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Re: User Agents Do Not Implement Absolute Length Units, Places Responsive Design in Jeopardy

From: Brian Blakely <anewpage.media@gmail.com>
Date: Wed, 5 Oct 2011 13:21:31 -0400
Message-ID: <CAJGQg4Erjw7HsVY=Ri7_+NF6_2aEc0UxBWT3drXtFHumpn4Guw@mail.gmail.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: www-style@w3.org
I meant 96 - brain fart, thanks.

The problem isn't resolution detection.  The problem is that we're using
pixel resolution to do *size *detection.  Adjusting a layout for small-size
displays is currently achieved by defining max-width MQs at about 640 *
pixels*, when it really should be 3.5 *inches* (ballpark).

-Brian


On Wed, Oct 5, 2011 at 11:46 AM, Tab Atkins Jr. <jackalmage@gmail.com>wrote:

> On Wed, Oct 5, 2011 at 7:17 AM, Brian Blakely <anewpage.media@gmail.com>
> wrote:
> > See spec for a refresh:
> http://www.w3.org/TR/css3-values/#absolute-lengths
> > As far as I know, UAs have never actually implemented this, but always
> > pretended to anyway.  If you size something as "1in", you're more than
> > likely going to get 90px, regardless of the accuracy of this output.
>
> No, you're going to get exactly 96px.  Several (all?) of the UAs agree
> on this now.
>
>
> > This is important because physical screen dimensions are going to become
> > very crucial in the near-term for content and layout delivery, especially
> in
> > regards to Media Queries.
> > The problem which was years away is now an impending reality: the day
> when
> > 720p+ mobile devices become the norm.  Unless these devices are all
> > pixel-doubling and -quadrupling without exception, using Media Queries
> for
> > the most common responsive design practice — horizontal resolution
> detection
> > in pixels — won't work anymore.  They will simply cease to be a solution,
> > leaving no replacement.
>
> Once we reach 720 dpi or so, the problem pretty much solves itself
> (actually, that should happen somewhere around ubiquitous 300dpi).  At
> that point, the maximum difference that "1in" can be from a physical
> inch is pretty small.  Resolution-detection using pixels stops
> working, but that was always an accidental benefit.
>
>
> > We need a new way to do generic device detection, or we need absolute
> length
> > units to work.
> > Anyone from representative groups (Mozilla, Chrome Team, Apple) want to
> > comment?  Does the spec need to be changed?
>
> Can you describe the problem more directly?  Do you need better ways
> to do resolution detection?
>
> ~TJ
>
Received on Wednesday, 5 October 2011 17:24:20 GMT

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