Function lv_scale_set_text_src 

pub unsafe extern "C" fn lv_scale_set_text_src(
    obj: *mut lv_obj_t,
    txt_src: *mut *const c_char,
)

Set custom text source for major ticks labels. @param obj pointer to Scale Widget @param txt_src pointer to an array of strings which will be display at major ticks; last element must be a NULL pointer.