更新扑动中地图的相对位置

Question

Hello下面的代码使用google_maps_flutter和location包显示了一张带有用户位置的地图，下面的代码正确地显示了带有经纬度初始位置的地图。但当用户从设备启动应用程序时，该位置并不是用户的实际位置，而是保持在初始位置，我该如何解决这个问题？

颤振代码：

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:location/location.dart';
import 'package:MyApp/View/Cantieri/mediterranesn_diet_view.dart'
show MediterranesnDietView;
import 'package:MyApp/View/Cantieri/title_view.dart' show TitleView;
import 'package:MyApp/View/Home_theme.dart';
import 'package:MyApp/View/MarcaTempo/FunzioneMarcatempoView.dart'
show MarcaTempoListView;
//Valori longitudine e latitudine
double longitudine = 12.4818, latitudine = 41.9109;
LatLng _center = LatLng(latitudine, longitudine);
//Recupero e salvataggio dei valori del gps di longitudine e latitudine
Future<void> _getGpsValue() async {
//Instanzio l'oggetto che si occupa di recuperare i dati per la marcatura
var location = new Location();
location.onLocationChanged().listen((LocationData currentLocation) async {
longitudine = currentLocation.longitude;
latitudine = currentLocation.latitude;
_center = LatLng(latitudine, longitudine);
});
Timer(Duration(seconds: 1), () {
print("E' passato 1 secondo");
print("Latitudine: " +
latitudine.toString() +
"n Longitudine: " +
longitudine.toString());
});
}
class MyDiaryScreen extends StatefulWidget {
const MyDiaryScreen({Key key, this.animationController}) : super(key: key);
final AnimationController animationController;
@override
_MyDiaryScreenState createState() => _MyDiaryScreenState();
}
class _MyDiaryScreenState extends State<MyDiaryScreen>
with TickerProviderStateMixin {
GoogleMapController mapController;
var width;
void _onMapCreated(GoogleMapController controller) {
mapController = controller;
}
List<Widget> listViews = <Widget>[];
final ScrollController scrollController = ScrollController();
Animation<double> topBarAnimation;
double topBarOpacity = 0.0;
@override
void initState() {
_getGpsValue();
topBarAnimation = Tween<double>(begin: 0.0, end: 1.0).animate(
CurvedAnimation(
parent: widget.animationController,
curve: Interval(0, 0.5, curve: Curves.fastOutSlowIn)));
addAllListData();
scrollController.addListener(() {
if (scrollController.offset >= 24) {
if (topBarOpacity != 1.0) {
setState(() {
topBarOpacity = 1.0;
});
}
} else if (scrollController.offset <= 24 &&
scrollController.offset >= 0) {
if (topBarOpacity != scrollController.offset / 24) {
setState(() {
topBarOpacity = scrollController.offset / 24;
});
}
} else if (scrollController.offset <= 0) {
if (topBarOpacity != 0.0) {
setState(() {
topBarOpacity = 0.0;
});
}
}
});
super.initState();
}
void addAllListData() {
_getGpsValue();
const int count = 9;
//Prima view che comprende il titolo della Posizione
listViews.add(
TitleView(
titleTxt: 'Posizione',
subTxt: '',
animation: Tween<double>(begin: 0.0, end: 1.0).animate(CurvedAnimation(
parent: widget.animationController,
curve:
Interval((1 / count) * 0, 1.0, curve: Curves.fastOutSlowIn))),
animationController: widget.animationController,
),
);
//Inserimento del modulo con le informazioni sulla posizione
listViews.add(
MediterranesnDietView(
animation: Tween<double>(begin: 0.0, end: 1.0).animate(CurvedAnimation(
parent: widget.animationController,
curve:
Interval((1 / count) * 1, 1.0, curve: Curves.fastOutSlowIn))),
animationController: widget.animationController,
),
);
//Inserimento del titolo di registrazione
listViews.add(
TitleView(
titleTxt: 'Registrazione',
subTxt: '',
animation: Tween<double>(begin: 0.0, end: 1.0).animate(CurvedAnimation(
parent: widget.animationController,
curve:
Interval((1 / count) * 2, 1.0, curve: Curves.fastOutSlowIn))),
animationController: widget.animationController,
),
);
//Inserimento dei button per il marcatempo
listViews.add(
MarcaTempoListView(
mainScreenAnimation: Tween<double>(begin: 0.0, end: 1.0).animate(
CurvedAnimation(
parent: widget.animationController,
curve: Interval((1 / count) * 3, 1.0,
curve: Curves.fastOutSlowIn))),
mainScreenAnimationController: widget.animationController,
),
);
//Inserimento del titolo di registrazione
listViews.add(
TitleView(
titleTxt: 'Mappa',
subTxt: '',
animation: Tween<double>(begin: 0.0, end: 1.0).animate(CurvedAnimation(
parent: widget.animationController,
curve:
Interval((1 / count) * 2, 1.0, curve: Curves.fastOutSlowIn))),
animationController: widget.animationController,
),
);
listViews.add(new Container(
width: width,
height: 400.0,
child: GoogleMap(
onMapCreated: _onMapCreated,
initialCameraPosition: CameraPosition(
target: _center,
zoom: 6.0,
))));
}
Future<bool> getData(BuildContext context) async {
await Future<dynamic>.delayed(const Duration(milliseconds: 50));
width = MediaQuery.of(context).size.width;
return true;
}
Widget getMainListViewUI() {
return FutureBuilder<bool>(
future: getData(context),
builder: (BuildContext context, AsyncSnapshot<bool> snapshot) {
if (!snapshot.hasData) {
return const SizedBox();
} else {
return ListView.builder(
shrinkWrap: true,
controller: scrollController,
padding: EdgeInsets.only(
top: AppBar().preferredSize.height +
MediaQuery.of(context).padding.top +
24,
bottom: 62 + MediaQuery.of(context).padding.bottom,
),
itemCount: listViews.length,
scrollDirection: Axis.vertical,
itemBuilder: (BuildContext context, int index) {
widget.animationController.forward();
return listViews[index];
},
);
}
},
);
}
//Recupero della barra per la UI
Widget getAppBarUI() {
return Column(
children: <Widget>[
AnimatedBuilder(
animation: widget.animationController,
builder: (BuildContext context, Widget child) {
return FadeTransition(
opacity: topBarAnimation,
child: Transform(
transform: Matrix4.translationValues(
0.0, 30 * (1.0 - topBarAnimation.value), 0.0),
child: Container(
decoration: BoxDecoration(
color: TemaApp.white.withOpacity(topBarOpacity),
borderRadius: const BorderRadius.only(
bottomLeft: Radius.circular(32.0),
),
boxShadow: <BoxShadow>[
BoxShadow(
color: TemaApp.grey.withOpacity(0.4 * topBarOpacity),
offset: const Offset(1.1, 1.1),
blurRadius: 10.0),
],
),
child: Column(
children: <Widget>[
SizedBox(
height: MediaQuery.of(context).padding.top,
),
Padding(
padding: EdgeInsets.only(
left: 16,
right: 16,
top: 16 - 8.0 * topBarOpacity,
bottom: 12 - 8.0 * topBarOpacity),
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Expanded(
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Text(
'Marcatempo',
textAlign: TextAlign.left,
style: TextStyle(
fontFamily: TemaApp.fontName,
fontWeight: FontWeight.w700,
fontSize: 22 + 6 - 6 * topBarOpacity,
letterSpacing: 1.2,
color: TemaApp.darkerText,
),
),
),
),
],
),
)
],
),
),
),
);
},
)
],
);
}
@override
Widget build(BuildContext context) {
return Container(
color: TemaApp.background,
child: Scaffold(
backgroundColor: Colors.transparent,
resizeToAvoidBottomPadding: true,
body: Stack(
children: <Widget>[
//getMap(),
getMainListViewUI(),
getAppBarUI(),
SizedBox(
height: MediaQuery.of(context).padding.bottom,
)
],
),
),
);
}
}

Answer 1

您需要在_getGpsValue()内部调用setState()来更新用户的位置。

setState(() {
longitudine = currentLocation.longitude;
latitudine = currentLocation.latitude;
_center = LatLng(latitudine, longitudine);
})

根据文件：

调用setState会通知框架该对象的更改方式可能会影响用户界面在该子树中，这导致框架为本州反对。