/*
  staff-symbol-referencer.cc -- implement Staff_symbol_referencer

  source file of the GNU LilyPond music typesetter

  (c) 1999--2004 Han-Wen Nienhuys <hanwen@cs.uu.nl>
*/

#include <math.h>

#include "staff-symbol-referencer.hh"
#include "staff-symbol.hh"
#include "output-def.hh"
#include "libc-extension.hh"


int
Staff_symbol_referencer::line_count (Grob *me)
{
 Grob *st = get_staff_symbol (me);
 return st ? Staff_symbol::line_count (st) : 0;
}

bool
Staff_symbol_referencer::on_staffline (Grob *me)
{
  return on_staffline (me, (int) rint (get_position (me)));
}

/*
  This does not take size into account.
  maybe rename: on_virtual_staffline, on_staff_or_ledger_line?
 */
bool
Staff_symbol_referencer::on_staffline (Grob *me, int pos)
{
  int sz = line_count (me) - 1;
  return ((pos + sz) % 2) == 0;
}

Grob*
Staff_symbol_referencer::get_staff_symbol (Grob *me)
{
  if (Staff_symbol::has_interface (me))
    return me;
  
  SCM st = me->get_property ("staff-symbol");
  return unsmob_grob (st);
}

Real
Staff_symbol_referencer::staff_space (Grob *me)
{
  Grob *st = get_staff_symbol (me);
  if (st)
    return Staff_symbol::staff_space (st);
  return 1.0;
}

Real
Staff_symbol_referencer::line_thickness (Grob *me)
{
  Grob *st = get_staff_symbol (me);
  if (st)
    return Staff_symbol::get_line_thickness (st);
  return me->get_layout ()->get_dimension (ly_symbol2scm ("linethickness"));
}

Real
Staff_symbol_referencer::get_position (Grob *me)
{
  Real p = 0.0;
  Grob *st = get_staff_symbol (me);
  Grob *c = st ? me->common_refpoint (st, Y_AXIS) : 0;
  if (st && c)
    {
      Real y = me->relative_coordinate (c, Y_AXIS)
	- st->relative_coordinate (c, Y_AXIS);

      p += 2.0 * y / Staff_symbol::staff_space (st);
      return p;
    }
  else if (!st)
    {
      return me->relative_coordinate (me->get_parent (Y_AXIS), Y_AXIS) * 2;
    }
  return robust_scm2double (me->get_property ("staff-position"), p);
}

int
Staff_symbol_referencer::get_rounded_position (Grob*me)
{
  return int (rint (get_position (me)));
}

LY_DEFINE (ly_grob_staff_position, "ly:grob-staff-position",
	   1, 0,0, (SCM sg),
	   "Return the Y-position of @var{sg} relative to the staff.")
{
  Grob *g = unsmob_grob (sg);

  SCM_ASSERT_TYPE (g, sg, SCM_ARG1, __FUNCTION__, "grob");
  Real pos = Staff_symbol_referencer::get_position (g);

  if (fabs (rint (pos) -pos) < 1e-6) // ugh.
    return scm_int2num ((int) my_round (pos));
  else
    return scm_make_real (pos);
}


/* should use offset callback!  */
MAKE_SCHEME_CALLBACK (Staff_symbol_referencer,callback,2);
SCM
Staff_symbol_referencer::callback (SCM element_smob, SCM)
{
  Grob *me = unsmob_grob (element_smob);

  SCM pos = me->get_property ("staff-position");
  Real off = 0.0;
  if (scm_is_number (pos))
    {
      Real space = Staff_symbol_referencer::staff_space (me);
      off = scm_to_double (pos) * space / 2.0;
      me->set_property ("staff-position", scm_int2num (0));
    }

  return scm_make_real (off);
}

/*  This sets the position relative to the center of the staff symbol.

The function is hairy, because it can be called in two situations:

1. There is no staff yet; we must set staff-position

2. There is a staff, and perhaps someone even applied a
translate_axis (). Then we must compensate for the translation

In either case, we set a callback to be sure that our new position
will be extracted from staff-position */

void
Staff_symbol_referencer::set_position (Grob *me, Real p)
{
  Grob *st = get_staff_symbol (me);
  if (st && me->common_refpoint (st, Y_AXIS))
    {
      Real oldpos = get_position (me);
      me->set_property ("staff-position", scm_make_real (p - oldpos));
    }
  else
    me->set_property ("staff-position", scm_make_real (p));

  me->add_offset_callback (Staff_symbol_referencer::callback_proc, Y_AXIS);
}

/* Half of the height, in staff space, i.e. 2.0 for a normal staff. */
Real
Staff_symbol_referencer::staff_radius (Grob *me)
{
  return (line_count (me) - 1) / 2.0;
}

int
compare_position (Grob *const &a, Grob *const &b)
{
  return sign (Staff_symbol_referencer::get_position ((Grob*)a)
	       - Staff_symbol_referencer::get_position ((Grob*) b));
}

ADD_INTERFACE (Staff_symbol_referencer,"staff-symbol-referencer-interface",
	       "An object whose Y position is meant relative to a staff "
	       "symbol. "
	       "These usually have @code{Staff_symbol_referencer::callback} "
	       "in their @code{Y-offset-callbacks}. "
	       ,
	       "staff-position");

