+
+MAKE_SCHEME_CALLBACK (Staff_symbol, height,1);
+SCM
+Staff_symbol::height (SCM smob)
+{
+ Grob *me = unsmob_grob (smob);
+ Real t = me->layout ()->get_dimension (ly_symbol2scm ("line-thickness"));
+ t *= robust_scm2double (me->get_property ("thickness"), 1.0);
+
+ SCM line_positions = me->get_property ("line-positions");
+
+ Interval y_ext;
+ Real space = staff_space (me);
+ if (scm_is_pair (line_positions))
+ {
+ for (SCM s = line_positions; scm_is_pair (s);
+ s = scm_cdr (s))
+ y_ext.add_point (scm_to_double (scm_car (s)) * 0.5 * space);
+ }
+ else
+ {
+ int l = Staff_symbol::line_count (me);
+ Real height = (l - 1) * staff_space (me) / 2;
+ y_ext = Interval (-height, height);
+ }
+ y_ext.widen (t/2);
+ return ly_interval2scm (y_ext);
+}
+
+bool
+Staff_symbol::on_line (Grob *me, int pos)
+{
+ SCM line_positions = me->get_property ("line-positions");
+ if (scm_is_pair (line_positions))
+ {
+ Real min_line = HUGE_VAL;
+ Real max_line = -HUGE_VAL;
+ for (SCM s = line_positions; scm_is_pair (s); s = scm_cdr (s))
+ {
+ Real current_line = scm_to_double (scm_car (s));
+ if (pos == current_line)
+ return true;
+ if (current_line > max_line)
+ max_line = current_line;
+ if (current_line < min_line)
+ min_line = current_line;
+
+ }
+ if (pos < min_line)
+ return (( (int) (rint (pos - min_line)) % 2) == 0);
+ if (pos > max_line)
+ return (( (int) (rint (pos - max_line)) % 2) == 0);
+
+ return false;
+ }
+ else
+ return ((abs (pos + line_count (me)) % 2) == 1);
+}
+
+ADD_INTERFACE (Staff_symbol,
+ "This spanner draws the lines of a staff. A staff symbol"
+ " defines a vertical unit, the @emph{staff space}. Quantities"
+ " that go by a half staff space are called @emph{positions}."
+ " The center (i.e., middle line or space) is position@tie{}0."
+ " The length of the symbol may be set by hand through the"
+ " @code{width} property.",
+
+ /* properties */
+ "ledger-line-thickness "
+ "line-count "
+ "line-positions "
+ "staff-space "
+ "thickness "
+ "width "
+ );