how to set distance between users using Geolocator in flutter

Question

I am currently trying to give access to users to do something when users are in radius x meters from position that I have determined. So, what I mean is.. I declare a position with x latitude and y longitude.. and then if users position is 500 meters from position that I have declare, they can access something else... is there a way to do that? here is part of my code

Position _mine;
  Future _searchMe() async {
    if ((await Geolocator().isLocationServiceEnabled())) {
      final Geolocator geolocator = Geolocator()..forceAndroidLocationManager;
      geolocator
          .getCurrentPosition(desiredAccuracy: LocationAccuracy.high)
          .then((Position position) {
        setState(() {
          _mine = position;
        });
        print(_mine.latitude);
      }).catchError((err) {
        print(err);
      });
    } else {
      print("ok");
      showDialog(
          context: context,
          builder: (BuildContext context) {
            return AlertDialog(
              content:
                  const Text('Make sure your GPS is on !'),
              actions: <Widget>[
                FlatButton(
                    child: Text('ok'),
                    onPressed: () {
                      Navigator.of(context, rootNavigator: true).pop();
                    })
              ],
            );
          });
    }
  }

The Geolocator package provides a distanceBetween method. You can pass it the lat long of your determined position and the lat long of the device's current position and it will return the distance between the two points in metres. See: https://pub.dev/packages/geolocator#calculate-distance — Alfred Jingle, Apr 15 '20 at 15:00

score 2 · Answer 1 · answered Apr 17 '20 at 07:27

You can probably do something like below :

double _countDistance(double userLatitude, double userLongitude) {
    return Distance().as(
      LengthUnit.Kilometer,
      LatLng(declaredLocation.latitude, declaredLocation.longitude),
      LatLng(userLatitude, userLongitude),
    );
  }

Exaplanation :

The Distance().as method takes three parameters : A. unit e.g. kilometer, meter etc. B. first lat-long C. second lat-long

The above function would calculate the distance in km. You can add this code in yours and do something when the user is within 500 meters.

how to set distance between users using Geolocator in flutter

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