在一页中使用多颤动块

Posted 2023-02-23

【中文标题】在一页中使用多颤动块

【英文标题】：Use multi flutter bloc in one page

【发布时间】：2020-07-28 08:42:04

【问题描述】：

我正在尝试学习和使用flutter bloc，我创建了一个项目来监听用户位置，并从服务中获取一些坐标，并在地图中显示这个坐标作为标记。所以这是 myApp 方法：

class MyApp extends StatelessWidget 
  @override
  Widget build(BuildContext context) 
    return MaterialApp(
      title: 'Material App',
      home: MultiBlocProvider(providers: [
        BlocProvider<FoursquareBloc>(create: (context) => sl<FoursquareBloc>()), //bloc page to get corrdinate
        BlocProvider<LocationBloc>(create: (context) => sl<LocationBloc>()), // bloc page to listen to change user location
      ], child: HomeFoursquareScreen()),
    );
  

HomeFoursquareScreen页面显示地图：

 Widget build(BuildContext context) 
    return BlocBuilder<LocationBloc, LocationState>(builder: (context, state) 
      if (state is LocationLoadingState) 
        return Center(child: CircularProgressIndicator());
       else if (state is LocationLoadedState) 
        print("LocationLoadedState");
        intMapCoordinate =
            LatLng(state.location.latitude, state.location.longitude);
       else if (state is UserLocationListeningState) 
        _controller.move(
            LatLng(state.location.latitude, state.location.longitude), 15.0);
      
      return FlutterMap(
        mapController: _controller,
        options: MapOptions(
          center: intMapCoordinate,
          zoom: 13.0,
        ),
        layers: [
          TileLayerOptions(
              urlTemplate: "https://s.tile.openstreetmap.org/z/x/y.png",
              subdomains: ['a', 'b', 'c']),
        ],
      );
    );
  

我很困惑，因为我不知道如何使用FoursquareBloc 获取坐标以在地图中显示为标记？

这是LocationBloc

class LocationBloc extends Bloc<LocationEvent, LocationState> 
  var location = Location();
  StreamSubscription<LocationData> _locationSubscription;
  LocationData currentLocation;
  @override
  LocationState get initialState => LocationLoadingState();

  @override
  Stream<LocationState> mapEventToState(
    LocationEvent event,
  ) async* 
    if (event is GetCurrentLocation) 
      yield* _mapToGetCurrentLocationState();
     else if (event is StartListeningForLiveLocation) 
      yield* _mapToStartListeningUserLocation();
    else if (event is AddLiveUserLocation) 
      yield UserLocationListeningState(event.location);
    

  

这是FoursquareBloc：

class FoursquareBloc extends Bloc<FoursquareEvent, FoursquareState> 
  final FoursquareRepository repo;
  FoursquareBloc(this.repo);

  @override
  FoursquareState get initialState => Empty();

  @override
  Stream<FoursquareState> mapEventToState(
    FoursquareEvent event,
  ) async* 
    if (event is GetVenuesByUserEvent) 
      yield Loading();
      try 
        final result = await repo.getVenuesByUser(event.lat, event.lng);
        yield Loaded(result);
       on Exception catch (e) 
        yield Error(e.toString());
      
    
  

它是否再次调用 BlocBuilder<LocationBloc, LocationState>(builder: (context, state) 下的 BlocBuilder 或者我必须使用 LocationBloc 构造函数在 LocationBloc 中调用 FoursquareBlo？

【问题讨论】：

你想让 HomeFoursquareScreen 小部件对这两个 bloc 做出反应吗？

Yes.in HomeFoursquareScreen 我想显示来自 locationBloc 的用户位置和来自 FoursquareBloc @PayamZahedi 的坐标

【参考方案1】：

我有同样的问题，直到现在 Flutter Bloc 库不支持 MultiBlocBuilder。您可以使用嵌套的 bloc 构建器或创建一个新的 bloc，它结合了其他两个状态。我创建了issue in Github，查看更多信息。