Gets vertical skylines from grob stencils

lily/skyline-pair.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 2008--2012 Han-Wen Nienhuys <hanwen@lilypond.org>
 
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
@@ skipping 38 matching lines @@
 }
 
 void
 Skyline_pair::raise (Real r)
 {
   skylines_[UP].raise (r);
   skylines_[DOWN].raise (r);
 }
 
 void
-Skyline_pair::grow (Real r)
-{
-  skylines_[UP].raise (r);
-  skylines_[DOWN].raise (-r);
-}
-
-void
 Skyline_pair::deholify ()
 {
   skylines_[UP].deholify ();
   skylines_[DOWN].deholify ();
 }
 
 void
 Skyline_pair::shift (Real r)
 {
   skylines_[UP].shift (r);
   skylines_[DOWN].shift (r);
 }
 
 void
 Skyline_pair::insert (Box const &b, Axis a)
 {
   skylines_[UP].insert (b, a);
   skylines_[DOWN].insert (b, a);
 }
 
 Real
-Skyline_pair::left ()
+Skyline_pair::left () const
 {
   return min (skylines_[UP].left (), skylines_[DOWN].left ());
 }
 
 Real
-Skyline_pair::right ()
+Skyline_pair::right () const
 {
   return max (skylines_[UP].right (), skylines_[DOWN].right ());
 }
 
+// This function comes with the same caveats as smallest_shift:
+// if the skylines are not contiguous, we may report false
+// intersections.
+bool
+Skyline_pair::intersects (Skyline_pair const &other) const
+{
+  return skylines_[UP].distance (other[DOWN]) > 0
+         && other[UP].distance (skylines_[DOWN]) > 0;
+}
+
 Real
-Skyline_pair::smallest_shift (Skyline_pair const& other, Direction d,
+Skyline_pair::smallest_shift (Skyline_pair const &other, Direction d,
                               Real h_pad, Real v_pad)
 {
   // If skylines_[UP] avoids other[DOWN] or skylines_[DOWN] avoids
-  // other[UP] then we will not intersect. Substitue LEFT for DOWN
-  // and RIGHT for UP in the case where the skyline is horizontal.
+  // other[UP] then we will not intersect.
   // Note that this is not guaranteed to return the smallest shift
   // if one Skyline_pair is not connected: the smallest_shift left
   // in the case of
   // AAA
   // BBBBBB
   //    AAA
   // will result in
   //    AAA
   // BBBBBB
   //       AAA
@@ skipping 80 matching lines @@
   Direction dir = robust_scm2dir (dir_scm, UP);
 
   if (dir == CENTER)
     {
       warning (_f ("direction must not be CENTER in ly:skyline-pair::skyline"));
       dir = UP;
     }
 
   return (*sp)[dir].smobbed_copy ();
 }