doc: Use the correct Doxygen Logo File Type in the Footer

[crasbe]

Contribution description

Apparently Doxygen changed the default file type from PNG to SVG at some point and the footer was never updated, leading to the ugly "image not found" symbol in the footer.
The SVG file is already present and accessible on the webserver ( https://doc.riot-os.org/doxygen.svg ) but not in the footer.html.

Current state:

With this PR:

Testing procedure

Check that the generated documentation contains the logo in the footer.

Apparently the old doxygen version (1.9.1) in the CI container has some issues displaying the SVG, because there is no size specification:

In newer Doxygen versions (1.12.0), the CSS settings for the footer were extended:

So you have test it locally, wait for the CI container to be updated or just trust me :D

Issues/PRs references

None.

[riot-ci]

Murdock results

✔️ PASSED

b00a3e9 doc: use the correct logo file type in the footer

Success	Failures	Total	Runtime
1	0	1	01m:20s

Artifacts

• Documentation preview

[mguetschow]

So you have test it locally, wait for the CI container to be updated or just trust me :D

... Or add that same CSS rule to our RIOT tree to fix it for all users?

[crasbe]

So you have test it locally, wait for the CI container to be updated or just trust me :D

... Or add that same CSS rule to our RIOT tree to fix it for all users?

I'm a bit torn here, because the old Doxygen versions are not supported anyway due to various bugs, which motivated #21277.

The footer-logo-width CSS parameter was introduced in 1.9.5, which was released in mid 2022: https://github.com/doxygen/doxygen/blob/Release_1_9_5/templates/html/doxygen.css#L447-L451

This might be a personal thing, but I'd rather have the users/developers update their Doxygen version that working around one bug while still having many other bugs.

[mguetschow]

I'm a bit torn here, because the old Doxygen versions are not supported anyway due to various bugs, which motivated #21277.

Sure I agree, but reality is that those versions are still around on developer machines. #21273 would continue to work around the markdown issue on local machines even when we have our CI and website doxygens updated. I don't think adding another CSS rule with a comment on it being a workaround would harm.

[crasbe]

Unfortunately I don't really have the CSS skills to develop a solution that won't interfere with future Doxygen updates.

Considering 22.04 LTS is the last LTS distro to use Doxygen 1.9.1 and 24.04 LTS uses 1.9.8 ( https://launchpad.net/ubuntu/noble/+source/doxygen ) which doesn't have the same issue anymore, I'm not convinced to include a hack that might cause issues in the future when it's long forgotten.
Likewise, I'd be in favor to remove the doc.md hack, once 1.14.0 is out and integrated into the CI system, for the same reason.

But I'm open for a third opinion (or a proposal for the CSS rule).

[mguetschow]

Summoning @kfessel here since he was advocating for keeping local user installations functional here #21273 (review).

Maybe an alternative solution would be to allow users to use the doxygen version in riotbuild when we got that one up to date at some point, probably with the fix proposed here: #21106 (comment)