如何解决map flutter中不稳定的折线

如何解决如何解决map flutter中不稳定的折线

我想在地图上绘制位置距离。然后当用户移动定位销时也会移动它。我已参考此 page。我面临的问题是折线有些时候出来了，有些时候没有出来。我使用的包是 google_maps_Flutter: ^2.0.3、lutter_polyline_points: ^0.2.6 和 location: ^4.1.1。任何人都可以帮助我吗？提前致谢。这是我的代码：

const double CAMERA_ZOOM = 18;
const double CAMERA_TILT = 80;
const double CAMERA_bearing = 30;
const LatLng SOURCE_LOCATION = LatLng(2.3896,122.2501);
const LatLng DEST_LOCATION = LatLng(-2.2855,122.2625);

class MapPage extends StatefulWidget {
  @override
  _MapPageState createState() => _MapPageState();
}

class _MapPageState extends State<MapPage> {
  Completer<GoogleMapController> _controller = Completer();
  Set<Marker> _markers = Set<Marker>();

  Set<polyline> _polylines = Set<polyline>();
  List<LatLng> polylineCoordinates = [];
  polylinePoints polylinePoints;

  String googleAPIKey = 'MY Google Api KEY';

  BitmapDescriptor sourceIcon;
  BitmapDescriptor destinationIcon;

  LocationData currentLocation;

  LocationData destinationLocation;

  Location location;

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

    location = new Location();
    polylinePoints = polylinePoints();

    location.onLocationChanged.listen((LocationData cLoc) {
      currentLocation = cLoc;
      updatePinOnMap();
    });

    setSourceAndDestinationIcons();

    setinitialLocation();
  }

  void setSourceAndDestinationIcons() async {
    sourceIcon = await BitmapDescriptor.fromAssetimage(
        ImageConfiguration(devicePixelRatio: 2.5),'assets/driving_pin.png');

    destinationIcon = await BitmapDescriptor.fromAssetimage(
        ImageConfiguration(devicePixelRatio: 2.5),'assets/destination_map_marker.png');
  }

  void setinitialLocation() async {
    currentLocation = await location.getLocation();

    destinationLocation = LocationData.fromMap({
      "latitude": DEST_LOCATION.latitude,"longitude": DEST_LOCATION.longitude,});
  }

  @override
  Widget build(BuildContext context) {
    CameraPosition initialCameraPosition = CameraPosition(
        zoom: CAMERA_ZOOM,tilt: CAMERA_TILT,bearing: CAMERA_bearing,target: SOURCE_LOCATION);

    if (currentLocation != null) {
      initialCameraPosition = CameraPosition(
          target: LatLng(currentLocation.latitude,currentLocation.longitude),zoom: CAMERA_ZOOM,bearing: CAMERA_bearing);
    }
    return Scaffold(
      body: Stack(
        children: <Widget>[
          GoogleMap(
            initialCameraPosition: initialCameraPosition,myLocationEnabled: true,compassEnabled: true,tiltGesturesEnabled: false,markers: _markers,polylines: _polylines,mapType: MapType.normal,onMapCreated: (GoogleMapController controller) {
              _controller.complete(controller);
              showPinsOnMap();
            },)
        ],),);
  }

  void showPinsOnMap() {
    //get a LatLng for the source location from the LocationData currentLocation object
    var pinPosition =
        LatLng(currentLocation.latitude,currentLocation.longitude);

    var destPosition =
        LatLng(destinationLocation.latitude,destinationLocation.longitude);

    _markers.add(Marker(
        markerId: MarkerId('sourcePin'),position: pinPosition,icon: sourceIcon));
    _markers.add(Marker(
        markerId: MarkerId('destPin'),position: destPosition,icon: destinationIcon));

    setpolylines();
  }

  void setpolylines() async {
    polylineResult result = await polylinePoints.getRouteBetweenCoordinates(
        googleAPIKey,PointLatLng(currentLocation.latitude,PointLatLng(
            destinationLocation.latitude,destinationLocation.longitude));

    if (result.points.isNotEmpty) {
      result.points.forEach((PointLatLng point) {
        polylineCoordinates.add(LatLng(point.latitude,point.longitude));
      });
      setState(() {
        _polylines.add(polyline(
            width: 5,polylineId: polylineId("poly"),color: Color.fromARGB(255,40,122,198),points: polylineCoordinates));
      });
    }
  }

  void updatePinOnMap() async {
    CameraPosition cameraPosition = CameraPosition(
      zoom: CAMERA_ZOOM,target: LatLng(currentLocation.latitude,);

    final GoogleMapController controller = await _controller.future;
    controller.animateCamera(CameraUpdate.newCameraPosition(cameraPosition));

    setState(() {
      var pinPosition =
          LatLng(currentLocation.latitude,currentLocation.longitude);

      _markers.add(Marker(
          markerId: MarkerId('sourcePin'),icon: sourceIcon));
    });
  }
}