[web] Treeshake keymaps for web (4% code size reduction in hello world) (#75945)

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

@@ -267,6 +267,17 @@ abstract class RawKeyEvent with Diagnosticable {
     String? character;
 
     final String keymap = message['keymap'] as String;
+    if (kIsWeb) {
+      final String? key = message['key'] as String?;
+      data = RawKeyEventDataWeb(
+        code: message['code'] as String? ?? '',
+        key: key ?? '',
+        metaState: message['metaState'] as int? ?? 0,
+      );
+      if (key != null && key.isNotEmpty) {
+        character = key;
+      }
+    } else {
       switch (keymap) {
         case 'android':
           data = RawKeyEventDataAndroid(
@@ -325,14 +336,6 @@ abstract class RawKeyEvent with Diagnosticable {
             character = String.fromCharCode(unicodeScalarValues);
           }
           break;
-      case 'web':
-        data = RawKeyEventDataWeb(
-          code: message['code'] as String? ?? '',
-          key: message['key'] as String? ?? '',
-          metaState: message['metaState'] as int? ?? 0,
-        );
-        character = message['key'] as String?;
-        break;
         case 'windows':
           final int characterCodePoint = message['characterCodePoint'] as int? ?? 0;
           data = RawKeyEventDataWindows(
@@ -345,6 +348,17 @@ abstract class RawKeyEvent with Diagnosticable {
             character = String.fromCharCode(characterCodePoint);
           }
           break;
+        case 'web':
+          final String? key = message['key'] as String?;
+          data = RawKeyEventDataWeb(
+            code: message['code'] as String? ?? '',
+            key: key ?? '',
+            metaState: message['metaState'] as int? ?? 0,
+          );
+          if (key != null && key.isNotEmpty) {
+            character = key;
+          }
+          break;
         default:
           /// This exception would only be hit on platforms that haven't yet
           /// implemented raw key events, but will only be triggered if the
@@ -352,7 +366,7 @@ abstract class RawKeyEvent with Diagnosticable {
           /// first place.
           throw FlutterError('Unknown keymap for key events: $keymap');
       }
-
+    }
     final String type = message['type'] as String;
     switch (type) {
       case 'keydown':

packages/flutter/test/widgets/raw_keyboard_listener_test.dart

@@ -42,6 +42,37 @@ void main() {
     expect(typedData.modifiers, RawKeyEventDataFuchsia.modifierLeftMeta);
     expect(typedData.isModifierPressed(ModifierKey.metaModifier, side: KeyboardSide.left), isTrue);
 
+    await tester.pumpWidget(Container());
+    focusNode.dispose();
+  }, skip: isBrowser); // This is a Fuchsia-specific test.
+
+  testWidgets('Web key event', (WidgetTester tester) async {
+    final List<RawKeyEvent> events = <RawKeyEvent>[];
+
+    final FocusNode focusNode = FocusNode();
+
+    await tester.pumpWidget(
+      RawKeyboardListener(
+        focusNode: focusNode,
+        onKey: events.add,
+        child: Container(),
+      ),
+    );
+
+    focusNode.requestFocus();
+    await tester.idle();
+
+    await tester.sendKeyEvent(LogicalKeyboardKey.metaLeft, platform: 'web');
+    await tester.idle();
+
+    expect(events.length, 2);
+    expect(events[0].runtimeType, equals(RawKeyDownEvent));
+    expect(events[0].data, isA<RawKeyEventDataWeb>());
+    final RawKeyEventDataWeb typedData = events[0].data as RawKeyEventDataWeb;
+    expect(typedData.code, 'MetaLeft');
+    expect(typedData.metaState, RawKeyEventDataWeb.modifierMeta);
+    expect(typedData.isModifierPressed(ModifierKey.metaModifier, side: KeyboardSide.left), isTrue);
+
     await tester.pumpWidget(Container());
     focusNode.dispose();
   });

packages/flutter_test/lib/src/event_simulation.dart

@@ -4,6 +4,7 @@
 
 import 'dart:io';
 
+import 'package:flutter/foundation.dart' show kIsWeb;
 import 'package:flutter/services.dart';
 import 'test_async_utils.dart';
 
@@ -85,6 +86,11 @@ class KeyEventSimulator {
 
   static int _getKeyCode(LogicalKeyboardKey key, String platform) {
     assert(_osIsSupported(platform), 'Platform $platform not supported for key simulation');
+    if (kIsWeb) {
+      // web doesn't have int type code. This check is used to treeshake
+      // keyboard map code.
+      return -1;
+    } else {
       late Map<int, LogicalKeyboardKey> map;
       switch (platform) {
         case 'android':
@@ -100,7 +106,7 @@ class KeyEventSimulator {
         // iOS doesn't do key codes, just scan codes.
           return -1;
         case 'web':
-        // web doesn't have int type code
+          // web doesn't have int type code.
           return -1;
         case 'linux':
           map = kGlfwToLogicalKey;
@@ -119,6 +125,8 @@ class KeyEventSimulator {
       assert(keyCode != null, 'Key $key not found in $platform keyCode map');
       return keyCode!;
     }
+  }
+
   static String _getWebKeyCode(LogicalKeyboardKey key) {
     String? result;
     for (final String code in kWebToLogicalKey.keys) {
@@ -134,6 +142,10 @@ class KeyEventSimulator {
   static PhysicalKeyboardKey _findPhysicalKey(LogicalKeyboardKey key, String platform) {
     assert(_osIsSupported(platform), 'Platform $platform not supported for key simulation');
     late Map<dynamic, PhysicalKeyboardKey> map;
+    if (kIsWeb) {
+      // This check is used to treeshake keymap code.
+      map = kWebToPhysicalKey;
+    } else {
       switch (platform) {
         case 'android':
           map = kAndroidToPhysicalKey;
@@ -157,6 +169,7 @@ class KeyEventSimulator {
           map = kWindowsToPhysicalKey;
           break;
       }
+    }
     PhysicalKeyboardKey? result;
     for (final PhysicalKeyboardKey physicalKey in map.values) {
       if (key.debugName == physicalKey.debugName) {
@@ -191,6 +204,13 @@ class KeyEventSimulator {
       'keymap': platform,
     };
 
+    if (kIsWeb) {
+      result['code'] = _getWebKeyCode(key);
+      result['key'] = key.keyLabel;
+      result['metaState'] = _getWebModifierFlags(key, isDown);
+      return result;
+    }
+
     switch (platform) {
       case 'android':
         result['keyCode'] = keyCode;