谷歌地图中的中心标记和用户位置会发生变化

Question

我有一个带有两个标记的地图，我已经设法将它们居中。我不确定这种方式是正确的，还是最有效的居中两个标记的方式，但它似乎很好。

我的问题是，我还将"myLocationEnabled"设置为true(地图上的蓝点表示您，即用户(。我需要将谷歌地图的摄像头对准这些标记和用户位置之间的中心。所以现在，我需要把三点放在中间。

如果最好的选择是创建一个自制的标记来表示用户的位置，我如何将相机放在三个标记之间？

LatLng _center;
String _mapStyle;
GoogleMapController googleMapController;
Set<Marker> markers = HashSet<Marker>();
BitmapDescriptor pinMerchantIcon;
BitmapDescriptor pinCustomerIcon;

void _onOrderPinged(GoogleMapController mapController) {
googleMapController = mapController;
setState(() {
markers.add(
Marker(
draggable: false,
markerId: MarkerId("Customer"),
icon: pinCustomerIcon,
position: LatLng(pingedList[0].userLat, pingedList[0].userLong),
),
);
});
setState(() {
markers.add(
Marker(
infoWindow: InfoWindow(
title: "Merchant",
),
draggable: false,
markerId: MarkerId("Pick Up"),
icon: pinMerchantIcon,
// position: _center,
position:
LatLng(pingedList[0].merchantLat, pingedList[0].merchantLong)),
);
});
mapController.setMapStyle(_mapStyle);

var merchantLatLongClosest =
Provider.of<DistanceProvider>(context, listen: false).distanceClosest(
widget.latitude,
widget.longitude,
pingedList[0].merchantLat,
pingedList[0].merchantLong);
var userLatLongClosest =
Provider.of<DistanceProvider>(context, listen: false).distanceClosest(
widget.latitude,
widget.longitude,
pingedList[0].userLat,
pingedList[0].userLong);
var distanceBetweenUserMerchant = 
Provider.of<DistanceProvider>(context, listen: false).distanceClosest(
pingedList[0].merchantLat,
pingedList[0].merchantLong,
pingedList[0].userLat,
pingedList[0].userLong,
);

final currentLatLng = userLatLongClosest < merchantLatLongClosest
? LatLng(pingedList[0].merchantLat, pingedList[0].merchantLong)
: LatLng(pingedList[0].userLat, pingedList[0].userLong);

final LatLng offerLatLng = LatLng(widget.latitude, widget.longitude);
LatLngBounds bound;
if(distanceBetweenUserMerchant > userLatLongClosest && distanceBetweenUserMerchant > merchantLatLongClosest){

if (userLatLongClosest < merchantLatLongClosest) {
if (offerLatLng.latitude > pingedList[0].merchantLat &&
offerLatLng.longitude > pingedList[0].merchantLong) {
bound = LatLngBounds(southwest: currentLatLng, northeast: offerLatLng);
} else if (offerLatLng.longitude > currentLatLng.longitude) {
bound = LatLngBounds(
southwest: LatLng(offerLatLng.latitude, currentLatLng.longitude),
northeast: LatLng(currentLatLng.latitude, offerLatLng.longitude));
} else if (offerLatLng.latitude > currentLatLng.latitude) {
bound = LatLngBounds(
southwest: LatLng(currentLatLng.latitude, offerLatLng.longitude),
northeast: LatLng(offerLatLng.latitude, currentLatLng.longitude));
} else {
bound = LatLngBounds(southwest: offerLatLng, northeast: currentLatLng);
}
} else {
if (offerLatLng.latitude > pingedList[0].userLat &&
offerLatLng.longitude > pingedList[0].userLong) {
bound = LatLngBounds(southwest: currentLatLng, northeast: offerLatLng);
} else if (offerLatLng.longitude > currentLatLng.longitude) {
bound = LatLngBounds(
southwest: LatLng(offerLatLng.latitude, currentLatLng.longitude),
northeast: LatLng(currentLatLng.latitude, offerLatLng.longitude));
} else if (offerLatLng.latitude > currentLatLng.latitude) {
bound = LatLngBounds(
southwest: LatLng(currentLatLng.latitude, offerLatLng.longitude),
northeast: LatLng(offerLatLng.latitude, currentLatLng.longitude));
} else {
bound = LatLngBounds(southwest: offerLatLng, northeast: currentLatLng);
}
}

} 

else if (userLatLongClosest < merchantLatLongClosest) {
if (offerLatLng.latitude > pingedList[0].merchantLat &&
offerLatLng.longitude > pingedList[0].merchantLong) {
bound = LatLngBounds(southwest: currentLatLng, northeast: offerLatLng);
} else if (offerLatLng.longitude > currentLatLng.longitude) {
bound = LatLngBounds(
southwest: LatLng(offerLatLng.latitude, currentLatLng.longitude),
northeast: LatLng(currentLatLng.latitude, offerLatLng.longitude));
} else if (offerLatLng.latitude > currentLatLng.latitude) {
bound = LatLngBounds(
southwest: LatLng(currentLatLng.latitude, offerLatLng.longitude),
northeast: LatLng(offerLatLng.latitude, currentLatLng.longitude));
} else {
bound = LatLngBounds(southwest: offerLatLng, northeast: currentLatLng);
}
} else {
if (offerLatLng.latitude > pingedList[0].userLat &&
offerLatLng.longitude > pingedList[0].userLong) {
bound = LatLngBounds(southwest: currentLatLng, northeast: offerLatLng);
} else if (offerLatLng.longitude > currentLatLng.longitude) {
bound = LatLngBounds(
southwest: LatLng(offerLatLng.latitude, currentLatLng.longitude),
northeast: LatLng(currentLatLng.latitude, offerLatLng.longitude));
} else if (offerLatLng.latitude > currentLatLng.latitude) {
bound = LatLngBounds(
southwest: LatLng(currentLatLng.latitude, offerLatLng.longitude),
northeast: LatLng(offerLatLng.latitude, currentLatLng.longitude));
} else {
bound = LatLngBounds(southwest: offerLatLng, northeast: currentLatLng);
}
}
CameraUpdate u2;
mapController.animateCamera(u2).then((void v) {
check(u2, mapController);
});
}
void check(CameraUpdate u, GoogleMapController c) async {
c.animateCamera(u);
googleMapController.animateCamera(u);
LatLngBounds l1 = await c.getVisibleRegion();
LatLngBounds l2 = await c.getVisibleRegion();
if (l1.southwest.latitude == -90 || l2.southwest.latitude == -90)
check(u, c);
}

@override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: [
Container(
child: GoogleMap(
markers: markers,
mapType: MapType.normal,
compassEnabled: false,
initialCameraPosition: CameraPosition(
target: _center,
),
onMapCreated: _onOrderPinged,
myLocationEnabled: true,
myLocationButtonEnabled: false,
),
)
],
),
);
}

Answer 1

我在Reddit上发布了这个问题。jamieownsu用一个完美的函数来回答。它还包括标记和用户的位置点。他的代码：

static LatLngBounds getLatLngBounds(List<LatLng> list) {
double x0, x1, y0, y1;
for (final latLng in list) {
if (x0 == null) {
x0 = x1 = latLng.latitude;
y0 = y1 = latLng.longitude;
} else {
if (latLng.latitude > x1) x1 = latLng.latitude;
if (latLng.latitude < x0) x0 = latLng.latitude;
if (latLng.longitude > y1) y1 = latLng.longitude;
if (latLng.longitude < y0) y0 = latLng.longitude;
}
}
return LatLngBounds(northeast: LatLng(x1, y1), southwest: LatLng(x0, y0));
}

mapController.animateCamera(CameraUpdate.newLatLngBounds(getLatLngBounds(...))

https://www.reddit.com/r/FlutterDev/comments/mrbodl/google_maps_flutter_update/