+/* Limitations/Bugs:
+
+(1) Elements from 'me->get_property ("elements")' must be
+ordered according to their y coordinates relative to their common
+axis group parent. Otherwise, the computation goes mad.
+
+(2) This method depends on bar_engraver not being removed from
+staff context. If bar_engraver is removed, the size of the staff
+lines is evaluated as 0, which results in a solid span bar line
+with faulty y coordinate. */
+
+/* This routine was originally by Juergen Reuter, but it was a on the
+ bulky side. Rewritten by Han-Wen. */
+SCM
+Span_bar::print (SCM smobbed_me)
+{
+ Grob *me = unsmob_grob (smobbed_me);
+ SCM elements = me->get_property ("elements");
+
+ Grob *refp = common_refpoint_of_list (elements, me, Y_AXIS);
+ Span_bar::evaluate_glyph (me);
+ SCM glyph = me->get_property ("glyph");
+
+ /* glyph may not be a string, when ME is killed by Hara Kiri in
+ between. */
+ if (!scm_is_string (glyph))
+ return SCM_EOL;
+
+ String glyph_string = ly_scm2string (glyph);
+
+ /* compose span_bar_mol */
+ Array<Interval> extents;
+ Grob *model_bar = 0;
+ for (SCM elts = elements; scm_is_pair (elts); elts = scm_cdr (elts))
+ {
+ Grob *bar = unsmob_grob (scm_car (elts));
+ Interval ext = bar->extent (refp, Y_AXIS);
+ if (ext.is_empty ())
+ continue;
+
+ extents.push (ext);
+ model_bar = bar;
+ }
+
+ if (!model_bar)
+ model_bar = me;
+
+ extents.sort (&Interval::left_comparison);
+
+ Stencil span_bar;
+ for (int i = 1; i < extents.size (); i ++)
+ {
+ Interval prev_extent = extents[i-1];
+ Interval ext = extents[i];
+ if (!prev_extent.is_empty ())
+ {
+ Interval l (prev_extent [UP],
+ ext[DOWN]);
+
+ if (l.is_empty ())
+ {
+ /* There is overlap between the bar lines. Do nothing. */
+ }
+ else
+ {
+ Stencil interbar = Bar_line::compound_barline (model_bar,
+ glyph_string,
+ l.length (),
+ false);
+ interbar.translate_axis (l.center (), Y_AXIS);
+ span_bar.add_stencil (interbar);
+ }
+ }
+ prev_extent = ext;
+ }
+
+ span_bar.translate_axis (- me->relative_coordinate (refp, Y_AXIS),
+ Y_AXIS);
+
+ return span_bar.smobbed_copy ();
+}
+
+MAKE_SCHEME_CALLBACK (Span_bar, width_callback, 2);
+SCM
+Span_bar::width_callback (SCM element_smob, SCM scm_axis)