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 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7
   8 */
   9
  10 #include "group-interface.hh"
  11 #include "spanner.hh"
  12 #include "engraver.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   virtual void process_music ();
  24   virtual void acknowledge_grob (Grob_info);
  25 };
  26
  27 Ledger_line_engraver::Ledger_line_engraver()
  28 {
  29   span_ = 0;
  30 }
  31
  32 void
  33 Ledger_line_engraver::process_music ()
  34 {
  35   if (!span_)
  36     {
  37       span_ = make_spanner("LedgerLineSpanner", SCM_EOL);
  38
  39       span_->set_bound (LEFT, unsmob_grob (get_property ("currentCommandColumn")));
  40     }
  41 }
  42
  43 void
  44 Ledger_line_engraver::finalize ()
  45 {
  46   if (span_)
  47     span_->set_bound (RIGHT,unsmob_grob (get_property ("currentCommandColumn")));
  48 }
  49
  50
  51 void
  52 Ledger_line_engraver::acknowledge_grob (Grob_info s)
  53 {
  54   if (!to_boolean (s.grob_->get_property ("no-ledgers")))
  55     Pointer_group_interface::add_grob (span_, ly_symbol2scm ("note-heads"),
  56                                        s.grob_);
  57 }
  58 ADD_TRANSLATOR (Ledger_line_engraver,
  59                    "Creates the spanner to draw ledger lines, and notices objects that need ledger lines",
  60                    /* creats*/       "LedgerLineSpanner",
  61                    /* accepts */     "",
  62                    /* acks  */      "ledgered-interface", // ledgered-interface?
  63                    /* reads */       "",
  64                    /* write */       "")