[vtkusers] Issues moving code to a function and returning a smart pointer

[David Doria]

On Fri, May 17, 2013 at 3:43 PM, Manuel Corrales
<manuelcorrales at gmail.com> wrote:
> Hello all. I have a simple code that reads an image using ITK, then it
> convert it to VTK and after that I display the image in a QVTKWidget. The
> code is this and works fine:
>
>      typedef itk::Image< double, 2 >         ImageType;
>       typedef itk::ImageToVTKImageFilter<ImageType> ConnectorType;
>       typedef itk::ImageFileReader<ImageType> ReaderType;
>
>       ReaderType::Pointer reader = ReaderType::New();
>       reader->SetFileName(file.c_str());
>       reader->Update();
>
>       ConnectorType::Pointer connector = ConnectorType::New();
>       connector->SetInput(reader->GetOutput());
>       connector->Update();
>       ImageReader *myReader = new ImageReader();
>       vtkSmartPointer<vtkImageViewer2> vtkImageViewer =
> vtkSmartPointer<vtkImageViewer2>::New();
>       vtkImageViewer->SetInput(connector->GetOutput());
>       vtkImageViewer->SetRenderWindow(this->qvtkWidget->GetRenderWindow());
>       vtkImageViewer->Render();
>
>
> Now if I change this code and create a separate function to perform the
> connection from ITK to VTK, I get a segfault:
>
> ImageReader *myReader = new ImageReader();
>       vtkSmartPointer<vtkImageViewer2> vtkImageViewer =
> myReader->renderITKReaderInVTK(file);
>       vtkImageViewer->SetRenderWindow(this->qvtkWidget->GetRenderWindow());
>       vtkImageViewer->Render();
>
> and the called function:
>
> vtkSmartPointer<vtkImageViewer2>
> ImageReader::renderITKReaderInVTK(std::string fileName) {
>     typedef itk::Image< double, 2 >         ImageType;
>     typedef itk::ImageToVTKImageFilter<ImageType> ConnectorType;
>     typedef itk::ImageFileReader<ImageType> ReaderType;
>
>     ReaderType::Pointer reader = ReaderType::New();
>     qDebug() << "Setting reader file name";
>     reader->SetFileName(fileName.c_str());
>     qDebug() << "Updating reader";
>     reader->Update();
>
>     ConnectorType::Pointer connector = ConnectorType::New();
>     qDebug() << "Setting input to connector";
>     connector->SetInput(reader->GetOutput());
>     qDebug() << "Updating connector";
>     connector->Update();
>
>     vtkSmartPointer<vtkImageViewer2> vtkImageViewer =
> vtkSmartPointer<vtkImageViewer2>::New();
>     qDebug() << "Setting connector outupt -> imageViewer input";
>     vtkImageViewer->SetInput(connector->GetOutput());
>     qDebug() << "Image viewer set up ready";
>     return vtkImageViewer;
> }
>
> Any ideas why the same code (I think) works if it is all together but fail
> when it's in a different function?
>
> Thanks in advance!
> Regards,
> Manuel.


It is much easier for us if you provide a compilable example of the
error. I tried the following, but it seems to work fine. If you can
provide something like this that segfaults, I'm sure someone can help
you out.

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkImageViewer2.h>

#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageToVTKImageFilter.h"

vtkSmartPointer<vtkImageViewer2> CreateImageViewer();

int main(int, char *[])
{

    typedef itk::Image< double, 2 >         ImageType;
     typedef itk::ImageToVTKImageFilter<ImageType> ConnectorType;
     typedef itk::ImageFileReader<ImageType> ReaderType;

     ReaderType::Pointer reader = ReaderType::New();
     reader->SetFileName("test.png");
     reader->Update();

     ConnectorType::Pointer connector = ConnectorType::New();
     connector->SetInput(reader->GetOutput());
     connector->Update();

     vtkSmartPointer<vtkImageViewer2> imageViewer = CreateImageViewer();
     imageViewer->SetInputData(connector->GetOutput());
     imageViewer->Render();

  return EXIT_SUCCESS;
}

vtkSmartPointer<vtkImageViewer2> CreateImageViewer()
{
    vtkSmartPointer<vtkImageViewer2> imageViewer =
vtkSmartPointer<vtkImageViewer2>::New();
    return imageViewer;
}