text_field_error

import 'dart:async';

import 'package:flutter/material.dart';

void main() => runApp(new MyApp());

class MyApp extends StatefulWidget {
  static MyAppState of(BuildContext context) => (context.inheritFromWidgetOfExactType(AppState) as AppState).data;

  @override
  MyAppState createState() => new MyAppState();
}

class MyAppState extends State<MyApp> {
  final GlobalKey<NavigatorState> key = GlobalKey<NavigatorState>();
  bool isLocked = true;

  NavigatorState get navigator => key.currentState;

  void pushRoute(FakeRoute route) {
    navigator.pushReplacement(PageRouteBuilder<void>(
      pageBuilder: (BuildContext _, Animation __, Animation ___) => appRoutes[route](),
    ));
  }

  void setIsLocked(bool isLocked) {
    if (this.isLocked != isLocked) {
      setState(() => this.isLocked = isLocked);
    }
  }

  @override
  Widget build(BuildContext context) {
    return AppState(
      data: this,
      isLocked: isLocked,
      child: new MaterialApp(
        navigatorKey: key,
        title: 'Flutter Demo',
        theme: new ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: const SplashScreen(),
      ),
    );
  }
}

class AppState extends InheritedWidget {
  const AppState({this.data, this.isLocked, Widget child}) : super(child: child);

  final MyAppState data;
  final bool isLocked;

  @override
  bool updateShouldNotify(InheritedWidget oldWidget) => (oldWidget as AppState).isLocked != isLocked;
}

class SplashScreen extends StatefulWidget {
  const SplashScreen();

  @override
  SplashScreenState createState() => new SplashScreenState();
}

class SplashScreenState extends State<SplashScreen> {
  @override
  void initState() {
    super.initState();
    Future.delayed(const Duration(seconds: 3), () {
      MyApp.of(context).pushRoute(FakeRoute.public);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceAround,
          children: <Widget>[
            FlutterLogo(size: 240.0),
            CircularProgressIndicator(strokeWidth: 1.0),
          ],
        ),
      ),
    );
  }
}

Map<FakeRoute, Widget Function()> appRoutes = <FakeRoute, Widget Function()>{
  PublicNavigator.route: () => const PublicNavigator(),
  PrivateNavigator.route: () => const PrivateNavigator(),
};

Route<dynamic> onGenerateRoute(RouteSettings settings, Map<String, WidgetBuilder> routes) {
  final String name = settings.name;
  final WidgetBuilder builder = routes[name];

  return MaterialPageRoute<dynamic>(
    builder: builder,
    settings: settings,
  );
}

enum FakeRoute { public, private }

class PublicRoutes {
  static const String public1 = '/';
  static const String public2 = '/2';
}

class PublicNavigator extends StatelessWidget {
  static const FakeRoute route = FakeRoute.public;

  const PublicNavigator();

  @override
  Widget build(BuildContext context) {
    final Map<String, WidgetBuilder> routes = <String, WidgetBuilder>{
      PublicRoutes.public1: (BuildContext context) => const PublicPage(i: 1),
      PublicRoutes.public2: (BuildContext context) => const PublicPage(i: 2),
    };

    return Navigator(
      key: key,
      initialRoute: PublicRoutes.public1,
      onGenerateRoute: (RouteSettings settings) => onGenerateRoute(settings, routes),
    );
  }
}

class PublicPage extends StatelessWidget {
  const PublicPage({Key key, @required this.i}) : super(key: key);
  final int i;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Public page $i')),
      body: Center(
        child: new Text(
          'Public page $i',
          style: Theme.of(context).textTheme.body1,
        ),
      ),
      floatingActionButton: RaisedButton.icon(
        color: Theme.of(context).primaryColor,
        icon: Icon(
          Icons.navigate_next,
          color: Colors.white,
        ),
        label: Text(
          i == 1 ? '2' : 'Private',
          style: const TextStyle(
            color: Colors.white,
          ),
        ),
        onPressed: i == 1
            ? () => Navigator.of(context).pushNamed(PublicRoutes.public2)
            : () => MyApp.of(context).pushRoute(FakeRoute.private),
      ),
    );
  }
}

class PrivateRoutes {
  static const String private1 = '/';
  static const String private2 = '/2';
  static const String locked = '/locked';
}

class PrivateNavigator extends StatelessWidget {
  static const FakeRoute route = FakeRoute.private;

  const PrivateNavigator();

  @override
  Widget build(BuildContext context) {
    final Map<String, WidgetBuilder> routes = <String, WidgetBuilder>{
      PrivateRoutes.private1: (BuildContext context) => const PrivatePage(i: 1),
      PrivateRoutes.private2: (BuildContext context) => const PrivatePage(i: 2),
      PrivateRoutes.locked: (BuildContext context) => const LockPage(),
    };

    return Stack(
      children: <Widget>[
        Navigator(
          key: key,
          initialRoute: PrivateRoutes.private1,
          onGenerateRoute: (RouteSettings settings) => onGenerateRoute(settings, routes),
        ),
        MyApp.of(context).isLocked ? const LockPage() : Container(),
      ],
    );
  }
}

class PrivatePage extends StatelessWidget {
  const PrivatePage({Key key, @required this.i}) : super(key: key);
  final int i;

  @override
  Widget build(BuildContext context) {
    return Theme(
      data: Theme.of(context).copyWith(
        primaryColor: Colors.red,
        accentColor: Colors.grey,
      ),
      child: Builder(
        builder: (BuildContext context) {
          return Scaffold(
            appBar: AppBar(title: Text('Private page $i')),
            body: Center(
              child: new Text(
                'Private page $i',
                style: Theme.of(context).textTheme.body1,
              ),
            ),
            floatingActionButton: Container(
              height: 120.0,
              child: i == 1
                  ? Column(
                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
                      children: <Widget>[
                        FloatingActionButton(
                          child: Icon(Icons.lock),
                          onPressed: () {
                            MyApp.of(context).setIsLocked(true);
                          },
                        ),
                        RaisedButton.icon(
                          color: Colors.grey,
                          icon: Icon(
                            Icons.navigate_next,
                            color: Colors.white,
                          ),
                          label: Text(
                            '2',
                            style: const TextStyle(
                              color: Colors.white,
                            ),
                          ),
                          onPressed: () => Navigator.of(context).pushNamed(PrivateRoutes.private2),
                        ),
                      ],
                    )
                  : FloatingActionButton(
                      child: Icon(Icons.lock),
                      onPressed: () {
                        MyApp.of(context).setIsLocked(true);
                      },
                    ),
            ),
          );
        },
      ),
    );
  }
}

class LockPage extends StatelessWidget {
  const LockPage();

  @override
  Widget build(BuildContext context) {
    return Theme(
      data: Theme.of(context).copyWith(
        primaryColor: Colors.purple,
        accentColor: Colors.deepPurple,
      ),
      child: Builder(
        builder: (BuildContext context) {
          return Scaffold(
            backgroundColor: Theme.of(context).primaryColor,
            body: Padding(
              padding: const EdgeInsets.all(16.0),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: <Widget>[
                  Text('Enter 5 characters to unlock, if you can, the keyboard won\'t open.'),
                  TextField(
                    decoration: InputDecoration(
                      hintText: 'password',
                    ),
                    onChanged: (String text) {
                      if (text.length >= 5) {
                        MyApp.of(context).setIsLocked(false);
                      }
                    },
                  ),
                  Text('Or you can cheat by taping the FloatingActionButton.'),
                ],
              ),
            ),
            floatingActionButton: FloatingActionButton(
              child: Icon(Icons.lock_open),
              onPressed: () => MyApp.of(context).setIsLocked(false),
            ),
          );
        },
      ),
    );
  }
}