W3C home > Mailing lists > Public > www-style@w3.org > July 2013

Re: A property for font antialiasing control on Mac OS X

From: Simon Fraser <smfr@me.com>
Date: Wed, 17 Jul 2013 21:47:22 -0700
Cc: www-style@w3.org
Message-id: <1E699EBE-EC61-472C-A84C-E65DF418358F@me.com>
To: "L. David Baron" <dbaron@dbaron.org>
On Jul 17, 2013, at 9:34 pm, "L. David Baron" <dbaron@dbaron.org> wrote:

> On Wednesday 2013-07-17 21:23 -0700, Simon Fraser wrote:
>> On Jul 17, 2013, at 2:57 pm, L. David Baron <dbaron@dbaron.org> wrote:
>> 
>>> The most significant use case for author control is that while
>>> subpixel antialiasing (on all platforms) often provides the best
>>> results for body text [2], its implementation on Mac OS X has a
>>> tendency to make light text on a dark background overly or even
>>> unreadably bold [2].  This problem is fully cross-browser on Mac OS
>>> X, in that all browsers on Mac OS X using the native text
>>> rasterization code (all major browsers, I believe) run into this
>>> problem.  In other words, there are many cases where subpixel AA is
>>> preferable, but also a number of cases where it produces very bad
>>> results that authors want to avoid.
>> 
>> I understand your argument that the main reason this property exists is because
>> of this "extra weight" problem on Mac. We (Apple) are aware of this issue.
>> 
>> However, it would surprise me if authors didn't also want control over sub pixel-
>> antialiasing itself.
>> 
>> I did a quick test on Windows, looking at IE10 and Firefox, with ClearType enabled
>> on the system. In a test case involving a 3D transform and opacity, Firefox applied
>> subpixel-AA to only some of the elements on the page. IE 10 seems to disable
>> ClearType for all web content, even though it was enabled for other UI in the system.
>> 
>> So clearly, even without the Mac problem, subpixel AA differences exists on non-Mac
>> platforms, and I suspect that discerning web authors would want control over it.
> 
> So what's the motivation for wanting this control?  Is it that the
> difference between subpixel AA and not subpixel AA was visible
> without close examination, and the authors wanted consistency?

I would think this would be the most common case, yes. Consistency between
different elements on the page, and between the same element at different times.
This is certainly the primary reason for current uses of -webkit-font-smoothing.

> Or is it that the authors have a preference for one or the other for
> a reason that shouldn't involve leaving the choice to the user's
> settings?


http://tanookisuitlabs.com/your-fonts-look-bad-in-chrome-heres-the-fix/ shows
that authors are willing to override the default font settings if they think it makes
text look better (at least in the context of Mac heaviness).

We really need to hear from designers to see if they care about subpixel-AA
on any platforms other than Mac.

Simon
Received on Thursday, 18 July 2013 04:47:53 UTC

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