toTileIndex method
Implementation
@override
TileIndex toTileIndex(LatLng location) {
final lng = location.longitude;
final lat = location.latitude;
double x = (lng + 180.0) / 360.0;
double sinLatitude = sin(lat * pi / 180.0);
double y =
0.5 - log((1.0 + sinLatitude) / (1.0 - sinLatitude)) / (4.0 * pi);
return TileIndex(x, y);
}