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<Score_element> 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
  66   optimal_paths[0] = first_node;
  67   int break_idx=1;
  68
  69   for (; break_idx< breaks.size (); break_idx++)
  70     {
  71       /*
  72         start with a short line, add measures. At some point
  73         the line becomes infeasible. Then we don't try to add more
  74         */
  75       int minimal_start_idx = -1;
  76       Column_x_positions minimal_sol;
  77       Column_x_positions backup_sol;
  78
  79       Real minimal_demerits = infinity_f;
  80
  81       for (int start_idx = break_idx; start_idx--;)
  82         {
  83           Link_array<Score_element> line = all.slice (breaks[start_idx], breaks[break_idx]+1);
  84
  85           line[0]     = dynamic_cast<Item*> (line[0])    ->find_prebroken_piece (RIGHT);
  86           line.top () = dynamic_cast<Item*> (line.top ())->find_prebroken_piece (LEFT);
  87
  88           Column_x_positions cp;
  89           cp.cols_ = line;
  90
  91           Interval line_dims
  92             = pscore_l_->paper_l_->line_dimensions_int (optimal_paths[start_idx].line_i_);
  93           Simple_spacer * sp = generate_spacing_problem (line, line_dims);
  94           sp->solve (&cp);
  95           delete sp;
  96
  97           if (start_idx == break_idx - 1)
  98             backup_sol = cp;    // in case everything fucks up
  99           if (!cp.satisfies_constraints_b_)
 100             break;
 101
 102
 103           Real this_demerits;
 104           if (optimal_paths[start_idx].demerits_f_ >= infinity_f)
 105             this_demerits = infinity_f;
 106           else
 107             this_demerits = combine_demerits (optimal_paths[start_idx].line_config_, cp)
 108               + optimal_paths[start_idx].demerits_f_;
 109
 110           if (this_demerits < minimal_demerits)
 111             {
 112               minimal_start_idx = start_idx;
 113               minimal_sol = cp;
 114               minimal_demerits = this_demerits;
 115             }
 116         }
 117
 118       int prev =break_idx - 1;
 119       if (minimal_start_idx < 0)
 120         {
 121           optimal_paths[break_idx].demerits_f_ = infinity_f;
 122           optimal_paths[break_idx].line_config_ = backup_sol;
 123         }
 124       else
 125         {
 126           prev = minimal_start_idx;
 127           optimal_paths[break_idx].line_config_ = minimal_sol;
 128           optimal_paths[break_idx].demerits_f_ = minimal_demerits;
 129         }
 130       optimal_paths[break_idx].prev_break_i_ = prev;
 131       optimal_paths[break_idx].line_i_ = optimal_paths[prev].line_i_ + 1;
 132
 133       if (! (break_idx % HAPPY_DOTS_I))
 134         progress_indication (String ("[") + to_str (break_idx) + "]");
 135     }
 136
 137   /* do the last one */
 138   if  (break_idx % HAPPY_DOTS_I)
 139         progress_indication (String ("[") + to_str (break_idx) + "]");
 140
 141
 142   progress_indication ("\n");
 143
 144   Array<int> final_breaks;
 145   Array<Column_x_positions> lines;
 146
 147   /* skip 0-th element, since it is a "dummy" elt*/
 148   for (int i = optimal_paths.size ()-1; i> 0;)
 149     {
 150       final_breaks.push (i);
 151       int prev = optimal_paths[i].prev_break_i_;
 152       assert (i > prev);
 153       i = prev;
 154     }
 155
 156   if (optimal_paths.top ().demerits_f_ >= infinity_f)
 157     warning (_ ("No feasible line breaking found"));
 158
 159   for (int i= final_breaks.size (); i--;)
 160     lines.push (optimal_paths[final_breaks[i]].line_config_);
 161
 162   return lines;
 163 }
 164
 165
 166 Gourlay_breaking::Gourlay_breaking ()
 167 {
 168 }
 169
 170
 171
 172 /*
 173   TODO: uniformity parameter to control rel. importance of spacing differences.
 174  */
 175 Real
 176 Gourlay_breaking::combine_demerits (Column_x_positions const &prev,
 177                                     Column_x_positions const &this_one) const
 178 {
 179   Real break_penalties = 0.0;
 180   Score_element * pc = this_one.cols_.top ();
 181   if (pc->original_l_)
 182     {
 183       SCM pen = pc->get_elt_property ("penalty");
 184       if (gh_number_p (pen))
 185         {
 186           break_penalties += gh_scm2double (pen);
 187         }
 188     }
 189
 190   return abs (this_one.force_f_) + abs (prev.force_f_ - this_one.force_f_)
 191     + break_penalties;
 192 }
 193