[whatwg] Simplified <picture> element draft

Adam Barth w3c at adambarth.com
Mon Nov 25 08:33:07 PST 2013

Thanks Yoav.  Tab asked me to provide some more feedback to this list,
but it's hard to tell from the lengthy discussion what proposal folks
are most interested in.  Is there an editor's draft or some other
relatively self-contained write-up that I could review?


On Mon, Nov 25, 2013 at 12:00 AM, Yoav Weiss <yoav at yoav.ws> wrote:
> This is a part of the proposal that got people excited. The linked document
> defines picture's source selection algorithm.
> It contains some parts that I'm not sure have a consensus around them yet:
> * It defines <picture> as controlling <img>, where earlier on this list we
> discussed mostly the opposite (<img> querying its parent <picture>, if one
> exists)
> * It defines <img> as a part of <picture>'s shadow DOM, which we need to
> see how it fits with having fallback <img> elements (which are necessary in
> the near future).
> This proposal does contain srcset as a subcomponent, but it's not the same
> srcset as defined in the HTML spec, but a modified version based on
> improvements from the src-N spec. (that cover the variable-width images
> use-case)
> The proposal will also require some changes to <img> and specifically, when
> not created by JS, <img> will have to avoid loading of resources until the
> element is added to the DOM, and can see if its direct parent is <picture>.
> If the parent is <picture>, <img> would then query the parent (or wait to
> be "controlled" by its parent), otherwise, it'll load its resources as
> usual.
> On Mon, Nov 25, 2013 at 8:33 AM, Adam Barth <w3c at adambarth.com> wrote:
>> I'm trying to sort out from the many messages on this topic which
>> proposal I should read in detail.  Is the one linked below the one
>> that people are most excited about?  I'm I correct in understand that
>> this proposal contains srcset as a subcomponent?
>> Thanks,
>> Adam
>> On Sat, Nov 23, 2013 at 3:04 PM, Kornel Lesiński <kornel at geekhood.net>
>> wrote:
>> >
>> > I've written down proposal for the simplified source selection algorithm:
>> >
>> > http://geekhood.net/picture-element.html
>> >
>> > This also includes variant of the idea from the recent "<picture> redux"
>> > proposal to use an actual <img> element as the basis for the <picture>
>> > element definition.
>> >
>> > This draft doesn't include all features of src-N *yet*, but I expect
>> this to
>> > be added either via extended srcset syntax to something like <source
>> sizes>
>> > once there's consensus how to approach this.
>> >
>> > To simplify implementation even further I've allowed UAs to flatten
>> fallback
>> > DOM to a plaintext string (in case they need to emulate <img alt> for
>> > existing screen readers or accessibility APIs).
>> >
>> > I've dropped usemap. It could be added, but I'm not sure if there is need
>> > for it.
>> >
>> > I've specified very few IDL attributes. This area may need to be
>> extended.
>> >
>> > --
>> > regards, Kornel

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