AVIF Image Format Support

[Nawor3565]

Describe the feature you'd like

Since the AVIF format now seems to be well supported among browsers, it would be useful to add support for the format to Bookstack. In fact, it seems like the format may already be functional as AVIF images are displayed in the "image format not supported" error pop-up when trying to upload one, so adding support may be trivial.

Describe the benefits this would bring to existing BookStack users

Support for a modern, high-qualify image compression format that is becoming more widely used

Can the goal of this request already be achieved via other means?

No, because this is a very specific request.

Have you searched for an existing open/closed issue?

• I have searched for existing issues and none cover my fundamental request

How long have you been using BookStack?

1 to 5 years

Additional context

It was recommended that I open a new request for this in #2505

[muelsyse-az]

I've looked into #2505 and I think that AVIF support should be OK to pursue now.

It's now supported on all major browsers (Edge being the last one to adopt it in Jan 2024) and it seems that the image-resizing library also fully supports AVIF.

[ssddanbrown]

Yeah, I'll go ahead and assign this for the next feature release.

Looks like php-gd supported this as of 8.1, which is now below our minimums, so that's fine.

Will need to check animation support across the support targets, since that can be problematic or need specific handling as experienced via other formats.

[ssddanbrown]

This has now been added via #5625, to be part of the next release.
Animation support is there, in the same way we handle animated png (gallery will show a still resized thumbnail, display image bypasses any of our scaling to retain animation).
There is a limitation that the format is not yet supported by our default PDF renderer, but that looks to be due somewhat soon (although is not assured).