Add support for uploading JPEG-XL .jxl files

[danmanix]

Problem statement

I am creating an archival system for artists. I am strongly encouraging the use of JXL files for upload as a means of getting archival quality at low file sizes.

I have managed to get support for this format working, but it took some hoops.

1. Re-registering JXL with filetype (no idea why, as it is included, but I had to do it anyway).
2. monkey-patch get_accept_attributes for the file-picker
3. monkey-patch Image.open
4. monkey-patch PillowImage init, format_name and mime_type

This is probably a terrible way of getting there.

Proposed solution

Enable this in core Willow, checking for the (current) dependency on pillow_jxl which would likely be many fewer lines of code in implementation.

JXL is hopefully making its way to the web (again), but for now it is useful as an upload format.

Alternative solutions

No response

Additional context

No response

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[laymonage]

Hi @danmanix thanks for the suggestion!

Enable this in core Willow

Since it looks like this needs to be done in Willow first, I think we should transfer this over to https://github.com/wagtail/Willow.

[thibaudcolas]

👋 thanks for the suggestion. Yep support will need to be added in Willow before Wagtail. And before that, via Pillow itself or a Pillow plugin.

It’s a pretty niche format currently but would definitely be nice to support for uploading only, and also for renditions if browser support got better.

Noting the relevant resources to check on updates with support:

• Can I use - JPEG XL
• Feature request on chrome bug tracker

[Stormheg]

Pillow is also working on official JPEG XL support, see python-pillow/Pillow#7848

I think as soon as that lands, Willow should add support for it, after which Wagtail could add support for JPEG XL.

I'd rather wait for Pillow to start supporting JPEG XL and not depend pillow_jxl because that is likely to become obsolete once there is official Pillow support.

As for browser support, as of today, Google Chrome and Firefox currently have added support but it is still behind an experimental feature flag. Once that changes, support should be wide-spread enough that Wagtail renditions should also be capable of outputting JXL images in my opinion.