+ evaluate_empty (unsmob_grob (smob));
+ evaluate_glyph (unsmob_grob (smob));
+
+ /*
+ no need to call Bar::before_line_breaking (), because the info
+ in ELEMENTS already has been procced by Bar::before_line_breaking().
+ */
+ return SCM_UNSPECIFIED;
+}
+
+MAKE_SCHEME_CALLBACK(Span_bar,center_on_spanned_callback,2);
+
+SCM
+Span_bar::center_on_spanned_callback (SCM element_smob, SCM axis)
+{
+ Grob *me = unsmob_grob (element_smob);
+ Axis a = (Axis) gh_scm2int (axis);
+ assert (a == Y_AXIS);
+ Interval i (get_spanned_interval (me));
+
+ /*
+ Bar::brew_molecule delivers a barline of y-extent (-h/2,h/2), so
+ we have to translate ourselves to be in the center of the
+ interval that we span. */
+ if (i.empty_b ())
+ {
+ me->suicide();
+ return gh_double2scm (0.0);
+ }