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
  11 #include "group-interface.hh"
  12 #include "spanner.hh"
  13 #include "engraver.hh"
  14 #include "ambitus.hh"
  15
  16 class Ledger_line_engraver : public Engraver
  17 {
  18   Spanner * span_;
  19
  20 public:
  21   TRANSLATOR_DECLARATIONS (Ledger_line_engraver);
  22
  23 protected:
  24   virtual void finalize ();
  25   virtual void process_music ();
  26   virtual void acknowledge_grob (Grob_info);
  27 };
  28
  29 Ledger_line_engraver::Ledger_line_engraver()
  30 {
  31   span_ = 0;
  32 }
  33
  34 void
  35 Ledger_line_engraver::process_music ()
  36 {
  37   if (!span_)
  38     {
  39       span_ = make_spanner("LedgerLineSpanner", SCM_EOL);
  40
  41       span_->set_bound (LEFT, unsmob_grob (get_property ("currentCommandColumn")));
  42     }
  43 }
  44
  45 void
  46 Ledger_line_engraver::finalize ()
  47 {
  48   if (span_)
  49     span_->set_bound (RIGHT,unsmob_grob (get_property ("currentCommandColumn")));
  50 }
  51
  52
  53 void
  54 Ledger_line_engraver::acknowledge_grob (Grob_info s)
  55 {
  56   Pointer_group_interface::add_grob (span_, ly_symbol2scm ("note-heads"),
  57                                      s.grob_);
  58 }
  59 ENTER_DESCRIPTION (Ledger_line_engraver,
  60                    "Creates spanner to draw ledger lines",
  61                    /* creats*/       "LedgerLineSpanner",
  62                    /* accepts */     "",
  63                    /* acks  */      "custos-interface note-head-interface", // ledgered-interface?
  64                    /* reads */       "",
  65                    /* write */       "")