[vtk-developers] about vtk python bindings and Qt

[Eric E. Monson]

Hey Clint,

Just in case this will be helpful to you in developing the PythonSIP install rules. I know it's a bit rambling, but hopefully it will make some sense.

On OS X, without the new SIP stuff, I usually don't do a "make instal" into /usr/local, but I do go to [vtk_src]/build/Wrapping/Python and do a "sudo python setup.py install", which puts all of the VTK Python stuff in an egg inside of my site-packages so that I don't have to set the PYTHONPATH at all, but can still "import vtk".

With your SIP stuff, to make "import vtk" work without explicitly setting the PYTHONPATH env variable, I have to copy both libvtkQtPython.so and QVTKPython.so to the site-packages/VTK-5.7.0-py2.6.egg/vtk directory. 

But, somehow with the way that QVTKPython.so imports other modules, even if all of the *PythonSIP.so libraries are sitting in the same directory as the *Python.so files, they're not "seen" when qvtk.py tries to run "from QVTKPython import *". (I get a LinkError: No module named vtkFilteringPythonSIP.) The *PythonSIP.so libraries seem to need to be in the PYTHONPATH for "import vtk" to work and really import QVTKWidget. I can do a bit of a hack and copy all of them into the site-packages/VTK-5.7.0-py2.6.egg/ directory, which is added to the PYTHONPATH by setup tools, but that seems like a non-standard place to put them.

One of the main reasons I bring this up is that it also impacts me when I try to create a standalone application bundle with my PyQt/VTK work. I've been using bundlebuilder and CMake's fixup_bundle to create the app bundles, and there, too, the only way I've figured out how to make it work with QVTKWidget is to put all of the *PythonSIP.so libraries in sort of a non-standard place (not with the rest of the VTK *Python.so files) so they'll be "seen".

As you can tell, I'm not an expert in any of this, but I guess I'm just passing it along in case it will either help with making install rules, or in case there is some other way of coding the SIP stuff so that the *Python.so and *PythonSIP.so files could all be installed in the same spot.

Thanks for putting up with my ramble, and for all the good work getting QVTKWidget wrapped.

-Eric

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Eric E Monson
Duke Visualization Technology Group


On Sep 16, 2010, at 12:34 PM, Clinton Stimpson wrote:

> 
> Ok, I see that it is installing libvtkQtPython to the wrong location.
> As a workaround until it is fixed, you can add /usr/local/lib/vtk-5.7/ to your 
> PYTHONPATH.
> 
> Clint
> 
> On Thursday, September 16, 2010 10:07:11 am Nicola Creati wrote:
>> This is the error:
>> 
>> Traceback (most recent call last):
>>  File "<stdin>", line 1, in <module>
>>  File
>> "/usr/local/lib/python2.6/dist-packages/VTK-5.7.0-py2.6.egg/vtk/qvtk.py",
>> line 8, in <module>
>>    from libvtkQtPython import *
>> ImportError: No module named libvtkQtPython
>> 
>> 
>> My libvtkQtPython.so and  libvtkQtPythonD.so are located in
>> /usr/local/lib/vtk-5.7/.
>> 
>> Nicola