W3C home > Mailing lists > Public > public-css-testsuite@w3.org > March 2008

RE: Microsoft contributing test cases to the CSS WG

From: Arron Eicholz <Arron.Eicholz@microsoft.com>
Date: Thu, 13 Mar 2008 10:00:02 -0700
To: Ian Hickson <ian@hixie.ch>, "L. David Baron" <dbaron@dbaron.org>
CC: "public-css-testsuite@w3.org" <public-css-testsuite@w3.org>
Message-ID: <66D5CB5D6AB0694592FAF5487C50368B1914D74BF7@NA-EXMSG-C111.redmond.corp.microsoft.com>

On Friday, March 07, 2008 2:00 AM, Ian Hickson wrote:

> I believe the x-height in Ahem is 0.8em. (Specifically, the sxHeight
> field
> of the OS/2 table is set to 800, and the em height of the font is 1000,
> at
> least according to Microsoft's ttfdump tool.)
>
> The bounding box of the 'x' and 'o' characters are 1em, though, so
> implementations that do bounding box measurements could get that
> instead.
>
> Under no circumstances is 0.5em a valid 'ex' height for this font,
> though.

Actually I think the height can be 0.5em for a valid 'ex' height in some cases. The problem is in the spec (section 4.3.2 paragraph 7, sentence 5) where it states this, "In the case where it is impossible or impractical to determine the x-height, a value of 0.5em should be used."

Because of the word 'impractical' this can mean that on certain systems the logic to go and find the x-height in the font may be too much work. Thus in that case the setting can be 0.5em.

> BTW, congratulations to Microsoft on your recent beta; the improvements
> are a great step in the right direction, and your contribution of this
> test suite is very encouraging.

Thank you for the compliment on the test suite. There are so many complex tests out on the web and there has never been a real finite number of tests that identify when you have complete support of any of the features of CSS. Our released test suite begins to address the support question. Quality tests are the next level where you start to get into combinations, how things interact, the rules of the specification and real world scenarios. We also released a handful of those tests as well.

--
Thanks,
Arron Eicholz


> -----Original Message-----
> From: Ian Hickson [mailto:ian@hixie.ch]
> Sent: Friday, March 07, 2008 2:00 AM
> To: L. David Baron
> Cc: Chris Wilson; public-css-testsuite@w3.org; Arron Eicholz
> Subject: Re: Microsoft contributing test cases to the CSS WG
>
> On Wed, 5 Mar 2008, L. David Baron wrote:
> >
> >  * at least on Linux, we get an incorrect ex-height out of the Ahem
> >    font (or at least different from the 0.5em that your tests
> >    expect; I think we get 1em), so we fail almost all of the ex-unit
> >    related tests
>
> I believe the x-height in Ahem is 0.8em. (Specifically, the sxHeight
> field
> of the OS/2 table is set to 800, and the em height of the font is 1000,
> at
> least according to Microsoft's ttfdump tool.)
>
> The bounding box of the 'x' and 'o' characters are 1em, though, so
> implementations that do bounding box measurements could get that
> instead.
>
> Under no circumstances is 0.5em a valid 'ex' height for this font,
> though.
>
>
> BTW, congratulations to Microsoft on your recent beta; the improvements
> are a great step in the right direction, and your contribution of this
> test suite is very encouraging.
>
> HTH,
> --
> Ian Hickson               U+1047E                )\._.,--....,'``.
> fL
> http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._
> ,.
> Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-
> .;.'
Received on Thursday, 13 March 2008 17:00:49 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 20 September 2010 17:51:56 GMT