flutter-plugins/example/lib/widgets/base/app_state.dart

import 'package:flutter/material.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';

abstract class AppState<T extends StatefulWidget> extends State<T>
    with WidgetsBindingObserver {
  Widget buildWide(
    BuildContext context,
    MediaQueryData media,
    AppLocalizations l10n,
  );

  void onPostFrameCallback() {}

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    WidgetsBinding.instance.addPostFrameCallback((_) {
      didChangeMetrics();
      Future.delayed(const Duration(milliseconds: 100), () {
        didChangeMetrics();
      });
      Future.delayed(const Duration(milliseconds: 200), () {
        didChangeMetrics();
      });
      Future.delayed(const Duration(milliseconds: 500), () {
        didChangeMetrics();
      });
    });
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) => buildWide(
        context,
        MediaQuery.of(context),
        AppLocalizations.of(context)!,
      );
}