Imported Upstream version 2.18.0

[lilypond.git] / lily / spacing-spanner.cc

diff --git a/lily/spacing-spanner.cc b/lily/spacing-spanner.cc
index 657ff0cd6a9d2b6541b87bfdd8f6a789dbdcf13b..022c6a121949543fa05c7fd4b4fba680aa8b1fea 100644 (file)
--- a/lily/spacing-spanner.cc
+++ b/lily/spacing-spanner.cc
@@ -223,79 +223,66 @@ Spacing_spanner::generate_pair_spacing (Grob *me,
 static void
 set_column_rods (vector<Grob *> const &cols, Real padding)
 {
-  /* distances[i] will be the minimum distance between column i and column i+1 */
-  vector<Real> distances;
+  /* distances[i] will be the distance betwen cols[i-1] and cols[i], and
+     overhangs[j] the amount by which cols[0 thru j] extend beyond cols[j]
+     when each column is placed as far to the left as possible. */
+  vector<Real> distances (cols.size ());
+  vector<Real> overhangs (cols.size ());
 
-  for (vsize i = 1; i < cols.size (); i++)
+  for (vsize i = 0; i < cols.size (); i++)
     {
-      assert (distances.size () == i - 1);
-
       Item *r = dynamic_cast<Item *> (cols[i]);
       Item *rb = r->find_prebroken_piece (LEFT);
 
       if (Separation_item::is_empty (r) && (!rb || Separation_item::is_empty (rb)))
-        {
-          distances.push_back (0);
-          continue;
-        }
+        continue;
 
       Skyline_pair *skys = Skyline_pair::unsmob (r->get_property ("horizontal-skylines"));
-      Real right_stickout = skys ? (*skys)[LEFT].max_height () : 0.0;
+      overhangs[i] = skys ? (*skys)[RIGHT].max_height () : 0.0;
+
+      if (0 == i) continue;
 
-      /* min rather than max because right-stickout will be negative if the right-hand column
+      /* min rather than max because stickout will be negative if the right-hand column
          sticks out a lot to the left */
-      right_stickout = min (right_stickout,
-                            Separation_item::conditional_skyline (r, cols[i - 1]).max_height ());
+      Real stickout = min (skys ? (*skys)[LEFT].max_height () : 0.0,
+                           Separation_item::conditional_skyline (r, cols[i - 1]).max_height ());
 
-      Drul_array<Item *> r_cols (r, rb);
-      Drul_array<Real> cur_dist (0.0, 0.0);
+      Real prev_distances = 0.0;
 
       /* This is an inner loop and hence it is potentially quadratic. However, we only continue
          as long as there is a rod to insert. Therefore, this loop will usually only execute
          a constant number of times per iteration of the outer loop. */
       for (vsize j = i; j--;)
         {
+          if (overhangs[j] + padding <= prev_distances + distances[i] + stickout)
+            break; // cols[0 thru j] cannot reach cols[i]
+
           Item *l = dynamic_cast<Item *> (cols[j]);
           Item *lb = l->find_prebroken_piece (RIGHT);
-          Skyline_pair *skys = Skyline_pair::unsmob (l->get_property ("horizontal-skylines"));
-          Real left_stickout = skys ? (*skys)[RIGHT].max_height () : 0.0;
-          bool done = true;
 
-          for (LEFT_and_RIGHT (d))
-            {
-              if (j < i - 1)
-                cur_dist[d] += distances[j];
+          Real dist = Separation_item::set_distance (l, r, padding);
+          distances[i] = max (distances[i], dist - prev_distances);
 
-              Item *r_col = r_cols[d];
-              bool touches = right_stickout - left_stickout + cur_dist[d] < 0.0;
-              Real dist = 0.0;
-
-              /* we set a distance for the line-starter column even if its non-broken counterpart
-                 doesn't touch the right column. */
-              if (lb)
-                Separation_item::set_distance (lb, r_col, padding);
-
-              if (touches || j == i - 1)
-                dist = Separation_item::set_distance (l, r_col, padding);
-
-              if (j == i - 1 && d == LEFT)
-                distances.push_back (dist);
-
-              if (j == i - 1)
-                cur_dist[d] = distances[j];
-
-              cur_dist[d] = max (cur_dist[d], dist);
-              done = done && !touches;
-
-              if (!rb)
-                break;
+          if (lb)
+            {
+              dist = Separation_item::set_distance (lb, r, padding);
+              // The left-broken version might reach more columns to the
+              // right than the unbroken version, by extending farther and/or
+              // nesting more closely;
+              if (j == i - 1) // check this, the first time we see each lb.
+                overhangs[j] = max (overhangs[j],
+                                    lb->extent (lb, X_AXIS)[RIGHT]
+                                    + distances[i] - dist);
             }
+          if (rb)
+            Separation_item::set_distance (l, rb, padding);
+          if (lb && rb)
+            Separation_item::set_distance (lb, rb, padding);
 
-          /* we need the empty check for gregorian notation, where there are a lot of
-             extraneous paper-columns that we need to skip over */
-          if (done && !Separation_item::is_empty (l))
-            break;
+          prev_distances += distances[j];
         }
+      overhangs[i] = max (overhangs[i],
+                          overhangs[i - 1] - distances[i]);
     }
 }