lily/staff-spacing.cc

   1 /*
   2   This file is part of LilyPond, the GNU music typesetter.
   3
   4   Copyright (C) 2001--2011  Han-Wen Nienhuys <hanwen@xs4all.nl>
   5
   6   LilyPond is free software: you can redistribute it and/or modify
   7   it under the terms of the GNU General Public License as published by
   8   the Free Software Foundation, either version 3 of the License, or
   9   (at your option) any later version.
  10
  11   LilyPond is distributed in the hope that it will be useful,
  12   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14   GNU General Public License for more details.
  15
  16   You should have received a copy of the GNU General Public License
  17   along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "staff-spacing.hh"
  21
  22 #include <cstdio>
  23 using namespace std;
  24
  25 #include "international.hh"
  26 #include "paper-column.hh"
  27 #include "separation-item.hh"
  28 #include "warn.hh"
  29 #include "bar-line.hh"
  30 #include "staff-symbol-referencer.hh"
  31 #include "note-column.hh"
  32 #include "stem.hh"
  33 #include "spacing-interface.hh"
  34 #include "accidental-placement.hh"
  35 #include "pointer-group-interface.hh"
  36 #include "directional-element-interface.hh"
  37
  38 /* A stem following a bar-line creates an optical illusion similar to the
  39    one mentioned in note-spacing.cc. We correct for it here.
  40
  41    TODO: should we still correct if there are accidentals/arpeggios before
  42    the stem?
  43 */
  44
  45 Real
  46 Staff_spacing::optical_correction (Grob *me, Grob *g, Interval bar_height)
  47 {
  48   if (!g || !Note_column::has_interface (g))
  49     return 0;
  50
  51   Grob *stem = Note_column::get_stem (g);
  52   Real ret = 0.0;
  53
  54   if (!bar_height.is_empty () && stem)
  55     {
  56       Direction d = get_grob_direction (stem);
  57       if (Stem::is_normal_stem (stem) && d == DOWN)
  58         {
  59
  60           /*
  61             can't look at stem-end-position, since that triggers
  62             beam slope computations.
  63           */
  64           Real stem_start = Stem::head_positions (stem) [d];
  65           Real stem_end = stem_start +
  66             d * robust_scm2double (stem->get_property ("length"), 7);
  67
  68           Interval stem_posns (min (stem_start, stem_end),
  69                                max (stem_end, stem_start));
  70
  71           stem_posns.intersect (bar_height);
  72
  73           ret = min (abs (stem_posns.length () / 7.0), 1.0);
  74           ret *= robust_scm2double (me->get_property ("stem-spacing-correction"), 1);
  75         }
  76     }
  77   return ret;
  78 }
  79
  80 /*
  81   Y-positions that are covered by BAR_GROB, in the case that it is a
  82   barline.  */
  83 Interval
  84 Staff_spacing::bar_y_positions (Grob *bar_grob)
  85 {
  86   Interval bar_size;
  87   bar_size.set_empty ();
  88   if (Bar_line::has_interface (bar_grob))
  89     {
  90       SCM glyph = bar_grob->get_property ("glyph-name");
  91       Grob *staff_sym = Staff_symbol_referencer::get_staff_symbol (bar_grob);
  92
  93       string glyph_string = scm_is_string (glyph) ? ly_scm2string (glyph) : "";
  94       if (glyph_string.substr (0, 1) == "|"
  95           || glyph_string.substr (0, 1) == ".")
  96         {
  97           Grob *common = bar_grob->common_refpoint (staff_sym, Y_AXIS);
  98           bar_size = bar_grob->extent (common, Y_AXIS);
  99           bar_size *= 1.0 / Staff_symbol_referencer::staff_space (bar_grob);
 100         }
 101     }
 102   return bar_size;
 103 }
 104
 105 Real
 106 Staff_spacing::next_notes_correction (Grob *me,
 107                                       Grob *last_grob)
 108 {
 109   Interval bar_size = bar_y_positions (last_grob);
 110   Grob *orig = me->original () ? me->original () : me;
 111   vector<Item*> note_columns = Spacing_interface::right_note_columns (orig);
 112
 113   Real max_optical = 0.0;
 114
 115   for (vsize i = 0; i < note_columns.size (); i++)
 116     max_optical = max (max_optical, optical_correction (me, note_columns[i], bar_size));
 117
 118   return max_optical;
 119 }
 120
 121 /* We calculate three things here: the ideal distance, the minimum distance
 122    (which is the distance at which collisions will occur) and the "fixed"
 123    distance, which is the distance at which things start to look really bad.
 124    We arrange things so that the fixed distance will be attained when the
 125    line is compressed with a force of 1.0 */
 126 Spring
 127 Staff_spacing::get_spacing (Grob *me, Grob *right_col)
 128 {
 129   Item *me_item = dynamic_cast<Item *> (me);
 130   Grob *left_col = me_item->get_column ();
 131
 132   Interval last_ext;
 133   Direction break_dir = me_item->break_status_dir ();
 134   Grob *last_grob = Spacing_interface::extremal_break_aligned_grob (me, LEFT,
 135                                                                     break_dir,
 136                                                                     &last_ext);
 137   if (!last_grob)
 138     {
 139       /*
 140         TODO:
 141
 142         Should  insert a adjustable space here? For excercises, you might want to
 143         use a staff without a clef in the beginning.
 144       */
 145
 146       /*
 147         we used to have a warning here, but it generates a lot of
 148         spurious error messages.
 149       */
 150       return Spring ();
 151     }
 152
 153   SCM alist = last_grob->get_property ("space-alist");
 154   if (!scm_list_p (alist))
 155     return Spring ();
 156
 157   SCM space_def = scm_sloppy_assq (ly_symbol2scm ("first-note"), alist);
 158   if (me_item->break_status_dir () == CENTER)
 159     {
 160       SCM nndef = scm_sloppy_assq (ly_symbol2scm ("next-note"), alist);
 161       if (scm_is_pair (nndef))
 162         space_def = nndef;
 163     }
 164
 165   if (!scm_is_pair (space_def))
 166     {
 167       programming_error ("unknown prefatory spacing");
 168       return Spring ();
 169     }
 170
 171   space_def = scm_cdr (space_def);
 172   Real distance = scm_to_double (scm_cdr (space_def));
 173   SCM type = scm_car (space_def);
 174
 175   Real fixed = last_ext[RIGHT];
 176   Real ideal = fixed + 1.0;
 177
 178   if (type == ly_symbol2scm ("fixed-space"))
 179     {
 180       fixed += distance;
 181       ideal = fixed;
 182     }
 183   else if (type == ly_symbol2scm ("extra-space"))
 184     ideal = fixed + distance;
 185   else if (type == ly_symbol2scm ("semi-fixed-space"))
 186     {
 187       fixed += distance / 2;
 188       ideal = fixed + distance / 2;
 189     }
 190   else if (type == ly_symbol2scm ("minimum-space"))
 191     ideal = last_ext[LEFT] + max (last_ext.length (), distance);
 192   else if (type == ly_symbol2scm ("minimum-fixed-space"))
 193     {
 194       fixed = last_ext[LEFT] + max (last_ext.length (), distance);
 195       ideal = fixed;
 196     }
 197
 198
 199   Real optical_correction = next_notes_correction (me, last_grob);
 200   Real min_dist = Paper_column::minimum_distance (left_col, right_col);
 201
 202   /* ensure that the "fixed" distance will leave a gap of at least 0.3 ss. */
 203   Real min_dist_correction = max (0.0, 0.3 + min_dist - fixed);
 204   Real correction = max (optical_correction, min_dist_correction);
 205
 206   fixed += correction;
 207   ideal += correction;
 208
 209   Spring ret (ideal, min_dist);
 210   ret.set_inverse_stretch_strength (max (0.0, ideal - fixed));
 211   return ret;
 212 }
 213
 214 ADD_INTERFACE (Staff_spacing,
 215                "This object calculates spacing details from a breakable"
 216                " symbol (left) to another object.  For example, it takes care"
 217                " of optical spacing from a bar line to a note.",
 218
 219                /* properties */
 220                "stem-spacing-correction "
 221                );