[vtkusers] vtkImageAlgorithm output to preallocated buffer

[Alessandro Volz]

I'm using vtkImageReslice to obtain a vtkImageData object that I read the output scalars from. All works fine.
I'm now in a situation where it would make sense that I preallocate thee output buffer for the reslice to write into.
Is there a way to do this? 
I thought I'd create a vtkImageData and SetScalarPointer on it, then SetOutput on the reslice. But I haven't been able to.
Is there a way I could do this? Maybe I should create a vtkImageData subclass?
Thanks,
Alessandro