From ctypes of libcgmic to a true C++ binding

[myselfhimself]

This is a just an issue to help me work on the next step:

• we currently have basic pytests passing for python2 and python3 in the Github Actions CI, they rely on a ctypes dynamic loading of a live built libcgmic.so library embedding libgmic. The code is ugly but working. This is acceptable at this POC state.
• we now want to create a python/c++ binding fulfilling the same test suite, in two variants which do not rely on libcgmic anymore:
  • python .py/.so module relying on libgmic.so
  • same embedding libgmic.so statically.

Inspiration for this binding: https://docs.microsoft.com/en-us/visualstudio/python/working-with-c-cpp-python-in-visual-studio?view=vs-2019
A gut feeling tells me I do not want to use any generator like SWIG..

[myselfhimself]

Numpy will drop Python 2.7 support from january 2020, following the official python2.7 support drop: https://numpy.org/neps/nep-0014-dropping-python2.7-proposal.html
=> Dropping 2.7 from the github workflow cpython variant CI

[myselfhimself]

Blender3d's builtin Python version is 3.5 for the 2.79 release (before latest):
https://blender.stackexchange.com/questions/98608/python-system-version-vs-python-blender-internal-version

[myselfhimself]

Inkscape 1.0 and 0.92.5 are to support python 2 & 3 for extensions : https://bugs.launchpad.net/ubuntu/+source/inkscape/+bug/1735363/comments/25

[myselfhimself]

Let us renounce to develop a cpython 2.7 binding and focus on python 3.x

[dtschump]

Yes, definitely !

[myselfhimself]

On the cpython .so implementation simple tests (import module, hello world, png generation and output) all pass but for the "pip install -e". See failing test suite.

Will now proceed to using either pip download a .so binary file or pip install of a so-called platform wheel to be custom built by architecture and python platform...

[myselfhimself]

Work is in progress and packaging effort now for all sorts of linux glibc versions (on centos & ubuntu namely) happens in the Github actions : https://github.com/dtschump/gmic-py/actions

[myselfhimself]

The Github Workflow seems to provide non-headless OSes because even selenium/google-chrome-based github projects run through it: https://help.github.com/en/actions/automating-your-workflow-with-github-actions/virtual-environments-for-github-hosted-runners
...So X11 functionalities basic testing could be achievable...

[myselfhimself]

Manylinux binary .whl files now compile.
They are uploaded here: https://pypi.org/project/gmic/2.8.0.dev1/#files
They do run nicely on a recent Ubuntu 18.04, despite being compiled on CentOS:

$ pip install --only-binary :all: --no-cache-dir gmic
Collecting gmic
  Downloading https://files.pythonhosted.org/packages/f1/ae/627d236501c4d6e44055e7a46e60f4f7075fb07b1291361242922dd72bd5/gmic-2.8.0.dev1-cp36-cp36m-manylinux1_x86_64.whl (6.0MB)
     |████████████████████████████████| 6.0MB 4.3MB/s 
Installing collected packages: gmic
Successfully installed gmic-2.8.0.dev1

Exceptions are handled grossly, but handled:

$ python3
Python 3.6.9 (default, Nov  7 2019, 10:44:02) 
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import gmic
>>> gmic.run("bonsoir")
Exception: *** Error in ./ *** Unknown command or filename 'bonsoir'.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
SystemError: <built-in function run> returned a result with an error set

basic commands do run:

>>> gmic.run('echo_stdout "gmic hey"')
gmic hey
True

[myselfhimself]

I will add the twine upload soon in the Github Workflow/Actions CI/CD, for binary + source packages.

[myselfhimself]

We have reproduced this issue of linking against gomp (-lgomp) on CentOS manylinux system from setup.py:
https://bugs.python.org/msg128974
This is disabled for now and may mean lacking Gmic OpenMP support for now, or possible crashes.
Additional pytest test cases should be made to ensure that, since all tests are run after building in the CI.

[myselfhimself]

X display work on Linux, windows do pop up, so the linking against Xlibs works OK!!!

~/Productions/GMIC/gmic-py/cpython/wheelhouse$ 
$ pip install gmic-2.8.0.dev1-cp36-cp36m-manylinux1_x86_64.whl
Processing ./gmic-2.8.0.dev1-cp36-cp36m-manylinux1_x86_64.whl
Installing collected packages: gmic
Successfully installed gmic-2.8.0.dev1
~/Productions/GMIC/gmic-py/cpython/wheelhouse$ 
$ python3
Python 3.6.9 (default, Nov  7 2019, 10:44:02) 
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import gmic
>>> gmic.run('echo_stdout "hello"')
hello
True
>>> gmic.run('sample lena display')
True
>>> gmic.run('sample leno display')

[myselfhimself]

Many more architecture binaries + source are now on Pypi : https://pypi.org/project/gmic/2.8.0.dev4/#files

[myselfhimself]

MacOSX 10.6 (with libcurl), ManyLinux 2010+2014 32+64bits (without libcurl but curl executable fallback) non-optimized builds are now out on PyPI: https://pypi.org/project/gmic/2.8.1.dev2/#files .
OpenMP is enabled for all and successfully pytest'ed.

Coming up soon : optimized builds, GmicImage support in gmic.run()