unprojectXY method
unproject cartesian x,y coordinates to LatLng.
Implementation
@override
LatLng unprojectXY(double x, double y) {
const d = 180 / math.pi;
return LatLng(
_inclusiveLat((2 * math.atan(math.exp(y / r)) - (math.pi / 2)) * d),
_inclusiveLng(x * d / r),
);
}