class MyTrihedron : public V3d_Trihedron
{
public:
  MyTrihedron() {}

  void UpdatePosition (const Handle(V3d_View)& theView)
  {
    const gp_Pnt anOrigin = gp::Origin();
    SetScale (0.1);
    Display (*theView);

    Graphic3d_Vec2i aPosOnScreen, aWinSize;
    theView->Convert (anOrigin.X(), anOrigin.Y(), anOrigin.Z(),
                      aPosOnScreen.x(), aPosOnScreen.y());
    theView->Window()->Size (aWinSize.x(), aWinSize.y());
    const bool isOriginOnScreen = aPosOnScreen.x() >= 0
                               && aPosOnScreen.x() <= aWinSize.x()
                               && aPosOnScreen.y() >= 0
                               && aPosOnScreen.y() <= aWinSize.y();
    if (isOriginOnScreen)
    {
      myTransformPers = new Graphic3d_TransformPers (Graphic3d_TMF_ZoomPers,
                                                     anOrigin);
    }
    else
    {
      myTransformPers = new Graphic3d_TransformPers (Graphic3d_TMF_TriedronPers,
                                                     Aspect_TOTP_LEFT_LOWER);
      SetPosition (Aspect_TOTP_LEFT_LOWER);
    }
    if (!myStructure.IsNull())
    {
      myStructure->SetTransformPersistence (myTransformPers);
    }
  }
};

void appOnViewRedraw (const Handle(V3d_View)& theView)
{
  static Handle(MyTrihedron) myTrihedron = new MyTrihedron();
  myTrihedron->UpdatePosition (theView);
  theView->Redraw();
}