Use realfavicongenerator API to build high-res PNG favicons

[Bisaloo]

fix #845, fix #869

This is still WIP but I'm putting it here if you want to have a first look and tell me if I'm going in the wrong direction. I still need to:

• Add tests
• Test with other input formats such as svg
• Verify that docs are up to date everywhere
• Add documentation for build_favicon()
• ??

Among others, I would like you to review:

• verbosity: more / less?
• paths: path of the template, path of the resulting favicons
• API key. At the moment, I'm using the demo API key but we probably need to register our own. One for all pkgdown users, hardcoded in the code? Asking users to register one themselves would introduce more complexity.

[hadley]

This is great and much simpler than I had anticipated! I have given you a bunch of comments to help make the code more robust (these are tips I've learned through getting them all wrong myself!)

I'm also wondering if it would be better to pull this out into a separate build_favicons() that the user would need to call explicitly? Otherwise we're potentially hitting this API every time we build the site. (We could store the favicons in pkgdown/favicons maybe?)

[hadley]

I think we should use a shared key that I register, providing an option for users to override if they want to provide their own.

[Bisaloo]

@hadley, thank you for your comments. I addressed some of them and I will probably have a look at the rest tomorrow.

I did the last changes in numerous small commits to make it easier to review. But once everything is ready to go, I can rebase & squash and force push.

I'm also wondering if it would be better to pull this out into a separate build_favicons() that the user would need to call explicitly? Otherwise we're potentially hitting this API every time we build the site. (We could store the favicons in pkgdown/favicons maybe?)

Yeah, I forgot, I was thinking we could maybe add a check at the beginning of this function or in build_site() and only go through with the API if the master logo.png hash has changed. What do you think? It would probably be simpler for users than calling build_favicons explicitly.

[jayhesselberth]

Do we want a better default favicon while we're at this? Currently it's a (lo-res) blank black hex.

[hadley]

@Bisaloo I think it would be better to be explicit about it and force the user to call a function. (Also you don't need to squash on your end, as I can squash when merging)

@jayhesselberth I think we can ditch the default favicon now that we no longer need magick.

[Bisaloo]

So I just tested and this works perfectly for svg icons. find_logo() should thus probably be tweaked to detect logo.svg (and even prioritize it compared to logo.png). Should I do this here or in another PR?

[hadley]

Yes, should definitely prefer svg logos now. I think it's fine to include that here since it should be a fairly small change.

[hadley]

I'd suggest that you also run the function on pkgdown itself and check in the results.

[Bisaloo]

Sorry, I force pushed while fixing the conflicts. Only old commit that changed is related to NEWS.md. You stopped your review at 76c56a1. New commits start at 4984fd9.

[Bisaloo]

The API also creates a bunch of files that we don't use (favicon.ico, apple-touch-icon-60x60.png, apple-touch-icon-76x76.png, apple-touch-icon-120x120.png): should I remove them or add them to the head.html template?

[hadley]

I think we should include them to the template too.

We probably also need to make the template only include them if the favicons are actually present

[Bisaloo]

We probably also need to make the template only include them if the favicons are actually present

I'm not sure how to do that 😕

[hadley]

In that case, let me do a final review of this work, and then I can merge it. Then I can figure out how to let the template know.

[hadley]

Are you happy for me to merge this now?

[Bisaloo]

Yeah, I just tested locally one last time and everything seems to work fine so I guess it's good to go.

[hadley]

Awesome, thank you so much for all your hard work on this!

[Bisaloo]

Thank you for all your comments!

And don't forget to register your API key 😉

[hadley]

I signed up yesterday, but still haven't received the email 😢