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--2000 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7 */
   8 #include <math.h>               // rint
   9
  10 #include "gourlay-breaking.hh"
  11 #include "column-x-positions.hh"
  12 #include "debug.hh"
  13 #include "paper-column.hh"
  14 #include "paper-score.hh"
  15 #include "paper-def.hh"
  16 #include "simple-spacer.hh"
  17 #include "line-of-score.hh"
  18
  19 /// How often to print operator pacification marks?
  20 const int HAPPY_DOTS_I = 3;
  21
  22 /**
  23   Helper to trace back an optimal path
  24  */
  25 struct Break_node {
  26   /** this was the previous. If negative, this break should not be
  27     considered: this path has infinite energy
  28
  29     */
  30   int prev_break_i_;
  31   /**
  32      Which system number so far?
  33    */
  34   int line_i_;
  35
  36   Real demerits_f_;
  37   Column_x_positions line_config_;
  38
  39   Break_node ()
  40   {
  41     prev_break_i_ = -1;
  42     line_i_ = 0;
  43     demerits_f_ = 0;
  44   }
  45 };
  46
  47 /**
  48   This algorithms is adapted from the OSU Tech report on breaking lines.
  49
  50   this function is longish, but not very complicated.
  51
  52  */
  53 Array<Column_x_positions>
  54 Gourlay_breaking::do_solve () const
  55 {
  56   Array<Break_node> optimal_paths;
  57   Link_array<Paper_column> all =
  58     pscore_l_->line_l_->column_l_arr ();
  59
  60   Array<int> breaks = find_break_indices ();
  61
  62   optimal_paths.set_size (breaks.size ());
  63
  64   Break_node first_node ;
  65   first_node.line_config_.energy_f_ = 0;
  66
  67   optimal_paths[0] = first_node;
  68   int break_idx=1;
  69
  70   for (; break_idx< breaks.size (); break_idx++)
  71     {
  72       /*
  73         start with a short line, add measures. At some point
  74         the line becomes infeasible. Then we don't try to add more
  75         */
  76       int minimal_start_idx = -1;
  77       Column_x_positions minimal_sol;
  78       Column_x_positions backup_sol;
  79
  80       Real minimal_demerits = infinity_f;
  81
  82       for (int start_idx = break_idx; start_idx--;)
  83         {
  84           Link_array<Paper_column> line = all.slice (breaks[start_idx], breaks[break_idx]+1);
  85
  86           line[0] = dynamic_cast<Paper_column*>(line[0]->find_broken_piece (RIGHT));
  87           line.top () =  dynamic_cast<Paper_column*>(line.top ()->find_broken_piece (LEFT));
  88
  89           Column_x_positions cp;
  90           cp.cols_ = line;
  91
  92           Interval line_dims
  93             = pscore_l_->paper_l_->line_dimensions_int (optimal_paths[start_idx].line_i_);
  94           Simple_spacer * sp = generate_spacing_problem (line, line_dims);
  95           sp->solve (&cp);
  96           delete sp;
  97
  98           if (start_idx == break_idx - 1)
  99             backup_sol = cp;    // in case everything fucks up
 100           if (!cp.satisfies_constraints_b_)
 101             break;
 102
 103
 104           Real this_demerits;
 105           if (optimal_paths[start_idx].demerits_f_ >= infinity_f)
 106             this_demerits = infinity_f;
 107           else
 108             this_demerits = combine_demerits (optimal_paths[start_idx].line_config_, cp)
 109               + optimal_paths[start_idx].demerits_f_;
 110
 111           if (this_demerits < minimal_demerits)
 112             {
 113               minimal_start_idx = start_idx;
 114               minimal_sol = cp;
 115               minimal_demerits = this_demerits;
 116             }
 117         }
 118
 119       int prev =break_idx - 1;
 120       if (minimal_start_idx < 0)
 121         {
 122           optimal_paths[break_idx].demerits_f_ = infinity_f;
 123           optimal_paths[break_idx].line_config_ = backup_sol;
 124         }
 125       else
 126         {
 127           prev = minimal_start_idx;
 128           optimal_paths[break_idx].line_config_ = minimal_sol;
 129           optimal_paths[break_idx].demerits_f_ = minimal_demerits;
 130         }
 131       optimal_paths[break_idx].prev_break_i_ = prev;
 132       optimal_paths[break_idx].line_i_ = optimal_paths[prev].line_i_ + 1;
 133
 134       if (! (break_idx % HAPPY_DOTS_I))
 135         progress_indication (String ("[") + to_str (break_idx) + "]");
 136     }
 137
 138   /* do the last one */
 139   if  (break_idx % HAPPY_DOTS_I)
 140         progress_indication (String ("[") + to_str (break_idx) + "]");
 141
 142
 143   progress_indication ("\n");
 144
 145   Array<int> final_breaks;
 146   Array<Column_x_positions> lines;
 147
 148   /* skip 0-th element, since it is a "dummy" elt*/
 149   for (int i = optimal_paths.size ()-1; i> 0;)
 150     {
 151       final_breaks.push (i);
 152       int prev = optimal_paths[i].prev_break_i_;
 153       assert (i > prev);
 154       i = prev;
 155     }
 156
 157   if (optimal_paths.top ().demerits_f_ >= infinity_f)
 158     warning (_ ("No feasible line breaking found"));
 159
 160   for (int i= final_breaks.size (); i--;)
 161     lines.push (optimal_paths[final_breaks[i]].line_config_);
 162
 163   return lines;
 164 }
 165
 166
 167 Gourlay_breaking::Gourlay_breaking ()
 168 {
 169   energy_bound_f_ = infinity_f;
 170 }
 171
 172
 173
 174 /*
 175   TODO: uniformity parameter to control rel. importance of spacing differences.
 176  */
 177 Real
 178 Gourlay_breaking::combine_demerits (Column_x_positions const &prev,
 179                                     Column_x_positions const &this_one) const
 180 {
 181   Real break_penalties = 0.0;
 182   Paper_column * pc = this_one.cols_.top ();
 183   if (pc->original_l_)
 184     {
 185       SCM pen = pc->get_elt_property ("penalty");
 186       if (gh_number_p (pen))
 187         {
 188           break_penalties += gh_scm2double (pen);
 189         }
 190     }
 191
 192   return abs (this_one.force_f_) + abs (prev.force_f_ - this_one.force_f_)
 193     + break_penalties;
 194 }
 195