我的颤振资产图像没有被用作谷歌地图的标记图标

Question

我创建了一个自定义图像，用作我的标记图标，用于我的颤振应用程序上的谷歌地图上的一个标记。不幸的是，这没有按计划工作，而是显示默认图标。任何人都可以发现 eroor 吗？我当然不能。作为旁注，我的 if 语句中的任何内容都没有打印在控制台中。另一天的问题？

这是我用来设置标记的代码：

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,
    );
  }
}

我的终端也收到错误消息：E/Parcel (22617): Reading a NULL string not supported here。 E/Parcel (22617)：此处不支持读取 NULL 字符串。

Answer 1

你的代码有很多问题，我只是重构了地图逻辑代码的重要部分。

但重要的问题是您没有确保restaurantMarker 的初始化。我在这里添加了一个检查 isSetupReady;

首先，确保您已将图标资产 assets/images/yellow_MarkerR.png 添加到您的 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...'));
  }
}

Answer 2

看起来您没有正确检索代码上的标记图标，因为您仅将其定义为 restaurantmarker。以下是解决此问题的方法：

首先，您需要确保在pubspec.yaml 的Flutter: 部分下定义了您的图标：

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

然后，您需要在地图加载之前调用initState() 内的BitmapDescriptor.fromAssetImage 以获取图标：

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