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