Function lv_anim_set_user_data 

pub unsafe extern "C" fn lv_anim_set_user_data(
    a: *mut lv_anim_t,
    user_data: *mut c_void,
)

Set the custom user data field of the animation. @param a pointer to an initialized lv_anim_t variable @param user_data pointer to the new user_data.