Function ncplane_translate 

pub unsafe extern "C" fn ncplane_translate(
    src: *const ncplane,
    dst: *const ncplane,
    y: *mut c_int,
    x: *mut c_int,
)

provided a coordinate relative to the origin of ‘src’, map it to the same absolute coordinate relative to the origin of ‘dst’. either or both of ‘y’ and ‘x’ may be NULL. if ‘dst’ is NULL, it is taken to be the standard plane.