Specify srcset/sizes on img (was: Tweak example 3)

[zcorpan]

This example is in the spec:

<picture>
 <source media="(min-width: 45em)" srcset="large-1.jpg, large-2.jpg 2x">
 <source media="(min-width: 18em)" srcset="med-1.jpg, med-2.jpg 2x">
 <source srcset="small-1.jpg, small-2.jpg 2x">
 <img src="small-1.jpg" alt="The president giving an award." width="500" height="500">
</picture>

I think this could be:

<picture>
 <source media="(min-width: 45em)" srcset="large-1.jpg, large-2.jpg 2x">
 <source media="(min-width: 18em)" srcset="med-1.jpg, med-2.jpg 2x">
 <img src="small-1.jpg" srcset="small-2.jpg 2x" alt="The president giving an award." width="500" height="500">
</picture>

right?

[yoavweiss]

It can be, assuming that srcset's DPR switching in img is here to stay.

I think there are 3 options forward with regard to srcset@img:

1. Leave its DPR switching as is, which would mean srcset is different between <img> and <source>
2. Modify it to match <source>'s srcset, which would probably mean adding a sizes element to <img>.
3. Drop it entirely, leaving only srcset@source

I'm in favor of 2, but I'm not sure it won't complicate matters.

[zcorpan]

I think we should specify (2), that seems best for authors long-term.

[Wilto]

Agreed on option two.

[igrigorik]

Re, option 2: at which point we might as well add media to img and get rid of source? :P

Just playing devils advocate.. I'm not convinced the extra complexity is worth it. What's so special about source that allows it to have media whereas img has all other functionality? FWIW, I'd +1 option 3.

[yoavweiss]

I'm not convinced the extra complexity is worth it

I'm not 100% convinced either, but I'm not sure what that complexity is. I don't think specifying it would be complicated (@tabatkins - correct me if I'm wrong). I don't think implementing it would be significantly complicated either (the syntax parsers can be reused, etc).

The advantage of 2, is that is enables to get rid of the last source of the picture markup, and if there's only one source (i.e. no art-direction), it enables to support variable width images and DPR switching without <picture> at all.

3 is simpler in the sense that it gives the developer less options.

@tabatkins - What do you say?

[zcorpan]

(2) is probably less complexity compared to the current situation with different specs for <source srcset> and <img srcset>.

As to why not use img instead of source: it wouldn't have a good back-compat story, I don't know what the algorithm would be like, and the markup would look pretty confusing I think.

(3) would mean that it's not OK to ship a subset implementation of only <img srcset>.

[tabatkins]

I think #2 is fine. I haven't done it yet only because I was trying to leave <img> alone, but I recognize that it's probably the best way forward.