public static void ClearFast(this AnnotationPathPointCollection collection)
 {
     collection.SuspendUpdates();
     while (collection.Count > 0)
     {
         collection.RemoveAt(collection.Count - 1);
     }
     collection.ResumeUpdates();
 }
 public PolylineAnnotation()
 {
     GraphicsPathPoints = new AnnotationPathPointCollection();
 }