+LY_DEFINE (ly_grob_robust_relative_extent, "ly:grob-robust-relative-extent",
+ 3, 0, 0, (SCM grob, SCM refp, SCM axis),
+ "Get the extent in @var{axis} direction of @var{grob} relative to "
+ "the grob @var{refp}, or (0,0) if empty")
+{
+ Grob *sc = unsmob_grob (grob);
+ Grob *ref = unsmob_grob (refp);
+
+ SCM_ASSERT_TYPE (sc, grob, SCM_ARG1, __FUNCTION__, "grob");
+ SCM_ASSERT_TYPE (ref, refp, SCM_ARG2, __FUNCTION__, "grob");
+ SCM_ASSERT_TYPE (is_axis (axis), axis, SCM_ARG3, __FUNCTION__, "axis");
+
+ Axis a = Axis (scm_to_int (axis));
+
+ if (ref->common_refpoint (sc, a) != ref)
+ {
+ // ugh. should use other error message
+ SCM_ASSERT_TYPE (false, refp, SCM_ARG2, __FUNCTION__, "common refpoint");
+ }
+
+ return ly_interval2scm (robust_relative_extent (sc, ref, a));
+}