2 beam.cc -- implement Beam
4 source file of the GNU LilyPond music typesetter
6 (c) 1997--2000 Han-Wen Nienhuys <hanwen@cs.uu.nl>
7 Jan Nieuwenhuizen <janneke@gnu.org>
13 * shorter! (now +- 1000 lines)
15 * move paper vars to scm
17 remove *-hs variables, and do all y-position stuff in staff-space.
21 #include <math.h> // tanh.
23 #include "molecule.hh"
24 #include "directional-element-interface.hh"
28 #include "least-squares.hh"
30 #include "paper-def.hh"
32 #include "group-interface.hh"
33 #include "staff-symbol-referencer.hh"
34 #include "cross-staff.hh"
40 Beam::add_stem (Grob*me, Grob*s)
42 Pointer_group_interface:: add_element(me, "stems", s);
44 s->add_dependency (me);
46 assert (!Stem::beam_l (s));
47 s->set_grob_property ("beam", me->self_scm ());
49 add_bound_item (dynamic_cast<Spanner*> (me), dynamic_cast<Item*> (s));
53 Beam::get_multiplicity (Grob*me)
56 for (SCM s = me->get_grob_property ("stems"); gh_pair_p (s); s = gh_cdr (s))
58 Grob * sc = unsmob_grob (gh_car (s));
60 if (Stem::has_interface (sc))
61 m = m >? Stem::beam_count (sc,LEFT) >? Stem::beam_count (sc,RIGHT);
67 After pre-processing all directions should be set.
68 Several post-processing routines (stem, slur, script) need stem/beam
70 Currenly, this means that beam has set all stem's directions.
71 [Alternatively, stems could set its own directions, according to
72 their beam, during 'final-pre-processing'.]
74 MAKE_SCHEME_CALLBACK(Beam,before_line_breaking,1);
76 Beam::before_line_breaking (SCM smob)
78 Grob * me = unsmob_grob (smob);
81 if (visible_stem_count (me) < 2)
83 warning (_ ("beam has less than two stems"));
86 if (!Directional_element_interface::get (me))
87 Directional_element_interface::set (me, get_default_dir (me));
90 set_stem_directions (me);
91 set_stem_shorten (me);
97 Beam::get_default_dir (Grob*me)
99 Drul_array<int> total;
100 total[UP] = total[DOWN] = 0;
101 Drul_array<int> count;
102 count[UP] = count[DOWN] = 0;
105 Link_array<Item> stems=
106 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
108 for (int i=0; i <stems.size (); i++)
109 do { // HUH -- waar slaat dit op?
111 Direction sd = Directional_element_interface::get (s);
112 int current = sd ? (1 + d * sd)/2
113 : Stem::get_center_distance (s, (Direction)-d);
121 } while (flip(&d) != DOWN);
123 SCM func = me->get_grob_property ("dir-function");
124 SCM s = gh_call2 (func,
125 gh_cons (gh_int2scm (count[UP]),
126 gh_int2scm (count[DOWN])),
127 gh_cons (gh_int2scm (total[UP]),
128 gh_int2scm (total[DOWN])));
130 if (gh_number_p (s) && gh_scm2int (s))
134 If dir is not determined: get default
136 return to_dir (me->get_grob_property ("default-neutral-direction"));
141 Set all stems with non-forced direction to beam direction.
142 Urg: non-forced should become `without/with unforced' direction,
143 once stem gets cleaned-up.
146 Beam::set_stem_directions (Grob*me)
148 Link_array<Item> stems
149 =Pointer_group_interface__extract_elements (me, (Item*) 0, "stems");
150 Direction d = Directional_element_interface::get (me);
152 for (int i=0; i <stems.size (); i++)
155 SCM force = s->remove_grob_property ("dir-forced");
156 if (!gh_boolean_p (force) || !gh_scm2bool (force))
157 Directional_element_interface ::set (s,d);
162 Beam::auto_knees (Grob*me)
164 if (!auto_knee (me,"auto-interstaff-knee-gap", true))
165 auto_knee (me, "auto-knee-gap", false);
169 Simplistic auto-knees; only consider vertical gap between two
172 `Forced' stem directions are ignored. If you don't want auto-knees,
173 don't set, or unset autoKneeGap/autoInterstaffKneeGap.
176 Beam::auto_knee (Grob*me, String gap_str, bool interstaff_b)
180 SCM gap = me->get_grob_property (gap_str.ch_C());
182 Direction d = Directional_element_interface::get (me);
183 Link_array<Item> stems=
184 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
186 if (gh_number_p (gap))
188 Spanner*sp = dynamic_cast<Spanner*> (me);
189 int auto_gap_i = gh_scm2int (gap);
190 for (int i=1; i < stems.size (); i++)
192 bool is_b = (bool)(calc_interstaff_dist (stems[i], sp)
193 - calc_interstaff_dist (stems[i-1], sp));
194 int l_y = (int)(Stem::head_positions(stems[i-1])[d]);
195 int l_i = (int)calc_interstaff_dist (stems[i-1], sp);
197 int r_y = (int)(Stem::head_positions(stems[i])[d]);
198 int r_i = (int)calc_interstaff_dist (stems[i], sp);
200 int gap_i = r_y - l_y;
202 if ((abs (gap_i) >= auto_gap_i) && (!interstaff_b || is_b))
204 knee_y = (r_y + l_y) / 2;
212 for (int i=0; i < stems.size (); i++)
215 int y = (int)(Stem::head_positions(s)[d]);
216 int y_i = (int)calc_interstaff_dist (s, dynamic_cast<Spanner*> (me));
219 Directional_element_interface::set (s,y < knee_y ? UP : DOWN);
220 s->set_grob_property ("dir-forced", SCM_BOOL_T);
227 Set stem's shorten property if unset.
229 take some y-position (chord/beam/nearest?) into account
230 scmify forced-fraction
233 Beam::set_stem_shorten (Grob*m)
235 Spanner*me = dynamic_cast<Spanner*> (m);
236 if (!visible_stem_count (me))
239 Real forced_fraction = forced_stem_count (me) / visible_stem_count (me);
240 if (forced_fraction < 0.5)
243 int multiplicity = get_multiplicity (me);
245 SCM shorten = me->get_grob_property ("beamed-stem-shorten");
246 if (shorten == SCM_EOL)
249 int sz = scm_ilength (shorten);
251 Real staff_space = Staff_symbol_referencer::staff_space (me);
252 SCM shorten_elt = scm_list_ref (shorten, gh_int2scm (multiplicity <? (sz - 1)));
253 Real shorten_f = gh_scm2double (shorten_elt) * staff_space;
255 /* cute, but who invented me -- how to customise ? */
256 if (forced_fraction < 1)
259 Link_array<Item> stems=
260 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
262 for (int i=0; i < stems.size (); i++)
265 if (Stem::invisible_b (s))
267 if (gh_number_p (s->get_grob_property ("shorten")))
268 s->set_grob_property ("shorten", gh_double2scm (shorten_f));
273 Set elt properties height and y-position if not set.
274 Adjust stem lengths to reach beam.
276 MAKE_SCHEME_CALLBACK(Beam,after_line_breaking,1);
278 Beam::after_line_breaking (SCM smob)
280 Grob * me = unsmob_grob (smob);
282 /* first, calculate y, dy */
284 calc_default_position_and_height (me, &y, &dy);
285 if (visible_stem_count (me))
287 if (suspect_slope_b (me, y, dy))
290 Real damped_dy = calc_slope_damping_f (me, dy);
291 Real quantised_dy = quantise_dy_f (me, damped_dy);
293 y += (dy - quantised_dy) / 2;
297 until here, we used only stem_info, which acts as if dir=up
299 y *= Directional_element_interface::get (me);
300 dy *= Directional_element_interface::get (me);
303 Real half_space = Staff_symbol_referencer::staff_space (me) / 2;
305 /* weird: why do we do calc_position_and_height () ? regardless of
309 /* check for user-override of dy */
310 SCM s = me->remove_grob_property ("height-hs");
313 dy = gh_scm2double (s) * half_space;
315 me->set_grob_property ("height", gh_double2scm (dy));
317 /* check for user-override of y */
318 s = me->remove_grob_property ("y-position-hs");
321 y = gh_scm2double (s) * half_space;
325 /* we can modify y, so we should quantise y */
326 Real y_shift = check_stem_length_f (me, y, dy);
328 y = quantise_y_f (me,y, dy, 0);
329 set_stem_length (me, y, dy);
330 y_shift = check_stem_length_f (me, y, dy);
332 if (y_shift > half_space / 4)
337 for significantly lengthened or shortened stems,
338 request quanting the other way.
341 if (abs (y_shift) > half_space / 2)
342 quant_dir = sign (y_shift) * Directional_element_interface::get (me);
343 y = quantise_y_f (me, y, dy, quant_dir);
346 // UGH. Y is not in staff position unit?
347 // Ik dacht datwe daar juist van weg wilden?
348 set_stem_length (me, y, dy);
349 me->set_grob_property ("y-position", gh_double2scm (y));
351 return SCM_UNSPECIFIED;
355 See Documentation/tex/fonts.doc
358 Beam::calc_default_position_and_height (Grob*me,Real* y, Real* dy)
362 if (visible_stem_count (me) <= 1)
365 Real first_ideal = Stem::calc_stem_info (first_visible_stem (me)).idealy_f_;
366 if (first_ideal == Stem::calc_stem_info (last_visible_stem (me)).idealy_f_)
373 Array<Offset> ideals;
375 // ugh -> use commonx
376 Real x0 = first_visible_stem (me)->relative_coordinate (0, X_AXIS);
377 Link_array<Item> stems=
378 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
380 for (int i=0; i < stems.size (); i++)
383 if (Stem::invisible_b (s))
385 ideals.push (Offset (s->relative_coordinate (0, X_AXIS) - x0,
386 Stem::calc_stem_info (s).idealy_f_));
389 minimise_least_squares (&dydx, y, ideals); // duh, takes references
391 Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - x0;
396 Beam::suspect_slope_b (Grob*me, Real y, Real dy)
398 /* first, calculate y, dy */
400 steep slope running against lengthened stem is suspect
402 Real first_ideal = Stem::calc_stem_info (first_visible_stem (me)).idealy_f_;
403 Real last_ideal = Stem::calc_stem_info (last_visible_stem (me)).idealy_f_;
404 Real lengthened = gh_scm2double (me->get_grob_property ("outer-stem-length-limit"));
405 Real steep = gh_scm2double (me->get_grob_property ("slope-limit"));
407 // ugh -> use commonx
408 Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - first_visible_stem (me)->relative_coordinate (0, X_AXIS);
409 Real dydx = dy && dx ? dy/dx : 0;
411 if (((y - first_ideal > lengthened) && (dydx > steep))
412 || ((y + dy - last_ideal > lengthened) && (dydx < -steep)))
420 This neat trick is by Werner Lemberg,
421 damped = tanh (slope)
422 corresponds with some tables in [Wanske]
425 Beam::calc_slope_damping_f (Grob*me,Real dy)
427 SCM damp = me->get_grob_property ("damping");
428 int damping = gh_scm2int (damp);
432 // ugh -> use commonx
433 Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS)
434 - first_visible_stem (me)->relative_coordinate (0, X_AXIS);
435 Real dydx = dy && dx ? dy/dx : 0;
436 dydx = 0.6 * tanh (dydx) / damping;
443 Beam::calc_stem_y_f (Grob*me,Item* s, Real y, Real dy)
445 int beam_multiplicity = get_multiplicity (me);
446 int stem_multiplicity = (Stem::flag_i (s) - 2) >? 0;
448 SCM space_proc = me->get_grob_property ("space-function");
449 SCM space = gh_call1 (space_proc, gh_int2scm (beam_multiplicity));
451 Real thick = gh_scm2double (me->get_grob_property ("thickness")) ;
452 Real interbeam_f = gh_scm2double (space) ;
454 // ugh -> use commonx
455 Real x0 = first_visible_stem (me)->relative_coordinate (0, X_AXIS);
456 Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - x0;
457 Real stem_y = (dy && dx ? (s->relative_coordinate (0, X_AXIS) - x0) / dx * dy : 0) + y;
460 Direction dir = Directional_element_interface::get (me);
461 Direction sdir = Directional_element_interface::get (s);
467 * (thick / 2 + (beam_multiplicity - 1) * interbeam_f);
471 // huh, why not for first visible?
472 if (Staff_symbol_referencer::staff_symbol_l (s)
473 != Staff_symbol_referencer::staff_symbol_l (last_visible_stem (me)))
474 stem_y += Directional_element_interface::get (me)
475 * (beam_multiplicity - stem_multiplicity) * interbeam_f;
482 Beam::check_stem_length_f (Grob*me,Real y, Real dy)
486 Direction dir = Directional_element_interface::get (me);
488 Link_array<Item> stems=
489 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
491 for (int i=0; i < stems.size(); i++)
494 if (Stem::invisible_b (s))
497 Real stem_y = calc_stem_y_f (me, s, y, dy);
500 Stem_info info = Stem::calc_stem_info (s);
502 // if (0 > info.maxy_f_ - stem_y)
503 shorten = shorten <? info.maxy_f_ - stem_y;
504 // if (0 < info.miny_f_ - stem_y)
505 lengthen = lengthen >? info.miny_f_ - stem_y;
508 if (lengthen && shorten)
509 warning (_ ("weird beam vertical offset"));
511 /* when all stems are too short, normal stems win */
512 return dir * ((shorten) ? shorten : lengthen);
516 Hmm. At this time, beam position and slope are determined. Maybe,
517 stem directions and length should set to relative to the chord's
518 position of the beam. */
520 Beam::set_stem_length (Grob*me,Real y, Real dy)
522 Real half_space = Staff_symbol_referencer::staff_space (me)/2;
523 Link_array<Item> stems=
524 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
527 for (int i=0; i < stems.size (); i++)
530 if (Stem::invisible_b (s))
533 Real stem_y = calc_stem_y_f (me, s, y, dy);
535 /* caution: stem measures in staff-positions */
536 Stem::set_stemend (s,(stem_y + calc_interstaff_dist (s, dynamic_cast<Spanner*> (me))) / half_space);
541 [Ross] (simplification of)
542 Set dy complying with:
544 - thick / 2 + staffline_f / 2
545 - thick + staffline_f
549 Beam::quantise_dy_f (Grob*me,Real dy)
553 SCM proc = me->get_grob_property ("height-quants");
554 SCM quants = gh_call2 (proc, me->self_scm (),
555 gh_double2scm (me->paper_l ()->get_var ("stafflinethickness")
559 for (SCM s = quants; gh_pair_p (s); s = gh_cdr (s))
560 a.push (gh_scm2double (gh_car (s)));
565 Real staff_space = Staff_symbol_referencer::staff_space (me);
567 Interval iv = quantise_iv (a, abs (dy)/staff_space) * staff_space;
568 Real q = (abs (dy) - iv[SMALLER] <= iv[BIGGER] - abs (dy))
572 return q * sign (dy);
576 Prevent interference from stafflines and beams.
577 See Documentation/tex/fonts.doc
579 We only need to quantise the (left) y-position of the beam,
580 since dy is quantised too.
581 if extend_b then stems must *not* get shorter
584 Beam::quantise_y_f (Grob*me,Real y, Real dy, int quant_dir)
586 int multiplicity = get_multiplicity (me);
588 Real staff_space = Staff_symbol_referencer::staff_space (me);
589 Real thick = me->paper_l ()->get_var ("stafflinethickness");
592 SCM proc = me->get_grob_property ("vertical-position-quant-function");
593 SCM quants = scm_apply (proc,
595 gh_list (gh_int2scm (multiplicity),
596 gh_double2scm (dy/staff_space),
597 gh_double2scm (thick/staff_space),
598 SCM_EOL, SCM_UNDEFINED));
602 for (; gh_pair_p (quants); quants = gh_cdr (quants))
603 a.push (gh_scm2double (gh_car (quants)));
608 Real up_y = Directional_element_interface::get (me) * y;
609 Interval iv = quantise_iv (a, up_y/staff_space) * staff_space;
611 Real q = up_y - iv[SMALLER] <= iv[BIGGER] - up_y
612 ? iv[SMALLER] : iv[BIGGER];
614 q = iv[(Direction)quant_dir];
616 return q * Directional_element_interface::get (me);
620 Beam::set_beaming (Grob*me,Beaming_info_list *beaming)
622 Link_array<Grob> stems=
623 Pointer_group_interface__extract_elements (me, (Grob*)0, "stems");
626 for (int i=0; i < stems.size(); i++)
630 /* Don't overwrite user override (?) */
631 if (Stem::beam_count (stems[i], d) == 0
632 /* Don't set beaming for outside of outer stems */
633 && ! (d == LEFT && i == 0)
634 && ! (d == RIGHT && i == stems.size () -1))
636 int b = beaming->infos_.elem (i).beams_i_drul_[d];
637 Stem::set_beaming (stems[i], b, d);
640 while (flip (&d) != LEFT);
647 beams to go with one stem.
652 Beam::stem_beams (Grob*me,Item *here, Item *next, Item *prev)
654 // ugh -> use commonx
655 if ((next && !(next->relative_coordinate (0, X_AXIS) > here->relative_coordinate (0, X_AXIS))) ||
656 (prev && !(prev->relative_coordinate (0, X_AXIS) < here->relative_coordinate (0, X_AXIS))))
657 programming_error ("Beams are not left-to-right");
659 Real staffline_f = me->paper_l ()->get_var ("stafflinethickness");
660 int multiplicity = get_multiplicity (me);
662 SCM space_proc = me->get_grob_property ("space-function");
663 SCM space = gh_call1 (space_proc, gh_int2scm (multiplicity));
665 Real thick = gh_scm2double (me->get_grob_property ("thickness")) ;
666 Real interbeam_f = gh_scm2double (space) ;
668 Real bdy = interbeam_f;
669 Real stemdx = staffline_f;
671 // ugh -> use commonx
672 Real dx = visible_stem_count (me) ?
673 last_visible_stem (me)->relative_coordinate (0, X_AXIS) - first_visible_stem (me)->relative_coordinate (0, X_AXIS)
675 Real dy = gh_scm2double (me->get_grob_property ("height"));
676 Real dydx = dy && dx ? dy/dx : 0;
682 if (!Stem::first_head (here))
685 int t = Stem::type_i (here);
687 SCM proc = me->get_grob_property ("flag-width-function");
688 SCM result = gh_call1 (proc, gh_int2scm (t));
689 nw_f = gh_scm2double (result);
693 Direction dir = Directional_element_interface::get (me);
695 /* half beams extending to the left. */
698 int lhalfs= lhalfs = Stem::beam_count (here,LEFT) - Stem::beam_count (prev,RIGHT);
699 int lwholebeams= Stem::beam_count (here,LEFT) <? Stem::beam_count (prev,RIGHT) ;
701 Half beam should be one note-width,
702 but let's make sure two half-beams never touch
704 Real w = here->relative_coordinate (0, X_AXIS) - prev->relative_coordinate (0, X_AXIS);
707 if (lhalfs) // generates warnings if not
708 a = Lookup::beam (dydx, w, thick);
709 a.translate (Offset (-w, -w * dydx));
710 for (int j = 0; j < lhalfs; j++)
713 b.translate_axis (-dir * bdy * (lwholebeams+j), Y_AXIS);
714 leftbeams.add_molecule (b);
720 int rhalfs = Stem::beam_count (here,RIGHT) - Stem::beam_count (next,LEFT);
721 int rwholebeams= Stem::beam_count (here,RIGHT) <? Stem::beam_count (next,LEFT) ;
723 Real w = next->relative_coordinate (0, X_AXIS) - here->relative_coordinate (0, X_AXIS);
724 Molecule a = Lookup::beam (dydx, w + stemdx, thick);
725 a.translate_axis( - stemdx/2, X_AXIS);
729 SCM gap = me->get_grob_property ("gap");
730 if (gh_number_p (gap))
732 int gap_i = gh_scm2int ( (gap));
733 int nogap = rwholebeams - gap_i;
735 for (; j < nogap; j++)
738 b.translate_axis (-dir * bdy * j, Y_AXIS);
739 rightbeams.add_molecule (b);
741 // TODO: notehead widths differ for different types
744 a = Lookup::beam (dydx, w + stemdx, thick);
747 for (; j < rwholebeams; j++)
750 b.translate (Offset (Stem::invisible_b (here) ? 0 : gap_f, -dir * bdy * j));
751 rightbeams.add_molecule (b);
756 a = Lookup::beam (dydx, w, thick);
758 for (; j < rwholebeams + rhalfs; j++)
761 b.translate_axis (- dir * bdy * j, Y_AXIS);
762 rightbeams.add_molecule (b);
766 leftbeams.add_molecule (rightbeams);
769 Does beam quanting think of the asymetry of beams?
770 Refpoint is on bottom of symbol. (FIXTHAT) --hwn.
776 TODO: it would be nice to introduce y-position via callbacks.
779 MAKE_SCHEME_CALLBACK(Beam,brew_molecule,1);
781 Beam::brew_molecule (SCM smob)
783 Grob * me =unsmob_grob (smob);
786 if (!gh_pair_p (me->get_grob_property ("stems")))
789 Link_array<Item>stems =
790 Pointer_group_interface__extract_elements (me, (Item*) 0, "stems");
791 if (visible_stem_count (me))
793 // ugh -> use commonx
794 x0 = first_visible_stem (me)->relative_coordinate (0, X_AXIS);
795 dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - x0;
799 x0 = stems[0]->relative_coordinate (0, X_AXIS);
800 dx = stems.top()->relative_coordinate (0, X_AXIS) - x0;
804 Real dy = gh_scm2double (me->get_grob_property ("height"));
805 Real dydx = dy && dx ? dy/dx : 0;
806 Real y = gh_scm2double (me->get_grob_property ("y-position"));
809 for (int j=0; j <stems.size (); j++)
812 Item * prev = (j > 0)? stems[j-1] : 0;
813 Item * next = (j < stems.size()-1) ? stems[j+1] :0;
815 Molecule sb = stem_beams (me, i, next, prev);
816 Real x = i->relative_coordinate (0, X_AXIS)-x0;
817 sb.translate (Offset (x, x * dydx + y));
818 mol.add_molecule (sb);
820 mol.translate_axis (x0
821 - dynamic_cast<Spanner*> (me)->get_bound (LEFT)->relative_coordinate (0, X_AXIS), X_AXIS);
823 return mol.smobbed_copy ();
827 Beam::forced_stem_count (Grob*me)
829 Link_array<Item>stems =
830 Pointer_group_interface__extract_elements ( me, (Item*) 0, "stems");
832 for (int i=0; i < stems.size (); i++)
836 if (Stem::invisible_b (s))
839 if (((int)Stem::chord_start_f (s))
840 && (Stem::get_direction (s ) != Stem::get_default_dir (s )))
850 use filter and standard list functions.
853 Beam::visible_stem_count (Grob*me)
855 Link_array<Item>stems =
856 Pointer_group_interface__extract_elements (me, (Item*) 0, "stems");
858 for (int i = stems.size (); i--;)
860 if (!Stem::invisible_b (stems[i]))
867 Beam::first_visible_stem(Grob*me)
869 Link_array<Item>stems =
870 Pointer_group_interface__extract_elements ( me, (Item*) 0, "stems");
872 for (int i = 0; i < stems.size (); i++)
874 if (!Stem::invisible_b (stems[i]))
881 Beam::last_visible_stem(Grob*me)
883 Link_array<Item>stems =
884 Pointer_group_interface__extract_elements ( me, (Item*) 0, "stems");
885 for (int i = stems.size (); i--;)
887 if (!Stem::invisible_b (stems[i]))
896 handle rest under beam (do_post: beams are calculated now)
897 what about combination of collisions and rest under beam.
901 rest -> stem -> beam -> interpolate_y_position ()
903 MAKE_SCHEME_CALLBACK(Beam,rest_collision_callback,2);
905 Beam::rest_collision_callback (SCM element_smob, SCM axis)
907 Grob *rest = unsmob_grob (element_smob);
908 Axis a = (Axis) gh_scm2int (axis);
910 assert (a == Y_AXIS);
912 Grob * st = unsmob_grob (rest->get_grob_property ("stem"));
915 return gh_double2scm (0.0);
916 Grob * beam = unsmob_grob (stem->get_grob_property ("beam"));
917 if (!beam || !Beam::has_interface (beam) || !Beam::visible_stem_count (beam))
918 return gh_double2scm (0.0);
920 // make callback for rest from this.
925 // todo: make sure this calced already.
926 SCM s = beam->get_grob_property ("height");
928 beam_dy = gh_scm2double (s);
930 s = beam->get_grob_property ("y-position");
932 beam_y = gh_scm2double (s);
934 // ugh -> use commonx
935 Real x0 = first_visible_stem(beam)->relative_coordinate (0, X_AXIS);
936 Real dx = last_visible_stem(beam)->relative_coordinate (0, X_AXIS) - x0;
937 Real dydx = beam_dy && dx ? beam_dy/dx : 0;
939 Direction d = Stem::get_direction (stem);
940 Real beamy = (stem->relative_coordinate (0, X_AXIS) - x0) * dydx + beam_y;
942 Real staff_space = Staff_symbol_referencer::staff_space (rest);
945 Real rest_dim = rest->extent (rest, Y_AXIS)[d]*2.0 / staff_space ; // refp??
948 = gh_scm2double (rest->get_grob_property ("minimum-beam-collision-distance"));
950 minimum_dist + -d * (beamy - rest_dim) >? 0;
952 int stafflines = Staff_symbol_referencer::line_count (rest);
954 // move discretely by half spaces.
955 int discrete_dist = int (ceil (dist));
957 // move by whole spaces inside the staff.
958 if (discrete_dist < stafflines+1)
959 discrete_dist = int (ceil (discrete_dist / 2.0)* 2.0);
961 return gh_double2scm (-d * discrete_dist);
966 Beam::has_interface (Grob*me)
968 return me->has_interface (ly_symbol2scm ("beam-interface"));
972 Beam::set_interface (Grob*me)
975 why the init? No way to tell difference between default and user
977 me->set_grob_property ("height", gh_int2scm (0)); // ugh.
978 me->set_grob_property ("y-position" ,gh_int2scm (0));
979 me->set_interface (ly_symbol2scm("beam-interface"));