[whatwg] Simplified <picture> element draft
ian at hixie.ch
Mon Mar 10 12:47:59 PDT 2014
On Tue, 7 Jan 2014, Yoav Weiss wrote:
> On Tue, Jan 7, 2014 at 6:20 PM, Boris Zbarsky <bzbarsky at mit.edu> 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.
> I agree that iframes complicate things, since the parent document's
> external CSS can modify their viewport dimensions, so there's an
> inherent race condition there.
It's sort of a race, but it settles, right?
> Since this case is not the majority case, we could bail out of it by
> delaying the iframe's subresource loading that rely on viewport
> dimensions until the parent's layout is considered "done" (e.g. all its
> <head> CSS was parsed and applied)
The <iframe> can change dimensions long after that, still (e.g. if it's
sized based on other content later in the page, as in a complex table).
I'm sure browsers can optimise a bit here, but it's not clear to me that
there's anything we need to explicitly require.
Ian Hickson U+1047E )\._.,--....,'``. fL
http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,.
Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
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