+
+Real
+Staff_symbol::get_line_thickness (Grob *me)
+{
+ Real lt = me->layout ()->get_dimension (ly_symbol2scm ("line-thickness"));
+
+ return robust_scm2double (me->get_property ("thickness"), 1.0) * lt;
+}
+
+Real
+Staff_symbol::get_ledger_line_thickness (Grob *me)
+{
+ SCM lt_pair = me->get_property ("ledger-line-thickness");
+ Offset z = robust_scm2offset (lt_pair, Offset (1.0, 0.1));
+
+ return z[X_AXIS] * get_line_thickness (me) + z[Y_AXIS] * staff_space (me);
+}
+
+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);
+}
+
+
+
+
+ADD_INTERFACE (Staff_symbol, "staff-symbol-interface",
+ "This spanner draws the lines of a staff. "
+ "A staff symbol definines a vertical unit, the staff space. "
+ "Quantities that go by a half staff space are called positions "
+ "The center (i.e. middle line "
+ "or space) is position 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 "
+ );