Fix Chinese pinyin input issues in the editor

lib/src/code/code.dart

@@ -326,10 +326,21 @@ class Code {
     TextSelection oldSelection,
     TextEditingValue visibleAfter,
   ) {
-    final visibleRangeAfter = visibleAfter.getChangedRange(
-          TextEditingValue(text: visibleText, selection: oldSelection),
+    final clampedOldSelection = _clampSelection(
+      oldSelection,
+      visibleText.length,
+    );
+    final clampedVisibleAfter = visibleAfter.copyWith(
+      selection: _clampSelection(
+        visibleAfter.selection,
+        visibleAfter.text.length,
+      ),
+    );
+
+    final visibleRangeAfter = clampedVisibleAfter.getChangedRange(
+          TextEditingValue(text: visibleText, selection: clampedOldSelection),
         ) ??
-        visibleAfter.text.getChangedRange(
+        clampedVisibleAfter.text.getChangedRange(
           visibleText,
           attributeChangeTo: TextAffinity.upstream,
         );
@@ -395,7 +406,7 @@ class Code {
     }
 
     final fullTextAfter = rangeBefore.textBefore(text) +
-        visibleRangeAfter.textInside(visibleAfter.text) +
+        visibleRangeAfter.textInside(clampedVisibleAfter.text) +
         rangeBefore.textAfter(text);
 
     // The line at [start] has changed for sure.
@@ -529,4 +540,21 @@ class Code {
       visibleSectionNames: visibleSectionNames,
     );
   }
+
+  static TextSelection _clampSelection(TextSelection selection, int textLength) {
+    int clampOffset(int offset) {
+      if (offset < 0) {
+        return 0;
+      }
+      if (offset > textLength) {
+        return textLength;
+      }
+      return offset;
+    }
+
+    return selection.copyWith(
+      baseOffset: clampOffset(selection.baseOffset),
+      extentOffset: clampOffset(selection.extentOffset),
+    );
+  }
 }

lib/src/code_field/code_controller.dart

@@ -64,7 +64,7 @@ class CodeController extends TextEditingController {
   }
 
   AnalysisResult analysisResult;
-  String _lastAnalyzedText = '';
+  var _lastAnalyzedText = '';
   Timer? _debounce;
 
   final AbstractNamedSectionParser? namedSectionParser;
@@ -85,7 +85,7 @@ class CodeController extends TextEditingController {
   final bool _isTabReplacementEnabled;
 
   /* Computed members */
-  String _languageId = '';
+  var _languageId = '';
 
   ///Contains names of named sections, those will be visible for user.
   ///If it is not empty, all another code except specified will be hidden.
@@ -125,7 +125,7 @@ class CodeController extends TextEditingController {
   @visibleForTesting
   TextSpan? lastTextSpan;
 
-  bool _disposed = false;
+  var _disposed = false;
 
   late final actions = <Type, Action<Intent>>{
     CommentUncommentIntent: CommentUncommentAction(controller: this),
@@ -173,6 +173,8 @@ class CodeController extends TextEditingController {
     _code = _createCode(text ?? '');
     fullText = text ?? '';
 
+    debugPrint('CodeController initialized with text:\n$text');
+
     addListener(_scheduleAnalysis);
     addListener(_updateSearchResult);
     _searchSettingsController.addListener(_updateSearchResult);
@@ -317,13 +319,22 @@ class CodeController extends TextEditingController {
   }
 
   KeyEventResult onKey(KeyEvent event) {
+    if (hasActiveComposition) {
+      return KeyEventResult.ignored;
+    }
+
     if (event is KeyDownEvent || event is KeyRepeatEvent) {
       return _onKeyDownRepeat(event);
     }
 
     return KeyEventResult.ignored; // The framework will handle.
   }
 
+  bool get hasActiveComposition {
+    final composing = value.composing;
+    return composing.isValid && !composing.isCollapsed;
+  }
+
   KeyEventResult _onKeyDownRepeat(KeyEvent event) {
     if (event.isCtrlF(HardwareKeyboard.instance.logicalKeysPressed)) {
       showSearch();
@@ -345,6 +356,10 @@ class CodeController extends TextEditingController {
   }
 
   void onEnterKeyAction() {
+    if (hasActiveComposition) {
+      return;
+    }
+
     if (popupController.shouldShow) {
       insertSelectedWord();
       return;
@@ -368,6 +383,10 @@ class CodeController extends TextEditingController {
   }
 
   void onTabKeyAction() {
+    if (hasActiveComposition) {
+      return;
+    }
+
     if (popupController.shouldShow) {
       insertSelectedWord();
       return;
@@ -443,10 +462,29 @@ class CodeController extends TextEditingController {
 
   @override
   set value(TextEditingValue newValue) {
+    final hadActiveCompositionInOldValue = hasActiveComposition;
     final hasTextChanged = newValue.text != super.value.text;
     final hasSelectionChanged = newValue.selection != super.value.selection;
+    final hasComposingChanged = newValue.composing != super.value.composing;
+    final hasActiveComposingInNewValue =
+        newValue.composing.isValid && !newValue.composing.isCollapsed;
 
-    if (!hasTextChanged && !hasSelectionChanged) {
+    if (!hasTextChanged && !hasSelectionChanged && !hasComposingChanged) {
+      return;
+    }
+
+    if (hasActiveComposingInNewValue || hadActiveCompositionInOldValue) {
+      if (readOnly && hasTextChanged) {
+        return;
+      }
+
+      // During IME composition, preserve platform-provided editing state
+      // and avoid applying editor transforms that may break composition commit.
+      // Keep internal code state in sync so highlighted rendering doesn't drift.
+      if (hasTextChanged) {
+        _updateCodeIfChanged(newValue.text);
+      }
+      super.value = newValue;
       return;
     }
 
@@ -917,6 +955,17 @@ class CodeController extends TextEditingController {
     TextStyle? style,
     bool? withComposing,
   }) {
+    // IME composition (e.g. pinyin) depends on composing-aware rendering.
+    // When composing is active, delegate to Flutter's default implementation
+    // so the composing range is preserved and rendered correctly.
+    if (hasActiveComposition) {
+      return super.buildTextSpan(
+        context: context,
+        style: style,
+        withComposing: withComposing ?? true,
+      );
+    }
+
     final spanBeforeSearch = _createTextSpan(
       context: context,
       style: style,

lib/src/code_field/code_field.dart

@@ -102,20 +102,6 @@ final _shortcuts = <ShortcutActivator, Intent>{
     meta: true,
   ): const SearchIntent(),
 
-  // Dismiss
-  LogicalKeySet(
-    LogicalKeyboardKey.escape,
-  ): const DismissIntent(),
-
-  // EnterKey
-  LogicalKeySet(
-    LogicalKeyboardKey.enter,
-  ): const EnterKeyIntent(),
-
-  // TabKey
-  LogicalKeySet(
-    LogicalKeyboardKey.tab,
-  ): const TabKeyIntent(),
 };
 
 class CodeField extends StatefulWidget {
@@ -422,6 +408,22 @@ class _CodeFieldState extends State<CodeField> {
 
     textStyle = defaultTextStyle.merge(widget.textStyle);
 
+    final isComposingText = widget.controller.hasActiveComposition;
+    final shortcuts = {
+      ..._shortcuts,
+      if (!isComposingText) ...{
+        LogicalKeySet(
+          LogicalKeyboardKey.escape,
+        ): const DismissIntent(),
+        LogicalKeySet(
+          LogicalKeyboardKey.enter,
+        ): const EnterKeyIntent(),
+        LogicalKeySet(
+          LogicalKeyboardKey.tab,
+        ): const TabKeyIntent(),
+      },
+    };
+
     final codeField = TextField(
       focusNode: _focusNode,
       scrollPadding: widget.padding,
@@ -463,7 +465,7 @@ class _CodeFieldState extends State<CodeField> {
 
     return FocusableActionDetector(
       actions: widget.controller.actions,
-      shortcuts: _shortcuts,
+      shortcuts: shortcuts,
       child: Container(
         decoration: widget.decoration,
         color: _backgroundCol,

test/src/code_field/code_controller_set_value_test.dart

@@ -4,6 +4,45 @@ import 'package:flutter_test/flutter_test.dart';
 import '../common/create_app.dart';
 
 void main() {
+  test('Composing-only updates are applied', () {
+    final controller = createController('');
+    controller.value = const TextEditingValue(
+      text: 'ni',
+      selection: TextSelection.collapsed(offset: 2),
+      composing: TextRange(start: 0, end: 1),
+    );
+
+    controller.value = const TextEditingValue(
+      text: 'ni',
+      selection: TextSelection.collapsed(offset: 2),
+      composing: TextRange(start: 0, end: 2),
+    );
+
+    expect(controller.value.composing, const TextRange(start: 0, end: 2));
+    controller.dispose();
+  });
+
+  test('Composing text is committed correctly after IME selection', () {
+    final controller = createController('}');
+    controller.selection = const TextSelection.collapsed(offset: 1);
+
+    controller.value = const TextEditingValue(
+      text: '} ni',
+      selection: TextSelection.collapsed(offset: 4),
+      composing: TextRange(start: 2, end: 4),
+    );
+
+    controller.value = const TextEditingValue(
+      text: '} 你',
+      selection: TextSelection.collapsed(offset: 3),
+      composing: TextRange.empty,
+    );
+
+    expect(controller.text, '} 你');
+    expect(controller.fullText, '} 你');
+    controller.dispose();
+  });
+
   testWidgets(
       'Backspace or delete at a folded block collapse point '
       '=> Do nothing.', (wt) async {

test/src/code_field/code_controller_shortcut_test.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/services.dart';
+import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 import '../common/create_app.dart';
@@ -111,6 +112,28 @@ void main() {
         expect(controller.text, example.visibleTextAfter, reason: example.name);
       }
     });
+
+    test('IME composition bypasses popup arrow key handling', () {
+      final controller = createController('');
+      controller.popupController.show(['one', 'two']);
+      controller.value = const TextEditingValue(
+        text: 'ni',
+        selection: TextSelection.collapsed(offset: 2),
+        composing: TextRange(start: 0, end: 2),
+      );
+
+      final result = controller.onKey(
+        const KeyDownEvent(
+          timeStamp: Duration.zero,
+          physicalKey: PhysicalKeyboardKey.arrowDown,
+          logicalKey: LogicalKeyboardKey.arrowDown,
+        ),
+      );
+
+      expect(result, KeyEventResult.ignored);
+      expect(controller.popupController.selectedIndex, 0);
+      controller.dispose();
+    });
   });
 }