lily/tempo-performer.cc

   1 /*
   2   tempo-performer.cc -- implement Tempo_performer
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1997--2009 Jan Nieuwenhuizen <janneke@gnu.org>
   7 */
   8
   9 #include "performer.hh"
  10
  11 #include "audio-item.hh"
  12 #include "duration.hh"
  13 #include "stream-event.hh"
  14
  15 #include "translator.icc"
  16
  17 class Tempo_performer : public Performer
  18 {
  19 public:
  20   TRANSLATOR_DECLARATIONS (Tempo_performer);
  21   ~Tempo_performer ();
  22
  23 protected:
  24
  25   virtual void derived_mark () const;
  26   void stop_translation_timestep ();
  27   void process_music ();
  28 private:
  29   Audio_tempo *audio_;
  30   SCM last_tempo_;
  31 };
  32
  33 void
  34 Tempo_performer::derived_mark () const
  35 {
  36   scm_gc_mark (last_tempo_);
  37 }
  38
  39 Tempo_performer::Tempo_performer ()
  40 {
  41   last_tempo_ = SCM_EOL;
  42   audio_ = 0;
  43 }
  44
  45 Tempo_performer::~Tempo_performer ()
  46 {
  47 }
  48
  49 void
  50 Tempo_performer::process_music ()
  51 {
  52   SCM w = get_property ("tempoWholesPerMinute");
  53   if (unsmob_moment (w)
  54       && !ly_is_equal (w, last_tempo_))
  55     {
  56       Rational r = unsmob_moment (w)->main_part_;
  57       r *= Rational (4, 1);
  58
  59       audio_ = new Audio_tempo (r.to_int ());
  60
  61       Audio_element_info info (audio_, 0);
  62       announce_element (info);
  63
  64       last_tempo_ = w;
  65     }
  66 }
  67
  68 void
  69 Tempo_performer::stop_translation_timestep ()
  70 {
  71   if (audio_)
  72     {
  73       audio_ = 0;
  74     }
  75 }
  76
  77 ADD_TRANSLATOR (Tempo_performer,
  78                 /* doc */
  79                 "",
  80
  81                 /* create */
  82                 "",
  83
  84                 /* read */
  85                 "tempoWholesPerMinute ",
  86
  87                 /* write */
  88                 ""
  89                 );