FLIF support

[RichardEllicott]

requesting this format to be supported

it achieves a 43% smaller file size than lossless png, 14% smaller than a lossless webp

https://flif.info/index.html

[anderlli0053]

@reduz @akien-mga

[fire]

How does adding FLIF support help?

For example:

I assisted zylann with openexr export because it was necessary to have a format that can export 16bit or 32bit per component channels to an image.

Godot uses an internal packing for image formats called stex when exported, so the size saving doesn't help.

The use cases for FLIF sounds like png use cases, just use png?

[fire]

Thirdly FLIF is LGPL v3 and that is less compatible with Godot's MIT license.

I cannot find any other implementation.

https://www.reddit.com/r/programming/comments/3n7yvx/flif_free_lossless_image_format/cvlmnb3/ mentioned that it is slow, but I haven't tested those claims.

[Calinou]

Given FLIF's encoder license and the low activity of its development repository (last commit on 2018-10-26 as of writing), I think we should close this. See also this GitHub issue for more context.

Also, keep in mind FLIF is relatively slow to decode/encode compared to other formats such as PNG or even WebP. This can affect loading times negatively, making its use in games impractical.