lily/spacing-options.cc

   1 /*
   2   spacing-options.cc -- implement Spacing_options
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2006 Han-Wen Nienhuys <hanwen@lilypond.org>
   7
   8 */
   9
  10 #include "spacing-spanner.hh"
  11 #include "grob.hh"
  12 #include "misc.hh"
  13 #include "moment.hh"
  14
  15 void
  16 Spacing_options::init_from_grob (Grob *me)
  17 {
  18   increment_ = robust_scm2double (me->get_property ("spacing-increment"), 1);
  19
  20   packed_ = to_boolean (me->get_property ("packed-spacing"));
  21   stretch_uniformly_ = to_boolean (me->get_property ("uniform-stretching"));
  22   float_nonmusical_columns_
  23     = to_boolean (me->get_property ("strict-note-spacing"));
  24   float_grace_columns_
  25     = to_boolean (me->get_property ("strict-grace-spacing"));
  26   shortest_duration_space_ = robust_scm2double (me->get_property ("shortest-duration-space"), 1);
  27
  28
  29   Moment shortest_dur = robust_scm2moment (me->get_property ("common-shortest-duration"),
  30                                            Moment (Rational (1,8), Rational (1,16)));
  31
  32   if (shortest_dur.main_part_)
  33     global_shortest_ = shortest_dur.main_part_;
  34   else
  35     global_shortest_ = shortest_dur.grace_part_;
  36
  37 }
  38
  39 Spacing_options::Spacing_options ()
  40 {
  41   packed_ = false;
  42   stretch_uniformly_ = false;
  43   float_nonmusical_columns_ = false;
  44   float_grace_columns_ = false;
  45
  46   shortest_duration_space_ = 2.0;
  47   increment_ = 1.2;
  48
  49   global_shortest_ = Rational (1, 8);
  50 }
  51
  52
  53
  54 /*
  55   Get the measure wide ant for arithmetic spacing.
  56 */
  57 Real
  58 Spacing_options::get_duration_space (Rational d,
  59                                      bool *expand_only) const
  60 {
  61   Real k = shortest_duration_space_;
  62
  63   if (d < global_shortest_)
  64     {
  65       /*
  66         We don't space really short notes using the log of the
  67         duration, since it would disproportionally stretches the long
  68         notes in a piece. In stead, we use geometric spacing with constant 0.5
  69         (i.e. linear.)
  70
  71         This should probably be tunable, to use other base numbers.
  72
  73         In Mozart hrn3 by EB., we have 8th note = 3.9 mm (total), 16th note =
  74         3.6 mm (total).  head-width = 2.4, so we 1.2mm for 16th, 1.5
  75         mm for 8th. (white space), suggesting that we use
  76
  77         (1.2 / 1.5)^{-log2(duration ratio)}
  78
  79
  80       */
  81       Rational ratio = d / global_shortest_;
  82
  83       return ((k - 1) + double (ratio)) * increment_;
  84     }
  85   else
  86     {
  87       /*
  88         John S. Gourlay. ``Spacing a Line of Music, '' Technical
  89         Report OSU-CISRC-10/87-TR35, Department of Computer and
  90         Information Science, The Ohio State University, 1987.
  91       */
  92       Real log = log_2 (global_shortest_);
  93       k -= log;
  94       *expand_only = false;
  95
  96       return (log_2 (d) + k) * increment_;
  97     }
  98 }
  99