lily/instrument-switch-engraver.cc

   1 /*
   2   instrument-switch-engraver.cc -- implement
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2006--2008 Han-Wen Nienhuys <hanwen@lilypond.org>
   7
   8 */
   9
  10 #include "engraver.hh"
  11 #include "item.hh"
  12 #include "translator.icc"
  13
  14
  15 class Instrument_switch_engraver : public Engraver
  16 {
  17
  18   TRANSLATOR_DECLARATIONS (Instrument_switch_engraver);
  19 protected:
  20   Grob *text_;
  21   SCM cue_name_;
  22
  23   void stop_translation_time_step ();
  24   void process_music ();
  25 };
  26
  27
  28 Instrument_switch_engraver::Instrument_switch_engraver ()
  29 {
  30   cue_name_ = SCM_EOL;
  31   text_ = 0;
  32 }
  33
  34 /*
  35   TODO: should use an event.
  36  */
  37 void
  38 Instrument_switch_engraver::process_music ()
  39 {
  40   SCM cue_text = get_property ("instrumentCueName");
  41
  42   if (!scm_is_eq (cue_name_, cue_text))
  43     {
  44       text_ = make_item ("InstrumentSwitch", SCM_EOL);
  45       text_->set_property ("text", cue_text);
  46       cue_name_ = cue_text;
  47     }
  48 }
  49
  50 void
  51 Instrument_switch_engraver::stop_translation_time_step ()
  52 {
  53   text_ = 0;
  54 }
  55
  56 ADD_TRANSLATOR (Instrument_switch_engraver,
  57                 /* doc */
  58                 "Create a cue text for taking instrument.",
  59
  60                 /* create */
  61                 "InstrumentSwitch ",
  62
  63                 /* read */
  64                 "instrumentCueName ",
  65
  66                 /* write */
  67                 ""
  68                 );