我的颤振资产图像未用作 Google 地图的标记图标

Question

我创建了一个自定义图像，用作我的颤振应用程序上谷歌地图上标记之一的标记图标。 不幸的是，这没有按计划工作，而是显示默认图标。有人能发现情欲吗？我当然不能。作为旁注，控制台中未打印我的 if 语句中的任何内容。改天的问题？

这是我用来获取标记的代码：

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,
);
}
}

我的终端中也收到一个错误，说：E/包裹 (22617(：此处不支持读取 NULL 字符串。 E/包裹 (22617(：此处不支持读取 NULL 字符串。

Answer 1

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Flutter:部分下定义了pubspec.yaml上的图标：

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

然后，您需要在initState()内调用BitmapDescriptor.fromAssetImage以获取地图加载之前的图标：

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

Answer 2

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。

但重要的问题是你没有为restaurantMarker的初始化投保。我在这里添加了一个检查，isSetupReady;

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...'));
}
}