-
-Interval
-Beam::no_visible_stem_positions (Grob *me, Interval default_value)
-{
- extract_grob_set (me, "stems", stems);
- if (stems.empty ())
- return default_value;
-
- Interval head_positions;
- Slice multiplicity;
- for (vsize i = 0; i < stems.size(); i++)
- {
- head_positions.unite (Stem::head_positions (stems[i]));
- multiplicity.unite (Stem::beam_multiplicity (stems[i]));
- }
-
- Direction dir = get_grob_direction (me);
- Real y = head_positions[dir]
- * 0.5 * Staff_symbol_referencer::staff_space (me)
- + dir * get_beam_translation (me) * (multiplicity.length () + 1);
-
- y /= Staff_symbol_referencer::staff_space (me);
- return Interval (y,y);
-}
-
-
-/*
- Compute a first approximation to the beam slope.
-*/
-MAKE_SCHEME_CALLBACK (Beam, calc_least_squares_positions, 2);
-SCM
-Beam::calc_least_squares_positions (SCM smob, SCM /* posns */)
-{
- Grob *me = unsmob_grob (smob);
-
- int count = normal_stem_count (me);
- Interval pos (0,0);
- if (count < 1)
- return ly_interval2scm (no_visible_stem_positions (me, pos));
-
- vector<Real> x_posns;
- extract_grob_set (me, "normal-stems", stems);
- Grob *commonx = common_refpoint_of_array (stems, me, X_AXIS);
- Grob *commony = common_refpoint_of_array (stems, me, Y_AXIS);
-
- Real my_y = me->relative_coordinate (commony, Y_AXIS);
-
- Grob *fvs = first_normal_stem (me);
- Grob *lvs = last_normal_stem (me);
-
- Interval ideal (Stem::get_stem_info (fvs).ideal_y_
- + fvs->relative_coordinate (commony, Y_AXIS) - my_y,
- Stem::get_stem_info (lvs).ideal_y_
- + lvs->relative_coordinate (commony, Y_AXIS) - my_y);
-
- Real x0 = first_normal_stem (me)->relative_coordinate (commonx, X_AXIS);
- for (vsize i = 0; i < stems.size (); i++)
- {
- Grob *s = stems[i];
-
- Real x = s->relative_coordinate (commonx, X_AXIS) - x0;
- x_posns.push_back (x);
- }
- Real dx = last_normal_stem (me)->relative_coordinate (commonx, X_AXIS) - x0;
-
- Real y = 0;
- Real slope = 0;
- Real dy = 0;
- Real ldy = 0.0;
- if (!ideal.delta ())
- {
- Interval chord (Stem::chord_start_y (stems[0]),
- Stem::chord_start_y (stems.back ()));
-
- /* Simple beams (2 stems) on middle line should be allowed to be
- slightly sloped.
-
- However, if both stems reach middle line,
- ideal[LEFT] == ideal[RIGHT] and ideal.delta () == 0.
-
- For that case, we apply artificial slope */
- if (!ideal[LEFT] && chord.delta () && count == 2)
- {
- /* FIXME. -> UP */
- Direction d = (Direction) (sign (chord.delta ()) * UP);
- pos[d] = get_thickness (me) / 2;
- pos[-d] = -pos[d];
- }
- else
- pos = ideal;
-
- /*
- For broken beams this doesn't work well. In this case, the
- slope esp. of the first part of a broken beam should predict
- where the second part goes.
- */
- ldy = pos[RIGHT] - pos[LEFT];
- }
- else
- {
- vector<Offset> ideals;
- for (vsize i = 0; i < stems.size (); i++)
- {
- Grob *s = stems[i];
- ideals.push_back (Offset (x_posns[i],
- Stem::get_stem_info (s).ideal_y_
- + s->relative_coordinate (commony, Y_AXIS)
- - my_y));
- }
-
- minimise_least_squares (&slope, &y, ideals);
-
- dy = slope * dx;
-
- set_minimum_dy (me, &dy);
-
- ldy = dy;
- pos = Interval (y, (y + dy));
- }
-
- /*
- "position" is relative to the staff.
- */
- scale_drul (&pos, 1 / Staff_symbol_referencer::staff_space (me));
-
- me->set_property ("least-squares-dy", scm_from_double (ldy));
- return ly_interval2scm (pos);
-}
-
-/*
- We can't combine with previous function, since check concave and
- slope damping comes first.
-
- TODO: we should use the concaveness to control the amount of damping
- applied.
-*/
-MAKE_SCHEME_CALLBACK (Beam, shift_region_to_valid, 2);