Question

我正在尝试学习和使用flutter bloc来创建一个项目，该项目可以侦听用户的位置，还可以从服务中获取一些坐标，并将此坐标显示在地图中作为标记。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来获取坐标以在地图上显示为标记？

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());
      }
    }
  }
}

它是否再次在BlocBuilder<LocationBloc, LocationState>(builder: (context, state)下调用BlocBuilder还是我必须使用LocationBloc构造函数在LocationBloc内部调用FoursquareBlo？

Answer 1

我遇到了同样的问题，直到现在Flutter Bloc库都不支持MultiBlocBuilder。您可以使用嵌套的bloc生成器或创建将其他两个状态组合在一起的新bloc。我进行issue in Github检查以获取更多信息。

在一页中使用多扑集团

1 个答案: