lily/ledger-line-engraver.cc

   1 /*
   2   ledger-line-engraver.cc -- implement Ledger_line_engraver
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2004--2006 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7 */
   8
   9 #include "pointer-group-interface.hh"
  10 #include "spanner.hh"
  11 #include "engraver.hh"
  12 #include "staff-symbol.hh"
  13
  14 class Ledger_line_engraver : public Engraver
  15 {
  16   Spanner *span_;
  17
  18 public:
  19   TRANSLATOR_DECLARATIONS (Ledger_line_engraver);
  20
  21 protected:
  22   virtual void finalize ();
  23   void process_music ();
  24
  25   DECLARE_ACKNOWLEDGER (ledgered);
  26   DECLARE_ACKNOWLEDGER (staff_symbol);
  27
  28   void start_spanner ();
  29   void stop_spanner ();
  30 };
  31
  32 Ledger_line_engraver::Ledger_line_engraver ()
  33 {
  34   span_ = 0;
  35 }
  36
  37 void
  38 Ledger_line_engraver::start_spanner ()
  39 {
  40   assert (!span_);
  41   span_ = make_spanner ("LedgerLineSpanner", SCM_EOL);
  42
  43   span_->set_bound (LEFT, unsmob_grob (get_property ("currentCommandColumn")));
  44 }
  45
  46 void
  47 Ledger_line_engraver::process_music ()
  48 {
  49   /*
  50     Need to do this, otherwise the first note might miss ledgers.
  51   */
  52   if (!span_)
  53     start_spanner ();
  54 }
  55
  56 void
  57 Ledger_line_engraver::finalize ()
  58 {
  59   stop_spanner ();
  60 }
  61
  62 void
  63 Ledger_line_engraver::stop_spanner ()
  64 {
  65   if (span_)
  66     {
  67       span_->set_bound (RIGHT, unsmob_grob (get_property ("currentCommandColumn")));
  68       Pointer_group_interface::set_ordered (span_, ly_symbol2scm ("elements"), false);
  69       span_ = 0;
  70     }
  71 }
  72
  73 void
  74 Ledger_line_engraver::acknowledge_staff_symbol (Grob_info s)
  75 {
  76   Spanner *sym = dynamic_cast<Spanner *> (s.grob ());
  77
  78   if (!span_
  79       || (span_->get_bound (LEFT) != sym->get_bound (LEFT)
  80           && sym->get_bound (LEFT)))
  81     {
  82       stop_spanner ();
  83       start_spanner ();
  84     }
  85 }
  86
  87 void
  88 Ledger_line_engraver::acknowledge_ledgered (Grob_info s)
  89 {
  90   if (span_)
  91     {
  92       if (!to_boolean (s.grob ()->get_property ("no-ledgers")))
  93         Pointer_group_interface::add_grob (span_, ly_symbol2scm ("note-heads"),
  94                                            s.grob ());
  95     }
  96 }
  97
  98 #include "translator.icc"
  99
 100 ADD_ACKNOWLEDGER (Ledger_line_engraver, ledgered);
 101 ADD_ACKNOWLEDGER (Ledger_line_engraver, staff_symbol);
 102 ADD_TRANSLATOR (Ledger_line_engraver,
 103                 "Creates the spanner to draw ledger lines, and notices objects that need ledger lines",
 104                 /* create */ "LedgerLineSpanner",
 105                 /* accept */ "",
 106                 /* read */ "",
 107                 /* write */ "")