[whatwg] Simplified <picture> element draft

[Ian Hickson]

On Tue, 7 Jan 2014, Boris Zbarsky wrote:
> On 1/7/14 12:01 PM, Yoav Weiss wrote:
> > I'd love to get some more details regarding that. I'll start a 
> > mozilla.dev.platform thread on the subject, since it's Gecko specific.
> 
> It's actually not entirely Gecko-specific.
> 
> Consider a display:none iframe.  How should viewport-size-related media 
> queries be evaluated in such a thing?  The specs don't define it, as far 
> as I can tell.  In fact, the specs don't actually define anything useful 
> for the viewport of a framed document at all, as far as I can see.  CSS 
> just assumes a viewport exists, and HTML doesn't define anything about 
> frames setting up a viewport for the document inside them...
> 
> But say they defined it.  How would the viewport of a display:none 
> iframe be defined, exactly?
> 
> Last I checked, UAs just end up doing wildly different things in this 
> situation.

IMHO this should probably be in the CSS spec, but I'm happy to spec 
something if CSS doesn't want to pick this up. It's probably just a matter 
of saying, in the rendering section, that nested browsing contexts that 
aren't _being_rendered_ (or that are <frame>s outside <frameset>s) get a 
0x0 viewport. (Viewports that are being rendered seem to have an 
unambiguous dimension, but let me know if I'm missing something here too.)

Right now, Chrome and Firefox seem to report 0 as the body.offsetWidth for 
a hidden iframe. (Couldn't get a result for Safari; don't have IE here.)

   http://software.hixie.ch/utilities/js/live-dom-viewer/saved/2725
   For Chrome (since it puts data: in the wrong origin)

   http://software.hixie.ch/utilities/js/live-dom-viewer/saved/2726
   For Firefox (since for some reason the message in 2725 isn't sent?)

Can you elaborate on the widly different things? What should I be testing?

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
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