if (!fileName.isEmpty()) {
vtkSmartPointer<vtkWindowToImageFilter> w2i = vtkSmartPointer<vtkWindowToImageFilter>::New();
w2i->SetInput(widget->GetRenderWindow());
if (!fileName.isEmpty()) {
vtkSmartPointer<vtkWindowToImageFilter> w2i = vtkSmartPointer<vtkWindowToImageFilter>::New();
w2i->SetInput(widget->GetRenderWindow());