spacing-determine-loose-columns.cc

/*
  This file is part of LilyPond, the GNU music typesetter.

  Copyright (C) 2005--2012 Han-Wen Nienhuys <hanwen@xs4all.nl>

  LilyPond is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  LilyPond is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "staff-spacing.hh"

#include "spacing-options.hh"
#include "system.hh"
#include "paper-column.hh"
#include "column-x-positions.hh"
#include "pointer-group-interface.hh"
#include "spacing-interface.hh"
#include "spacing-spanner.hh"
#include "note-spacing.hh"
#include "moment.hh"
#include "grob-array.hh"
#include "break-align-interface.hh"
#include "warn.hh"

/*
  Return whether COL is fixed to its neighbors by some kind of spacing
  constraint.


  If in doubt, then we're not loose; the spacing engine should space
  for it, risking suboptimal spacing.

  (Otherwise, we might risk core dumps, and other weird stuff.)
*/
static bool
is_loose_column (Grob *l, Grob *col, Grob *r, Spacing_options const *options)
{
  if (!to_boolean (col->get_property ("allow-loose-spacing")))
    return false;

  if ((options->float_nonmusical_columns_
       || options->float_grace_columns_)
      && Paper_column::when_mom (col).grace_part_)
    {
      return true;
    }

  if (Paper_column::is_musical (col))
    return false;

  /*
    If this column doesn't have a proper neighbor, we should really
    make it loose, but spacing it correctly is more than we can
    currently can handle.

    (this happens in the following situation:

    |
    |    clef G
    *

    |               |      ||
    |               |      ||
    O               O       ||


    the column containing the clef is really loose, and should be
    attached right to the first column, but that is a lot of work for
    such a borderline case.)

  */

  Item *r_neighbor = unsmob_item (col->get_object ("right-neighbor"));
  Item *l_neighbor = unsmob_item (col->get_object ("left-neighbor"));

  if (!l_neighbor || !r_neighbor)
    return false;

  /* If a non-empty column (ie. not \bar "") is placed nicely in series with
     its neighbor (ie. no funny polyphonic stuff), don't make it loose.
  */
  if (l == l_neighbor && r == r_neighbor && col->extent (col, X_AXIS).length () > 0)
    return false;

  /*
    Only declare loose if the bounds make a little sense.  This means
    some cases (two isolated, consecutive clef changes) won't be
    nicely folded, but hey, then don't do that.
  */
  if (! ((Paper_column::is_musical (l_neighbor) || Paper_column::is_breakable (l_neighbor))
         && (Paper_column::is_musical (r_neighbor) || Paper_column::is_breakable (r_neighbor))))
    return false;

  /*
    in any case, we don't want to move bar lines.
  */
  extract_grob_set (col, "elements", elts);
  for (vsize i = elts.size (); i--;)
    {
      Grob *g = elts[i];
      if (g && Break_alignment_interface::has_interface (g))
        {
          extract_grob_set (g, "elements", gelts);
          for (vsize j = gelts.size (); j--;)
            {
              Grob *h = gelts[j];

              if (h && h->get_property ("break-align-symbol") == ly_symbol2scm ("staff-bar"))
                {
                  extract_grob_set (h, "elements", helts);
                  for (vsize k = helts.size (); k--;)
                    if ("" != robust_scm2string (helts[k]->get_property ("glyph-name"), ""))
                      return false;
                }
            }
        }
    }

  return true;
}

void
Spacing_spanner::set_distances_for_loose_col (Grob *me, Grob *c,
                                              Drul_array<Item *> next_door,
                                              Spacing_options const *options)
{
  Drul_array<Real> dists (0, 0);

  for (LEFT_and_RIGHT (d))
    {
      Item *lc = dynamic_cast<Item *> ((d == LEFT) ? next_door[LEFT] : c);
      Item *rc = dynamic_cast<Item *> (d == LEFT ? c : next_door[RIGHT]);

      extract_grob_set (lc, "spacing-wishes", wishes);
      for (vsize k = wishes.size (); k--;)
        {
          Grob *sp = wishes[k];
          if (Spacing_interface::left_column (sp) != lc
              || Spacing_interface::right_column (sp) != rc)
            continue;

          if (Note_spacing::has_interface (sp))
            {
              /*
                The note spacing should be taken from the musical
                columns.
              */
              Spring base = note_spacing (me, lc, rc, options);
              Spring spring = Note_spacing::get_spacing (sp, rc, base, options->increment_);

              dists[d] = max (dists[d], spring.min_distance ());
            }
          else if (Staff_spacing::has_interface (sp))
            {
              Spring spring = Staff_spacing::get_spacing (sp, rc, 0.0);

              dists[d] = max (dists[d], spring.min_distance ());
            }
          else
            programming_error ("Subversive spacing wish");
        }
    }

  Rod r;
  r.distance_ = dists[LEFT] + dists[RIGHT];
  r.item_drul_ = next_door;

  r.add_to_cols ();
}

/*
  Remove columns that are not tightly fitting from COLS. In the
  removed columns, set 'between-cols to the columns where it is in
  between.
*/
void
Spacing_spanner::prune_loose_columns (Grob *me,
                                      vector<Grob *> *cols,
                                      Spacing_options *options)
{
  vector<Grob *> newcols;
  for (vsize i = 0; i < cols->size (); i++)
    {
      Grob *c = cols->at (i);

      bool loose = (i > 0 && i + 1 < cols->size ())
                   && is_loose_column (cols->at (i - 1), c, cols->at (i + 1), options);

      /* Breakable columns never get pruned; even if they are loose,
        their broken pieces are not.  However, we mark them so that
        the spacing can take their mid-line looseness into account. */
      if (loose && Paper_column::is_breakable (c))
        {
          loose = false;
          c->set_property ("maybe-loose", SCM_BOOL_T);
        }
      /*
        Unbreakable columns which only contain page-labels also
        never get pruned, otherwise the labels are lost before they can
        be collected by the System: so we mark these columns too.
      */
      if (!loose && !Paper_column::is_breakable (c)
          && scm_is_pair (c->get_property ("labels")))
        {
          extract_grob_set (c, "elements", elts);
          if (elts.empty ())
            c->set_property ("maybe-loose", SCM_BOOL_T);
        }

      if (loose)
        {
          Grob *right_neighbor = unsmob_grob (c->get_object ("right-neighbor"));
          Grob *left_neighbor = unsmob_grob (c->get_object ("left-neighbor"));

          /*
            Either object can be non existent, if the score ends
            prematurely.
          */
          if (!right_neighbor || !left_neighbor)
            {
              c->programming_error ("Cannot determine neighbors for floating column.");
              c->set_object ("between-cols", scm_cons (cols->at (i - 1)->self_scm (),
                                                       cols->at (i + 1)->self_scm ()));
            }
          else
            {
              c->set_object ("between-cols", scm_cons (left_neighbor->self_scm (),
                                                       right_neighbor->self_scm ()));

              /*
                Set distance constraints for loose columns
              */
              Drul_array<Item *> next_door (dynamic_cast<Item *> (left_neighbor),
                                            dynamic_cast<Item *> (right_neighbor));

              set_distances_for_loose_col (me, c, next_door, options);
            }
        }

      else
        newcols.push_back (c);
    }

  *cols = newcols;
}

/*
  Set neighboring columns determined by the spacing-wishes grob property.
*/
void
Spacing_spanner::set_explicit_neighbor_columns (vector<Grob *> const &cols)
{
  for (vsize i = 0; i < cols.size (); i++)
    {
      extract_grob_set (cols[i], "spacing-wishes", wishes);
      for (vsize j = wishes.size (); j--;)
        {
          Item *wish = dynamic_cast<Item *> (wishes[j]);
          Item *left_col = wish->get_column ();
          int left_rank = Paper_column::get_rank (left_col);
          int min_right_rank = INT_MAX;

          extract_grob_set (wish, "right-items", right_items);
          for (vsize k = right_items.size (); k--;)
            {
              Item *right_col = dynamic_cast<Item *> (right_items[k])->get_column ();
              int right_rank = Paper_column::get_rank (right_col);

              if (right_rank < min_right_rank)
                {
                  left_col->set_object ("right-neighbor", right_col->self_scm ());
                  min_right_rank = right_rank;
                }

              Grob *old_left_neighbor = unsmob_grob (right_col->get_object ("left-neighbor"));
              if (!old_left_neighbor || left_rank > Paper_column::get_rank (old_left_neighbor))
                right_col->set_object ("left-neighbor", left_col->self_scm ());
            }
        }
    }
}

/*
  Set neighboring columns that have no left/right-neighbor set
  yet. Only do breakable non-musical columns, and musical columns.
  Why only these? --jneem
*/
void
Spacing_spanner::set_implicit_neighbor_columns (vector<Grob *> const &cols)
{
  for (vsize i = 0; i < cols.size (); i++)
    {
      Item *it = dynamic_cast<Item *> (cols[i]);
      if (!Paper_column::is_breakable (it) && !Paper_column::is_musical (it))
        continue;

      if (i && !unsmob_grob (cols[i]->get_object ("left-neighbor")))
        cols[i]->set_object ("left-neighbor", cols[i - 1]->self_scm ());
      if (i + 1 < cols.size () && !unsmob_grob (cols[i]->get_object ("right-neighbor")))
        cols[i]->set_object ("right-neighbor", cols[i + 1]->self_scm ());
    }
}