lily/timing-engraver.cc

   1 /*
   2   timing-grav.cc -- implement Timing_engraver
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1997--2004 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7 */
   8 #include "context.hh"
   9 #include "grob-info.hh"
  10 #include "multi-measure-rest.hh"
  11 #include "timing-translator.hh"
  12 #include "engraver.hh"
  13 #include "grob.hh"
  14
  15 /**
  16   Do time bookkeeping
  17  */
  18 class Timing_engraver : public Timing_translator, public Engraver
  19 {
  20 protected:
  21   /* Needed to know whether we're advancing in grace notes, or not. */
  22   Moment last_moment_;
  23
  24   virtual void start_translation_timestep ();
  25   virtual void stop_translation_timestep ();
  26
  27 public:
  28   TRANSLATOR_DECLARATIONS (Timing_engraver);
  29 };
  30
  31
  32 Timing_engraver::Timing_engraver ()
  33 {
  34   last_moment_.main_part_ = Rational (-1);
  35 }
  36
  37
  38
  39 void
  40 Timing_engraver::start_translation_timestep ()
  41 {
  42   Timing_translator::start_translation_timestep ();
  43
  44   SCM automatic_bars = get_property ("automaticBars");
  45   Moment now = now_mom ();
  46   SCM which = get_property ("whichBar");
  47
  48   /* Set the first bar of the score? */
  49   if (!gh_string_p (which))
  50     which
  51       = (now.main_part_ || now.main_part_ == last_moment_.main_part_)
  52       ? SCM_EOL : scm_makfrom0str ("|");
  53
  54   Moment mp = measure_position ();
  55   bool start_of_measure = (last_moment_.main_part_ != now.main_part_
  56                            && !mp.main_part_);
  57
  58   if (start_of_measure)
  59     {
  60       Moment mlen = Moment (measure_length ());
  61       unsmob_grob (get_property ("currentCommandColumn"))
  62         ->set_property ("measure-length", mlen.smobbed_copy ());
  63     }
  64
  65   if (!gh_string_p (which) && to_boolean (automatic_bars))
  66     {
  67       SCM always = get_property ("barAlways");
  68
  69       if ( start_of_measure || (to_boolean (always)))
  70         {
  71           /* should this work, or be junked?  See input/bugs/no-bars.ly */
  72           which = get_property ("defaultBarType");
  73         }
  74     }
  75
  76   daddy_context_->set_property ("whichBar", which);
  77 }
  78
  79 void
  80 Timing_engraver::stop_translation_timestep ()
  81 {
  82   Timing_translator::stop_translation_timestep ();
  83   daddy_context_->set_property ("whichBar", SCM_EOL);
  84   last_moment_ = now_mom ();
  85 }
  86
  87
  88 ENTER_DESCRIPTION (Timing_engraver,
  89 /* descr */       " Responsible for synchronizing timing information from staves.  "
  90 "Normally in @code{Score}.  In order to create polyrhythmic music, "
  91 "this engraver should be removed from @code{Score} and placed in "
  92 "@code{Staff}. "
  93 "\n\nThis engraver adds the alias @code{Timing} to its containing context."
  94
  95                    ,
  96 /* creats*/       "",
  97 /* accepts */     "",
  98 /* acks  */      "",
  99 /* reads */       "timeSignatureFraction automaticBars whichBar barAlways defaultBarType skipBars timing measureLength measurePosition currentBarNumber",
 100 /* write */       "");