X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Foptimal-page-breaking.cc;h=4bcf05f8e49e71604b3f4d62229dac5470b98a2c;hb=90e4d7057f3857da049dfda3d130017d4719bd6b;hp=b3d5fe1f7b12d9767e9edf1975e2f8b3d258b74c;hpb=d61cf3bbdb1c6670a127ba3baddf2f04d3e34fd3;p=lilypond.git

diff --git a/lily/optimal-page-breaking.cc b/lily/optimal-page-breaking.cc
index b3d5fe1f7b..4bcf05f8e4 100644
--- a/lily/optimal-page-breaking.cc
+++ b/lily/optimal-page-breaking.cc
@@ -1,7 +1,7 @@
 /*
   This file is part of LilyPond, the GNU music typesetter.
 
-  Copyright (C) 2006--2012 Joe Neeman <joeneeman@gmail.com>
+  Copyright (C) 2006--2015 Joe Neeman <joeneeman@gmail.com>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -64,12 +64,21 @@ Optimal_page_breaking::solve ()
       best = space_systems_on_best_pages (0, first_page_num);
 
       page_count = best.systems_per_page_.size ();
-      min_sys_count = ideal_sys_count - best.systems_per_page_.back ();
+      if (page_count == 0)
+        {
+          min_sys_count = 0;
+        }
+      else
+        {
+          min_sys_count = ideal_sys_count - best.systems_per_page_.back ();
 
-      if (page_count > 1 && best.systems_per_page_[page_count - 2] > 1)
-        min_sys_count -= best.systems_per_page_[page_count - 2];
+          if (page_count > 1 && best.systems_per_page_[page_count - 2] > 1)
+            min_sys_count -= best.systems_per_page_[page_count - 2];
 
-      min_sys_count = max (min_sys_count, (vsize)1);
+          if (min_sys_count > ideal_sys_count  // subtraction wrapped around
+              || min_sys_count <= 0)
+            min_sys_count = 1;
+        }
     }
   else
     {
@@ -103,7 +112,7 @@ Optimal_page_breaking::solve ()
 
   if (page_count == 1)
     message (_ ("Fitting music on 1 page..."));
-  else if (scm_is_integer (forced_page_count))
+  else if (scm_is_integer (forced_page_count) || page_count == 0)
     message (_f ("Fitting music on %d pages...", (int)page_count));
   else
     message (_f ("Fitting music on %d or %d pages...", (int)page_count - 1, (int)page_count));
@@ -161,8 +170,7 @@ Optimal_page_breaking::solve ()
     }
 
   /* try a larger number of systems than the ideal line breaking number. This
-     is more or less C&P, but the loop bounds make it difficult to try something
-     like do {...} while (flip(&d) != UP). */
+     is more or less C&P. */
   bound = ideal_line_division;
   for (vsize sys_count = ideal_sys_count + 1; sys_count <= max_sys_count; sys_count++)
     {