[RawKeyboard] Fix Linux remapped CapsLock throws (#115009)

Co-authored-by: Bruno Leroux <bruno.leroux@gmail.com>

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

@@ -824,9 +824,18 @@ class RawKeyboard {
         modifierKeys[physicalModifier] = _allModifiers[physicalModifier]!;
       }
     }
-    _allModifiersExceptFn.keys
-      .where((PhysicalKeyboardKey key) => !anySideKeys.contains(key))
-      .forEach(_keysPressed.remove);
+    // On Linux, CapsLock key can be mapped to a non-modifier logical key:
+    // https://github.com/flutter/flutter/issues/114591.
+    // This is also affecting Flutter Web on Linux.
+    final bool nonModifierCapsLock = (event.data is RawKeyEventDataLinux  || event.data is RawKeyEventDataWeb)
+      && _keysPressed[PhysicalKeyboardKey.capsLock] != null
+      && _keysPressed[PhysicalKeyboardKey.capsLock] != LogicalKeyboardKey.capsLock;
+    for (final PhysicalKeyboardKey physicalKey in _allModifiersExceptFn.keys) {
+      final bool skipReleasingKey = nonModifierCapsLock && physicalKey == PhysicalKeyboardKey.capsLock;
+      if (!anySideKeys.contains(physicalKey) && !skipReleasingKey) {
+        _keysPressed.remove(physicalKey);
+      }
+    }
     if (event.data is! RawKeyEventDataFuchsia && event.data is! RawKeyEventDataMacOs) {
       // On Fuchsia and macOS, the Fn key is not considered a modifier key.
       _keysPressed.remove(PhysicalKeyboardKey.fn);

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

@@ -106,8 +106,8 @@ class RawKeyEventDataWeb extends RawKeyEventData {
       return maybeLocationKey;
     }
 
-    // Look to see if the [code] is one we know about and have a mapping for.
-    final LogicalKeyboardKey? newKey = kWebToLogicalKey[code];
+    // Look to see if the [key] is one we know about and have a mapping for.
+    final LogicalKeyboardKey? newKey = kWebToLogicalKey[key];
     if (newKey != null) {
       return newKey;
     }

packages/flutter/test/services/raw_keyboard_test.dart

@@ -350,6 +350,33 @@ void main() {
       );
     }, skip: isBrowser); // [intended] This is a GLFW-specific test.
 
+    Future<void> simulateGTKKeyEvent(bool keyDown, int scancode, int keycode, int modifiers) async {
+      final Map<String, dynamic> data = <String, dynamic>{
+          'type': keyDown ? 'keydown' : 'keyup',
+          'keymap': 'linux',
+          'toolkit': 'gtk',
+          'scanCode': scancode,
+          'keyCode': keycode,
+          'modifiers': modifiers,
+        };
+      // Dispatch an empty key data to disable HardwareKeyboard sanity check,
+      // since we're only testing if the raw keyboard can handle the message.
+      // In a real application, the embedder responder will send the correct key data
+      // (which is tested in the engine).
+      TestDefaultBinaryMessengerBinding.instance!.keyEventManager.handleKeyData(const ui.KeyData(
+        type: ui.KeyEventType.down,
+        timeStamp: Duration.zero,
+        logical: 0,
+        physical: 0,
+        character: null,
+        synthesized: false,
+      ));
+      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+        SystemChannels.keyEvent.name,
+        SystemChannels.keyEvent.codec.encodeMessage(data),
+        (ByteData? data) {},
+      );
+    }
 
     // Regression test for https://github.com/flutter/flutter/issues/93278 .
     //
@@ -357,38 +384,11 @@ void main() {
     // result in a AltRight down event without Alt bitmask.
     testWidgets('keysPressed modifiers are synchronized with key events on Linux GTK (down events)', (WidgetTester tester) async {
       expect(RawKeyboard.instance.keysPressed, isEmpty);
-      Future<void> simulate(bool keyDown, int scancode, int keycode, int modifiers) async {
-        final Map<String, dynamic> data = <String, dynamic>{
-            'type': keyDown ? 'keydown' : 'keyup',
-            'keymap': 'linux',
-            'toolkit': 'gtk',
-            'scanCode': scancode,
-            'keyCode': keycode,
-            'modifiers': modifiers,
-          };
-        // Dispatch an empty key data to disable HardwareKeyboard sanity check,
-        // since we're only testing if the raw keyboard can handle the message.
-        // In real application the embedder responder will send correct key data
-        // (which is tested in the engine.)
-        TestDefaultBinaryMessengerBinding.instance!.keyEventManager.handleKeyData(const ui.KeyData(
-          type: ui.KeyEventType.down,
-          timeStamp: Duration.zero,
-          logical: 0,
-          physical: 0,
-          character: null,
-          synthesized: false,
-        ));
-        await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
-          SystemChannels.keyEvent.name,
-          SystemChannels.keyEvent.codec.encodeMessage(data),
-          (ByteData? data) {},
-        );
-      }
 
-      await simulate(true,  0x6c/*AltRight*/,  0xffea/*AltRight*/,  0x2000000);
-      await simulate(true,  0x32/*ShiftLeft*/, 0xfe08/*NextGroup*/, 0x2000008/*MOD3*/);
-      await simulate(false, 0x6c/*AltRight*/,  0xfe03/*AltRight*/,  0x2002008/*MOD3|Reserve14*/);
-      await simulate(true,  0x6c/*AltRight*/,  0xfe03/*AltRight*/,  0x2002000/*Reserve14*/);
+      await simulateGTKKeyEvent(true,  0x6c/*AltRight*/,  0xffea/*AltRight*/,  0x2000000);
+      await simulateGTKKeyEvent(true,  0x32/*ShiftLeft*/, 0xfe08/*NextGroup*/, 0x2000008/*MOD3*/);
+      await simulateGTKKeyEvent(false, 0x6c/*AltRight*/,  0xfe03/*AltRight*/,  0x2002008/*MOD3|Reserve14*/);
+      await simulateGTKKeyEvent(true,  0x6c/*AltRight*/,  0xfe03/*AltRight*/,  0x2002000/*Reserve14*/);
       expect(
         RawKeyboard.instance.keysPressed,
         equals(
@@ -399,6 +399,56 @@ void main() {
       );
     }, skip: isBrowser); // [intended] This is a GTK-specific test.
 
+    // Regression test for https://github.com/flutter/flutter/issues/114591 .
+    //
+    // On Linux, CapsLock can be remapped to a non-modifier key.
+    testWidgets('CapsLock should not be release when remapped on Linux', (WidgetTester tester) async {
+      expect(RawKeyboard.instance.keysPressed, isEmpty);
+
+      await simulateGTKKeyEvent(true,  0x42/*CapsLock*/,  0xff08/*Backspace*/,  0x2000000);
+      expect(
+        RawKeyboard.instance.keysPressed,
+        equals(
+          <LogicalKeyboardKey>{
+            LogicalKeyboardKey.backspace,
+          },
+        ),
+      );
+    }, skip: isBrowser); // [intended] This is a GTK-specific test.
+
+    // Regression test for https://github.com/flutter/flutter/issues/114591 .
+    //
+    // On Web, CapsLock can be remapped to a non-modifier key.
+    testWidgets('CapsLock should not be release when remapped on Web', (WidgetTester _) async {
+      final List<RawKeyEvent> events = <RawKeyEvent>[];
+      RawKeyboard.instance.addListener(events.add);
+      addTearDown(() {
+        RawKeyboard.instance.removeListener(events.add);
+      });
+      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+        SystemChannels.keyEvent.name,
+        SystemChannels.keyEvent.codec.encodeMessage(const <String, dynamic>{
+          'type': 'keydown',
+          'keymap': 'web',
+          'code': 'CapsLock',
+          'key': 'Backspace',
+          'location': 0,
+          'metaState': 0,
+          'keyCode': 8,
+        }),
+        (ByteData? data) { },
+      );
+
+      expect(
+        RawKeyboard.instance.keysPressed,
+        equals(
+          <LogicalKeyboardKey>{
+            LogicalKeyboardKey.backspace,
+          },
+        ),
+      );
+    }, skip: !isBrowser); // [intended] This is a Browser-specific test.
+
     testWidgets('keysPressed modifiers are synchronized with key events on web', (WidgetTester tester) async {
       expect(RawKeyboard.instance.keysPressed, isEmpty);
       // Generate the data for a regular key down event. Change the modifiers so