lily/time-signature-engraver.cc

   1 /*
   2   time-signature-engraver.cc -- implement Time_signature_engraver
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1997--2008 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7 */
   8
   9 #include "engraver-group.hh"
  10
  11 #include "item.hh"
  12 #include "international.hh"
  13 #include "misc.hh"
  14 #include "time-signature.hh"
  15 #include "warn.hh"
  16
  17 /**
  18    generate time_signatures.
  19 */
  20 class Time_signature_engraver : public Engraver
  21 {
  22   Item *time_signature_;
  23   SCM last_time_fraction_;
  24
  25 protected:
  26   virtual void derived_mark () const;
  27   void stop_translation_timestep ();
  28   void process_music ();
  29 public:
  30   TRANSLATOR_DECLARATIONS (Time_signature_engraver);
  31 };
  32
  33 void
  34 Time_signature_engraver::derived_mark () const
  35 {
  36   scm_gc_mark (last_time_fraction_);
  37 }
  38
  39 Time_signature_engraver::Time_signature_engraver ()
  40 {
  41   time_signature_ = 0;
  42   last_time_fraction_ = SCM_BOOL_F;
  43 }
  44
  45 void
  46 Time_signature_engraver::process_music ()
  47 {
  48   /*
  49     not rigorously safe, since the value might get GC'd and
  50     reallocated in the same spot */
  51   SCM fr = get_property ("timeSignatureFraction");
  52   if (!time_signature_
  53       && last_time_fraction_ != fr
  54       && scm_is_pair (fr))
  55     {
  56       int den = scm_to_int (scm_cdr (fr));
  57       if (den != (1 << intlog2 (den)))
  58         {
  59           /*
  60             Todo: should make typecheck?
  61
  62             OTOH, Tristan Keuris writes 8/20 in his Intermezzi.
  63           */
  64           warning (_f ("strange time signature found: %d/%d",
  65                        int (scm_to_int (scm_car (fr))),
  66                        den));
  67         }
  68
  69       time_signature_ = make_item ("TimeSignature", SCM_EOL);
  70       time_signature_->set_property ("fraction", fr);
  71
  72       if (last_time_fraction_ == SCM_BOOL_F)
  73         time_signature_->set_property ("break-visibility",
  74                                        get_property ("implicitTimeSignatureVisibility"));
  75
  76       last_time_fraction_ = fr;
  77     }
  78 }
  79
  80 void
  81 Time_signature_engraver::stop_translation_timestep ()
  82 {
  83   time_signature_ = 0;
  84 }
  85
  86 #include "translator.icc"
  87
  88 ADD_TRANSLATOR (Time_signature_engraver,
  89                 /* doc */
  90                 "Create a @ref{TimeSignature} whenever"
  91                 " @code{timeSignatureFraction} changes.",
  92
  93                 /* create */
  94                 "TimeSignature ",
  95
  96                 /* read */
  97                 "implicitTimeSignatureVisibility "
  98                 "timeSignatureFraction ",
  99
 100                 /* write */
 101                 ""
 102                 );