Question

我已经创建了一个自定义图像，用作我的flutter应用程序上google地图上我的一个标记的标记图标。不幸的是，这不能按计划工作，而是显示默认图标。有人能发现这个错误吗？我当然不能。附带说明一下，控制台中的if语句中没有任何内容。还有一天有问题吗？

这是我用来建立标记的代码：

var map;
var rmarker;
final restaurantmarker = BitmapDescriptor.fromAssetImage(
        ImageConfiguration(), 'assets/images/yellow_MarkerR.png')
    .then((value) => rmarker = value);
final mapp = location.getLocation().then((value) => map = value);

final _markers = [
  Marker(
    markerId: MarkerId("my_location"),
    position: LatLng(41.16599, -110.75792),
    infoWindow: InfoWindow(title: "YOUR HOME"),
  ),
  Marker(
      markerId: MarkerId("RESTAURANT"),
      icon: rmarker,
      position: LatLng(40.16599, -110.75792),
      infoWindow: InfoWindow(title: "Restaurant"))
];
final setmarkers = _markers.toSet();

class NearbyScreen extends StatelessWidget {
  void initState() {
    startService();
  }

  @override
  //LocationHelper.mapviewpointer(latitude: )
  Widget build(BuildContext context) {
    return /* !_serviceEnabled ? Center(child:Text("Page cannot be viewed"),) :
        map == null
            ? Center(
                child: Text("Null response"),
              )
            :*/
        GoogleMap(
      initialCameraPosition: CameraPosition(
          target: LatLng(41.16599,
              -110.75792 /*map.latitude, map.longitude
 double.parse(coordinates[0]), double.parse(coordinates[1]) */
              )),
      //minMaxZoomPreference: MinMaxZoomPreference(10, 20),
      zoomControlsEnabled: true,
      markers: setmarkers,
    );
  }
}

这是完整的代码：

Future<bool> assignService(Location loc) async {
  bool servicestatus = await loc.serviceEnabled();
  print("Service status $servicestatus");
  return servicestatus;
}

Future<PermissionStatus> assignPermission(Location loc) async {
  var hasPermission = await loc.hasPermission();
  print("Permission status $hasPermission");
  return hasPermission;
}

Location location = Location();

var _serviceEnabled;
var _serve = assignService(location).then((value) => _serviceEnabled = value);

//var _permissionGranted = assignPermission(location);
var _permissionGranted;
var _permi =
    assignPermission(location).then((value) => _permissionGranted = value);

void startService() {
  if (!_serviceEnabled) {
    _serviceEnabled = assignService(location);
    print("service disabled");
    if (!_serviceEnabled) {
      return;
    }
  }

  if (_permissionGranted == PermissionStatus.denied) {
    _permissionGranted = assignPermission(location);
    print("permission denied");
    if (_permissionGranted != PermissionStatus.granted) {
      return;
    }
  }
}

var map;
var rmarker;
final restaurantmarker = BitmapDescriptor.fromAssetImage(
        ImageConfiguration(), 'assets/images/yellow_MarkerR.png')
    .then((value) => rmarker = value);
final mapp = location.getLocation().then((value) => map = value);

final _markers = [
  Marker(
    markerId: MarkerId("my_location"),
    position: LatLng(41.16599, -110.75792),
    infoWindow: InfoWindow(title: "YOUR HOME"),
  ),
  Marker(
      markerId: MarkerId("RESTAURANT"),
      icon: rmarker,
      position: LatLng(40.16599, -110.75792),
      infoWindow: InfoWindow(title: "Restaurant"))
];
final setmarkers = _markers.toSet();

class NearbyScreen extends StatelessWidget {
  void initState() {
    startService();
  }

  @override
  //LocationHelper.mapviewpointer(latitude: )
  Widget build(BuildContext context) {
    return /* !_serviceEnabled ? Center(child:Text("Page cannot be viewed"),) :
        map == null
            ? Center(
                child: Text("Null response"),
              )
            :*/
        GoogleMap(
      initialCameraPosition: CameraPosition(
          target: LatLng(41.16599,
              -110.75792 /*map.latitude, map.longitude
 double.parse(coordinates[0]), double.parse(coordinates[1]) */
              )),
      //minMaxZoomPreference: MinMaxZoomPreference(10, 20),
      zoomControlsEnabled: true,
      markers: setmarkers,
    );
  }
}

我的终端中也出现错误消息：E / Parcel（22617）：读取此处不支持的NULL字符串。 E / Parcel（22617）：此处不支持读取NULL字符串。

Answer 1

您似乎没有正确检索代码上的标记图标，因为您仅将其定义为restaurantmarker。这是解决问题的方法：

首先，您需要确保在pubspec.yaml下的Flutter:上定义了图标：

Flutter:
    assets:
      - assets/images/yellow_MarkerR.png

然后，您将需要在BitmapDescriptor.fromAssetImage内调用initState()来获取图标，然后再加载地图：

void initState() {
     BitmapDescriptor.fromAssetImage(
        ImageConfiguration(), 'assets/images/yellow_MarkerR.png')
     .then((value) => rmarker = value);
}

Answer 2

您的代码有很多问题，我只是将代码的重要部分重构为地图逻辑。

但是重要的问题是您不能确保restaurantMarker的初始化。我在此处添加了isSetupReady;

的支票

首先，请确保已将图标资产assets/images/yellow_MarkerR.png添加到pubsepc.yaml文件中。

import 'package:flutter/material.dart';

class NearbyScreen extends StatefulWidget {
  @override
  _NearbyScreenState createState() => _NearbyScreenState();
}

class _NearbyScreenState extends State<NearbyScreen> {
  var _markers;
  var setmarkers;
  var restaurantMarker;
  bool isSetupReady = false;

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

  doSetup() async {
    restaurantMarker = await BitmapDescriptor.fromAssetImage(
        ImageConfiguration(), 'assets/images/yellow_MarkerR.png');
    _markers = [
      Marker(
        markerId: MarkerId("my_location"),
        position: LatLng(41.16599, -110.75792),
        infoWindow: InfoWindow(title: "YOUR HOME"),
      ),
      Marker(
          markerId: MarkerId("RESTAURANT"),
          icon: rmarker,
          position: LatLng(40.16599, -110.75792),
          infoWindow: InfoWindow(title: "Restaurant"))
    ];
    setmarkers = _markers.toSet();
    setState(() {
      isSetupReady = true;
    });
  }

  @override
  //LocationHelper.mapviewpointer(latitude: )
  Widget build(BuildContext context) {
    return /* !_serviceEnabled ? Center(child:Text("Page cannot be viewed"),) :
        map == null
            ? Center(
                child: Text("Null response"),
              )
            :*/
        isSetupReady
            ? GoogleMap(
                initialCameraPosition: CameraPosition(
                    target: LatLng(41.16599,
                        -110.75792 /*map.latitude, map.longitude
 double.parse(coordinates[0]), double.parse(coordinates[1]) */
                        )),
                //minMaxZoomPreference: MinMaxZoomPreference(10, 20),
                zoomControlsEnabled: true,
                markers: setmarkers,
              )
            : Center(child: Text('Loading Maps...'));
  }
}

我颤抖的资产图片没有被用作Google地图的标记图标

2 个答案: