lily/default-bar-line-engraver.cc

   1 /*
   2   timing-engraver.cc -- implement Default_bar_line_engraver
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1997--2006 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7 */
   8
   9 #include "engraver.hh"
  10 #include "context.hh"
  11 #include "multi-measure-rest.hh"
  12 #include "grob.hh"
  13 #include "warn.hh"
  14
  15 class Default_bar_line_engraver : public Engraver
  16 {
  17 protected:
  18   /* Need to know whether we're advancing in grace notes, or not. */
  19   Moment last_moment_;
  20
  21   void start_translation_timestep ();
  22   void stop_translation_timestep ();
  23
  24 public:
  25   TRANSLATOR_DECLARATIONS (Default_bar_line_engraver);
  26 };
  27
  28 #include "translator.icc"
  29
  30 ADD_TRANSLATOR (Default_bar_line_engraver,
  31                 "This engraver determines what kind of automatic bar "
  32                 "lines should be produced, "
  33                 "and sets @code{whichBar} "
  34                 "accordingly. It should be at the same "
  35                 "level as @ref{Timing_translator}. ",
  36
  37                 /* create */ "",
  38                 /* accept */ "",
  39
  40                 /* read */
  41                 "automaticBars "
  42                 "barAlways "
  43                 "defaultBarType "
  44                 "measureLength "
  45                 "whichBar "
  46                 "measurePosition ",
  47
  48                 /* write */ "automaticBars");
  49
  50 Default_bar_line_engraver::Default_bar_line_engraver ()
  51 {
  52   last_moment_.main_part_ = Rational (-1);
  53 }
  54
  55 void
  56 Default_bar_line_engraver::start_translation_timestep ()
  57 {
  58   SCM automatic_bars = get_property ("automaticBars");
  59   Moment now = now_mom ();
  60   SCM which = get_property ("whichBar");
  61
  62   /* Set the first bar of the score? */
  63   if (!scm_is_string (which))
  64     which = SCM_EOL;
  65
  66   Moment mp = measure_position (context ());
  67   bool start_of_measure = (last_moment_.main_part_ != now.main_part_
  68                            && !mp.main_part_);
  69
  70   if (!scm_is_string (which) && to_boolean (automatic_bars))
  71     {
  72       SCM always = get_property ("barAlways");
  73
  74       if ((start_of_measure && last_moment_.main_part_ >= Moment (0))
  75           || to_boolean (always))
  76         {
  77           /* should this work, or be junked?  See input/bugs/no-bars.ly */
  78           which = get_property ("defaultBarType");
  79         }
  80     }
  81
  82   context ()->set_property ("whichBar", which);
  83 }
  84
  85 void
  86 Default_bar_line_engraver::stop_translation_timestep ()
  87 {
  88   context ()->set_property ("whichBar", SCM_EOL);
  89   last_moment_ = now_mom ();
  90 }