使用當前位置繪制到目的地的折線，並在帶有標記 flutter 的谷歌地圖上添加標記

Question

我有一個帶有谷歌 map 的應用程序，該應用程序獲取我的當前位置，map 上有兩個標記，標記的一個點和折線是從前一個屏幕傳遞的坐標。 我希望折線的起點是我當前的位置。 我還想將我當前的位置用作第一個標記。 如果折線和標記會隨着司機的移動而改變 position，那就太好了。 但這不是現在的優先事項。

到目前為止我所做的：我能夠獲得我當前的位置。 我能夠從硬編碼坐標繪制折線到目標位置（目標位置由前一個屏幕提供）

我想做什么： 使用我的當前位置作為我的折線的起點 使用我的當前位置添加標記 當驅動程序移動時更新折線和標記。

這是我到目前為止的代碼。

class _MyAppState extends State<RoutePage> {
  late GoogleMapController mapController;
  // Starting point latitude
  // 5.6609595, -0.017155699999989338)
  double _originLatitude = 5.555700;
  // Starting point longitude
  double _originLongitude = -0.196300;
  // Destination latitude
  double? destLatitude;
  // Destination Longitude
  double? destLongitude;
  // Markers to show points on the map
  Map<MarkerId, Marker> markers = {};
  Map<PolylineId, Polyline> polylines = {};
  List<LatLng> polylineCoordinates = [];

  PolylinePoints polylinePoints = PolylinePoints();


  Completer<GoogleMapController> _controller = Completer();

  late Position currentPosition;

  var geoLocator = Geolocator();
  late Geolocator geolocatorTwo;
  var locationOptions = LocationOptions(accuracy: LocationAccuracy.bestForNavigation, distanceFilter: 4);

  Future<LatLng> getCurrentPositiion() async {
    Position position = await Geolocator.getCurrentPosition(desiredAccuracy: LocationAccuracy.bestForNavigation);
    currentPosition = position;
    LatLng pos = LatLng(position.latitude, position.longitude);
    mapController.animateCamera((CameraUpdate.newLatLng(pos)));
    print('MyPosition');
    print(currentPosition);
    print(pos.longitude);
    print(pos.latitude);
    print(position.longitude);
    print(position.latitude);
    print(pos);
    return pos;
  }

  static const LatLng _center = const LatLng(45.521563, -122.677433);

  @override
  void initState() {

    /// add origin marker origin marker
    _addMarker(
      LatLng(_originLatitude, _originLongitude),
      "origin",
      BitmapDescriptor.defaultMarker,
    );

    // Add destination marker
    _addMarker(
      LatLng(double.parse(widget.vendors!.latitude), double.parse(widget.vendors!.longitude)),
      "destination",
      BitmapDescriptor.defaultMarkerWithHue(90),
    );
    _getPolyline();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(

        body: GoogleMap(
          padding: EdgeInsets.only(top: 135),
          myLocationButtonEnabled: true,
          myLocationEnabled: true,
          mapType: MapType.normal,
          initialCameraPosition: googlePlex,
          onMapCreated: (GoogleMapController controller){
            _controller.complete(controller);
            mapController=controller;
            getCurrentPositiion();
          },
          polylines: Set<Polyline>.of(polylines.values),
          markers: Set<Marker>.of(markers.values),
        ),
      ),
    );
  }


  // This method will add markers to the map based on the LatLng position
  _addMarker(LatLng position, String id, BitmapDescriptor descriptor) {
    MarkerId markerId = MarkerId(id);
    Marker marker =
    Marker(markerId: markerId, icon: descriptor, position: position);
    markers[markerId] = marker;
  }

  _addPolyLine(List<LatLng> polylineCoordinates) {
    PolylineId id = PolylineId("poly");
    Polyline polyline = Polyline(
      polylineId: id,
      points: polylineCoordinates,
      width: 8,
    );
    polylines[id] = polyline;
    setState(() {});
  }

  void _getPolyline() async {
    List<LatLng> polylineCoordinates = [];

    print("In the Polyline");
    print(currentPosition);
    print(currentPosition.longitude);


    PolylineResult result = await polylinePoints.getRouteBetweenCoordinates(
      "APP KEY",
      PointLatLng(_originLatitude, _originLongitude),
      PointLatLng(double.parse(widget.vendors!.latitude), double.parse(widget.vendors!.longitude)),
      travelMode: TravelMode.driving,
    );
    if (result.points.isNotEmpty) {
      result.points.forEach((PointLatLng point) {
        polylineCoordinates.add(LatLng(point.latitude, point.longitude));
      });
    } else {
      print(result.errorMessage);
    }
    _addPolyLine(polylineCoordinates);
  }

  void getLocationUpdates(){
    var homeTabPositionStream = Geolocator.getPositionStream().listen((Position position) {
      currentPosition = position;
      LatLng pos = LatLng(position.latitude, position.longitude);
      mapController.animateCamera(CameraUpdate.newLatLng(pos));
    });
  }
}

我錯過了什么，為什么我不能只使用currentPosition.latitude和currentPosition.longitude ？

Answer 1

我試圖以這樣一種方式修改您的代碼，即它使用您當前的位置作為多段線的起點，並使用 latlng 作為原點標記。 請參閱隨附的屏幕截圖。

我的默認位置在 GooglePlex 中，我只是在它附近設置了目的地 latlng (dest_location)。 你可以把你的設置在你所在位置附近的某個地方。

此外，這篇文章可能會有所幫助，因此請查看。 :)

const LatLng dest_location = LatLng(37.42796133580664, -122.085749655962);

class _TrackingState extends State<Tracking> {
  GoogleMapController mapController;

  // Markers to show points on the map
  Map<MarkerId, Marker> markers = {};
  Map<PolylineId, Polyline> polylines = {};
  List<LatLng> polylineCoordinates = [];

  PolylinePoints polylinePoints = PolylinePoints();

  Completer<GoogleMapController> _controller = Completer();
  static final CameraPosition _kGooglePlex = CameraPosition(
    target: LatLng(37.42796133580664, -122.085749655962),
    zoom: 14.4746,
  );

  Position currentPosition;
  var geoLocator = Geolocator();
  var locationOptions = LocationOptions(
      accuracy: LocationAccuracy.bestForNavigation, distanceFilter: 4);

  void getCurrentPosition() async {
    currentPosition = await Geolocator.getCurrentPosition(
        desiredAccuracy: LocationAccuracy.bestForNavigation);
  }

  @override
  void initState() {
    super.initState();
    getCurrentPosition();
  }

  @override
  Widget build(BuildContext context) {
    CameraPosition initialCameraPosition = _kGooglePlex;
    if (currentPosition != null) {
      initialCameraPosition = CameraPosition(
          target: LatLng(currentPosition.latitude, currentPosition.longitude),
          zoom: 14.4746);
    }
    return MaterialApp(
      home: Scaffold(
        body: GoogleMap(
          padding: EdgeInsets.only(top: 135),
          myLocationButtonEnabled: true,
          myLocationEnabled: true,
          mapType: MapType.normal,
          initialCameraPosition: initialCameraPosition,
          onMapCreated: (GoogleMapController controller) {
            _controller.complete(controller);
            mapController = controller;
            _getPolyline();
          },
          polylines: Set<Polyline>.of(polylines.values),
          markers: Set<Marker>.of(markers.values),
        ),
      ),
    );
  }

  // This method will add markers to the map based on the LatLng position
  _addMarker(LatLng position, String id, BitmapDescriptor descriptor) {
    MarkerId markerId = MarkerId(id);
    Marker marker =
        Marker(markerId: markerId, icon: descriptor, position: position);
    markers[markerId] = marker;
  }

  _addPolyLine(List<LatLng> polylineCoordinates) {
    PolylineId id = PolylineId("poly");
    Polyline polyline = Polyline(
      polylineId: id,
      points: polylineCoordinates,
      width: 8,
    );
    polylines[id] = polyline;
    setState(() {});
  }

  void _getPolyline() async {
    /// add origin marker origin marker
    _addMarker(
      LatLng(currentPosition.latitude, currentPosition.longitude),
      "origin",
      BitmapDescriptor.defaultMarker,
    );

    // Add destination marker
    _addMarker(
      LatLng(dest_location.latitude, dest_location.longitude),
      "destination",
      BitmapDescriptor.defaultMarkerWithHue(90),
    );

    List<LatLng> polylineCoordinates = [];

    PolylineResult result = await polylinePoints.getRouteBetweenCoordinates(
      "API KEY",
      PointLatLng(currentPosition.latitude, currentPosition.longitude),
      PointLatLng(dest_location.latitude, dest_location.longitude),
      travelMode: TravelMode.walking,
    );
    if (result.points.isNotEmpty) {
      result.points.forEach((PointLatLng point) {
        polylineCoordinates.add(LatLng(point.latitude, point.longitude));
      });
    } else {
      print(result.errorMessage);
    }
    _addPolyLine(polylineCoordinates);
  }
}