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 initialize ();
  26   virtual void stop_translation_timestep ();
  27
  28 public:
  29   TRANSLATOR_DECLARATIONS (Timing_engraver);
  30 };
  31
  32
  33 Timing_engraver::Timing_engraver ()
  34 {
  35   last_moment_.main_part_ = Rational (-1);
  36 }
  37
  38
  39 void
  40 Timing_engraver::initialize ()
  41 {
  42   Timing_translator::initialize ();
  43
  44   SCM which = get_property ("whichBar");
  45   Moment now = now_mom ();
  46
  47   /* Set the first bar of the score? */
  48   if (!ly_c_string_p (which))
  49     which = (now.main_part_ || now.main_part_ == last_moment_.main_part_)
  50       ? SCM_EOL : scm_makfrom0str ("|");
  51
  52   context ()->set_property ("whichBar", which);
  53 }
  54
  55
  56 void
  57 Timing_engraver::start_translation_timestep ()
  58 {
  59   Timing_translator::start_translation_timestep ();
  60
  61   SCM automatic_bars = get_property ("automaticBars");
  62   Moment now = now_mom ();
  63   SCM which = get_property ("whichBar");
  64
  65   /* Set the first bar of the score? */
  66   if (!ly_c_string_p (which))
  67     which = SCM_EOL;
  68
  69   Moment mp = measure_position ();
  70   bool start_of_measure = (last_moment_.main_part_ != now.main_part_
  71                            && !mp.main_part_);
  72
  73   if (start_of_measure)
  74     {
  75       Moment mlen = Moment (measure_length ());
  76       unsmob_grob (get_property ("currentCommandColumn"))
  77         ->set_property ("measure-length", mlen.smobbed_copy ());
  78     }
  79
  80   if (!ly_c_string_p (which) && to_boolean (automatic_bars))
  81     {
  82       SCM always = get_property ("barAlways");
  83
  84       if ( start_of_measure || (to_boolean (always)))
  85         {
  86           /* should this work, or be junked?  See input/bugs/no-bars.ly */
  87           which = get_property ("defaultBarType");
  88         }
  89     }
  90
  91   context ()->set_property ("whichBar", which);
  92 }
  93
  94 void
  95 Timing_engraver::stop_translation_timestep ()
  96 {
  97   Timing_translator::stop_translation_timestep ();
  98   context ()->set_property ("whichBar", SCM_EOL);
  99   last_moment_ = now_mom ();
 100 }
 101
 102
 103 ENTER_DESCRIPTION (Timing_engraver,
 104 /* descr */       " Responsible for synchronizing timing information from staves.  "
 105 "Normally in @code{Score}.  In order to create polyrhythmic music, "
 106 "this engraver should be removed from @code{Score} and placed in "
 107 "@code{Staff}. "
 108 "\n\nThis engraver adds the alias @code{Timing} to its containing context."
 109
 110                    ,
 111 /* creats*/       "",
 112 /* accepts */     "",
 113 /* acks  */      "",
 114 /* reads */       "timeSignatureFraction automaticBars whichBar barAlways defaultBarType skipBars timing measureLength measurePosition currentBarNumber",
 115 /* write */       "");