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--2004 Jan Nieuwenhuizen <janneke@gnu.org>
   7 */
   8
   9
  10 #include "audio-item.hh"
  11 #include "performer.hh"
  12
  13 class Tempo_performer : public Performer
  14 {
  15 public:
  16   TRANSLATOR_DECLARATIONS (Tempo_performer);
  17   ~Tempo_performer ();
  18
  19 protected:
  20
  21   virtual bool try_music (Music* req);
  22   virtual void stop_translation_timestep ();
  23   virtual void create_audio_elements ();
  24
  25 private:
  26 Music* tempo_req_;
  27   Audio_tempo* audio_;
  28 };
  29
  30 Tempo_performer::Tempo_performer ()
  31 {
  32   tempo_req_ = 0;
  33   audio_ = 0;
  34 }
  35
  36 Tempo_performer::~Tempo_performer ()
  37 {
  38 }
  39
  40
  41 void
  42 Tempo_performer::create_audio_elements ()
  43 {
  44   if (tempo_req_)
  45     {
  46
  47       SCM met = tempo_req_->get_property ("metronome-count");
  48       Duration *d = unsmob_duration (tempo_req_->get_property ("tempo-unit"));
  49
  50       Rational r =  (d->get_length () / Moment (Rational (1, 4)) * Moment (ly_scm2int (met))).main_part_;
  51
  52       audio_ = new Audio_tempo (int (r));
  53
  54       Audio_element_info info (audio_, tempo_req_);
  55       announce_element (info);
  56       tempo_req_ = 0;
  57     }
  58 }
  59
  60 void
  61 Tempo_performer::stop_translation_timestep ()
  62 {
  63   if (audio_)
  64     {
  65       play_element (audio_);
  66       audio_ = 0;
  67     }
  68 }
  69
  70 bool
  71 Tempo_performer::try_music (Music* req)
  72 {
  73   if (tempo_req_)
  74     return false;
  75
  76       tempo_req_ = req;
  77       return true;
  78 }
  79
  80
  81
  82
  83 ENTER_DESCRIPTION (Tempo_performer, "","",
  84                    "metronome-change-event",
  85                    "","","" );