Framework can receive TextEditingDeltas from engine

packages/flutter/lib/services.dart

@@ -42,6 +42,7 @@ export 'src/services/system_chrome.dart';
 export 'src/services/system_navigator.dart';
 export 'src/services/system_sound.dart';
 export 'src/services/text_editing.dart';
+export 'src/services/text_editing_delta.dart';
 export 'src/services/text_formatter.dart';
 export 'src/services/text_input.dart';
 export 'src/services/text_layout_metrics.dart';

packages/flutter/lib/src/services/text_input.dart

@@ -23,6 +23,7 @@ import 'platform_channel.dart';
 import 'system_channels.dart';
 import 'system_chrome.dart';
 import 'text_editing.dart';
+import 'text_editing_delta.dart';
 
 export 'dart:ui' show TextAffinity;
 
@@ -467,6 +468,7 @@ class TextInputConfiguration {
     this.textCapitalization = TextCapitalization.none,
     this.autofillConfiguration = AutofillConfiguration.disabled,
     this.enableIMEPersonalizedLearning = true,
+    this.enableDeltaModel = false,
   }) : assert(inputType != null),
        assert(obscureText != null),
        smartDashesType = smartDashesType ?? (obscureText ? SmartDashesType.disabled : SmartDashesType.enabled),
@@ -476,7 +478,8 @@ class TextInputConfiguration {
        assert(keyboardAppearance != null),
        assert(inputAction != null),
        assert(textCapitalization != null),
-       assert(enableIMEPersonalizedLearning != null);
+       assert(enableIMEPersonalizedLearning != null),
+       assert(enableDeltaModel != null);
 
   /// The type of information for which to optimize the text input control.
   final TextInputType inputType;
@@ -622,6 +625,7 @@ class TextInputConfiguration {
     TextCapitalization? textCapitalization,
     bool? enableIMEPersonalizedLearning,
     AutofillConfiguration? autofillConfiguration,
+    bool? enableDeltaModel,
   }) {
     return TextInputConfiguration(
       inputType: inputType ?? this.inputType,
@@ -636,8 +640,22 @@ class TextInputConfiguration {
       keyboardAppearance: keyboardAppearance ?? this.keyboardAppearance,
       enableIMEPersonalizedLearning: enableIMEPersonalizedLearning?? this.enableIMEPersonalizedLearning,
       autofillConfiguration: autofillConfiguration ?? this.autofillConfiguration,
+      enableDeltaModel: enableDeltaModel ?? this.enableDeltaModel,
     );
   }
+
+  /// Whether to enable that the engine sends text input updates to the
+  /// framework as [TextEditingDelta]'s or as one [TextEditingValue].
+  ///
+  /// When this is enabled platform text input updates will
+  /// come through [TextInputClient.updateEditingValueWithDeltas].
+  ///
+  /// When this is disabled platform text input updates will come through
+  /// [TextInputClient.updateEditingValue].
+  ///
+  /// Defaults to false. Cannot be null.
+  final bool enableDeltaModel;
+
   /// Returns a representation of this object as a JSON object.
   Map<String, dynamic> toJson() {
     final Map<String, dynamic>? autofill = autofillConfiguration.toJson();
@@ -655,6 +673,7 @@ class TextInputConfiguration {
       'keyboardAppearance': keyboardAppearance.toString(),
       'enableIMEPersonalizedLearning': enableIMEPersonalizedLearning,
       if (autofill != null) 'autofill': autofill,
+      'enableDeltaModel' : enableDeltaModel,
     };
   }
 }
@@ -956,6 +975,13 @@ abstract class TextInputClient {
   /// formatting.
   void updateEditingValue(TextEditingValue value);
 
+  /// Requests that this client update its editing state by applying the delta
+  /// received from the engine.
+  ///
+  /// The [TextEditingDelta] is treated as a change that will be applied to the client's
+  /// value.
+  void updateEditingValueWithDeltas(List<TextEditingDelta> textEditingDeltas);
+
   /// Requests that this client perform the given action.
   void performAction(TextInputAction action);
 
@@ -1447,6 +1473,27 @@ class TextInput {
       case 'TextInputClient.updateEditingState':
         _currentConnection!._client.updateEditingValue(TextEditingValue.fromJSON(args[1] as Map<String, dynamic>));
         break;
+      case 'TextInputClient.updateEditingStateWithDeltas':
+        final List<TextEditingDelta> batchDeltas = <TextEditingDelta>[];
+
+        final Map<String, dynamic> encoded = args[1] as Map<String, dynamic>;
+
+        // On Android there could be a situation where multiple edits done to
+        // an editing state are accumulated before being sent to the framework.
+        // This is called batch editing on Android, and on other platforms the
+        // TextInputPlugin does not adhere to this type of editing.
+        if (encoded['batchDeltas'] != null) {
+          for (final dynamic encodedDelta in encoded['batchDeltas']) {
+            final TextEditingDelta delta = TextEditingDelta.fromJSON(encodedDelta as Map<String, dynamic>);
+            batchDeltas.add(delta);
+          }
+        } else {
+          final TextEditingDelta delta = TextEditingDelta.fromJSON(encoded);
+          batchDeltas.add(delta);
+        }
+
+        _currentConnection!._client.updateEditingValueWithDeltas(batchDeltas);
+        break;
       case 'TextInputClient.performAction':
         _currentConnection!._client.performAction(_toTextInputAction(args[1] as String));
         break;

packages/flutter/lib/src/widgets/editable_text.dart

@@ -1795,6 +1795,39 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
   @override
   TextEditingValue get currentTextEditingValue => _value;
 
+  @override
+  void updateEditingValueWithDeltas(List<TextEditingDelta> textEditingDeltas) {
+    TextEditingValue value = _value;
+    for (final TextEditingDelta delta in textEditingDeltas) {
+      print('Delta class type: ' + delta.runtimeType.toString());
+      print('Delta old text: ' + delta.oldText);
+      if (delta is TextEditingDeltaInsertion) {
+        print('inserted text: ' + (delta as TextEditingDeltaInsertion).textInserted);
+        print('insertion offset: ' + (delta as TextEditingDeltaInsertion).insertionOffset.toString());
+      } else if (delta is TextEditingDeltaDeletion) {
+        print('Deleted text: ' + (delta as TextEditingDeltaDeletion).textDeleted);
+        print(
+            'Beginning of deleted range: ' + (delta as TextEditingDeltaDeletion).deletedRange.start.toString());
+        print('End of deleted range: ' + (delta as TextEditingDeltaDeletion).deletedRange.end.toString());
+
+      } else if (delta is TextEditingDeltaReplacement) {
+        print('text being replaced: ' + (delta as TextEditingDeltaReplacement).textReplaced);
+        print('replacement source: ' + (delta as TextEditingDeltaReplacement).replacementText);
+        print(
+            'beginning of replaced range: ' + (delta as TextEditingDeltaReplacement).replacedRange.start.toString());
+        print('end of replaced range: ' + (delta as TextEditingDeltaReplacement).replacedRange.end.toString());
+      }
+      print('Delta beginning of new selection: ' +
+          delta.selection.start.toString());
+      print('Delta end of new selection: ' + delta.selection.end.toString());
+      print('Delta beginning of new composing: ' +
+          delta.composing.start.toString());
+      print('Delta end of new composing: ' + delta.composing.end.toString());
+      value = delta.apply(value);
+    }
+    updateEditingValue(value);
+  }
+
   @override
   void updateEditingValue(TextEditingValue value) {
     // This method handles text editing state updates from the platform text
@@ -2687,6 +2720,7 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
       keyboardAppearance: widget.keyboardAppearance,
       autofillConfiguration: autofillConfiguration,
       enableIMEPersonalizedLearning: widget.enableIMEPersonalizedLearning,
+      enableDeltaModel: true,
     );
   }
 

packages/flutter/test/services/autofill_test.dart

@@ -106,6 +106,19 @@ class FakeAutofillClient implements TextInputClient, AutofillClient {
     latestMethodCall = 'updateEditingValue';
   }
 
+  @override
+  void updateEditingValueWithDeltas(List<TextEditingDelta> textEditingDeltas) {
+    TextEditingValue newEditingValue = currentTextEditingValue;
+
+    for (final TextEditingDelta delta in textEditingDeltas) {
+      newEditingValue = delta.apply(newEditingValue);
+    }
+
+    currentTextEditingValue = newEditingValue;
+
+    latestMethodCall = 'updateEditingValueWithDeltas';
+  }
+
   @override
   AutofillScope? currentAutofillScope;