/*   
  note-head-line-engraver.cc -- implement Note_head_line_engraver
  
  source file of the GNU LilyPond music typesetter
  
  (c) 2000--2001 Jan Nieuwenhuizen <janneke@gnu.org>
 */

#include "engraver.hh"
#include "group-interface.hh"
#include "item.hh"
#include "musical-request.hh"
#include "spanner.hh"
#include "stem.hh"
#include "rhythmic-head.hh"
#include "side-position-interface.hh"
#include "staff-symbol-referencer.hh"
#include "translator-group.hh"

/**
   Create line-spanner grobs for glissandi (and possibly other) 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:
  virtual void acknowledge_grob (Grob_info);
  virtual void create_grobs ();
  virtual void stop_translation_timestep ();
  virtual bool try_music (Music *);

private:
  Spanner* line_; 
  Request* req_;
  Request* last_req_;
  Translator* last_staff_;
  bool follow_;
  Grob* head_;
  Grob* last_head_;
};

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

bool
Note_head_line_engraver::try_music (Music* m)
{
  if (!req_)
    {
      if (Glissando_req *r = dynamic_cast<Glissando_req*> (m))
	{
	  req_ = r;
	  return true;
	}
    }
  return false;
}

void
Note_head_line_engraver::acknowledge_grob (Grob_info info)
{
  if (Rhythmic_head::has_interface (info.grob_l_))
    {
      head_ = info.grob_l_;
      if (to_boolean (get_property ("followVoice")))
	{
	  Translator_group  * tr = daddy_trans_l_;
	  while (tr && tr->type_str_ != "Staff")
	    tr = tr->daddy_trans_l_ ;

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


void
Note_head_line_engraver::create_grobs ()
{
  if (!line_ && (follow_ || last_req_) && last_head_ && head_
      && (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_ = new Spanner (get_property ("VoiceFollower"));
      else
	line_ = new Spanner (get_property ("Glissando"));
	  
      line_->set_bound (LEFT, last_head_);
      line_->set_bound (RIGHT, head_);
	  
	  /* Note, mustn't set y-parent of breakable symbol to simple item:
	     one of the two broken parts won't have an y-parent! */
	  /* X parent is set by set_bound */
      line_->set_parent (Staff_symbol_referencer::staff_symbol_l (last_head_),
			 Y_AXIS);
	  
      announce_grob (line_, last_req_);
      last_req_ = 0;	

      follow_ = false;
    }
}

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

  if (req_)
    {
      last_req_ = req_;
      req_ =0;
    }
}




ENTER_DESCRIPTION(Note_head_line_engraver,
/* descr */       "Engrave a line between two note heads, for example a glissando.
If followVoice is set, staff switches also generate a line.",
/* creats*/       "Glissando VoiceFollower",
/* acks  */       "rhythmic-head-interface",
/* reads */       "followVoice",
/* write */       "");
