lily/time-signature-engraver.cc

   1 /*
   2   time_signature-reg.cc -- implement Time_signature_engraver
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c)  1997--2000 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7 */
   8
   9 #include "time-signature.hh"
  10 #include "command-request.hh"
  11 #include "engraver.hh"
  12
  13
  14 #include "engraver-group-engraver.hh"
  15
  16
  17 /**
  18   generate time_signatures.
  19   */
  20 class Time_signature_engraver : public Engraver {
  21 protected:
  22   virtual void stop_translation_timestep();
  23   virtual void create_grobs ();
  24 public:
  25   VIRTUAL_COPY_CONS(Translator);
  26   Item * time_signature_p_;
  27   SCM last_time_fraction_;
  28   Time_signature_engraver();
  29 };
  30
  31
  32 Time_signature_engraver::Time_signature_engraver()
  33 {
  34   time_signature_p_ =0;
  35   last_time_fraction_ = SCM_BOOL_F;
  36 }
  37
  38 void
  39 Time_signature_engraver::create_grobs()
  40 {
  41   /*
  42     not rigorously safe, since the value might get GC'd and
  43     reallocated in the same spot */
  44   SCM fr= get_property ("timeSignatureFraction");
  45   if (!time_signature_p_ && last_time_fraction_ != fr)
  46     {
  47       last_time_fraction_ = fr;
  48       time_signature_p_ = new Item (get_property ("TimeSignature"));
  49       time_signature_p_->set_grob_property ("fraction",fr);
  50
  51       if (time_signature_p_)
  52         announce_grob (time_signature_p_, 0);
  53     }
  54
  55 }
  56
  57
  58
  59 void
  60 Time_signature_engraver::stop_translation_timestep()
  61 {
  62   if (time_signature_p_)
  63     {
  64       typeset_grob (time_signature_p_);
  65       time_signature_p_ =0;
  66     }
  67 }
  68
  69
  70 ADD_THIS_TRANSLATOR(Time_signature_engraver);
  71
  72