lily/time-signature-engraver.cc

   1 /*
   2   This file is part of LilyPond, the GNU music typesetter.
   3
   4   Copyright (C) 1997--2010 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 "engraver-group.hh"
  21
  22 #include "item.hh"
  23 #include "international.hh"
  24 #include "misc.hh"
  25 #include "time-signature.hh"
  26 #include "warn.hh"
  27
  28 /**
  29    generate time_signatures.
  30 */
  31 class Time_signature_engraver : public Engraver
  32 {
  33   Item *time_signature_;
  34   SCM last_time_fraction_;
  35
  36 protected:
  37   virtual void derived_mark () const;
  38   void stop_translation_timestep ();
  39   void process_music ();
  40 public:
  41   TRANSLATOR_DECLARATIONS (Time_signature_engraver);
  42 };
  43
  44 void
  45 Time_signature_engraver::derived_mark () const
  46 {
  47   scm_gc_mark (last_time_fraction_);
  48 }
  49
  50 Time_signature_engraver::Time_signature_engraver ()
  51 {
  52   time_signature_ = 0;
  53   last_time_fraction_ = SCM_BOOL_F;
  54 }
  55
  56 void
  57 Time_signature_engraver::process_music ()
  58 {
  59   /*
  60     not rigorously safe, since the value might get GC'd and
  61     reallocated in the same spot */
  62   SCM fr = get_property ("timeSignatureFraction");
  63   if (!time_signature_
  64       && last_time_fraction_ != fr
  65       && scm_is_pair (fr))
  66     {
  67       int den = scm_to_int (scm_cdr (fr));
  68       if (den != (1 << intlog2 (den)))
  69         {
  70           /*
  71             Todo: should make typecheck?
  72
  73             OTOH, Tristan Keuris writes 8/20 in his Intermezzi.
  74           */
  75           warning (_f ("strange time signature found: %d/%d",
  76                        int (scm_to_int (scm_car (fr))),
  77                        den));
  78         }
  79
  80       time_signature_ = make_item ("TimeSignature", SCM_EOL);
  81       time_signature_->set_property ("fraction", fr);
  82
  83       if (last_time_fraction_ == SCM_BOOL_F)
  84         time_signature_->set_property ("break-visibility",
  85                                        get_property ("implicitTimeSignatureVisibility"));
  86
  87       last_time_fraction_ = fr;
  88     }
  89 }
  90
  91 void
  92 Time_signature_engraver::stop_translation_timestep ()
  93 {
  94   time_signature_ = 0;
  95 }
  96
  97 #include "translator.icc"
  98
  99 ADD_TRANSLATOR (Time_signature_engraver,
 100                 /* doc */
 101                 "Create a @ref{TimeSignature} whenever"
 102                 " @code{timeSignatureFraction} changes.",
 103
 104                 /* create */
 105                 "TimeSignature ",
 106
 107                 /* read */
 108                 "implicitTimeSignatureVisibility "
 109                 "timeSignatureFraction ",
 110
 111                 /* write */
 112                 ""
 113                 );