issue_109437

main.dart

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() => runApp(const MaterialApp(home: HomePage()));

extension HumanReadableRawKeyEventX on RawKeyEvent {
  String get details => [
        this is RawKeyDownEvent ? 'down' : 'up',
        '$logicalKey',
        '$physicalKey',
      ].join('\n');
}

class KeyLogger extends StatefulWidget {
  final FocusNode focus;
  const KeyLogger({
    required this.focus,
    super.key,
  });

  @override
  State<KeyLogger> createState() => _KeyLoggerState();
}

class _KeyLoggerState extends State<KeyLogger> {
  late final ValueNotifier<List<RawKeyEvent>> _events;
  late final ScrollController _controller;

  @override
  void initState() {
    _events = ValueNotifier([])..addListener(_onEventsUpdated);
    _controller = ScrollController();
    super.initState();
  }

  @override
  void dispose() {
    _events..removeListener(_onEventsUpdated)..dispose();
    _controller.dispose();
    super.dispose();
  }

  void addEvent(RawKeyEvent event) => _events.value = [..._events.value, event];

  void _onEventsUpdated() {
    _controller.animateTo(
      _controller.position.maxScrollExtent,
      duration: kThemeAnimationDuration,
      curve: Curves.easeIn,
    );
  }

  @override
  Widget build(context) => RawKeyboardListener(
        focusNode: widget.focus,
        onKey: addEvent,
        autofocus: true,
        child: ValueListenableBuilder<List<RawKeyEvent>>(
          valueListenable: _events,
          builder: (context, events, child) => ListView.separated(
            controller: _controller,
            itemCount: events.length,
            itemBuilder: (context, index) => Text(events[index].details),
            separatorBuilder: (context, index) => const Divider(),
          ),
        ),
      );
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  late final FocusNode _focus;
  late final ValueNotifier<bool> _hasFocus;

  @override
  void initState() {
    _focus = FocusNode()..addListener(_onFocusChanged);
    _hasFocus = ValueNotifier(_focus.hasFocus);
    super.initState();
  }

  @override
  void dispose() {
    _focus
      ..removeListener(_onFocusChanged)
      ..dispose();
    _hasFocus.dispose();
    super.dispose();
  }

  void _onFocusChanged() {
    _hasFocus.value = _focus.hasFocus;
  }

  void _changeFocus() {
    _focus.hasFocus ? _focus.unfocus() : _focus.requestFocus();
  }

  @override
  Widget build(context) => Scaffold(
        body: KeyLogger(focus: _focus),
        floatingActionButton: FloatingActionButton(
          onPressed: _changeFocus,
          child: ValueListenableBuilder<bool>(
            valueListenable: _hasFocus,
            builder: (context, hasFocus, child) =>
                hasFocus ? const Icon(Icons.done) : const Icon(Icons.error),
          ),
        ),
      );
}