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Re: [css-size-adjust] Specifying text-size-adjust: <percentage>

From: L. David Baron <dbaron@dbaron.org>
Date: Tue, 1 Mar 2016 17:16:23 +0800
To: Philip Rogers <pdr@chromium.org>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, www-style <www-style@w3.org>
Message-ID: <20160301091623.GA20585@pescadero.dbaron.org>
On Friday 2016-01-08 16:45 -0800, Philip Rogers wrote:
> Thanks Tab!
> 
> I've updated the wording (changed slightly to match the terms used in the
> spec):
> change:
> https://github.com/progers/csswg-drafts/commit/bd192715923dbe0af1207fce195dbb11a3a4fab1
> preview:
> https://rawgit.com/progers/csswg-drafts/master/css-size-adjust/Overview.html#adjustment-control
> 
> Anyone else have thoughts on this change?

Sorry for the delay here.

I guess this seems reasonable if that's what the compatible behavior
is, except it needs to be conditional on "when displaying on a small
device" (which itself may need to be defined better).  That's
because this definition (even more than the others) is dependent on
when text size adjustment "happens" vs.  "doesn't happen".

(Also, presumably Tab's wording needs
s/font-size-adjust/text-size-adjust/.)

-David

> On Mon, Jan 4, 2016 at 1:13 PM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
> 
> > On Mon, Jan 4, 2016 at 10:22 AM, Philip Rogers <pdr@chromium.org> wrote:
> > > The text-size-adjust CSS keyword has a prefixed implementation in most
> > major
> > > engines today (an exception being chromium) which lets authors control
> > how
> > > adjustment works. The <percentage> value is currently underspecified and
> > I'd
> > > like to spec it to match both Trident and WebKit.
> > >
> > > Ideally, we'd remove <percentage> but the httparchive data shows
> > percentage
> > > values are pretty common (1.2% of all files [1]). Because the
> > implementation
> > > is not too onerous and supporting percentages with ease the transition to
> > > unprefixed properties, I'd like to spec it instead of remove it.
> > >
> > > I'd like to define <percentage> as a set value that gets multiplied by
> > the
> > > specified font size. Percentage values are not relative to any other
> > > adjustment and text-size-adjust: 100% is equivalent to text-size-adjust:
> > > none. Trident and WebKit appear use this logic [2] and it is compatible
> > with
> > > existing pages and MS/MDN documentation [3,4]. For posterity, Gecko does
> > not
> > > support <percentage> and Chromium does not yet implement
> > text-size-adjust at
> > > all.
> > >
> > > I have a preview of this change at:
> > >
> > https://github.com/progers/csswg-drafts/commit/1f80533bc0f5eb8e97fbf4ae113af5f731756140
> > > And a preview of the updated spec at:
> > >
> > https://rawgit.com/progers/csswg-drafts/master/css-size-adjust/Overview.html#adjustment-control
> >
> > I recommend instead writing:
> >
> > > User agents must not do automatic size adjustment.  The computed value
> > of font-size must be multiplied by the percentage.
> > >
> > > Note: This means that ''font-size-adjust: 100%;'' is equivalent to
> > ''font-size-adjust: none;''.
> >
> > ~TJ
> >

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)

Received on Tuesday, 1 March 2016 09:16:54 UTC

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