public AuxiliaryLineRectangleObserver(Polyline polyline, AuxiliaryController ac)
 {
     Polyline = polyline;
     AC       = ac;
     AC.Attach(this);
     Draw(AC);
 }
 public TrimmingImageLengthObserver(ContentControl cc, ImageController ic, AuxiliaryController ac)
 {
     CC = cc;
     IC = ic;
     AC = ac;
     AC.Attach(this);
     Draw(AC);
 }