hydrated_bloc 6.0.0 hydrated_bloc: ^6.0.0 copied to clipboard
An extension to the bloc state management library which automatically persists and restores bloc states.
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:hydrated_bloc/hydrated_bloc.dart';
void main() async {
// https://github.com/flutter/flutter/pull/38464
// Changes in Flutter v1.9.4 require you to call WidgetsFlutterBinding.ensureInitialized()
// before using any plugins if the code is executed before runApp.
// As a result, you will need the following line if you're using Flutter >=1.9.4.
WidgetsFlutterBinding.ensureInitialized();
HydratedBloc.storage = await HydratedStorage.build();
runApp(App());
}
class App extends StatelessWidget {
@override
Widget build(BuildContext context) {
return BlocProvider(
create: (_) => BrightnessCubit(),
child: BlocBuilder<BrightnessCubit, Brightness>(
builder: (context, brightness) {
return MaterialApp(
theme: ThemeData(brightness: brightness),
home: BlocProvider<CounterBloc>(
create: (_) => CounterBloc(),
child: CounterPage(),
),
);
},
),
);
}
}
class CounterPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
final textTheme = Theme.of(context).textTheme;
return Scaffold(
appBar: AppBar(title: const Text('Counter')),
body: BlocBuilder<CounterBloc, int>(
builder: (BuildContext context, int state) {
return Center(
child: Text('$state', style: textTheme.headline2),
);
},
),
floatingActionButton: Column(
crossAxisAlignment: CrossAxisAlignment.end,
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
Padding(
padding: const EdgeInsets.symmetric(vertical: 5.0),
child: FloatingActionButton(
child: const Icon(Icons.brightness_6),
onPressed: () {
context.bloc<BrightnessCubit>().toggleBrightness();
},
),
),
Padding(
padding: const EdgeInsets.symmetric(vertical: 5.0),
child: FloatingActionButton(
child: const Icon(Icons.add),
onPressed: () {
context.bloc<CounterBloc>().add(CounterEvent.increment);
},
),
),
Padding(
padding: const EdgeInsets.symmetric(vertical: 5.0),
child: FloatingActionButton(
child: const Icon(Icons.remove),
onPressed: () {
context.bloc<CounterBloc>().add(CounterEvent.decrement);
},
),
),
Padding(
padding: const EdgeInsets.symmetric(vertical: 5.0),
child: FloatingActionButton(
child: const Icon(Icons.delete_forever),
onPressed: () async {
final counterBloc = context.bloc<CounterBloc>();
await counterBloc.clear();
counterBloc.add(CounterEvent.reset);
},
),
),
],
),
);
}
}
enum CounterEvent { increment, decrement, reset }
class CounterBloc extends Bloc<CounterEvent, int> with HydratedMixin {
CounterBloc() : super(0) {
hydrate();
}
@override
Stream<int> mapEventToState(CounterEvent event) async* {
switch (event) {
case CounterEvent.decrement:
yield state - 1;
break;
case CounterEvent.increment:
yield state + 1;
break;
case CounterEvent.reset:
yield 0;
break;
}
}
@override
int fromJson(Map<String, dynamic> json) => json['value'] as int;
@override
Map<String, int> toJson(int state) => {'value': state};
}
class BrightnessCubit extends HydratedCubit<Brightness> {
BrightnessCubit() : super(Brightness.light);
void toggleBrightness() {
emit(state == Brightness.light ? Brightness.dark : Brightness.light);
}
@override
Brightness fromJson(Map<String, dynamic> json) {
return Brightness.values[json['brightness'] as int];
}
@override
Map<String, dynamic> toJson(Brightness state) {
return <String, int>{'brightness': state.index};
}
}