Make wx dependency optional for CLI usage

[meawoppl]

wxPython is kinda annoying/needy to install, and the way the imports are currently make it tough to use headless w/o installing a bunch of extra stuff. This PR uses an existing environment variable to gate the import of wx to areas of the code that actually use GUI elements.

Quick summary of changes:

• Add get_wx() in compat.py to gate wx imports behind INTERACTIVE_HTML_BOM_NO_DISPLAY environment variable
• Allows headless HTML BOM generation without wxPython installed
• GUI features like --show-dialog still require wx

Usage

INTERACTIVE_HTML_BOM_NO_DISPLAY=1 python -m InteractiveHtmlBom.generate_interactive_bom board.kicad_pcb --no-browser

[qu1ck]

This change is not needed.

[meawoppl]

I am honestly a bit confused on how this line of code works now that I look at it. I am not sure how this imports resolves... regardless, it triggers import of the __init__ here I think:
https://github.com/openscopeproject/InteractiveHtmlBom/blob/master/InteractiveHtmlBom/__init__.py

Would you prefer I replace the imports there with the get_wx() singleton or move the import?

[qu1ck]

This file is not part of the package, it exists solely for convenience where you can just download the repo and drop it as a whole in kicad's plugin dir. KiCad's plugin system will run this init file and the import initializes kicad plugin, that's all it does. This file is irrelevant for cli use case so just leave it unchanged.

[meawoppl]

This makes sense wrt. to the existance of the plugin import, that said, that import will still trigger the __init__.py one folder up so would you prefer I replace the imports there with the get_wx() singleton we add here?

[qu1ck]

It doesn't matter what it triggers, this code does not run when you use ibom in cli mode. Leave it unchanged.

one folder up

This is the topmost level init, there is no one folder up. When you run cli it only uses inner folder as a package, this top level folder may as well not exist.

[qu1ck]

This should be kept.

[meawoppl]

This is a bit confusing as this would nominally only run if not creating a wx app, correct?

I feel like we shouldn't have to disable asserts if not even importing wx...

I can move it into the if create_wx_app block, but I think that would be a behavior change. What is this line of code really about?

[qu1ck]

Kicad's code sometimes throws GUI asserts requiring user input to close even when wx app is not created. This line suppresses that so that the app does not crash or get blocked without a desktop environment.

[meawoppl]

Fixed

[meawoppl]

I think I got everything, lmk if you want anything else changed/tweaked.

[qu1ck]

Tested it and it works fine except when wx is not available the error is cryptic.

[qu1ck]

Add a check here if wx is None and create_wx_app is true then show an error "wxpython is required unless INTERACTIVE_HTML_BOM_NO_DISPLAY environment variable is set" and exit early.

[qu1ck]

Thank you for your contribution.

[meawoppl]

Np. Thanks for making a nice thing.

I might end up running this on a very large number of boards. Any interest in a port of the formats extractors to Rust? I think this would be a couple afternoons work.

[qu1ck]

To what end? If you think about performance gains I doubt you will gain much considering more time is spent in kicad bindings than actual python stuff unless it's a very large board.
Also do you have rust bindings for old kicad api? This plugin does not use new api yet and even rust bindings for those are just experimental afaik.