suspend selection updates in TextBoxTextInputMethodClient until all changes are completed (#15659)

src/Android/Avalonia.Android/AndroidInputMethod.cs

@@ -117,16 +117,20 @@ namespace Avalonia.Android
 
         private void OnSelectionChanged()
         {
-            if (Client is null)
+            if (Client is null || _inputConnection is null)
             {
                 return;
             }
 
+            OnSurroundingTextChanged();
+
             var selection = Client.Selection;
 
-            _imm.UpdateSelection(_host, selection.Start, selection.End, selection.Start, selection.End);
+            _inputConnection.SetSelection(selection.Start, selection.End);
+
+            var composition = _inputConnection.EditableWrapper.CurrentComposition;
 
-            _inputConnection?.SetSelection(selection.Start, selection.End);
+            _imm.UpdateSelection(_host, selection.Start, selection.End, composition.Start, composition.End);
         }
 
         private void _client_SurroundingTextChanged(object? sender, EventArgs e)
@@ -140,8 +144,6 @@ namespace Avalonia.Android
         {
             if (_inputConnection is null || _inputConnection.IsInBatchEdit)
                 return;
-
-            OnSurroundingTextChanged();
             OnSelectionChanged();
         }
 

src/Avalonia.Controls/TextBox.cs

@@ -406,6 +406,8 @@ namespace Avalonia.Controls
             if (IsUndoEnabled && _undoRedoHelper.TryGetLastState(out state) && state.Text == Text)
                 _undoRedoHelper.UpdateLastState();
 
+            using var _ = _imClient.BeginChange();
+
             var newValue = e.GetNewValue<int>();
             SetCurrentValue(SelectionStartProperty, newValue);
             SetCurrentValue(SelectionEndProperty, newValue);
@@ -1216,6 +1218,8 @@ namespace Avalonia.Controls
 
             var keymap = Application.Current!.PlatformSettings!.HotkeyConfiguration;
 
+            using var _ = _imClient.BeginChange();
+
             bool Match(List<KeyGesture> gestures) => gestures.Any(g => g.Matches(e));
             bool DetectSelection() => e.KeyModifiers.HasAllFlags(keymap.SelectionModifiers);
 
@@ -1547,6 +1551,8 @@ namespace Avalonia.Controls
             var text = Text;
             var clickInfo = e.GetCurrentPoint(this);
 
+            using var _ = _imClient.BeginChange();
+
             if (text != null && (e.Pointer.Type == PointerType.Mouse || e.ClickCount >= 2) && clickInfo.Properties.IsLeftButtonPressed &&
                 !(clickInfo.Pointer?.Captured is Border))
             {
@@ -1631,6 +1637,7 @@ namespace Avalonia.Controls
             {
                 return;
             }
+            using var _ = _imClient.BeginChange();
 
             // selection should not change during pointer move if the user right clicks
             if (e.Pointer.Captured == _presenter && e.GetCurrentPoint(this).Properties.IsLeftButtonPressed)
@@ -1713,6 +1720,8 @@ namespace Avalonia.Controls
                 return;
             }
 
+            using var _ = _imClient.BeginChange();
+
             if (e.Pointer.Type != PointerType.Mouse && !_isDoubleTapped)
             {
                 var text = Text;
@@ -1857,6 +1866,8 @@ namespace Avalonia.Controls
                 return;
             }
 
+            using var _ = _imClient.BeginChange();
+
             var text = Text ?? string.Empty;
             var selectionStart = SelectionStart;
             var selectionEnd = SelectionEnd;
@@ -2017,6 +2028,8 @@ namespace Avalonia.Controls
         /// </summary>
         public void SelectAll()
         {
+            using var _ = _imClient.BeginChange();
+
             SetCurrentValue(SelectionStartProperty, 0);
             SetCurrentValue(SelectionEndProperty, Text?.Length ?? 0);
         }
@@ -2034,6 +2047,8 @@ namespace Avalonia.Controls
             if (IsReadOnly)
                 return true;
 
+            using var _ = _imClient.BeginChange();
+
             var (start, end) = GetSelectionRange();
 
             if (start != end)
@@ -2141,6 +2156,8 @@ namespace Avalonia.Controls
             var text = Text ?? string.Empty;
             var selectionStart = CaretIndex;
 
+            using var _ = _imClient.BeginChange();
+
             MoveHorizontal(-1, true, false, false);
 
             if (SelectionEnd > 0 &&
@@ -2160,6 +2177,8 @@ namespace Avalonia.Controls
                 return;
             }
 
+            using var _ = _imClient.BeginChange();
+
             SetCurrentValue(SelectionStartProperty, CaretIndex);
 
             MoveHorizontal(1, true, true, false);

src/Avalonia.Controls/TextBoxTextInputMethodClient.cs

@@ -2,6 +2,7 @@ using System;
 using Avalonia.Controls.Presenters;
 using Avalonia.Input.TextInput;
 using Avalonia.Media.TextFormatting;
+using Avalonia.Reactive;
 using Avalonia.Utilities;
 
 namespace Avalonia.Controls
@@ -10,6 +11,8 @@ namespace Avalonia.Controls
     {
         private TextBox? _parent;
         private TextPresenter? _presenter;
+        private bool _selectionChanged;
+        private bool _isInChange;
 
         public override Visual TextViewVisual => _presenter!;
 
@@ -190,8 +193,30 @@ namespace Avalonia.Controls
 
             if (e.Property == TextBox.SelectionStartProperty || e.Property == TextBox.SelectionEndProperty)
             {
-                RaiseSelectionChanged();
+                if (_isInChange)
+                    _selectionChanged = true;
+                else
+                    RaiseSelectionChanged();
             }
         }
+
+        internal IDisposable BeginChange()
+        {
+            if (_isInChange)
+                return Disposable.Empty;
+
+            _isInChange = true;
+            return Disposable.Create(RaiseEvents);
+        }
+
+        private void RaiseEvents()
+        {
+            _isInChange = false;
+
+            if (_selectionChanged)
+                RaiseSelectionChanged();
+
+            _selectionChanged = false;
+        }
     }
 }