lily/optimal-page-breaking.cc

   1 /*
   2   optimal-page-breaking.cc -- implement a page-breaker that
   3   will break pages in such a way that both horizontal and
   4   vertical spacing will be acceptable
   5
   6   source file of the GNU LilyPond music typesetter
   7
   8   (c) 2006--2007 Joe Neeman <joeneeman@gmail.com>
   9 */
  10
  11 #include "international.hh"
  12 #include "optimal-page-breaking.hh"
  13 #include "output-def.hh"
  14 #include "page-spacing.hh"
  15 #include "paper-book.hh"
  16 #include "paper-score.hh"
  17 #include "prob.hh"
  18 #include "system.hh"
  19
  20 static bool
  21 is_break (Grob *g)
  22 {
  23   (void) g; /* shutup warning */
  24   return false;
  25 }
  26
  27 Optimal_page_breaking::Optimal_page_breaking (Paper_book *pb)
  28   : Page_breaking (pb, is_break)
  29 {
  30 }
  31
  32 Optimal_page_breaking::~Optimal_page_breaking ()
  33 {
  34 }
  35
  36 SCM
  37 Optimal_page_breaking::solve ()
  38 {
  39   vsize end = last_break_position ();
  40   vsize max_sys_count = max_system_count (0, end);
  41   vsize first_page_num = robust_scm2int (book_->paper_->c_variable ("first-page-number"), 1);
  42   SCM forced_page_count = book_->paper_->c_variable ("page-count");
  43
  44   set_to_ideal_line_configuration (0, end);
  45
  46   Page_spacing_result best;
  47   vsize page_count = robust_scm2int (forced_page_count, 1);
  48   Line_division ideal_line_division = current_configuration (0);
  49   Line_division best_division = ideal_line_division;
  50   vsize min_sys_count = 1;
  51   vsize ideal_sys_count = system_count ();
  52
  53   if (!scm_is_integer (forced_page_count))
  54     {
  55       /* find out the ideal number of pages */
  56       message (_ ("Finding the ideal number of pages..."));
  57
  58       best = space_systems_on_best_pages (0, first_page_num);
  59       page_count = best.systems_per_page_.size ();
  60
  61       ideal_sys_count = best.system_count ();
  62       min_sys_count = ideal_sys_count - best.systems_per_page_.back ();
  63
  64       if (page_count > 1 && best.systems_per_page_[page_count - 2] > 1)
  65         min_sys_count -= best.systems_per_page_[page_count - 2];
  66     }
  67   else
  68     {
  69       /* todo: the following line will spit out programming errors if the
  70          ideal line spacing doesn't fit on PAGE_COUNT pages */
  71       best = space_systems_on_n_pages (0, page_count, first_page_num);
  72       min_sys_count = page_count;
  73     }
  74
  75   if (page_count == 1)
  76     message (_ ("Fitting music on 1 page..."));
  77   else if (scm_is_integer (forced_page_count))
  78     message (_f ("Fitting music on %d pages...", (int)page_count));
  79   else
  80     message (_f ("Fitting music on %d or %d pages...", (int)page_count-1, (int)page_count));
  81
  82   /* try a smaller number of systems than the ideal number for line breaking */
  83   Line_division bound = ideal_line_division;
  84   for (vsize sys_count = ideal_sys_count; --sys_count >= min_sys_count;)
  85     {
  86       Page_spacing_result best_for_this_sys_count;
  87       set_current_breakpoints (0, end, sys_count, Line_division (), bound);
  88
  89       for (vsize i = 0; i < current_configuration_count (); i++)
  90         {
  91           vsize min_p_count = min_page_count (i, first_page_num);
  92           Page_spacing_result cur;
  93
  94           if (min_p_count == page_count || scm_is_integer (forced_page_count))
  95             cur = space_systems_on_n_pages (i, page_count, first_page_num);
  96           else
  97             cur = space_systems_on_n_or_one_more_pages (i, page_count-1, first_page_num);
  98
  99           if (cur.demerits_ < best_for_this_sys_count.demerits_ || isinf (best_for_this_sys_count.demerits_))
 100             {
 101               best_for_this_sys_count = cur;
 102               bound = current_configuration (i);
 103             }
 104         }
 105
 106       if (best_for_this_sys_count.demerits_ < best.demerits_ || isinf (best.demerits_))
 107         {
 108           best = best_for_this_sys_count;
 109           best_division = bound;
 110         }
 111
 112       /* if the pages are stretched on average, stop trying to reduce sys_count */
 113       if (best_for_this_sys_count.page_count () < page_count
 114           && best_for_this_sys_count.average_force () > 0)
 115         break;
 116
 117
 118       if (isinf (best_for_this_sys_count.demerits_))
 119         break;
 120     }
 121
 122   /* try a larger number of systems than the ideal line breaking number. This
 123      is more or less C&P, but the loop bounds make it difficult to try something
 124      like do {...} while (flip(&d) != UP). */
 125   bound = ideal_line_division;
 126   for (vsize sys_count = ideal_sys_count+1; sys_count <= max_sys_count; sys_count++)
 127     {
 128       Real best_demerits_for_this_sys_count = infinity_f;
 129       set_current_breakpoints (0, end, sys_count, bound);
 130
 131       for (vsize i = 0; i < current_configuration_count (); i++)
 132         {
 133           vsize min_p_count = min_page_count (i, first_page_num);
 134           Page_spacing_result cur;
 135
 136           if (min_p_count > page_count)
 137             continue;
 138           else
 139             cur = space_systems_on_n_pages (i, page_count, first_page_num);
 140
 141           if (cur.demerits_ < best.demerits_ || isinf (best.demerits_))
 142             {
 143               best = cur;
 144               best_division = current_configuration (i);
 145             }
 146
 147           if (cur.demerits_ < best_demerits_for_this_sys_count || isinf (best_demerits_for_this_sys_count))
 148             {
 149               best_demerits_for_this_sys_count = cur.demerits_;
 150               bound = current_configuration (i);
 151             }
 152         }
 153       if (isinf (best_demerits_for_this_sys_count))
 154         break;
 155     }
 156
 157   message (_ ("Drawing systems..."));
 158   break_into_pieces (0, end, best_division);
 159   SCM lines = systems ();
 160   return make_pages (best.systems_per_page_, lines);
 161 }
 162