Enable cairo python bindings?

[JamesRamm]

How to enable cairo python bindings in the mapnik build?

HAVE_CAIRO is defined and mapnik builds with cairo support. But mapnik.have_pycairo() returns false.

[JamesRamm]

Browsing the code, looks like I need to make sure HAVE_PYCAIRO is defined aswell - mapnik_python.cpp checks for both HAVE_CAIRO and HAVE_PYCAIRO.

I suppose this will not be enough though, because mapnik_python.cpp is gonna attempt to #include pycairo.h and it looks like the cairo build undertaken when building the dependencies didn't do anything about pycairo.. hmf.

So I'm thinking I need to install pycairo, then ensure that my python\include directory where pycairo.h is hopefully gonna turn up is in my list of includes for mapnik-gyp...
Is this the 'normal' way of building with pycairo support?

[JamesRamm]

Any info on this?
related: mapnik/mapnik-packaging#22

I suspect I am simply not correctly defining library paths in the gyp file, but there isn't much to go on to figure it out....

[JamesRamm]

Adding cairo.lib to the libraries section of the _mapnik target in the gyp file seems to have done the trick. Also need to add the -lcairo flag.

Easy when you know how - this could really do with documenting.

[JamesRamm]

Mapnik built with pycairo, but attempting to render to a pycairo context causes the python interpreter to hang.
Seg fault perhaps?

Clearly there is something not right in the build...

[springmeyer]

I think you are on the right track. I've never tried to get pycairo working on windows, so thanks for helping with this. Can you describe how to installed pycairo exactly?

[JamesRamm]

Here is what I've done (evidently it is wrong as mapnik won't render with cairo, but mapnik does build happily)

Ok..the version of pycairo I had installed when building was py2cairo-1.10.0 and I just downloaded the installer from gohlke (http://www.lfd.uci.edu/~gohlke/pythonlibs/) and ran it. That gave me a pycairo.h file in my python installation and a package called cairo containing _cairo.pyd.

In the gyp & bat file, I made sure that the python version being used was the one to which I had installed pycairo. In the _mapnik target section I added cairo.lib and pycairo.h.

This was it. Mapnik builds and tests pass.

Then I tried to run python with mapnik/cairo. First it complained about missing dll's and I followed a tutorial in issue #22 to fill in the missing deps. Cairo then works from python, but attempting to call mapnik.render with a cairo Context ends up with python.exe hanging/crashing.

There is obv. something bad happening at some point, but I am at a loss as to where. Do we need to build our own pycairo bindings?.

I'll put up a step-by-step of what I changed in the build files a little later...