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我刚开始学习颤振，我正在尝试使用谷歌地图构建一个移动应用程序。我正在关注一个教程，该教程正在构建一个始终跟踪我的位置的应用程序：

例子

它工作得很好，问题是当我尝试放大/缩小时，即使我没有移动，它也会以默认缩放将我带回我的位置。

即使我正在移动，我也试图能够放大/缩小，并且只有在我点击按钮时才能将我收回我的位置。

这是源代码：

import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:location/location.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Maps',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Map Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  StreamSubscription _locationSubscription;
  Location _locationTracker = Location();
  Marker marker;
  Circle circle;
  GoogleMapController _controller;

  static final CameraPosition initialLocation = CameraPosition(
    target: LatLng(37.42796133580664, -122.085749655962),
    zoom: 14.4746,
  );

  Future<Uint8List> getMarker() async {
    ByteData byteData = await DefaultAssetBundle.of(context).load("assets/car_icon.png");
    return byteData.buffer.asUint8List();
  }

  void updateMarkerAndCircle(LocationData newLocalData, Uint8List imageData) {
    LatLng latlng = LatLng(newLocalData.latitude, newLocalData.longitude);
    this.setState(() {
      marker = Marker(
          markerId: MarkerId("home"),
          position: latlng,
          rotation: newLocalData.heading,
          draggable: false,
          zIndex: 2,
          flat: true,
          anchor: Offset(0.5, 0.5),
          icon: BitmapDescriptor.fromBytes(imageData));
      circle = Circle(
          circleId: CircleId("car"),
          radius: newLocalData.accuracy,
          zIndex: 1,
          strokeColor: Colors.blue,
          center: latlng,
          fillColor: Colors.blue.withAlpha(70));
    });
  }

  void getCurrentLocation() async {
    try {

      Uint8List imageData = await getMarker();
      var location = await _locationTracker.getLocation();

      updateMarkerAndCircle(location, imageData);

      if (_locationSubscription != null) {
        _locationSubscription.cancel();
      }


      _locationSubscription = _locationTracker.onLocationChanged().listen((newLocalData) {
        if (_controller != null) {
          _controller.animateCamera(CameraUpdate.newCameraPosition(new CameraPosition(
              bearing: 192.8334901395799,
              target: LatLng(newLocalData.latitude, newLocalData.longitude),
              tilt: 0,
              zoom: 18.00)));
          updateMarkerAndCircle(newLocalData, imageData);
        }
      });

    } on PlatformException catch (e) {
      if (e.code == 'PERMISSION_DENIED') {
        debugPrint("Permission Denied");
      }
    }
  }

  @override
  void dispose() {
    if (_locationSubscription != null) {
      _locationSubscription.cancel();
    }
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: GoogleMap(
        mapType: MapType.hybrid,
        initialCameraPosition: initialLocation,
        markers: Set.of((marker != null) ? [marker] : []),
        circles: Set.of((circle != null) ? [circle] : []),
        onMapCreated: (GoogleMapController controller) {
          _controller = controller;
        },

      ),
      floatingActionButton: FloatingActionButton(
          child: Icon(Icons.location_searching),
          onPressed: () {
            getCurrentLocation();
          }),
    );
  }
}

请帮帮我！谢谢。

4

2 回答 2

1

你可以试试这个
声明一个变量，在你的位置改变时保持你的位置

Map _position;

在您的位置更改监听器

_locationSubscription = _locationTracker.onLocationChanged().listen((newLocalData) {
  setState(() {
    _position = {
      "lat": newLocalData.latitude,
      "lng": newLocalData.longitude,
      "heading": newLocalData.heading,
    };
  });
  if (_controller != null) updateMarkerAndCircle(newLocalData, imageData);
});

最后，每次要将地图居中到当前位置时调用此方法

void _gotoCurrentPosition() {
    if (null != _controller && null != _position) {
      _controller.animateCamera(CameraUpdate.newCameraPosition(new CameraPosition(
         bearing: _position["heading"],
         target: LatLng(_position["lat"], _position["lng"]),
         tilt: 0,
         zoom: 18.00),
       ),);
    }
}
于 2020-12-22T07:38:00.503 回答
0

这个想法是您的应用程序专注于您的位置，当您尝试覆盖某个操作时，它将继续专注于关注您的位置的第一个味道。您必须分离您的方法，因此当您的应用程序专注于您的位置时，您仍然可以通过覆盖第一个方法 onTap 或 onCameraMove 来取消焦点。

_locationSubscription = _locationTracker.onLocationChanged().listen((newLocalData) {
    if (_controller != null) {
      _controller.animateCamera(CameraUpdate.newCameraPosition(new CameraPosition(
          bearing: 192.8334901395799,
          target: LatLng(newLocalData.latitude, newLocalData.longitude),
          tilt: 0,
          zoom: 18.00)));
      updateMarkerAndCircle(newLocalData, imageData);
    }
  });

这就是为什么当您尝试移动地图时地图会将您带回您的位置的原因，因为相机始终会动画到您的位置位置

于 2020-12-22T10:53:29.827 回答