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[css-writing-modes-3] Firefox and baseline-alignment of inline boxes in orthogonal flow

From: Gérard Talbot <css21testsuite@gtalbot.org>
Date: Sat, 27 Dec 2014 14:56:09 -0500
To: Public CSS Test suite mailing list <public-css-testsuite@w3.org>
Message-ID: <fa6aed7493b6fe901946f9fede73e74a@gtalbot.org>

Related tests
-------------

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/block-flow-direction-011.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/block-flow-direction-012.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/block-flow-direction-013.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/block-flow-direction-014.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/block-flow-direction-015.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/block-flow-direction-016.htm


http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/line-box-direction-011.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/line-box-direction-012.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/line-box-direction-013.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/line-box-direction-014.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/line-box-direction-015.htm

http://test.csswg.org/suites/css-writing-modes-3_dev/nightly-unstable/html/line-box-direction-016.htm


After a long thinking about those 12 tests, I decided to keep the 
'vertical-align: top' declarations in those inline-block tests. I am 
convinced Firefox 37.0a1 build 20141215 just has a implementation bug 
when doing baseline-alignment of inline boxes in orthogonal flow. Since 
those tests are testing, targeting something specific (blocks direction 
and line box direction) and not baseline-alignment of inline boxes onto 
a line box, then the 12 tests really and truly pass what the tests are 
checking if the machine or humans can read the big yellow PASS word. So, 
it's better to make human checking of tests and machine+software 
checking of tests consistent with regards to baseline-alignment.

I will of course create vertical-alignment of inline-block tests 
elsewhere in the test suite later; I could just reuse those tests... 
otherwise reduce those tests and use green+red colors to help human 
decisions.

The vertical offsets of 6px and 26px that we can see in Firefox 37 (when 
toggling on and off the 'vertical-align: top' declaration in 
block-flow-direction-01[1-6] and in line-box-direction-01[1-6] tests) 
are explainable, can be deduced; the 6px vertical offset is exactly 30% 
of the font-size (30% is the difference between 
central-baseline-alignment and alphabetical-baseline-alignement for Ahem 
font) and the 26px vertical offset appears to be 1 line box height plus 
that 30% of the Ahem font-size.

It appears to me that Firefox 37 applies central-baseline-alignment to 
the inline-block which is rendered horizontally when Chrome 39 instead 
(and rightly so) applies alphabetical-baseline-alignment to the 
inline-block.

Gérard
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Received on Saturday, 27 December 2014 19:56:45 UTC

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