Implement ImageEncoder for hdr where color type is Rgba32F

[johannesvollmer]

• impl encoder for hdr where rgba32f for now
• add new output format

this unlocks:

• ImageBuffer.write_with_encoder, which unlocks DynamicImage.write_with_encoder
• free_functions::write_buffer_impl, which unlocks all the sweet stuff (DynamicImage.write_to, ImageBuffer.write_to)

[johannesvollmer]

please give me some hints as to what kind of tests I can add to make sure this works as expected :)
(if any)

[johannesvollmer]

can we add a reference test that compares images written with HDR to images written with EXR? How does that work in the current test suite?

[fintelia]

The relevant file is tests/reference_images.rs. I'm not super familiar with how it works, but shouldn't be too hard to figure out from there

[fintelia]

If you're interested in reviving this PR, I think it is in good shape. Just needs a rebase and ideally also updates to ImageFormat::{can_write, writing_enabled}

[zhouhang95]

If you're interested in reviving this PR, I think it is in good shape. Just needs a rebase and ideally also updates to ImageFormat::{can_write, writing_enabled}

Sorry, I'm not good at github workflow. I don't konw how to change this pr.

[fintelia]

Can this be included in the chain of zip calls above? Roughly the same as the old version, but passing flattened_rgbe_pixels instead of scanline

[johannesvollmer]

this should be possible, maybe this was done to minimize the diff for an easier review. unfortunately i don't have time at the moment :/

[fintelia]

@zhouhang95 GitHub only lets the original PR author or a repository maintainer update a PR

[johannesvollmer]

but it should be possible to checkout the branch of this pr and then open a new pr with your own branch :)
branch: https://github.com/johannesvollmer/image/tree/add-hdr-rgb32f-encoder-trait
more info: github checking out pull request locally