没有为“GoogleMapController”类型定义方法“addMarker”

Posted 2023-02-18

【中文标题】没有为“GoogleMapController”类型定义方法“addMarker”

【英文标题】：The method 'addMarker' isn't defined for the type 'GoogleMapController'

【发布时间】：2021-12-22 09:00:49

【问题描述】：

我正在添加 removeMarker 和 addMarker，但它显示 - “方法 'addMarker' 没有为类型 'GoogleMapController' 定义。尝试将名称更正为现有方法的名称，或定义一个名为 'addMarker' 的方法'。”

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:geoflutterfire/geoflutterfire.dart';
import 'package:rxdart/rxdart.dart';
import 'dart:async';


void main() => runApp(MyApp());

class MyApp extends StatelessWidget 
  @override
  Widget build(BuildContext context) 
    return const MaterialApp(
        home: Scaffold(
          body: FireMap(),
        )
    );
  


class FireMap extends StatefulWidget 
  const FireMap(Key? key) : super(key: key);

  @override
  State createState() => FireMapState();



class FireMapState extends State<FireMap> 
  late GoogleMapController mapController;
  Location location = Location();
  //Firestore firestore = Firestore.instance;
  FirebaseFirestore firestore = FirebaseFirestore.instance;
  Geoflutterfire geo = Geoflutterfire();

  // Stateful Data
  BehaviorSubject<double> radius = BehaviorSubject();
  late Stream<dynamic>query;

  // Subscription
  late StreamSubscription subscription;

  build(context) 
    return Stack(children: [

      GoogleMap(
        initialCameraPosition: const CameraPosition(
            target: LatLng(24.142, -110.321),
            zoom: 15
        ),
        onMapCreated: _onMapCreated,
        myLocationEnabled: true,
        mapType: MapType.hybrid,
        compassEnabled: true,
        onCameraMove: _animateToUser(),
      ),
      Positioned(
          bottom: 50,
          right: 10,
          child:
          FlatButton(
              child: const Icon(Icons.pin_drop, color: Colors.white),
              color: Colors.green,
              onPressed: _addGeoPoint
          )
      ),
      Positioned(
          bottom: 50,
          left: 10,
          child: Slider(
            min: 100.0,
            max: 500.0,
            divisions: 4,
            value: radius.value,
            label: 'Radius $radius.valuekm',
            activeColor: Colors.green,
            inactiveColor: Colors.green.withOpacity(0.2),
            onChanged: _updateQuery,
          )
      )
    ]);
  
  _onMapCreated(GoogleMapController controller) 
    _startQuery();
    setState(() 
      mapController = controller;
    );
  

  addMarker() 
    final Marker marker = Marker(
        markerId: MarkerId,
        position: mapController.cameraPosition.target,
        icon: BitmapDescriptor.defaultMarker,
        infoWindow: InfoWindow.noText,
        //infoWindowText: const InfoWindowText('Magic Marker', '????????????')
    );
    mapController.addMarker();
  

  _animateToUser() async 
    var pos = await location.getLocation();
    mapController.animateCamera(CameraUpdate.newCameraPosition(
        CameraPosition(
          target: LatLng(pos['latitude'], pos['longitude']),
          zoom: 17.0,
        )
    )
    );
  
  Future<DocumentReference> _addGeoPoint() async 
    var pos = await location.getLocation();
    GeoFirePoint point = geo.point(latitude: pos['latitude'], longitude: pos['longitude']);
    return firestore.collection('locations').add(
      'position': point.data,
      'name': 'Yay I can be queried!'
    );
  

  void _updateMarkers(List<DocumentSnapshot> documentList) 
    print(documentList);
    mapController.clearMarkers;
    for (var document in documentList) 
      GeoPoint pos = document.data['position']['geopoint'];
      double distance = document.data['distance'];
      var marker = MarkerOptions(
          position: LatLng(pos.latitude, pos.longitude),
          icon: BitmapDescriptor.defaultMarker,
          infoWindowText: InfoWindowText('Magic Marker', '$distance kilometers from query center')
      );


      mapController.addMarker(marker);
    
  

  _startQuery() async 
    // Get users location
    var pos = await location.getLocation();
    double lat = pos['latitude'];
    double lng = pos['longitude'];


   
    var ref = firestore.collection('locations');
    GeoFirePoint center = geo.point(latitude: lat, longitude: lng);

 
    subscription = radius.switchMap((rad) 
      return geo.collection(collectionRef: ref).within(
          center: center,
          radius: rad,
          field: 'position',
          strictMode: true
      );
    ).listen(_updateMarkers);
  

  _updateQuery(value) 
    final zoomMap = 
      100.0: 12.0,
      200.0: 10.0,
      300.0: 7.0,
      400.0: 6.0,
      500.0: 5.0
    ;
    final zoom = zoomMap[value];
    mapController.moveCamera(CameraUpdate.zoomTo(zoom));

    setState(() 
      radius.add(value);
    );
  

  @override
  dispose() 
    subscription.cancel();
    super.dispose();
  

没有为“GoogleMapController”类型定义获取器“clearMarkers”。尝试导入定义“clearMarkers”的库，将名称更正为现有 getter 的名称，或定义名为“clearMarkers”的 getter 或字段。没有为“FireMapState”类型定义“MarkerOptions”方法。尝试更正name 为现有方法的名称，或定义名为“MarkerOptions”的方法。方法“InfoWindowText”未为“FireMapState”类型定义。尝试将名称更正为现有方法的名称，或定义名为“InfoWindowText”的方法。

在这段代码中发现了这个错误。

【参考方案1】：

GoogleMapController 没有 addMarker 方法。要在地图上添加标记，您需要将 Marker() 对象列表传递给您的 GoogleMaps() 小部件。操作方法如下：

您需要初始化一个列表，您将在其中存储所有 Marker() 对象：

 List<Marker> _markers = <Marker>[];

您可以使用_markers.add() 在该列表中添加Marker() 对象。例如，这可以在initState() 方法中完成：

@override
void initState() 
  // TODO: implement initState
  super.initState();
  _markers.add(
    Marker(
      markerId: MarkerId('markerId'),
      position: LatLng(37.421946, -122.084090),
    ),
   );

最后，您可以将Marker() 对象列表添加到您的GoogleMap() 小部件：

GoogleMap(
  mapType: MapType.normal,
  markers: Set.from(_markers), /* <---- here is how to add the list of markers */
  initialCameraPosition: _initialCameraPosition,
  onMapCreated: _onMapCreated,
),

您可以通过从_markers[] 列表中删除标记来删除它。