lily/gourlay-breaking.cc

   1 /*
   2   gourlay-breaking.cc -- implement Gourlay_breaking
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c)  1997--1998 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7 */
   8
   9 #include "gourlay-breaking.hh"
  10 #include "colhpos.hh"
  11 #include "spring-spacer.hh"
  12 #include "debug.hh"
  13 #include "p-col.hh"
  14 #include "p-score.hh"
  15 #include "paper-def.hh"
  16
  17 const HAPPY_DOTS_I = 3;
  18
  19 /**
  20   Helper to trace back an optimal path
  21  */
  22 struct Break_node {
  23   /** this was the previous. If negative, this break should not be
  24     considered: this path has infinite energy
  25
  26     */
  27   int prev_break_i_;
  28   int line_i_;
  29   Real energy_f_;
  30   Column_x_positions line_config_;
  31   Break_node ()
  32   {
  33     prev_break_i_ = -1;
  34     line_i_ = 0;
  35   }
  36 };
  37
  38 /**
  39   This algorithms is adapted from
  40  */
  41
  42 Array<Column_x_positions>
  43 Gourlay_breaking::do_solve () const
  44 {
  45   Array<Break_node> optimal_paths;
  46   Line_of_cols all = all_cols ();
  47   Array<int> breaks = find_break_indices ();
  48
  49   optimal_paths.set_size (breaks.size ());
  50
  51   Break_node first_node ;
  52   first_node.prev_break_i_ = -1;
  53   first_node.line_config_.energy_f_ = 0;
  54   first_node.line_i_ = 0;
  55
  56   optimal_paths[0] = first_node;
  57   int break_idx=1;
  58
  59
  60   for (; break_idx< breaks.size (); break_idx++)
  61     {
  62       Array<int> candidates;
  63       Array<Column_x_positions> candidate_lines;
  64       Pointer_list<Line_spacer*> spacer_p_list;
  65
  66       /*
  67         start with a short line, add measures. At some point
  68         the line becomes infeasible. Then we don't try to add more
  69         */
  70       for (int start_idx = break_idx; start_idx--;)
  71         {
  72           if  (break_idx - start_idx > max_measures_i_)
  73             break;
  74
  75           if (optimal_paths[start_idx].prev_break_i_ < 0
  76               && optimal_paths[start_idx].line_config_.energy_f_)
  77
  78             continue;
  79
  80           Line_of_cols line = all.slice (breaks[start_idx], breaks[break_idx]+1);
  81
  82           line[0] = line[0]->postbreak_l ();
  83           line.top () = line.top ()->prebreak_l ();
  84
  85           if (!feasible (line))
  86             break;
  87
  88           Column_x_positions approx;
  89           approx.cols = line;
  90
  91           approx.spacer_l_ = generate_spacing_problem (line,
  92             pscore_l_->paper_l_->line_dimensions_int (optimal_paths[start_idx].line_i_));
  93           spacer_p_list.bottom ().add (approx.spacer_l_);
  94
  95           ( (Break_algorithm*)this)->approx_stats_.add (approx.cols);
  96           approx.approximate_solve_line ();
  97
  98           if  (approx.energy_f_  > energy_bound_f_)
  99             {
 100               continue;
 101             }
 102
 103
 104           // this is a likely candidate. Store it.
 105           candidate_lines.push (approx);
 106           candidates.push (start_idx);
 107         }
 108
 109
 110       int minimal_j = -1;
 111       Real minimal_energy = infinity_f;
 112       for (int j=0; j < candidates.size (); j++)
 113         {
 114           int start = candidates[j];
 115           if (optimal_paths[start].line_config_.energy_f_
 116                + candidate_lines[j].energy_f_  > minimal_energy)
 117
 118             continue;
 119
 120           if (!candidate_lines[j].satisfies_constraints_b_)
 121             {
 122               candidate_lines[j].solve_line ();
 123               ( (Break_algorithm*)this)->exact_stats_.add (candidate_lines[j].cols);
 124             }
 125
 126           Real this_energy
 127             = optimal_paths[start].line_config_.energy_f_
 128             + candidate_lines[j].energy_f_ ;
 129
 130           if (this_energy < minimal_energy)
 131             {
 132               minimal_j = j;
 133               minimal_energy = this_energy;
 134             }
 135         }
 136
 137       if (minimal_j < 0)
 138         {
 139           optimal_paths[break_idx].prev_break_i_ = -1;
 140           optimal_paths[break_idx].line_config_.energy_f_ = infinity_f;
 141         }
 142       else
 143         {
 144           optimal_paths[break_idx].prev_break_i_ = candidates[minimal_j];
 145           optimal_paths[break_idx].line_config_ = candidate_lines[minimal_j];
 146           optimal_paths[break_idx].line_i_ =
 147             optimal_paths[optimal_paths[break_idx].prev_break_i_].line_i_ + 1;
 148         }
 149
 150       if (! (break_idx % HAPPY_DOTS_I))
 151         *mlog << "[" << break_idx << "]" << flush;
 152     }
 153
 154   if  (break_idx % HAPPY_DOTS_I)
 155     *mlog << "[" << break_idx << "]" << flush;
 156
 157   Array<int> final_breaks;
 158
 159   Array<Column_x_positions> lines;
 160
 161   /* skip 0-th element, since it is a "dummy" elt*/
 162   for (int i = optimal_paths.size ()-1; i> 0;)
 163     {
 164       final_breaks.push (i);
 165       assert (i > optimal_paths[i].prev_break_i_);
 166
 167       // there was no "feasible path"
 168       if (!optimal_paths[i].line_config_.config.size ()) {
 169         final_breaks.set_size (0);
 170         break;
 171       }
 172       i = optimal_paths[i].prev_break_i_;
 173     }
 174
 175
 176   for (int i= final_breaks.size (); i--;)
 177     lines.push (optimal_paths[final_breaks[i]].line_config_);
 178
 179   return lines;
 180 }
 181
 182
 183 Gourlay_breaking::Gourlay_breaking ()
 184 {
 185   get_line_spacer = Spring_spacer::constructor;
 186   energy_bound_f_ = infinity_f;
 187   max_measures_i_ = INT_MAX;
 188 }
 189
 190 void
 191 Gourlay_breaking::do_set_pscore ()
 192 {
 193   energy_bound_f_ = pscore_l_->paper_l_->get_var ("gourlay_energybound");
 194   max_measures_i_ =int (rint (pscore_l_->paper_l_->get_var ("gourlay_maxmeasures")));
 195 }
 196