Function r_core::r_print_zoom_buf

pub unsafe extern "C" fn r_print_zoom_buf(
    p: *mut RPrint, 
    user: *mut c_void, 
    cb: RPrintZoomCallback, 
    from: c_ulonglong, 
    to: c_ulonglong, 
    len: c_int, 
    maxlen: c_int
)