X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fpage-spacing.cc;h=ab8085c1d59b92900fd46cd7ac72f59f425e3f91;hb=794dcbdb52faf4292036cd1b0270a956cf4316a3;hp=78ad9a842a6561e2df7c02438b5089ab52ee57ab;hpb=e23b3a0ae90cd22ed684396c437435f2c0b5a773;p=lilypond.git

diff --git a/lily/page-spacing.cc b/lily/page-spacing.cc
index 78ad9a842a..ab8085c1d5 100644
--- a/lily/page-spacing.cc
+++ b/lily/page-spacing.cc
@@ -4,7 +4,7 @@
 
   source file of the GNU LilyPond music typesetter
 
-  (c) 2006--2007 Joe Neeman <joeneeman@gmail.com>
+  (c) 2006--2009 Joe Neeman <joeneeman@gmail.com>
 */
 
 #include "page-spacing.hh"
@@ -16,8 +16,9 @@
 void
 Page_spacing::calc_force ()
 {
-  /* If the first system is a title, we add back in the page-top-space. */
-  Real height = first_line_.title_ ? page_height_ + page_top_space_ : page_height_;
+  Real height = page_height_
+    - breaker_->min_whitespace_at_top_of_page (first_line_)
+    - breaker_->min_whitespace_at_bottom_of_page (last_line_);
 
   if (rod_height_ + last_line_.bottom_padding_ >= height)
     force_ = infinity_f;
@@ -154,17 +155,14 @@ Page_spacer::solve (vsize page_count)
   if (extra_systems)
     {
       ret.systems_per_page_.back () += extra_systems;
-      ret.demerits_ += 200000;
+      ret.force_.back () = BAD_SPACING_PENALTY;
     }
   if (extra_pages)
     {
-      ret.force_.insert (ret.force_.end (), extra_pages, 200000);
+      ret.force_.insert (ret.force_.end (), extra_pages, BAD_SPACING_PENALTY);
       ret.systems_per_page_.insert (ret.systems_per_page_.end (), extra_pages, 0);
-      ret.demerits_ += 200000;
     }
 
-
-  ret.demerits_ += ret.penalty_;
   return ret;
 }
 
@@ -185,44 +183,66 @@ Page_spacer::resize (vsize page_count)
   max_page_count_ = page_count;
 }
 
+// Carries out one step in the dynamic programming algorithm for putting systems
+// on a fixed number of pages. One call to this routine calculates the best
+// configuration for putting lines 0 through LINE-1 on PAGE+1 pages, provided that
+// we have previously called calc_subproblem(page-1, k) for every k < LINE.
+//
+// This algorithm is similar to the constrained-breaking algorithm.
 bool
 Page_spacer::calc_subproblem (vsize page, vsize line)
 {
   bool last = line == lines_.size () - 1;
   Page_spacing space (breaker_->page_height (page + first_page_num_, last),
-		      breaker_->page_top_space ());
+		      breaker_);
   Page_spacing_node &cur = state_.at (line, page);
   bool ragged = ragged_ || (ragged_last_ && last);
+  int line_count = 0;
 
   for (vsize page_start = line+1; page_start > page && page_start--;)
     {
       Page_spacing_node const *prev = page > 0 ? &state_.at (page_start-1, page-1) : 0;
 
       space.prepend_system (lines_[page_start]);
-      if (page_start < line && (isinf (space.force_) || (space.force_ < 0 && ragged)))
+
+      // This 'if' statement is a little hard to parse. It won't consider this configuration
+      // if it is overfull unless the current configuration is the first one with this start
+      // point. We also make an exception (and consider this configuration) if the previous
+      // configuration we tried had fewer lines than min-systems-per-page.
+      if (!breaker_->too_few_lines (line_count)
+	  && page_start < line
+	  && (isinf (space.force_) || (space.force_ < 0 && ragged)))
 	break;
 
+      line_count += lines_[page_start].compressed_nontitle_lines_count_;
       if (page > 0 || page_start == 0)
 	{
+	  // If the last page is ragged, set its force to zero. This way, we will leave
+	  // the last page half-empty rather than trying to balance things out
+	  // (which only makes sense in non-ragged situations).
 	  if (line == lines_.size () - 1 && ragged && last && space.force_ > 0)
 	    space.force_ = 0;
 
-	  /* we may have to deal with single lines that are taller than a page */
+	  Real demerits = space.force_ * space.force_;
+	  /* If a single line is taller than a page, we need to consider it as
+	     a possible solution (but we give it a very bad score). */
 	  if (isinf (space.force_) && page_start == line)
-	    space.force_ = -200000;
+	    demerits = BAD_SPACING_PENALTY;
+	  demerits += (prev ? prev->demerits_ : 0);
 
-	  Real dem = fabs (space.force_) + (prev ? prev->demerits_ : 0);
-	  Real penalty = 0;
+	  Real penalty = breaker_->line_count_penalty (line_count);
 	  if (page_start > 0)
-	    penalty = lines_[page_start-1].page_penalty_
+	    penalty += lines_[page_start-1].page_penalty_
 	      + (page % 2 == 0) ? lines_[page_start-1].turn_penalty_ : 0;
 
-	  dem += penalty;
-	  if (dem < cur.demerits_ || page_start == line)
+	  demerits += penalty;
+	  if (demerits < cur.demerits_ || page_start == line)
 	    {
-	      cur.demerits_ = dem;
+	      cur.demerits_ = demerits;
 	      cur.force_ = space.force_;
 	      cur.penalty_ = penalty + (prev ? prev->penalty_ : 0);
+	      cur.system_count_status_ = breaker_->line_count_status (line_count)
+		| (prev ? prev->system_count_status_ : 0);
 	      cur.prev_ = page_start - 1;
 	    }
 	}