[webkit-dev] The SrcN responsive images proposal

Maciej Stachowiak mjs at apple.com
Fri Nov 8 11:44:07 PST 2013

On Nov 7, 2013, at 2:38 PM, Tab Atkins Jr. <jackalmage at gmail.com> wrote:

> On Thu, Nov 7, 2013 at 9:24 AM, Timothy Hatcher <timothy at apple.com> wrote:
>> As I replied before, there should only be one attribute — srcset.
> I have a serious suggestion - could we rename srcset to src-n
> (literally, "src-n"), and then just ship it?  This puns in three
> interesting ways:
> 1. If src-N is never accepted, it's still an attribute that holds N
> src values, so src-n works well.
> 2. If src-N is accepted, but as a single attribute, src-n is just
> named perfectly to match the proposal name.
> 3. If src-N is accepted fully, the obvious ordering is clearly src-1,
> src-2, src-3, ..., src-n, which matches the fallback we want.
> A guaranteed "last fallback" is legitimately useful for the full src-N
> proposal, so I'm totally okay with integrating that into my proposal.
> This'll let us ship now, and then continue to discuss src-N for a
> while, with whatever solution we land on still having a consistent
> name. Win for authors no matter what the result is.

Further discussion will go to whatwg, which is a better place to discuss technical details of the src-N proposal, but I wanted to comment on this:

(1) In the case that src-N is never adopted, or is adopted in single-attribute form, "srcset" matching the CSS image-set() function will be more useful than "src-n" matching a hypothetical proposal based on multiple attributes.

(2) Neither "src-n" nor "srcset" is super-obvious as a final fallback, but either is a rule that could plausibly be learned.

(3) In the absence of considerations about matching anything else, "source set" better conveys the idea of selecting from multiple sources than "source n", at least to me.

So I don't think your proposal is super helpful to enable a future transition. What might be helpful:

(A) Change srcset parsing in implementations now to be compatible to extension with an additional list level (for instance, drop everything after the first "||").
(B) Remove support for the "w" and "h" specifiers from srcset implementations since no one loves those and they are apparently not really adequate to addressing their use case.
(C) Ship srcset with these two changes ASAP.

This would leave the field open to either extending the microsyntax or adding more attributes or both. And authors will at least have a way to address the multi-resolution-only case, a case where I believe we have no substantial controversy about the right solution.


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