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Re: [csswg-drafts] [mediaqueries] Queries for image support (#656)

From: Amelia Bellamy-Royds via GitHub <sysbot+gh@w3.org>
Date: Sat, 13 Jul 2019 18:14:20 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-511143033-1563041658-sysbot+gh@w3.org>
I remembered about this discussion following a twitter thread asking how to test for WebP support. Tim Petrusky [reports that](https://mobile.twitter.com/TimPietrusky/status/1150099543654109184) having to use JPEG instead of WebP for background images increases download size by 50%.  Bumping the thread to get some more attention on it.

For image _format_ support, there are two ways we could handle it:

- inside the [`image()` or `image-set()`](https://drafts.csswg.org/css-images-4/#image-set-notation) functions (if we get commitments to actually implement such things!)
- as a conditional @-rule, such as a media query or a special `@supports` rule syntax

For "did this particular content image (or other element linking an external resource) fail to load/parse correctly", I think standardizing the Mozilla broken image pseudo-class is valid.  We could also add a second pseudo for the "waiting to load" state, which becomes more important with native lazy loading.

For overall image / external resource download settings, I still think this makes the most sense as a media query.  But at least some use cases could be handled by the other features above.


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Received on Saturday, 13 July 2019 18:14:22 UTC

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