Gets vertical skylines from grob stencils

lily/bezier.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 1998--2012 Jan Nieuwenhuizen <janneke@gnu.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 127 matching lines @@
 #endif
 
   return o;
 }
 
 Real
 Bezier::slope_at_point (Real t) const
 {
   Offset second_order[3];
   Offset third_order[2];
-  
+
   for (vsize i = 0; i < 3; i++)
     second_order[i] = ((control_[i + 1] - control_[i]) * t) + control_[i];
 
   for (vsize i = 0; i < 2; i++)
     third_order[i] = ((second_order[i + 1] - second_order[i]) * t) + second_order[i];
 
   if (third_order[1][X_AXIS] - third_order[0][X_AXIS] == 0)
     return infinity_f;
 
   return (third_order[1][Y_AXIS] - third_order[0][Y_AXIS]) / (third_order[1][X_AXIS] - third_order[0][X_AXIS]);
@@ skipping 97 matching lines @@
   Interval iv;
   for (vsize i = sols.size (); i--;)
     {
       Offset p (curve_point (sols[i]));
       if (p[ax] >= l && p[ax] <= r)
         iv.add_point (p[bx]);
     }
 
   //  or intersections of the curve with the bounding lines at L and R.
   Interval lr (l, r);
-  Direction dir = LEFT;
-  do
+  for (LEFT_and_RIGHT (dir))
     {
       vector<Real> v = get_other_coordinates (ax, lr[dir]);
       for (vsize i = v.size (); i--;)
         iv.add_point (v[i]);
     }
-  while (flip (&dir) != LEFT);
 
   if (iv.is_empty ())
     {
       programming_error ("Bezier curve does not cross region of concern");
       return 0.0;
     }
 
   return iv.at (d);
 }
 
@@ skipping 113 matching lines @@
   else
     subdivide (t_min, &bez1, &bez2);
   if (t_max == 1.0)
     return bez2;
   else
     {
       bez2.subdivide ((t_max - t_min) / (1 - t_min), &bez3, &bez4);
       return bez3;
     }
 }