[vtkusers] Moving a class from 4.0 to 3.2

[Prabhu Ramachandran]

hi,

>>>>> "EB" == Eric Boix <frog at creatis.insa-lyon.fr> writes:

    EB>         Dear vtk[3-4].X + Python[1-2].Y users,

    EB>         I would like to use the new vtkPNGWriter (thanks dear
    EB> developpers) vtkClass as taken from vtk version4.0. Alas I
    EB> failed in using vtk4.0.  I simply couldn't get VTK4.0 +
    EB> Python2.1 + wxPython2.3 + MyApplication to run as smoothly as
    EB> vtk3.2Nightly + python1.5 +...+ MyApplication. For sure
    EB> MyApplication and my low milage are to blame ! [flame me here]

I suggest that you try to stick to vtk 4.0 + Python2.1 and
wxPython2.3.  I have been using all of these under linux except for
wxPython (I use verson 2.2.6) and it works well.  If you have specific
problems let me know.  Will _try_ to help.

<snip>

    EB>         Anyhow, here are my questions : is there any reason
    EB> for this "porting" strategy to fail (like a deep
    EB> incompatiblity in the data structures implied by the different
    EB> versions of vtkObjectFactory::CreateInstance, or something
    EB> even more obscure to me) ?  Is there a simple work-around or
    EB> should my approach be definitively discouraged ? [flame me
    EB> here again]

The png writer needs to be linked with libpng.so and maybe with
libzlib.so.  So I have no idea how you are going to work your way to
make VTK 3.2 do that _easily_.  It is possible but IMHO worth porting
your app to 4.0 rather than going through porting vtkPNGWriter to 3.2.
By porting the writer you will be forced to re-hack your solution each
time you update your 3.2 tree.  Also, there is going to be a time when
you eventually have to upgrade to 4.0.

prabhu