/*
  note-head-line-engraver.cc -- implement Note_head_line_engraver

  source file of the GNU LilyPond music typesetter

  (c) 2000--2005 Jan Nieuwenhuizen <janneke@gnu.org>
*/

#include "engraver.hh"
#include "pointer-group-interface.hh"
#include "stem.hh"
#include "rhythmic-head.hh"
#include "side-position-interface.hh"
#include "staff-symbol-referencer.hh"
#include "context.hh"

/**
   Create line-spanner grobs for lines that connect note heads.

   TODO: have the line commit suicide if the notes are connected with
   either slur or beam.
*/
class Note_head_line_engraver : public Engraver
{
public:
  TRANSLATOR_DECLARATIONS (Note_head_line_engraver);

protected:
  DECLARE_ACKNOWLEDGER (rhythmic_head);
  void process_acknowledged ();
  void stop_translation_timestep ();

private:
  Spanner *line_;
  Context *last_staff_;
  bool follow_;
  Grob *head_;
  Grob *last_head_;
};

Note_head_line_engraver::Note_head_line_engraver ()
{
  line_ = 0;
  follow_ = false;
  head_ = 0;
  last_head_ = 0;
  last_staff_ = 0;
}

void
Note_head_line_engraver::acknowledge_rhythmic_head (Grob_info info)
{
  head_ = info.grob ();
  if (to_boolean (get_property ("followVoice")))
    {
      Context *tr = context ();
      while (tr && !tr->is_alias (ly_symbol2scm ("Staff")))
	tr = tr->get_parent_context ();

      if (tr
	  && tr->is_alias (ly_symbol2scm ("Staff")) && tr != last_staff_)
	{
	  if (last_head_)
	    follow_ = true;
	  last_staff_ = tr;
	}
    }
}

void
Note_head_line_engraver::process_acknowledged ()
{
  if (!line_ && follow_ && last_head_ && head_)
    {
      /* TODO: Don't follow if there's a beam.

      We can't do beam-stuff here, since beam doesn't exist yet.
      Should probably store follow_ in line_, and suicide at some
      later point */
      if (follow_)
	line_ = make_spanner ("VoiceFollower", head_->self_scm ());

      line_->set_bound (LEFT, last_head_);
      line_->set_bound (RIGHT, head_);

      follow_ = false;
    }
}

void
Note_head_line_engraver::stop_translation_timestep ()
{
  line_ = 0;
  if (head_)
    last_head_ = head_;
  head_ = 0;
}

#include "translator.icc"

ADD_ACKNOWLEDGER (Note_head_line_engraver, rhythmic_head);
ADD_TRANSLATOR (Note_head_line_engraver,
		/* doc */ "Engrave a line between two note heads, for example a glissando.  If "
		" followVoice is set, staff switches also generate a line.",
		/* create */ "Glissando VoiceFollower",
		/* accept */ "glissando-event",
		/* read */ "followVoice",
		/* write */ "");
