public static void GetFreePathWriter(out PixelFarm.Agg.VertexSource.PathWriter p)
 {
     if (s_pathWriters.Count > 0)
     {
         p = s_pathWriters.Pop();
     }
     else
     {
         p = new Agg.VertexSource.PathWriter();
     }
 }
 public static void ReleasePathWriter(ref PixelFarm.Agg.VertexSource.PathWriter p)
 {
     p.Clear();
     s_pathWriters.Push(p);
     p = null;
 }