;
 using Avalonia.Input.TextInput;
+using Avalonia.Media.TextFormatting;
 using Avalonia.Threading;
+using Avalonia.Utilities;
 using Avalonia.VisualTree;
 
 namespace Avalonia.Controls
@@ -54,7 +56,7 @@ namespace Avalonia.Controls
 
                 var lineStart = textLine.FirstTextSourceIndex;
 
-                var lineText = _presenter.Text?.Substring(lineStart, textLine.Length);
+                var lineText = GetTextLineText(textLine);
 
                 var anchorOffset = Math.Max(0, _parent.SelectionStart - lineStart);
 
@@ -69,6 +71,29 @@ namespace Avalonia.Controls
             }
         }
 
+        private static string GetTextLineText(TextLine textLine)
+        {
+            var builder = StringBuilderCache.Acquire(textLine.Length);
+
+            foreach (var run in textLine.TextRuns)
+            {
+                if(run.Text.Length > 0)
+                {
+#if NET6_0
+                    builder.Append(run.Text.Span);
+#else
+                    builder.Append(run.Text.Span.ToArray());
+#endif
+                }
+            }
+
+            var lineText = builder.ToString();
+
+            StringBuilderCache.Release(builder);
+
+            return lineText;
+        }
+
         public event EventHandler? TextViewVisualChanged;
 
         public event EventHandler? CursorRectangleChanged;
@@ -149,19 +174,6 @@ namespace Avalonia.Controls
             }
         }
 
-        public void DeleteSurroundingText(int beforeLength, int afterLength)
-        {
-            if (_parent != null && _presenter != null && string.IsNullOrEmpty(_presenter.PreeditText))
-            {
-                var start = _presenter.SelectionStart;
-
-                _parent.SelectionStart = start - beforeLength;
-                _parent.SelectionEnd = start + afterLength;
-
-                _parent.DeleteSelection(true);
-            }
-        }
-
         private void OnCaretBoundsChanged(object? sender, EventArgs e)
         {
             Dispatcher.UIThread.Post(() =>

src/Windows/Avalonia.Win32/Input/Imm32InputMethod.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Runtime.InteropServices;
 using System.Text;
 using Avalonia.Input.TextInput;
 using Avalonia.Threading;
@@ -79,9 +78,7 @@ namespace Avalonia.Win32.Input
         {
             HWND = hwnd;
             _parent = parent;
-            _active = false;
             _langId = PRIMARYLANGID(LGID(HKL));
-            _showCompositionWindow = true;
 
             _parent = parent;
 
@@ -105,7 +102,6 @@ namespace Avalonia.Win32.Input
             _parent = null;
             _client = null;
             _langId = 0;
-            _showCompositionWindow = false;
 
             IsComposing = false;
         }