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"
14 #include "libc-extension.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 return robust_scm2double ( me->get_grob_property ("staff-position"), p);
73 LY_DEFINE(ly_grob_staff_position,
74 "ly:grob-staff-position",
76 "Return the Y-position of this grob relative to the staff.")
78 Grob * g = unsmob_grob (sg);
80 SCM_ASSERT_TYPE (g, sg, SCM_ARG1, __FUNCTION__, "grob");
81 Real pos = Staff_symbol_referencer::get_position (g);
83 if (fabs (rint (pos) -pos) < 1e-6) // ugh.
84 return gh_int2scm ((int) my_round (pos));
86 return gh_double2scm (pos);
91 should use offset callback!
93 MAKE_SCHEME_CALLBACK (Staff_symbol_referencer,callback,2);
95 Staff_symbol_referencer::callback (SCM element_smob, SCM)
97 Grob *me = unsmob_grob (element_smob);
99 SCM pos = me->get_grob_property ("staff-position");
101 if (gh_number_p (pos))
103 Real space = Staff_symbol_referencer::staff_space (me);
104 off = gh_scm2double (pos) * space/2.0;
105 me->set_grob_property ("staff-position", gh_int2scm (0));
108 return gh_double2scm (off);
113 This sets the position relative to the center of the staff symbol.
115 The function is hairy, because it can be callled in two situations:
117 1. There is no staff yet; we must set staff-position
119 2. There is a staff, and perhaps someone even applied a
120 translate_axis (). Then we must compensate for the translation
122 In either case, we set a callback to be sure that our new position
123 will be extracted from staff-position
127 Staff_symbol_referencer::set_position (Grob*me,Real p)
129 Grob * st = get_staff_symbol (me);
130 if (st && me->common_refpoint (st, Y_AXIS))
132 Real oldpos = get_position (me);
133 me->set_grob_property ("staff-position", gh_double2scm (p - oldpos));
137 me->set_grob_property ("staff-position",
142 if (me->has_offset_callback_b (Staff_symbol_referencer::callback_proc, Y_AXIS))
145 me->add_offset_callback (Staff_symbol_referencer::callback_proc, Y_AXIS);
149 Half of the height, in staff space, i.e. 2.0 for a normal staff.
152 Staff_symbol_referencer::staff_radius (Grob*me)
154 return (line_count (me) -1) / 2.0;
159 compare_position (Grob *const &a, Grob * const &b)
161 return sign (Staff_symbol_referencer::get_position ((Grob*)a) -
162 Staff_symbol_referencer::get_position ((Grob*)b));
165 ADD_INTERFACE (Staff_symbol_referencer,"staff-symbol-referencer-interface",
166 "Object whose Y position is meaning with reference to a staff "
167 "symbol. Objects that have this interface should include "
168 "Staff_symbol_referencer::callback in their Y-offset-callback. "