Re: [ctypes-users] Returning propper pyobjects.

[Thomas H. <th...@ct...>]

tarjei schrieb:
> Hi,  I've written a short c-function to convert an image in OpenCV (a
> nice image analysis library) to a PyArray_Object * , and now I seek
> suggestions on how to import this through ctypes (the other option being
> to wrestle with SWIG).
> 
> The library in question is allready imported through cTypes (not by me)
> and now I'm trying find out how to map my function.
> 
> The function signature looks like this:
> PyArrayObject *  cvImageToPyArray(IplImage * image, int channel);
> 
> If someone could point me in the correct direction wrt to how to define
> the returntype I would be greatfull.

Short answer:  For calling funtions that use the Python calling convention
(do NOT release the GIL during the function call, check PyErr_Occurred() after
the function has returned) you must use the PyDLL object to load the library.
Then, you have to set the .restype attribute of the funtion object to py_object;
this will handle the refcount correctly (assuming that the funtion returns a new
reference).

> Even better would be some sample code doing the PyArrayObject mapping.

Sorry, no time for that.

Thomas