source file of the GNU LilyPond music typesetter
- (c) 1997--1999 Han-Wen Nienhuys <hanwen@cs.uu.nl>
+ (c) 1997--2000 Han-Wen Nienhuys <hanwen@cs.uu.nl>
Jan Nieuwenhuizen <janneke@gnu.org>
*/
-
/*
[TODO]
- * center beam symbol
+ * shorter! (now +- 1000 lines)
* less hairy code
+ * move paper vars to scm
+
+ remove *-hs variables, and do all y-position stuff in staff-space.
+*/
- */
-#include <math.h>
+#include <math.h> // tanh.
+#include "molecule.hh"
+#include "directional-element-interface.hh"
#include "beaming.hh"
-#include "proto.hh"
-#include "dimensions.hh"
#include "beam.hh"
#include "misc.hh"
-#include "debug.hh"
-#include "molecule.hh"
-#include "leastsquares.hh"
+#include "least-squares.hh"
#include "stem.hh"
#include "paper-def.hh"
#include "lookup.hh"
#include "group-interface.hh"
#include "staff-symbol-referencer.hh"
#include "cross-staff.hh"
+#include "item.hh"
+#include "spanner.hh"
+#include "warn.hh"
-Beam::Beam ()
+void
+Beam::add_stem (Score_element*me, Score_element*s)
{
- Group_interface g (this, "stems");
- g.set_interface ();
+ Pointer_group_interface:: add_element(me, "stems", s);
- slope_f_ = 0;
- left_y_ = 0;
-}
+ s->add_dependency (me);
-/*
- TODO: Fix this class. This is wildly inefficient.
- */
-Stem *
-Beam::stem (int i)const
-{
- return Group_interface__extract_elements ((Beam*) this, (Stem*) 0, "stems")[i];
-}
-
-int
-Beam::stem_count ()const
-{
- Group_interface gi (this, "stems");
- return gi.count ();
-}
+ assert (!Stem::beam_l (s));
+ s->set_elt_property ("beam", me->self_scm ());
-Stem*
-Beam::stem_top ()const
-{
- return Group_interface__extract_elements ((Beam*) this, (Stem*) 0, "stems")[stem_count () - 1];
+ add_bound_item (dynamic_cast<Spanner*> (me), dynamic_cast<Item*> (s));
}
-/* burp */
int
-Beam::visible_stem_count () const
+Beam::get_multiplicity (Score_element*me)
{
- int c = 0;
- for (int i = 0; i < stem_count (); i++)
+ int m = 0;
+ for (SCM s = me->get_elt_property ("stems"); gh_pair_p (s); s = gh_cdr (s))
{
- if (!stem (i)->invisible_b ())
- c++;
+ Score_element * sc = unsmob_element (gh_car (s));
+
+ if (Stem::has_interface (sc))
+ m = m >? Stem::beam_count (sc,LEFT) >? Stem::beam_count (sc,RIGHT);
}
- return c;
+ return m;
}
-Stem*
-Beam::first_visible_stem () const
+/*
+ After pre-processing all directions should be set.
+ Several post-processing routines (stem, slur, script) need stem/beam
+ direction.
+ Currenly, this means that beam has set all stem's directions.
+ [Alternatively, stems could set its own directions, according to
+ their beam, during 'final-pre-processing'.]
+ */
+MAKE_SCHEME_CALLBACK(Beam,before_line_breaking,1);
+SCM
+Beam::before_line_breaking (SCM smob)
{
- for (int i = 0; i < stem_count (); i++)
+ Score_element * me = unsmob_element (smob);
+
+ // Why?
+ if (visible_stem_count (me) < 2)
{
- Stem* s = stem (i);
- if (!s->invisible_b ())
- return s;
+ warning (_ ("beam has less than two stems"));
}
- assert (0);
- // sigh
- return 0;
-}
+ if (!Directional_element_interface::get (me))
+ Directional_element_interface::set (me, get_default_dir (me));
-Stem*
-Beam::last_visible_stem () const
-{
- for (int i = stem_count (); i > 0; i--)
- {
- Stem* s = stem (i - 1);
- if (!s->invisible_b ())
- return s;
- }
+ auto_knees (me);
+ set_stem_directions (me);
+ set_stem_shorten (me);
- assert (0);
- // sigh
- return 0;
+ return SCM_EOL;
}
-void
-Beam::add_stem (Stem*s)
+Direction
+Beam::get_default_dir (Score_element*me)
{
- Group_interface gi (this, "stems");
- gi.add_element (s);
-
- s->add_dependency (this);
+ Drul_array<int> total;
+ total[UP] = total[DOWN] = 0;
+ Drul_array<int> count;
+ count[UP] = count[DOWN] = 0;
+ Direction d = DOWN;
- assert (!s->beam_l ());
- s->set_elt_property ("beam", self_scm_);
+ Link_array<Item> stems=
+ Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
- if (!spanned_drul_[LEFT])
- set_bounds (LEFT,s);
- else
- set_bounds (RIGHT,s);
+ for (int i=0; i <stems.size (); i++)
+ do { // HUH -- waar slaat dit op?
+ Score_element *s = stems[i];
+ Direction sd = Directional_element_interface::get (s);
+ int current = sd ? (1 + d * sd)/2
+ : Stem::get_center_distance (s, (Direction)-d);
+
+ if (current)
+ {
+ total[d] += current;
+ count[d] ++;
+ }
+
+ } while (flip(&d) != DOWN);
+
+ SCM func = me->get_elt_property ("dir-function");
+ SCM s = gh_call2 (func,
+ gh_cons (gh_int2scm (count[UP]),
+ gh_int2scm (count[DOWN])),
+ gh_cons (gh_int2scm (total[UP]),
+ gh_int2scm (total[DOWN])));
+
+ if (gh_number_p (s) && gh_scm2int (s))
+ return to_dir (s);
+
+ /*
+ If dir is not determined: get default
+ */
+ return to_dir (me->get_elt_property ("default-neutral-direction"));
}
-Molecule*
-Beam::do_brew_molecule_p () const
+
+/*
+ Set all stems with non-forced direction to beam direction.
+ Urg: non-forced should become `without/with unforced' direction,
+ once stem gets cleaned-up.
+ */
+void
+Beam::set_stem_directions (Score_element*me)
{
- Molecule *mol_p = new Molecule;
- if (!stem_count ())
- return mol_p;
+ Link_array<Item> stems
+ =Pointer_group_interface__extract_elements (me, (Item*) 0, "stems");
+ Direction d = Directional_element_interface::get (me);
- Real x0 = first_visible_stem ()->hpos_f ();
- for (int j=0; j <stem_count (); j++)
+ for (int i=0; i <stems.size (); i++)
{
- Stem *i = stem (j);
- Stem * prev = (j > 0)? stem (j-1) : 0;
- Stem * next = (j < stem_count ()-1) ? stem (j+1) :0;
-
- Molecule sb = stem_beams (i, next, prev);
- Real x = i->hpos_f ()-x0;
- sb.translate (Offset (x, x * slope_f_ + left_y_));
- mol_p->add_molecule (sb);
+ Score_element *s = stems[i];
+ SCM force = s->remove_elt_property ("dir-forced");
+ if (!gh_boolean_p (force) || !gh_scm2bool (force))
+ Directional_element_interface ::set (s,d);
}
- mol_p->translate_axis (x0
- - spanned_drul_[LEFT]->relative_coordinate (0, X_AXIS), X_AXIS);
+}
- return mol_p;
-}
-
-Offset
-Beam::center () const
+void
+Beam::auto_knees (Score_element*me)
{
- Real w = (first_visible_stem ()->note_delta_f () + extent (X_AXIS).length ())/2.0;
- return Offset (w, w * slope_f_);
+ if (!auto_knee (me,"auto-interstaff-knee-gap", true))
+ auto_knee (me, "auto-knee-gap", false);
}
/*
Simplistic auto-knees; only consider vertical gap between two
- adjacent chords
+ adjacent chords.
+
+ `Forced' stem directions are ignored. If you don't want auto-knees,
+ don't set, or unset autoKneeGap/autoInterstaffKneeGap.
*/
bool
-Beam::auto_knee (SCM gap, bool interstaff_b)
+Beam::auto_knee (Score_element*me, String gap_str, bool interstaff_b)
{
- bool knee = false;
+ bool knee_b = false;
int knee_y = 0;
- if (gap != SCM_UNDEFINED)
+ SCM gap = me->get_elt_property (gap_str.ch_C());
+
+ Direction d = Directional_element_interface::get (me);
+ Link_array<Item> stems=
+ Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
+
+ if (gh_number_p (gap))
{
+ Spanner*sp = dynamic_cast<Spanner*> (me);
int auto_gap_i = gh_scm2int (gap);
- for (int i=1; i < stem_count (); i++)
+ for (int i=1; i < stems.size (); i++)
{
- bool is_b = (bool)(calc_interstaff_dist (stem (i), this)
- - calc_interstaff_dist (stem (i-1), this));
- int l_y = (int)(stem (i-1)->chord_start_f ())
- + (int)calc_interstaff_dist (stem (i-1), this);
- int r_y = (int)(stem (i)->chord_start_f ())
- + (int)calc_interstaff_dist (stem (i), this);
+ bool is_b = (bool)(calc_interstaff_dist (stems[i], sp)
+ - calc_interstaff_dist (stems[i-1], sp));
+ int l_y = (int)(Stem::head_positions(stems[i-1])[d])
+ + (int)calc_interstaff_dist (stems[i-1], sp);
+ int r_y = (int)(Stem::head_positions(stems[i])[d])
+ + (int)calc_interstaff_dist (stems[i], sp);
int gap_i = r_y - l_y;
- /*
- Forced stem directions are ignored. If you don't want auto-knees,
- don't set, or unset autoKneeGap/autoInterstaffKneeGap.
- */
if ((abs (gap_i) >= auto_gap_i) && (!interstaff_b || is_b))
{
knee_y = (r_y + l_y) / 2;
- knee = true;
+ knee_b = true;
break;
}
}
}
- if (knee)
+ if (knee_b)
{
- for (int i=0; i < stem_count (); i++)
+ for (int i=0; i < stems.size (); i++)
{
- int y = (int)(stem (i)->chord_start_f ())
- + (int)calc_interstaff_dist (stem (i), this);
- stem (i)->set_direction ( y < knee_y ? UP : DOWN);
- stem (i)->set_elt_property ("dir-forced", SCM_BOOL_T);
+ Item *s = stems[i];
+ int y = (int)(Stem::head_positions(s)[d])
+ + (int)calc_interstaff_dist (s, dynamic_cast<Spanner*> (me));
+
+ Directional_element_interface::set (s,y < knee_y ? UP : DOWN);
+ s->set_elt_property ("dir-forced", SCM_BOOL_T);
}
}
- return knee;
+ return knee_b;
}
-bool
-Beam::auto_knees ()
+/*
+ Set stem's shorten property if unset.
+ TODO:
+ take some y-position (chord/beam/nearest?) into account
+ scmify forced-fraction
+ */
+void
+Beam::set_stem_shorten (Score_element*m)
{
- if (auto_knee (get_elt_property ("auto-interstaff-knee-gap"), true))
- return true;
-
- return auto_knee (get_elt_property ("auto-knee-gap"), false);
-}
+ Spanner*me = dynamic_cast<Spanner*> (m);
+ if (!visible_stem_count (me))
+ return;
+ Real forced_fraction = forced_stem_count (me) / visible_stem_count (me);
+ if (forced_fraction < 0.5)
+ return;
-void
-Beam::do_pre_processing ()
-{
- /*
- urg: it seems that info on whether beam (voice) dir was forced
- is being junked here?
- */
- if (!get_direction ())
- set_direction ( get_default_dir ());
+ int multiplicity = get_multiplicity (me);
+
+ SCM shorten = me->get_elt_property ("beamed-stem-shorten");
+ if (shorten == SCM_EOL)
+ return;
+
+ int sz = scm_ilength (shorten);
- set_direction (get_direction ());
-}
+ Real staff_space = Staff_symbol_referencer::staff_space (me);
+ SCM shorten_elt = scm_list_ref (shorten, gh_int2scm (multiplicity <? (sz - 1)));
+ Real shorten_f = gh_scm2double (shorten_elt) * staff_space;
-void
-Beam::do_print () const
-{
-#ifndef NPRINT
- DEBUG_OUT << "slope_f_ " << slope_f_ << "left ypos " << left_y_;
- Spanner::do_print ();
-#endif
-}
+ /* cute, but who invented me -- how to customise ? */
+ if (forced_fraction < 1)
+ shorten_f /= 2;
-void
-Beam::do_post_processing ()
-{
- if (visible_stem_count () < 2)
+ Link_array<Item> stems=
+ Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
+
+ for (int i=0; i < stems.size (); i++)
{
- warning (_ ("beam with less than two stems"));
- set_elt_property ("transparent", SCM_BOOL_T);
- return;
+ Item* s = stems[i];
+ if (Stem::invisible_b (s))
+ continue;
+ if (gh_number_p (s->get_elt_property ("shorten")))
+ s->set_elt_property ("shorten", gh_double2scm (shorten_f));
}
- set_stem_shorten ();
- if (auto_knees ())
+}
+
+/*
+ Set elt properties height and y-position if not set.
+ Adjust stem lengths to reach beam.
+ */
+MAKE_SCHEME_CALLBACK(Beam,after_line_breaking,1);
+SCM
+Beam::after_line_breaking (SCM smob)
+{
+ Score_element * me = unsmob_element (smob);
+
+ /* first, calculate y, dy */
+ Real y, dy;
+ calc_default_position_and_height (me, &y, &dy);
+ if (visible_stem_count (me))
{
- /*
- if auto-knee did its work, most probably stem directions
- have changed, so we must recalculate all.
- */
- set_direction (get_default_dir ());
- set_direction (get_direction ());
+ if (suspect_slope_b (me, y, dy))
+ dy = 0;
- /* auto-knees used to only work for slope = 0
- anyway, should be able to set slope per beam
- set_elt_property ("damping", gh_int2scm(1000));
- */
+ Real damped_dy = calc_slope_damping_f (me, dy);
+ Real quantised_dy = quantise_dy_f (me, damped_dy);
- set_stem_shorten ();
+ y += (dy - quantised_dy) / 2;
+ dy = quantised_dy;
}
- calculate_slope ();
- set_stemlens ();
-}
-
+ /*
+ until here, we used only stem_info, which acts as if dir=up
+ */
+ y *= Directional_element_interface::get (me);
+ dy *= Directional_element_interface::get (me);
+ Real half_space = Staff_symbol_referencer::staff_space (me) / 2;
-Direction
-Beam::get_default_dir () const
-{
- Drul_array<int> total;
- total[UP] = total[DOWN] = 0;
- Drul_array<int> count;
- count[UP] = count[DOWN] = 0;
- Direction d = DOWN;
+ /* weird: why do we do calc_position_and_height () ? regardless of
+ this setting?
- for (int i=0; i <stem_count (); i++)
- do {
- Stem *s = stem (i);
- int current = s->get_direction ()
- ? (1 + d * s->get_direction ())/2
- : s->get_center_distance ((Direction)-d);
+ */
+ /* check for user-override of dy */
+ SCM s = me->remove_elt_property ("height-hs");
+ if (gh_number_p (s))
+ {
+ dy = gh_scm2double (s) * half_space;
+ }
+ me->set_elt_property ("height", gh_double2scm (dy));
- if (current)
+ /* check for user-override of y */
+ s = me->remove_elt_property ("y-position-hs");
+ if (gh_number_p (s))
+ {
+ y = gh_scm2double (s) * half_space;
+ }
+ else
+ {
+ /* we can modify y, so we should quantise y */
+ Real y_shift = check_stem_length_f (me, y, dy);
+ y += y_shift;
+ y = quantise_y_f (me,y, dy, 0);
+ set_stem_length (me, y, dy);
+ y_shift = check_stem_length_f (me, y, dy);
+
+ if (y_shift > half_space / 4)
{
- total[d] += current;
- count[d] ++;
+ y += y_shift;
+
+ /*
+ for significantly lengthened or shortened stems,
+ request quanting the other way.
+ */
+ int quant_dir = 0;
+ if (abs (y_shift) > half_space / 2)
+ quant_dir = sign (y_shift) * Directional_element_interface::get (me);
+ y = quantise_y_f (me, y, dy, quant_dir);
}
+ }
+ // UGH. Y is not in staff position unit?
+ // Ik dacht datwe daar juist van weg wilden?
+ set_stem_length (me, y, dy);
+ me->set_elt_property ("y-position", gh_double2scm (y));
- } while (flip(&d) != DOWN);
-
- /*
- [Ross] states that the majority of the notes dictates the
- direction (and not the mean of "center distance")
+ return SCM_UNSPECIFIED;
+}
- But is that because it really looks better, or because he wants
- to provide some real simple hands-on rules?
-
- We have our doubts, so we simply provide all sensible alternatives.
+/*
+ See Documentation/tex/fonts.doc
+ */
+void
+Beam::calc_default_position_and_height (Score_element*me,Real* y, Real* dy)
+{
+ *y = 0;
+ *dy = 0;
+ if (visible_stem_count (me) <= 1)
+ return;
- If dir is not determined: up (see stem::get_default_dir ()) */
+ Real first_ideal = Stem::calc_stem_info (first_visible_stem (me)).idealy_f_;
+ if (first_ideal == Stem::calc_stem_info (last_visible_stem (me)).idealy_f_)
+ {
+ *dy = 0;
+ *y = first_ideal;
+ return;
+ }
- Direction beam_dir = CENTER;
- Direction neutral_dir = (Direction)(int)paper_l ()->get_var ("stem_default_neutral_direction");
+ Array<Offset> ideals;
- SCM a = get_elt_property ("beam-dir-algorithm");
-
- if (a == ly_symbol2scm ("majority")) // should get default from paper.
- beam_dir = (count[UP] == count[DOWN]) ? neutral_dir
- : (count[UP] > count[DOWN]) ? UP : DOWN;
- else if (a == ly_symbol2scm ("mean"))
- // mean center distance
- beam_dir = (total[UP] == total[DOWN]) ? neutral_dir
- : (total[UP] > total[DOWN]) ? UP : DOWN;
- else if (a == ly_symbol2scm ("median"))
+ // ugh -> use commonx
+ Real x0 = first_visible_stem (me)->relative_coordinate (0, X_AXIS);
+ Link_array<Item> stems=
+ Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
+
+ for (int i=0; i < stems.size (); i++)
{
- // median center distance
- if (count[DOWN] && count[UP])
- {
- beam_dir = (total[UP] / count[UP] == total[DOWN] / count[DOWN])
- ? neutral_dir
- : (total[UP] / count[UP] > total[DOWN] / count[DOWN]) ? UP : DOWN;
- }
- else
- {
- beam_dir = (count[UP] == count[DOWN]) ? neutral_dir
- : (count[UP] > count[DOWN]) ? UP : DOWN;
- }
+ Item* s = stems[i];
+ if (Stem::invisible_b (s))
+ continue;
+ ideals.push (Offset (s->relative_coordinate (0, X_AXIS) - x0,
+ Stem::calc_stem_info (s).idealy_f_));
}
-
- return beam_dir;
+ Real dydx;
+ minimise_least_squares (&dydx, y, ideals); // duh, takes references
+
+ Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - x0;
+ *dy = dydx * dx;
}
-void
-Beam::set_direction (Direction d)
+bool
+Beam::suspect_slope_b (Score_element*me, Real y, Real dy)
{
- Directional_spanner::set_direction (d);
- for (int i=0; i <stem_count (); i++)
- {
- Stem *s = stem (i);
- s->set_elt_property ("beam-dir", gh_int2scm (d));
+ /* first, calculate y, dy */
+ /*
+ steep slope running against lengthened stem is suspect
+ */
+ Real first_ideal = Stem::calc_stem_info (first_visible_stem (me)).idealy_f_;
+ Real last_ideal = Stem::calc_stem_info (last_visible_stem (me)).idealy_f_;
+ Real lengthened = gh_scm2double (me->get_elt_property ("outer-stem-length-limit"));
+ Real steep = gh_scm2double (me->get_elt_property ("slope-limit"));
- SCM force = s->get_elt_property ("dir-forced"); // remove_prop?
- if (force == SCM_UNDEFINED)
- s->set_direction ( d);
+ // ugh -> use commonx
+ Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - first_visible_stem (me)->relative_coordinate (0, X_AXIS);
+ Real dydx = dy && dx ? dy/dx : 0;
+
+ if (((y - first_ideal > lengthened) && (dydx > steep))
+ || ((y + dy - last_ideal > lengthened) && (dydx < -steep)))
+ {
+ return true;
}
+ return false;
}
/*
- See Documentation/tex/fonts.doc
- */
-
-void
-Beam::solve_slope ()
+ This neat trick is by Werner Lemberg,
+ damped = tanh (slope)
+ corresponds with some tables in [Wanske]
+*/
+Real
+Beam::calc_slope_damping_f (Score_element*me,Real dy)
{
- assert (visible_stem_count () > 1);
+ SCM damp = me->get_elt_property ("damping");
+ int damping = gh_scm2int (damp);
- Least_squares l;
- Real x0 = first_visible_stem ()->hpos_f ();
- for (int i=0; i < stem_count (); i++)
+ if (damping)
{
- Stem* s = stem (i);
- if (s->invisible_b ())
- continue;
- l.input.push (Offset (s->hpos_f () - x0, s->calc_stem_info ().idealy_f_));
+ // ugh -> use commonx
+ Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS)
+ - first_visible_stem (me)->relative_coordinate (0, X_AXIS);
+ Real dydx = dy && dx ? dy/dx : 0;
+ dydx = 0.6 * tanh (dydx) / damping;
+ return dydx * dx;
}
- l.minimise (slope_f_, left_y_);
+ return dy;
}
-/*
- ugh. Naming: this doesn't check, but sets as well.
- */
Real
-Beam::check_stemlengths_f (bool set_b)
+Beam::calc_stem_y_f (Score_element*me,Item* s, Real y, Real dy)
{
- int multiplicity = multiplicity_i ();
+ int beam_multiplicity = get_multiplicity (me);
+ int stem_multiplicity = (Stem::flag_i (s) - 2) >? 0;
- Real interbeam_f = paper_l ()->interbeam_f (multiplicity);
+ SCM space_proc = me->get_elt_property ("space-function");
+ SCM space = gh_call1 (space_proc, gh_int2scm (beam_multiplicity));
- Real beam_f = gh_scm2double (get_elt_property ("beam-thickness"));
- Real staffline_f = paper_l ()-> get_var ("stafflinethickness");
- Real epsilon_f = staffline_f / 8;
- Real dy_f = 0.0;
- Real x0 = first_visible_stem ()->hpos_f ();
- Real internote_f = paper_l ()->get_var ("interline");
- for (int i=0; i < stem_count (); i++)
- {
- Stem* s = stem (i);
- if (s->invisible_b ())
- continue;
- Real y = (s->hpos_f () - x0) * slope_f_ + left_y_;
- Stem_info info = s->calc_stem_info ();
+ Real thick = gh_scm2double (me->get_elt_property ("thickness")) ;
+ Real interbeam_f = gh_scm2double (space) ;
- // correct for knee
- if (get_direction () != s->get_direction ())
- {
- y -= get_direction () * (beam_f / 2
- + (multiplicity - 1) * interbeam_f);
+ // ugh -> use commonx
+ Real x0 = first_visible_stem (me)->relative_coordinate (0, X_AXIS);
+ Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - x0;
+ Real stem_y = (dy && dx ? (s->relative_coordinate (0, X_AXIS) - x0) / dx * dy : 0) + y;
+ /* knee */
+ Direction dir = Directional_element_interface::get (me);
+ Direction sdir = Directional_element_interface::get (s);
+
+ /* knee */
+ if (dir!= sdir)
+ {
+ stem_y -= dir
+ * (thick / 2 + (beam_multiplicity - 1) * interbeam_f);
- Staff_symbol_referencer_interface s1 (s);
- Staff_symbol_referencer_interface s2 (stem_top ());
-
- if (!i
- && s1.staff_symbol_l () != s2.staff_symbol_l ())
- y += get_direction () * (multiplicity - (s->flag_i () - 2) >? 0)
- * interbeam_f;
- }
- /* caution: stem measures in staff-positions */
- if (set_b)
- s->set_stemend ((y - calc_interstaff_dist (s, this))
- / internote_f);
-
- y *= get_direction ();
- if (y > info.maxy_f_)
- dy_f = dy_f <? info.maxy_f_ - y;
- if (y < info.miny_f_)
- {
- // when all too short, normal stems win..
- if (dy_f < -epsilon_f)
- warning (_ ("weird beam vertical offset"));
- dy_f = dy_f >? info.miny_f_ - y;
- }
- }
- return dy_f;
+
+ // huh, why not for first visible?
+ if (Staff_symbol_referencer::staff_symbol_l (s)
+ != Staff_symbol_referencer::staff_symbol_l (last_visible_stem (me)))
+ stem_y += Directional_element_interface::get (me)
+ * (beam_multiplicity - stem_multiplicity) * interbeam_f;
+ }
+
+ return stem_y;
}
-void
-Beam::set_stem_shorten ()
+Real
+Beam::check_stem_length_f (Score_element*me,Real y, Real dy)
{
- if(!stem_count ())
- return;
+ Real shorten = 0;
+ Real lengthen = 0;
+ Direction dir = Directional_element_interface::get (me);
- int multiplicity = multiplicity_i();
+ Link_array<Item> stems=
+ Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
- if (multiplicity <= 0)
+ for (int i=0; i < stems.size(); i++)
{
- programming_error ("Singular beam");
- return;
- }
-
- int total_count_i = 0;
- int forced_count_i = 0;
- for (int i=0; i < stem_count (); i++)
- {
- Stem *s = stem (i);
-
- s->set_default_extents ();
- if (s->invisible_b ())
+ Item* s = stems[i];
+ if (Stem::invisible_b (s))
continue;
- if (((int)s->chord_start_f ()) && (s->get_direction () != s->get_default_dir ()))
- forced_count_i++;
- total_count_i++;
- }
- Real internote_f = paper_l ()->get_var ("interline");
- bool grace_b = get_elt_property ("grace") == SCM_BOOL_T;
- String type_str = grace_b ? "grace_" : "";
- int stem_max = (int)rint(paper_l ()->get_var ("stem_max"));
- Real shorten_f = paper_l ()->get_var (type_str + "forced_stem_shorten"
- + to_str (multiplicity <? stem_max)) * internote_f;
-
- for (int i=0; i < stem_count (); i++)
- {
- Stem *s = stem (i);
- /*
- Chord tremolo needs to beam over invisible stems of wholes
- */
- SCM trem = get_elt_property ("chord-tremolo");
- if (gh_boolean_p (trem) && gh_scm2bool (trem))
- {
- if (s->invisible_b ())
- continue;
- }
+ Real stem_y = calc_stem_y_f (me, s, y, dy);
+
+ stem_y *= dir;
+ Stem_info info = Stem::calc_stem_info (s);
- if (s->get_direction () == get_direction ())
- {
- if (forced_count_i == total_count_i)
- s->set_real ("shorten", shorten_f);
- else if (forced_count_i > total_count_i / 2)
- s->set_real ("shorten", shorten_f/2);
- }
+ // if (0 > info.maxy_f_ - stem_y)
+ shorten = shorten <? info.maxy_f_ - stem_y;
+ // if (0 < info.miny_f_ - stem_y)
+ lengthen = lengthen >? info.miny_f_ - stem_y;
}
+
+ if (lengthen && shorten)
+ warning (_ ("weird beam vertical offset"));
+
+ /* when all stems are too short, normal stems win */
+ return dir * ((shorten) ? shorten : lengthen);
}
+/*
+ Hmm. At this time, beam position and slope are determined. Maybe,
+ stem directions and length should set to relative to the chord's
+ position of the beam. */
void
-Beam::calculate_slope ()
+Beam::set_stem_length (Score_element*me,Real y, Real dy)
{
- if (!stem_count ())
- slope_f_ = left_y_ = 0;
- else if (first_visible_stem ()->calc_stem_info ().idealy_f_ == last_visible_stem ()->calc_stem_info ().idealy_f_)
- {
- slope_f_ = 0;
- left_y_ = first_visible_stem ()->calc_stem_info ().idealy_f_;
- left_y_ *= get_direction ();
- }
- else
- {
- solve_slope ();
- Real solved_slope_f = slope_f_;
+ Real half_space = Staff_symbol_referencer::staff_space (me)/2;
+ Link_array<Item> stems=
+ Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
- /*
- steep slope running against lengthened stem is suspect
- */
- Real dx_f = stem (stem_count () -1)->hpos_f () - first_visible_stem ()->hpos_f ();
-
- Real lengthened = paper_l ()->get_var ("beam_lengthened");
- Real steep = paper_l ()->get_var ("beam_steep_slope");
- if (((left_y_ - first_visible_stem ()->calc_stem_info ().idealy_f_ > lengthened)
- && (slope_f_ > steep))
- || ((left_y_ + slope_f_ * dx_f - last_visible_stem ()->calc_stem_info ().idealy_f_ > lengthened)
- && (slope_f_ < -steep)))
- {
- slope_f_ = 0;
- }
- /*
- This neat trick is by Werner Lemberg,
- damped = tanh (slope_f_)
- corresponds with some tables in [Wanske]
- */
- SCM damp = remove_elt_property ("damping");
- int damping = 1; // ugh.
- if (damp!= SCM_UNDEFINED)
- damping = gh_int2scm (damp);
-
- if (damping)
- slope_f_ = 0.6 * tanh (slope_f_) / damping;
-
- quantise_dy ();
+ for (int i=0; i < stems.size (); i++)
+ {
+ Item* s = stems[i];
+ if (Stem::invisible_b (s))
+ continue;
- Real damped_slope_dy_f = (solved_slope_f - slope_f_) * dx_f / 2;
- left_y_ += damped_slope_dy_f;
+ Real stem_y = calc_stem_y_f (me, s, y, dy);
- left_y_ *= get_direction ();
- slope_f_ *= get_direction ();
+ /* caution: stem measures in staff-positions */
+ Stem::set_stemend (s,(stem_y + calc_interstaff_dist (s, dynamic_cast<Spanner*> (me))) / half_space);
}
}
-void
-Beam::quantise_dy ()
+/*
+ [Ross] (simplification of)
+ Set dy complying with:
+ - zero
+ - thick / 2 + staffline_f / 2
+ - thick + staffline_f
+ + n * staff_space
+*/
+Real
+Beam::quantise_dy_f (Score_element*me,Real dy)
{
- /*
- [Ross] (simplification of)
- Try to set slope_f_ complying with y-span of:
- - zero
- - beam_f / 2 + staffline_f / 2
- - beam_f + staffline_f
- + n * interline
- */
-
- SCM q = get_elt_property ("slope-quantisation");
-
- if (q == ly_symbol2scm ("none"))
- return;
+ Array<Real> a;
- Staff_symbol_referencer_interface st (this);
- Real interline_f = st.staff_line_leading_f ();
+ SCM proc = me->get_elt_property ("height-quants");
+ SCM quants = gh_call2 (proc, me->self_scm (),
+ gh_double2scm (me->paper_l ()->get_var ("stafflinethickness")
+ / 1.0));
- Real staffline_f = paper_l ()->get_var ("stafflinethickness");
- Real beam_f = gh_scm2double (get_elt_property ("beam-thickness"));;
-
- Real dx_f = stem (stem_count () -1 )->hpos_f () - first_visible_stem ()->hpos_f ();
-
- Real dy_f = dx_f * abs (slope_f_);
- Real quanty_f = 0.0;
-
- Array<Real> allowed_fraction (3);
- allowed_fraction[0] = 0;
- allowed_fraction[1] = (beam_f / 2 + staffline_f / 2);
- allowed_fraction[2] = (beam_f + staffline_f);
+ for (SCM s = quants; gh_pair_p (s); s = gh_cdr (s))
+ a.push (gh_scm2double (gh_car (s)));
+
+ if (a.size () <= 1)
+ return dy;
- Interval iv = quantise_iv (allowed_fraction, interline_f, dy_f);
- quanty_f = (dy_f - iv[SMALLER] <= iv[BIGGER] - dy_f)
+ Real staff_space = Staff_symbol_referencer::staff_space (me);
+
+ Interval iv = quantise_iv (a, abs (dy)/staff_space) * staff_space;
+ Real q = (abs (dy) - iv[SMALLER] <= iv[BIGGER] - abs (dy))
? iv[SMALLER]
: iv[BIGGER];
-
- slope_f_ = (quanty_f / dx_f) * sign (slope_f_);
+
+ return q * sign (dy);
}
/*
-
- Prevent interference from stafflines and beams. See Documentation/tex/fonts.doc
-
+ Prevent interference from stafflines and beams.
+ See Documentation/tex/fonts.doc
+
+ We only need to quantise the (left) y-position of the beam,
+ since dy is quantised too.
+ if extend_b then stems must *not* get shorter
*/
-void
-Beam::quantise_left_y (bool extend_b)
+Real
+Beam::quantise_y_f (Score_element*me,Real y, Real dy, int quant_dir)
{
- /*
- we only need to quantise the start of the beam as dy is quantised too
- if extend_b then stems must *not* get shorter
- */
- SCM q = get_elt_property ("slope-quantisation");
-
+ int multiplicity = get_multiplicity (me);
- /*
- ----------------------------------------------------------
- ########
- ########
- ########
- --------------########------------------------------------
- ########
-
- hang straddle sit inter hang
- */
+ Real staff_space = Staff_symbol_referencer::staff_space (me);
+ Real thick = me->paper_l ()->get_var ("stafflinethickness");
- Staff_symbol_referencer_interface sinf (this);
- Real space = sinf.staff_line_leading_f ();
- Real staffline_f = paper_l ()->get_var ("stafflinethickness");
- Real beam_f = gh_scm2double (get_elt_property ("beam-thickness"));;
- /*
- [TODO]
- it would be nice to have all allowed positions in a runtime matrix:
- (multiplicity, minimum_beam_dy, maximum_beam_dy)
- */
-
- Real straddle = 0;
- Real sit = beam_f / 2 - staffline_f / 2;
- Real hang = space - beam_f / 2 + staffline_f / 2;
-
- /*
- Put all allowed positions into an array.
- Whether a position is allowed or not depends on
- strictness of quantisation, multiplicity and direction.
-
- For simplicity, we'll assume dir = UP and correct if
- dir = DOWN afterwards.
- */
- // isn't this asymmetric ? --hwn
+ SCM proc = me->get_elt_property ("vertical-position-quant-function");
+ SCM quants = scm_apply (proc,
+ me->self_scm (),
+ gh_list (gh_int2scm (multiplicity),
+ gh_double2scm (dy/staff_space),
+ gh_double2scm (thick/staff_space),
+ SCM_EOL, SCM_UNDEFINED));
- Real dy_f = get_direction () * left_y_;
+ Array<Real> a;
- Real beamdx_f = stem (stem_count () -1)->hpos_f () - first_visible_stem ()->hpos_f ();
- Real beamdy_f = beamdx_f * slope_f_;
+ for (; gh_pair_p (quants); quants = gh_cdr (quants))
+ a.push (gh_scm2double (gh_car (quants)));
- int multiplicity = multiplicity_i ();
+ if (a.size () <= 1)
+ return y;
- Array<Real> allowed_position;
- if (q == ly_symbol2scm ("normal"))
- {
- if ((multiplicity <= 2) || (abs (beamdy_f) >= staffline_f / 2))
- allowed_position.push (straddle);
- if ((multiplicity <= 1) || (abs (beamdy_f) >= staffline_f / 2))
- allowed_position.push (sit);
- allowed_position.push (hang);
- }
- else if (q == ly_symbol2scm ("traditional"))
- {
- // TODO: check and fix TRADITIONAL
- if ((multiplicity <= 2) || (abs (beamdy_f) >= staffline_f / 2))
- allowed_position.push (straddle);
- if ((multiplicity <= 1) && (beamdy_f <= staffline_f / 2))
- allowed_position.push (sit);
- if (beamdy_f >= -staffline_f / 2)
- allowed_position.push (hang);
- }
-
-
- Interval iv = quantise_iv (allowed_position, space, dy_f);
+ Real up_y = Directional_element_interface::get (me) * y;
+ Interval iv = quantise_iv (a, up_y/staff_space) * staff_space;
- Real quanty_f = dy_f - iv[SMALLER] <= iv[BIGGER] - dy_f ? iv[SMALLER] : iv[BIGGER];
- if (extend_b)
- quanty_f = iv[BIGGER];
+ Real q = up_y - iv[SMALLER] <= iv[BIGGER] - up_y
+ ? iv[SMALLER] : iv[BIGGER];
+ if (quant_dir)
+ q = iv[(Direction)quant_dir];
- left_y_ = get_direction () * quanty_f;
+ return q * Directional_element_interface::get (me);
}
void
-Beam::set_stemlens ()
-{
- Real staffline_f = paper_l ()->get_var ("stafflinethickness");
- // enge floots
- Real epsilon_f = staffline_f / 8;
-
-
- // je bent zelf eng --hwn.
- Real dy_f = check_stemlengths_f (false);
- for (int i = 0; i < 2; i++) // 2 ?
- {
- left_y_ += dy_f * get_direction ();
- quantise_left_y (dy_f);
- dy_f = check_stemlengths_f (true);
- if (abs (dy_f) <= epsilon_f)
- {
- break;
- }
- }
-}
-
-void
-Beam::set_beaming (Beaming_info_list *beaming)
+Beam::set_beaming (Score_element*me,Beaming_info_list *beaming)
{
+ Link_array<Score_element> stems=
+ Pointer_group_interface__extract_elements (me, (Score_element*)0, "stems");
+
Direction d = LEFT;
- for (int i=0; i < stem_count (); i++)
+ for (int i=0; i < stems.size(); i++)
{
do
{
- if (stem (i)->beam_count (d) < 0)
- stem (i)->set_beaming (beaming->infos_.elem (i).beams_i_drul_[d], d);
+ if (Stem::beam_count (stems[i], d) == 0)
+ Stem::set_beaming ( stems[i], beaming->infos_.elem (i).beams_i_drul_[d],d);
}
while (flip (&d) != LEFT);
}
-int
-Beam::multiplicity_i () const
-{
- int m = 0;
- for (SCM s = get_elt_property ("stems"); gh_pair_p (s); s = gh_cdr (s))
- {
- Score_element * sc = unsmob_element (gh_car (s));
-
- if (Stem * st = dynamic_cast<Stem*> (sc))
- m = m >? st->beam_count (LEFT) >? st->beam_count (RIGHT);
- }
- return m;
-}
-
/*
beams to go with one stem.
- clean me up.
+ FIXME: clean me up.
*/
Molecule
-Beam::stem_beams (Stem *here, Stem *next, Stem *prev) const
+Beam::stem_beams (Score_element*me,Item *here, Item *next, Item *prev)
{
- if ((next && !(next->hpos_f () > here->hpos_f ())) ||
- (prev && !(prev->hpos_f () < here->hpos_f ())))
+ // ugh -> use commonx
+ if ((next && !(next->relative_coordinate (0, X_AXIS) > here->relative_coordinate (0, X_AXIS))) ||
+ (prev && !(prev->relative_coordinate (0, X_AXIS) < here->relative_coordinate (0, X_AXIS))))
programming_error ("Beams are not left-to-right");
+ Real staffline_f = me->paper_l ()->get_var ("stafflinethickness");
+ int multiplicity = get_multiplicity (me);
- int multiplicity = multiplicity_i();
+ SCM space_proc = me->get_elt_property ("space-function");
+ SCM space = gh_call1 (space_proc, gh_int2scm (multiplicity));
- Real staffline_f = paper_l ()->get_var ("stafflinethickness");
- Real interbeam_f = paper_l ()->interbeam_f (multiplicity);
-
- Real beam_f = gh_scm2double (get_elt_property ("beam-thickness"));;
-
- Real dy = interbeam_f;
+ Real thick = gh_scm2double (me->get_elt_property ("thickness")) ;
+ Real interbeam_f = gh_scm2double (space) ;
+
+ Real bdy = interbeam_f;
Real stemdx = staffline_f;
- Real sl = slope_f_;
+
+ // ugh -> use commonx
+ Real dx = visible_stem_count (me) ?
+ last_visible_stem (me)->relative_coordinate (0, X_AXIS) - first_visible_stem (me)->relative_coordinate (0, X_AXIS)
+ : 0.0;
+ Real dy = gh_scm2double (me->get_elt_property ("height"));
+ Real dydx = dy && dx ? dy/dx : 0;
Molecule leftbeams;
Molecule rightbeams;
- // UGH
Real nw_f;
- if (!here->first_head ())
+ if (!Stem::first_head (here))
nw_f = 0;
- else if (here->type_i ()== 1)
- nw_f = paper_l ()->get_var ("wholewidth");
- else if (here->type_i () == 2)
- nw_f = paper_l ()->get_var ("notewidth") * 0.8;
- else
- nw_f = paper_l ()->get_var ("quartwidth");
+ else {
+ int t = Stem::type_i (here);
+ SCM proc = me->get_elt_property ("flag-width-function");
+ SCM result = gh_call1 (proc, gh_int2scm (t));
+ nw_f = gh_scm2double (result);
+ }
+
+
+ Direction dir = Directional_element_interface::get (me);
+
/* half beams extending to the left. */
if (prev)
{
- int lhalfs= lhalfs = here->beam_count (LEFT)
- - prev->beam_count (RIGHT);
- int lwholebeams= here->beam_count (LEFT) <? prev->beam_count (RIGHT);
+ int lhalfs= lhalfs = Stem::beam_count (here,LEFT) - Stem::beam_count (prev,RIGHT);
+ int lwholebeams= Stem::beam_count (here,LEFT) <? Stem::beam_count (prev,RIGHT) ;
/*
Half beam should be one note-width,
but let's make sure two half-beams never touch
*/
- Real w = here->hpos_f () - prev->hpos_f ();
+ Real w = here->relative_coordinate (0, X_AXIS) - prev->relative_coordinate (0, X_AXIS);
w = w/2 <? nw_f;
Molecule a;
if (lhalfs) // generates warnings if not
- a = lookup_l ()->beam (sl, w, beam_f);
- a.translate (Offset (-w, -w * sl));
+ a = Lookup::beam (dydx, w, thick);
+ a.translate (Offset (-w, -w * dydx));
for (int j = 0; j < lhalfs; j++)
{
Molecule b (a);
- b.translate_axis (-get_direction () * dy * (lwholebeams+j), Y_AXIS);
+ b.translate_axis (-dir * bdy * (lwholebeams+j), Y_AXIS);
leftbeams.add_molecule (b);
}
}
if (next)
{
- int rhalfs = here->beam_count (RIGHT) - next->beam_count (LEFT);
- int rwholebeams = here->beam_count(RIGHT) <? next->beam_count (LEFT);
+ int rhalfs = Stem::beam_count (here,RIGHT) - Stem::beam_count (next,LEFT);
+ int rwholebeams= Stem::beam_count (here,RIGHT) <? Stem::beam_count (next,LEFT) ;
- Real w = next->hpos_f () - here->hpos_f ();
- Molecule a = lookup_l ()->beam (sl, w + stemdx, beam_f);
+ Real w = next->relative_coordinate (0, X_AXIS) - here->relative_coordinate (0, X_AXIS);
+ Molecule a = Lookup::beam (dydx, w + stemdx, thick);
a.translate_axis( - stemdx/2, X_AXIS);
int j = 0;
Real gap_f = 0;
- SCM gap = get_elt_property ("beam-gap");
- if (gap != SCM_UNDEFINED)
+ SCM gap = me->get_elt_property ("gap");
+ if (gh_number_p (gap))
{
int gap_i = gh_scm2int ( (gap));
int nogap = rwholebeams - gap_i;
for (; j < nogap; j++)
{
Molecule b (a);
- b.translate_axis (-get_direction () * dy * j, Y_AXIS);
+ b.translate_axis (-dir * bdy * j, Y_AXIS);
rightbeams.add_molecule (b);
}
// TODO: notehead widths differ for different types
gap_f = nw_f / 2;
w -= 2 * gap_f;
- a = lookup_l ()->beam (sl, w + stemdx, beam_f);
+ a = Lookup::beam (dydx, w + stemdx, thick);
}
for (; j < rwholebeams; j++)
{
Molecule b (a);
- if (!here->invisible_b ())
- b.translate (Offset (gap_f, -get_direction () * dy * j));
- else
- b.translate (Offset (0, -get_direction () * dy * j));
+ b.translate (Offset (Stem::invisible_b (here) ? 0 : gap_f, -dir * bdy * j));
rightbeams.add_molecule (b);
}
w = w/2 <? nw_f;
if (rhalfs)
- a = lookup_l ()->beam (sl, w, beam_f);
+ a = Lookup::beam (dydx, w, thick);
for (; j < rwholebeams + rhalfs; j++)
{
Molecule b (a);
- b.translate_axis (-get_direction () * dy * j, Y_AXIS);
+ b.translate_axis (- dir * bdy * j, Y_AXIS);
rightbeams.add_molecule (b);
}
return leftbeams;
}
+MAKE_SCHEME_CALLBACK(Beam,brew_molecule,1);
+SCM
+Beam::brew_molecule (SCM smob)
+{
+ Score_element * me =unsmob_element (smob);
+
+ Molecule mol;
+ if (!gh_pair_p (me->get_elt_property ("stems")))
+ return SCM_EOL;
+ Real x0,dx;
+ Link_array<Item>stems =
+ Pointer_group_interface__extract_elements (me, (Item*) 0, "stems");
+ if (visible_stem_count (me))
+ {
+ // ugh -> use commonx
+ x0 = first_visible_stem (me)->relative_coordinate (0, X_AXIS);
+ dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - x0;
+ }
+ else
+ {
+ x0 = stems[0]->relative_coordinate (0, X_AXIS);
+ dx = stems.top()->relative_coordinate (0, X_AXIS) - x0;
+ }
+
+
+ Real dy = gh_scm2double (me->get_elt_property ("height"));
+ Real dydx = dy && dx ? dy/dx : 0;
+ Real y = gh_scm2double (me->get_elt_property ("y-position"));
+
+
+ for (int j=0; j <stems.size (); j++)
+ {
+ Item *i = stems[j];
+ Item * prev = (j > 0)? stems[j-1] : 0;
+ Item * next = (j < stems.size()-1) ? stems[j+1] :0;
+
+ Molecule sb = stem_beams (me, i, next, prev);
+ Real x = i->relative_coordinate (0, X_AXIS)-x0;
+ sb.translate (Offset (x, x * dydx + y));
+ mol.add_molecule (sb);
+ }
+ mol.translate_axis (x0
+ - dynamic_cast<Spanner*> (me)->get_bound (LEFT)->relative_coordinate (0, X_AXIS), X_AXIS);
+
+ return mol.create_scheme ();
+}
+
+int
+Beam::forced_stem_count (Score_element*me)
+{
+ Link_array<Item>stems =
+ Pointer_group_interface__extract_elements ( me, (Item*) 0, "stems");
+ int f = 0;
+ for (int i=0; i < stems.size (); i++)
+ {
+ Item *s = stems[i];
+
+ if (Stem::invisible_b (s))
+ continue;
+
+ if (((int)Stem::chord_start_f (s))
+ && (Stem::get_direction (s ) != Stem::get_default_dir (s )))
+ f++;
+ }
+ return f;
+}
+
+
+
+
+/* TODO:
+ use filter and standard list functions.
+ */
+int
+Beam::visible_stem_count (Score_element*me)
+{
+ Link_array<Item>stems =
+ Pointer_group_interface__extract_elements (me, (Item*) 0, "stems");
+ int c = 0;
+ for (int i = stems.size (); i--;)
+ {
+ if (!Stem::invisible_b (stems[i]))
+ c++;
+ }
+ return c;
+}
+
+Item*
+Beam::first_visible_stem(Score_element*me)
+{
+ Link_array<Item>stems =
+ Pointer_group_interface__extract_elements ( me, (Item*) 0, "stems");
+
+ for (int i = 0; i < stems.size (); i++)
+ {
+ if (!Stem::invisible_b (stems[i]))
+ return stems[i];
+ }
+ return 0;
+}
+
+Item*
+Beam::last_visible_stem(Score_element*me)
+{
+ Link_array<Item>stems =
+ Pointer_group_interface__extract_elements ( me, (Item*) 0, "stems");
+ for (int i = stems.size (); i--;)
+ {
+ if (!Stem::invisible_b (stems[i]))
+ return stems[i];
+ }
+ return 0;
+}
+
+
+/*
+ [TODO]
+ handle rest under beam (do_post: beams are calculated now)
+ what about combination of collisions and rest under beam.
+ Should lookup
+
+ rest -> stem -> beam -> interpolate_y_position ()
+*/
+MAKE_SCHEME_CALLBACK(Beam,rest_collision_callback,2);
+SCM
+Beam::rest_collision_callback (SCM element_smob, SCM axis)
+{
+ Score_element *rest = unsmob_element (element_smob);
+ Axis a = (Axis) gh_scm2int (axis);
+
+ assert (a == Y_AXIS);
+
+ Score_element * st = unsmob_element (rest->get_elt_property ("stem"));
+ Score_element * stem = st;
+ if (!stem)
+ return gh_double2scm (0.0);
+ Score_element * beam = unsmob_element (stem->get_elt_property ("beam"));
+ if (!beam || !Beam::has_interface (beam) || !Beam::visible_stem_count (beam))
+ return gh_double2scm (0.0);
+
+ // make callback for rest from this.
+ Real beam_dy = 0;
+ Real beam_y = 0;
+
+
+ // todo: make sure this calced already.
+ SCM s = beam->get_elt_property ("height");
+ if (gh_number_p (s))
+ beam_dy = gh_scm2double (s);
+
+ s = beam->get_elt_property ("y-position");
+ if (gh_number_p (s))
+ beam_y = gh_scm2double (s);
+
+ // ugh -> use commonx
+ Real x0 = first_visible_stem(beam)->relative_coordinate (0, X_AXIS);
+ Real dx = last_visible_stem(beam)->relative_coordinate (0, X_AXIS) - x0;
+ Real dydx = beam_dy && dx ? beam_dy/dx : 0;
+
+ Direction d = Stem::get_direction (stem);
+ Real beamy = (stem->relative_coordinate (0, X_AXIS) - x0) * dydx + beam_y;
+
+ Real staff_space = Staff_symbol_referencer::staff_space (rest);
+
+
+ Real rest_dim = rest->extent (rest, Y_AXIS)[d]*2.0 / staff_space ; // refp??
+
+ Real minimum_dist
+ = gh_scm2double (rest->get_elt_property ("minimum-beam-collision-distance"));
+ Real dist =
+ minimum_dist + -d * (beamy - rest_dim) >? 0;
+
+ int stafflines = Staff_symbol_referencer::line_count (rest);
+
+ // move discretely by half spaces.
+ int discrete_dist = int (ceil (dist));
+
+ // move by whole spaces inside the staff.
+ if (discrete_dist < stafflines+1)
+ discrete_dist = int (ceil (discrete_dist / 2.0)* 2.0);
+
+ return gh_double2scm (-d * discrete_dist);
+}
+
+
+bool
+Beam::has_interface (Score_element*me)
+{
+ return me->has_interface (ly_symbol2scm ("beam-interface"));
+}
+
+void
+Beam::set_interface (Score_element*me)
+{
+ /*
+ why the init? No way to tell difference between default and user
+ override. */
+ me->set_elt_property ("height", gh_int2scm (0)); // ugh.
+ me->set_elt_property ("y-position" ,gh_int2scm (0));
+ me->set_interface (ly_symbol2scm("beam-interface"));
+}