[RawKeyboard, Web, macOS] Upper keys should generate lower logical keys (#94827)

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

@@ -10,6 +10,16 @@ import 'keyboard_key.dart';
 import 'keyboard_maps.dart';
 import 'raw_keyboard.dart';
 
+/// Convert a UTF32 rune to its lower case.
+int runeToLowerCase(int rune) {
+  // Assume only Basic Multilingual Plane runes have lower and upper cases.
+  // For other characters, return them as is.
+  const int utf16BmpUpperBound = 0xD7FF;
+  if (rune > utf16BmpUpperBound)
+    return rune;
+  return String.fromCharCode(rune).toLowerCase().codeUnitAt(0);
+}
+
 /// Platform-specific key event data for macOS.
 ///
 /// This object contains information about key events obtained from macOS's
@@ -99,7 +109,7 @@ class RawKeyEventDataMacOs extends RawKeyEventData {
           // only tests BMP, it is fine to test keyLabel instead.
           !LogicalKeyboardKey.isControlCharacter(keyLabel) &&
           !_isUnprintableKey(keyLabel)) {
-        character = codePoints[0];
+        character = runeToLowerCase(codePoints[0]);
       }
     }
     if (character != null) {

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

@@ -104,7 +104,7 @@ class RawKeyEventDataWeb extends RawKeyEventData {
 
     final bool isPrintable = key.length == 1;
     if (isPrintable)
-      return LogicalKeyboardKey(key.codeUnitAt(0));
+      return LogicalKeyboardKey(key.toLowerCase().codeUnitAt(0));
 
     // This is a non-printable key that we don't know about, so we mint a new
     // key from `code`. Don't mint with `key`, because the `key` will always be

packages/flutter/test/services/raw_keyboard_test.dart

@@ -1415,14 +1415,13 @@ void main() {
       }
     });
 
-    test('Printable keyboard keys are correctly translated', () {
-      const String unmodifiedCharacter = 'a';
+    test('Lower letter keys are correctly translated', () {
       final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
         'type': 'keydown',
         'keymap': 'macos',
         'keyCode': 0x00000000,
         'characters': 'a',
-        'charactersIgnoringModifiers': unmodifiedCharacter,
+        'charactersIgnoringModifiers': 'a',
         'modifiers': 0x0,
       });
       final RawKeyEventDataMacOs data = keyAEvent.data as RawKeyEventDataMacOs;
@@ -1431,6 +1430,21 @@ void main() {
       expect(data.keyLabel, equals('a'));
     });
 
+    test('Upper letter keys are correctly translated', () {
+      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+        'type': 'keydown',
+        'keymap': 'macos',
+        'keyCode': 0x00000000,
+        'characters': 'A',
+        'charactersIgnoringModifiers': 'A',
+        'modifiers': 0x20002,
+      });
+      final RawKeyEventDataMacOs data = keyAEvent.data as RawKeyEventDataMacOs;
+      expect(data.physicalKey, equals(PhysicalKeyboardKey.keyA));
+      expect(data.logicalKey, equals(LogicalKeyboardKey.keyA));
+      expect(data.keyLabel, equals('A'));
+    });
+
     test('Control keyboard keys are correctly translated', () {
       final RawKeyEvent escapeKeyEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
         'type': 'keydown',
@@ -2482,7 +2496,7 @@ void main() {
       }
     });
 
-    test('Printable keyboard keys are correctly translated', () {
+    test('Lower letter keys are correctly translated', () {
       final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
@@ -2497,6 +2511,21 @@ void main() {
       expect(data.keyLabel, equals('a'));
     });
 
+    test('Upper letter keys are correctly translated', () {
+      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, Object?>{
+        'type': 'keydown',
+        'keymap': 'web',
+        'code': 'KeyA',
+        'key': 'A',
+        'location': 0,
+        'metaState': 0x1, // Shift
+      });
+      final RawKeyEventDataWeb data = keyAEvent.data as RawKeyEventDataWeb;
+      expect(data.physicalKey, equals(PhysicalKeyboardKey.keyA));
+      expect(data.logicalKey, equals(LogicalKeyboardKey.keyA));
+      expect(data.keyLabel, equals('A'));
+    });
+
     test('Control keyboard keys are correctly translated', () {
       final RawKeyEvent escapeKeyEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',