Makes sure that ledger lines do not overlap with accidentals. (issue 4898060)

[mtsolo]

Reviewers: ,

Description:
Makes sure that ledger lines do not overlap with accidentals.

Please review this at http://codereview.appspot.com/4898060/

Affected files:
  M lily/ledger-line-spanner.cc


Index: lily/ledger-line-spanner.cc
diff --git a/lily/ledger-line-spanner.cc b/lily/ledger-line-spanner.cc
index  
01238222147c9afbf4f33a2e6b62ac2018a46c9f..9487034eabdca68f4cf93df9251e596013b4203c  
100644
--- a/lily/ledger-line-spanner.cc
+++ b/lily/ledger-line-spanner.cc
@@ -18,6 +18,7 @@
 */

 #include <map>
+#include <set>
 using namespace std;

 #include "note-head.hh"
@@ -34,6 +35,7 @@ struct Ledger_line_spanner
   DECLARE_SCHEME_CALLBACK (set_spacing_rods, (SCM));
   static Stencil brew_ledger_lines (Grob *me,
                                     int pos,
+                                    set<int> &poss,
                                     Interval,
                                     Real, Real,
                                     Interval x_extent,
@@ -45,6 +47,7 @@ struct Ledger_line_spanner
 Stencil
 Ledger_line_spanner::brew_ledger_lines (Grob *staff,
                                         int pos,
+                                        set<int> &poss,
                                         Interval staff_extent,
                                         Real halfspace,
                                         Real ledgerlinethickness,
@@ -74,8 +77,16 @@ Ledger_line_spanner::brew_ledger_lines (Grob *staff,
                   : -dir * halfspace;

       offs += pos * halfspace;
+      set<int>::iterator it;
+      set<int> local_poss;
+
+      for (it = poss.begin (); it != poss.end (); it++)
+        local_poss.insert (max (0, line_count - *it));
+
       for (int i = 0; i < line_count; i++)
         {
+          if (local_poss.find (i) != local_poss.end () && i)
+            continue;
           Stencil ledger_line ((i == 0)
                                ? proto_first_line
                                : proto_ledger_line);
@@ -315,6 +326,17 @@ Ledger_line_spanner::print (SCM smob)
   // create ledgers for note heads
   Real ledgerlinethickness
     = Staff_symbol::get_ledger_line_thickness (staff);
+
+  Drul_array<set<int > > poss;
+  for (vsize i = heads.size (); i--;)
+    {
+      Item *h = dynamic_cast<Item *> (heads[i]);
+
+      int pos = Staff_symbol_referencer::get_rounded_position (h);
+      if (!staff_extent.contains (pos - sign (pos))  
&& !staff_extent.is_empty ())
+        poss[(Direction) sign (pos)].insert (sign (pos) * int (rint (pos -  
staff_extent[Direction (sign (pos))])) / 2);
+    }
+
   for (vsize i = heads.size (); i--;)
     {
       Item *h = dynamic_cast<Item *> (heads[i]);
@@ -347,7 +369,9 @@ Ledger_line_spanner::print (SCM smob)
               */
             }

-          ledgers.add_stencil (brew_ledger_lines (staff, pos, staff_extent,
+          ledgers.add_stencil (brew_ledger_lines (staff, pos,
+                                                  poss[(Direction) sign  
(pos)],
+                                                  staff_extent,
                                                   halfspace,
                                                   ledgerlinethickness,
                                                   ledger_size,