+ if (!scm_is_number (ly_assoc_get (ly_symbol2scm ("Y"), details, SCM_BOOL_F)))
+ {
+ Real y = 0.0;
+
+ Real extra_dy = robust_scm2double (me->get_property ("extra-dy"),
+ 0.0);
+
+ Grob *common_y = me->common_refpoint (me->get_bound (dir), Y_AXIS);
+ if (me->get_bound (dir)->break_status_dir ())
+ {
+ if (to_boolean (me->get_property ("simple-Y")))
+ {
+ Spanner *orig = dynamic_cast<Spanner *>(me->original ());
+ Spanner *extreme = dir == LEFT ? orig->broken_intos_.front () : orig->broken_intos_.back ();
+ Grob *e_bound = extreme->get_bound (dir);
+ Grob *e_common_y = extreme->common_refpoint (e_bound, Y_AXIS);
+ y = e_bound->extent (e_common_y, Y_AXIS).center ();
+ }
+ else
+ {
+ Spanner *next_sp = me->broken_neighbor (dir);
+ Item *next_bound = next_sp->get_bound (dir);
+
+ if (next_bound->break_status_dir ())
+ {
+ programming_error ("no note heads for the line spanner on neighbor line?"
+ " Confused.");
+ me->suicide ();
+ return SCM_EOL;
+ }
+
+ Spanner *next_bound_parent = parent_spanner (next_bound);
+ Interval next_ext = next_bound->extent (next_bound_parent, Y_AXIS);
+
+ /*
+ We want to know what would be the y-position of the next
+ bound (relative to my y-parent) if it belonged to the
+ same system as this bound. We rely on the fact that the
+ y-parent of the next bound is a spanner (probably the
+ VerticalAxisGroup of a staff) that extends over the break.
+ */
+ Spanner *next_bound_parent_on_this_line
+ = next_bound_parent->broken_neighbor (other_dir (dir));
+
+ if (next_bound_parent_on_this_line)
+ {
+ Grob *common = me->common_refpoint (next_bound_parent_on_this_line, Y_AXIS);
+ Real bound_offset = next_bound_parent_on_this_line->relative_coordinate (common, Y_AXIS);
+ y = next_ext.center () + bound_offset - me->relative_coordinate (common, Y_AXIS);
+ }
+ else
+ {
+ /*
+ We fall back to assuming that the distance between
+ staves doesn't change over line breaks.
+ */
+ programming_error ("next-bound's parent doesn't extend to this line");
+ Grob *next_system = next_bound->get_system ();
+ Grob *this_system = me->get_system ();
+ y = next_ext.center () + next_bound_parent->relative_coordinate (next_system, Y_AXIS)
+ - me->relative_coordinate (this_system, Y_AXIS);
+ }
+ }
+ }
+ else
+ {
+ Interval ii = me->get_bound (dir)->extent (common_y, Y_AXIS);
+ if (!ii.is_empty())
+ y = ii.center ();
+ details = scm_acons (ly_symbol2scm ("common-Y"), common_y->self_scm (), details);
+ }
+
+ y += dir * extra_dy / 2;
+ details = scm_acons (ly_symbol2scm ("Y"), scm_from_double (y), details);
+ }