flutter distance between two locations
double calculateDistance(lat1, lon1, lat2, lon2){
var p = 0.017453292519943295;
var a = 0.5 - cos((lat2 - lat1) * p)/2 +
cos(lat1 * p) * cos(lat2 * p) *
(1 - cos((lon2 - lon1) * p))/2;
return 12742 * asin(sqrt(a));
}
//it will return distance in KM