skia-python isn't detected albeit present

[blackbit42]

Since it was advised in https://github.com/30350n/pcb2blender/issues/62 that my blender was too old, I now created an environment in which I can run a new enough blender (4.1.1+dfsg-2+b1).

Unfortunately that setup is not as straight forward as I would like it to be and I ran into an issue.

Setup:

• Debian unstable/experimental chroot - This allows me to install a new enough blender without messing up my main Debian installation. Blender works as expected in the chroot.
• Python dependencies are installed in the chroot via venv and pip because not all dependencies are available via debian packages. (skia-python) is missing.

I've installed all required dependencies

• requests (which is an undocumented dependency by the way)
• numpy
• pillow
• skia-python

The first three entries in the list above are detected as expected, but skia-python isn't and I struggle to understand why.

I run blender like so: PYTHONPATH=$HOME/.venv/blender_deps/lib/python3.12/site-packages/ blender --python-use-system-env

the following works just fine: PYTHONPATH=$HOME/.venv/blender_deps/lib/python3.12/site-packages/:$HOME/.config/blender/4.1/scripts/addons/pcb2blender_importer/site-packages/ python3 -c 'from skia import SVGDOM, Color4f, Stream, Surface'

skia-python is in the same site-packages directory as all other dependencies. I am not sure why it isn't detected.

[30350n]

What's the specific error you are getting?

Any specific reason why you aren't using the automatic dependency installation mechanism this addon provides?

requests (which is an undocumented dependency by the way)

If packaged correctly, Blender should come with it's own python installation which already comes with requests and numpy installed.

Also note: The correct python version for Blender 4.1 is 3.11.7.

[blackbit42]

What's the specific error you are getting?

It's difficult to respond to that question in a straight-forward fashion. I worked through multiple issues with undetected / missing dependencies that I was able to address myself. Eventually I ended up with the situation described above. The addon dialog of blender now reports this: There are no python backtraces or something like that during startup of blender. Debian stopped to support pip as such a while ago. I have pip installed, but depressing the 'Install skia-python' button doesn't yield the intended effect, unsurprisingly. What is surprising though is that blender believes skia-python isn't there. In fact it is, as outlines above.

If packaged correctly, Blender should come with it's own python installation

This doesn't seem to be the case on Debian. The blender package doesn't depend on either requests or numpy. Can you provide a reference to the blender requirement? I am happy to open a Debian bug to get this fixed.

Also note: The correct python version for Blender 4.1 is 3.11.7.

The python version on my system is 3.11.2.

[30350n]

What is surprising though is that blender believes skia-python isn't there. In fact it is, as outlines above.

That UI in the preferences is not native, but comes from my addon (from the blender_addon_utils submodule to be exact. To check if skia is installed it'd checking if importlib_util.find_spec("skia") returns something. Not sure why that doesn't work in your case.

[30350n]

If packaged correctly, Blender should come with it's own python installation

This doesn't seem to be the case on Debian.

Are you sure about that? If you launch Blender normally (without --python-use-system-env) and open a python console in it, what does sys.executable evaluate to?

[blackbit42]

The python version on my system is 3.11.2.

That was an incorrect statement. My unstable chroot has python 3.12.4.

To check if skia is installed it'd checking if importlib_util.find_spec("skia") returns something. Not sure why that doesn't work in your case.

$ PYTHONPATH=$HOME/.venv/blender_deps/lib/python3.12/site-packages/:$HOME/.config/blender/4.1/scripts/addons/pcb2blender_importer/site-packages/ python3
Python 3.12.4 (main, Jun 12 2024, 19:06:53) [GCC 13.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import importlib.util
>>> importlib.util.find_spec("skia")
ModuleSpec(name='skia', loader=<_frozen_importlib_external.ExtensionFileLoader object at 0x7f8e5f39baa0>, origin='/home/blackbit/.venv/blender_deps/lib/python3.12/site-packages/skia.cpython-312-x86_64-linux-gnu.so')

Does this provide any insights?

If you launch Blender normally (without --python-use-system-env) and open a python console in it, what does sys.executable evaluate to?

PYTHON INTERACTIVE CONSOLE 3.11.9 (main, Apr 10 2024, 13:16:36) [GCC 13.2.0]

Builtin Modules:       bpy, bpy.data, bpy.ops, bpy.props, bpy.types, bpy.context, bpy.utils, bgl, gpu, blf, mathutils
Convenience Imports:   from mathutils import *; from math import *
Convenience Variables: C = bpy.context, D = bpy.data

>>> import sys
>>> sys.executable
'/home/blackbit/.venv/blender_deps/bin/python'

>>> 

lrwxrwxrwx 1 blackbit blackbit    7 2024-06-23 22:50 python -> python3
lrwxrwxrwx 1 blackbit blackbit   16 2024-06-23 22:50 python3 -> /usr/bin/python3
lrwxrwxrwx 1 blackbit blackbit    7 2024-06-23 22:50 python3.12 -> python3

$ /usr/bin/python3 -V
Python 3.12.4

[30350n]

>>> import sys
>>> sys.executable
'/home/blackbit/.venv/blender_deps/bin/python'

That looks like your environment variables are still messed up, it shouldn't use that venv by default.

$ PYTHONPATH=$HOME/.venv/blender_deps/lib/python3.12/site-packages/:$HOME/.config/blender/4.1/scripts/addons/pcb2blender_importer/site-packages/ python3
Python 3.12.4 (main, Jun 12 2024, 19:06:53) [GCC 13.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import importlib.util
>>> importlib.util.find_spec("skia")
ModuleSpec(name='skia', loader=<_frozen_importlib_external.ExtensionFileLoader object at 0x7f8e5f39baa0>, origin='/home/> blackbit/.venv/blender_deps/lib/python3.12/site-packages/skia.cpython-312-x86_64-linux-gnu.so')

Does this provide any insights?

Not really, as you are using your systems python version. Try evaluating importlib.util.find_spec("skia") from within Blender too.

[blackbit42]

That looks like your environment variables are still messed up, it shouldn't use that venv by default.

Any ideas?

YTHON INTERACTIVE CONSOLE 3.11.9 (main, Apr 10 2024, 13:16:36) [GCC 13.2.0]

Builtin Modules:       bpy, bpy.data, bpy.ops, bpy.props, bpy.types, bpy.context, bpy.utils, bgl, gpu, blf, mathutils
Convenience Imports:   from mathutils import *; from math import *
Convenience Variables: C = bpy.context, D = bpy.data

>>> import importlib.util
>>> importlib.util.find_spec("skia")
>>> 

that is from within blender.

[30350n]

Any ideas?

Is PYTHONPATH or BLENDER_SYSTEM_PYTHON still set? If so unset those.

>>> import importlib.util
>> importlib.util.find_spec("skia")
>> 

that is from within blender.

That's the problem. I'm guessing from skia import SVGDOM, Color4f, Stream, Surface doesn't here too?

[blackbit42]

raceback (most recent call last):
  File "<blender_console>", line 1, in <module>
ModuleNotFoundError: No module named 'skia'

>>> 

This is consistent with the statement the GUI makes. I am rather puzzled why after gradually installing other dependencies they were detected by the python environment inside blender correctly but skia isn't visible to blender.

[blackbit42]

Any thoughts, @30350n ?

[30350n]

Well Blender 4.2 has a new extension format now, which includes prebuilt dependencies and handles their installation (similarly to what my code already did). I have started implementing this on the blender-extension-support branch, but didn't actually release anything yet.

So as that's probably going to resolve this, I don't think it makes much sense looking into what's the exact issue here any further.

[30350n]

Closing this, as it should be resolved by installing the newest v2.13 version which uses the new Blender Extension Format!