[vtkusers] repeated imagerotation

[Matthias Zangl]

Hello!

I am trying to write a rotation which is interacted by the user. That means
the user is able to rotate the image on clicking a button.

This is working fine.

1. But every time I've to delete and create the vtkTransform-object -
otherwise I couldn't reset the transformation and the previous one would be
continued. I think there is a better way to care about this!

2. If I wouldn't re-create the vtkImageReslice every time (before rotating),
I am always getting warnings about the extent (Update extent does not lie
within whole extent) and the extent isn't adapted to the new rotation. I
could imagine to manually set the output extent, but I am also looking for
another method to correctly reset the vtkImageReslice. There should be one,
right?

Any hints are greatly appreciated!

Thanks in advance,
Matt