How to run vtkRenderWindow in background without display it to user - c++

Question

Im working in code which can create coronal, saggital, and axial image from dicom file, but In the same time I dont need to display renderWindow to user, and this is my code:
int main(int argc, char* argv[])
{
// Verify input arguments
if ( argc != 2 )
{
std::cout << "Usage: " << argv[0]
<< " FolderName" << std::endl;
return EXIT_FAILURE;
}
std::string folder = argv[1];
//std::string folder = "C:\\VTK\\vtkdata-5.8.0\\Data\\DicomTestImages";
// Read all the DICOM files in the specified directory.
vtkSmartPointer<vtkDICOMImageReader> reader =
vtkSmartPointer<vtkDICOMImageReader>::New();
reader->SetDirectoryName(folder.c_str());
reader->Update();
// Visualize
vtkSmartPointer<vtkImageViewer2> imageViewer =
vtkSmartPointer<vtkImageViewer2>::New();
imageViewer->SetInputConnection(reader->GetOutputPort());
imageViewer->SetSlice(0);
imageViewer->Render();
for(int k = 0; k < 3; k++){
cout<< k << endl;
if(k == 0){
imageViewer->SetSliceOrientationToYZ();
}else if(k == 1){
imageViewer->SetSliceOrientationToXZ();
}else{
imageViewer->SetSliceOrientationToXY();
}
int _MinSlice = imageViewer->GetSliceMin();
int _MaxSlice = imageViewer->GetSliceMax();
// Screenshot
vtkSmartPointer<vtkWindowToImageFilter> windowToImageFilter =
vtkSmartPointer<vtkWindowToImageFilter>::New();
vtkSmartPointer<vtkPNGWriter> writer =
vtkSmartPointer<vtkPNGWriter>::New();
for (int i = _MinSlice; i < _MaxSlice; i++){
vtkSmartPointer<vtkWindowToImageFilter> windowToImageFilter =
vtkSmartPointer<vtkWindowToImageFilter>::New();
vtkSmartPointer<vtkPNGWriter> writer =
vtkSmartPointer<vtkPNGWriter>::New();
windowToImageFilter->SetInput(imageViewer->GetRenderWindow());
windowToImageFilter->ReadFrontBufferOff(); // read from the back buffer
windowToImageFilter->Update();
std::string filename = "img/" + std::to_string(k) + "/" + std::to_string(i) + ".png";
char *y = new char[filename.length() + 1];
std::strcpy(y, filename.c_str());
writer->SetFileName(y);
writer->SetInputConnection(windowToImageFilter->GetOutputPort());
writer->Write();
imageViewer->SetSlice(i);
imageViewer->Render();
}
}
return EXIT_SUCCESS;
}
my issue is when try imageViewer->SetRenderWindow(NULL); Or imageViewer->GetRenderWindow()->Delete(); its will remove renderWindow instance, and code will be break, so that how I can keep renderWindow work in background without display it to user?
Thanks

Answer 1

You can use SetShowWindow(bool) or ShowWindowOff(), these methods are inherited from vtkWindow. Doing so should not stop the rendering pipeline (you can probably still use windowToImageFilter) but tbh I did not test it. Let us know if it worked.