Include Blurhash in ImageDetails

[fishcharlie]

Requirements

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Is your proposal related to a problem?

For users of a Lemmy client on slow internet connections not being able to see images while they are loading can lead to a subpar experience.

Describe the solution you'd like.

I'd love to see Lemmy return blurhash strings for images in the API. That way while images are loading for a client the client can temporarily display the blurhash of the image in place while it's loading.

Describe alternatives you've considered.

There aren't really any alternatives that I can think of here.

Additional context

I noticed that in 0.20.0 alpha it looks like there is a new ImageDetails object which is awesome and super helpful. Maybe a blurhash property could be added to that object?

[dessalines]

This is a wonderful idea.

I see that pictrs has blurhash support, although it seems to be on its own dedicated endpoint.

@asonix Would it be possible to return the blurhash with any of the details / image_details responses? If its a low-CPU operation, you probably wouldn't even need to add a setting for generating them, and just do it by default.

If that's not doable, then we can probably use the existing endpoints, and store that.

[fishcharlie]

@dessalines Might need to do some testing on if it is indeed a low CPU operation. Obviously the CPU cost is not nothing.

Just trade offs to consider there.

Please let me know if there is anything I can do to help drive this forward. And I'd be happy to help test this eventually!

[dessalines]

Pictrs is the image library lemmy uses, and how we complete it depends on asonix's answer.

I recently added an image_details table to store things like dimensions returned from pictrs, so its something I can probably handle without too much work. Thx tho!

cc @MV-GH @SleeplessOne1917 as this would be great to eventually add to jerboa and lemmy-ui-leptos also. Seems like there are decoder libraries for blurhash in most languages.

[asonix]

I think pict-rs could probably add blurhash to the image details. I'll look into that this weekend probably.

[asonix]

I just merged the change in pict-rs that will include blurhash in the image details responses: https://git.asonix.dog/asonix/pict-rs/pulls/75

Not sure when I'll release another stable version, but it will have this included when I do.

[dessalines]

Sweet, thx!