Fix windows build

[shagren]

I cannot build module on windows via command from README.md: like as --global-option=... not passed to setup.py.
But I can install module from source via python setup.py build_ext -I....
Option --no-use-pep517 is easiest workaround. Let's fix README.

Maybe after #39 some additional fix will be required to build system.

[shagren]

Like as this option helps: --no-use-pep517
There some glues:

• pip install --global-option=build_ext --global-option=... does not take options into account pypa/pip#6398
• Config settings support in PEP 517 pypa/pip#5771
• Add --global-option to egg_info command too pypa/pip#4383

[shagren]

@lpasselin ^

[lpasselin]

@shagren Would you mind trying to install similarly to how they do it here?

warning: I am not sure how to handle spaces in paths on windows.

C:\> set LIB=C:\Program Files\Azure Kinect SDK v1.4.1\sdk\windows-desktop\amd64\release\lib;%LIB%  
C:\> set INCLUDE=C:\Program Files\Azure Kinect SDK v1.4.1\sdk\include;%INCLUDE%  
C:\> pip install pyk4a

Then try example/viewer.py to make sure it can be imported.

[shagren]

@lpasselin ,

C:> set LIB=C:\Program Files\Azure Kinect SDK v1.4.1\sdk\windows-desktop\amd64\release\lib;%LIB%
C:> set INCLUDE=C:\Program Files\Azure Kinect SDK v1.4.1\sdk\include;%INCLUDE%
C:> pip install pyk4a

It's helps with pip. Module compiled and installed. This solution is better then my.

But viewer didn't work:

Traceback (most recent call last):
  File "viewer.py", line 3, in <module>
    import pyk4a
  File "c:\tmp\venv-pyk4a\lib\site-packages\pyk4a\__init__.py", line 1, in <module>
    from .calibration import Calibration, CalibrationType
  File "c:\tmp\venv-pyk4a\lib\site-packages\pyk4a\calibration.py", line 4, in <module>
    import k4a_module
ImportError: DLL load failed while importing k4a_module: The specified module could not be found.

I have tried to add C:\Program Files\Azure Kinect SDK v1.4.1\sdk\windows-desktop\amd64\release\bin to %PATH% but without success.

Next snippet added before import pyk4a helps:

from ctypes import c_wchar_p, windll  
from ctypes.wintypes import DWORD

AddDllDirectory = windll.kernel32.AddDllDirectory
AddDllDirectory.restype = DWORD
AddDllDirectory.argtypes = [c_wchar_p]
AddDllDirectory(r"C:\Program Files\Azure Kinect SDK v1.4.1\sdk\windows-desktop\amd64\release\bin")

[lpasselin]

I have tried to add C:\Program Files\Azure Kinect SDK v1.4.1\sdk\windows-desktop\amd64\release\bin to %PATH% but without success.

I think the problem is only from python 3.8, as detailed here: https://docs.python.org/3/whatsnew/3.8.html

DLL dependencies for extension modules and DLLs loaded with ctypes on Windows are now resolved more securely. Only the system paths, the directory containing the DLL or PYD file, and directories added with add_dll_directory() are searched for load-time dependencies. Specifically, PATH and the current working directory are no longer used, and modifications to these will no longer have any effect on normal DLL resolution.

So if I understand (didn't test), before python 3.8, we could load a DLL by simply including the directory to the PATH environment variable.

At runtime, import pyk4a doesn't work because it cannot find k4a.dll. We can fix this by adding some code to pyk4a.__init__.py

Your code works, probably for python versions 3.8 and before.

from ctypes import c_wchar_p, windll  
from ctypes.wintypes import DWORD

AddDllDirectory = windll.kernel32.AddDllDirectory
AddDllDirectory.restype = DWORD
AddDllDirectory.argtypes = [c_wchar_p]
AddDllDirectory(r"C:\Program Files\Azure Kinect SDK v1.4.1\sdk\windows-desktop\amd64\release\bin")

In python 3.8, we can now use os.add_dll_directory https://docs.python.org/3/library/os.html#os.add_dll_directory

os.add_dll_directory(r"C:\Program Files\Azure Kinect SDK v1.4.1\sdk\windows-desktop\amd64\release\bin")

1. My problem with both solutions is that we need to find the path of the directory containing the DLL. Is there a way to input that during the install like pip install pyk4a --k4a-root="C:\Program Files\Azure Kinect SDK v1.4.1\sdk\"? We would guess for LIB and INCLUDE and remember this k4a-root path to add the DLL at runtime?

2. An other solution is to use github actions to publish precompiled wheels to pypi for windows which would not require installing the k4a SDK by the users. These should include k4a.lib k4arecord.lib k4a.dll k4arecord.dll and depthengine_2_0.dll for every combination of versions {python, windows,k4a¹}. Total filesize for all the required files is around 3MB. This is acceptable if it saves users a lot of time. The solution would probably fix most windows noob problems but take us a while to setup. See example in this project https://github.com/sqlalchemy/sqlalchemy/blob/master/.github/workflows/create-wheels.yaml. Also this approach could make development on windows harder.

What do you think about this? Am I getting something wrong?

¹: we could also force the most recent k4a SDK version and ask people to upgrade their kinect firmware if they want to use pyk4a