2 staff-symbol-referencer.cc -- implement Staff_symbol_referencer
4 source file of the GNU LilyPond music typesetter
6 (c) 1999--2003 Han-Wen Nienhuys <hanwen@cs.uu.nl>
11 #include "staff-symbol-referencer.hh"
12 #include "staff-symbol.hh"
13 #include "paper-def.hh"
18 Staff_symbol_referencer::line_count (Grob*me)
20 Grob *st = get_staff_symbol (me);
21 return st ? Staff_symbol::line_count (st) : 0;
25 Staff_symbol_referencer::on_staffline (Grob*me)
27 return on_staffline (me, (int) rint (get_position (me)));
31 Staff_symbol_referencer::on_staffline (Grob*me, int pos)
33 int sz = line_count (me)-1;
34 return ((pos + sz) % 2) == 0;
38 Staff_symbol_referencer::get_staff_symbol (Grob*me)
40 SCM st = me->get_grob_property ("staff-symbol");
41 return unsmob_grob (st);
45 Staff_symbol_referencer::staff_space (Grob*me)
47 Grob * st = get_staff_symbol (me);
49 return Staff_symbol::staff_space (st);
55 Staff_symbol_referencer::get_position (Grob*me)
58 Grob * st = get_staff_symbol (me);
59 Grob * c = st ? me->common_refpoint (st, Y_AXIS) : 0;
62 Real y = me->relative_coordinate (c, Y_AXIS)
63 - st->relative_coordinate (c, Y_AXIS);
65 p += 2.0 * y / Staff_symbol::staff_space (st);
69 SCM pos = me->get_grob_property ("staff-position");
70 if (gh_number_p (pos))
71 return gh_scm2double (pos);
80 should use offset callback!
82 MAKE_SCHEME_CALLBACK (Staff_symbol_referencer,callback,2);
84 Staff_symbol_referencer::callback (SCM element_smob, SCM)
86 Grob *me = unsmob_grob (element_smob);
89 SCM pos = me->get_grob_property ("staff-position");
91 if (gh_number_p (pos))
93 Real space = Staff_symbol_referencer::staff_space (me);
94 off = gh_scm2double (pos) * space/2.0;
95 me->set_grob_property ("staff-position", gh_double2scm (0.0));
98 return gh_double2scm (off);
103 This sets the position relative to the center of the staff symbol.
105 The function is hairy, because it can be callled in two situations:
107 1. There is no staff yet; we must set staff-position
109 2. There is a staff, and perhaps someone even applied a
110 translate_axis (). Then we must compensate for the translation
112 In either case, we set a callback to be sure that our new position
113 will be extracted from staff-position
117 Staff_symbol_referencer::set_position (Grob*me,Real p)
119 Grob * st = get_staff_symbol (me);
120 if (st && me->common_refpoint (st, Y_AXIS))
122 Real oldpos = get_position (me);
123 me->set_grob_property ("staff-position", gh_double2scm (p - oldpos));
127 me->set_grob_property ("staff-position",
132 if (me->has_offset_callback_b (Staff_symbol_referencer::callback_proc, Y_AXIS))
135 me->add_offset_callback (Staff_symbol_referencer::callback_proc, Y_AXIS);
139 Half of the height, in staff space, i.e. 2.0 for a normal staff.
142 Staff_symbol_referencer::staff_radius (Grob*me)
144 return (line_count (me) -1) / 2.0;
149 compare_position (Grob *const &a, Grob * const &b)
151 return sign (Staff_symbol_referencer::get_position ((Grob*)a) -
152 Staff_symbol_referencer::get_position ((Grob*)b));
155 ADD_INTERFACE (Staff_symbol_referencer,"staff-symbol-referencer-interface",
156 "Object whose Y position is meaning with reference to a staff "
157 "symbol. Objects that have this interface should include "
158 "Staff_symbol_referencer::callback in their Y-offset-callback. "