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Re: Test harness and test suite assumptions wrt anti-aliasing (font smoothing, clearType)

From: L. David Baron <dbaron@dbaron.org>
Date: Sat, 17 Mar 2012 17:13:23 -0700
To: "Gérard Talbot" <css21testsuite@gtalbot.org>
Cc: John Daggett <jdaggett@mozilla.com>, Public CSS test suite mailing list <public-css-testsuite@w3.org>
Message-ID: <20120318001323.GA20580@pickering.dbaron.org>
On Saturday 2012-03-17 15:53 -0400, "Gérard Talbot" wrote:
> 
> Le Sam 17 mars 2012 3:24, John Daggett a écrit :
> >
> > Gérard Talbot wrote:
> >
> >> > Browsers typically render text with
> >> > subpixel antialiasing *and* with subpixel or integer-pixel
> >> > positioning. All browsers support subpixel anti-aliasing but only
> >> > Firefox/IE9 use subpixel positioning, Webkit/Opera use integer-pixel
> >> > positioning.
> 
> The whole test suite should not require user agents to use, to be using
> or to implement subpixel positioning technology. This should be loud and
> clear.

Sure, but it also shouldn't require the opposite.  Tests should be
written so they work either way.

> Fine. When using Ahem font, I have proposed to only use a font-size
> which in pixel units will be dividable by 5 without creating fractional
> remainder so that baseline alignment will be reliable, trustworthy in
> all browsers. I have adjusted a bunch of tests in that sense.

Yes, using Ahem in multiples of 5 is often useful, since many uses
of Ahem actually care about pixel accuracy of font metrics.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                           http://www.mozilla.org/   𝄂
Received on Sunday, 18 March 2012 00:13:53 GMT

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