main.dart

// Define two position variables
Position _northeastCoordinates;
Position _southwestCoordinates;

// Calculating to check that
// southwest coordinate <= northeast coordinate
if (startCoordinates.latitude <= destinationCoordinates.latitude) {
  _southwestCoordinates = startCoordinates;
  _northeastCoordinates = destinationCoordinates;
} else {
  _southwestCoordinates = destinationCoordinates;
  _northeastCoordinates = startCoordinates;
}

// Accommodate the two locations within the
// camera view of the map
mapController.animateCamera(
  CameraUpdate.newLatLngBounds(
    LatLngBounds(
      northeast: LatLng(
        _northeastCoordinates.latitude,
        _northeastCoordinates.longitude,
      ),
      southwest: LatLng(
        _southwestCoordinates.latitude,
        _southwestCoordinates.longitude,
      ),
    ),
    100.0, // padding 
  ),
);