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Re: Comments on 'line-height'-related tests for Quirks Mode

From: Simon Pieters <simonp@opera.com>
Date: Fri, 01 Mar 2013 16:39:11 +0100
Cc: "W3C CSS Test Suite" <public-css-testsuite@w3.org>
To: "Kang-Hao (Kenny) Lu" <kanghaol@oupeng.com>, "Alan Gresley" <alan@css-class.com>
Message-ID: <op.ws9xrmvqidj3kv@simons-macbook-pro.local>
On Fri, 23 Nov 2012 12:44:48 +0100, Alan Gresley <alan@css-class.com>
wrote:

> On 23/11/2012 9:07 PM, Kang-Hao (Kenny) Lu wrote:
>> (12/11/23 17:25), Simon Pieters wrote:
>>>>    # span { padding:1px 0 }
>>>>    # <div id=test><span></span></div>
>>>>    # <div id=ref></div><div id=s_ref></div>
>>>>
>>>> This is a bit puzzling, in particular about "<div id=s_ref></div>". I
>>>> think what this test runs into is this part of CSS 2.1 9.4.2:
>>>>
>>>>    # Line boxes are created as needed to hold inline-level content
>>>>    # within an inline formatting context. Line boxes that contain no
>>>>    # text, no preserved white space, no inline elements with non-zero
>>>>    # margins, padding, or borders, and no other in-flow content (such  
>>>> as
>>>>    # images, inline blocks or inline tables), and do not end with a
>>>>    # preserved newline must be treated as zero-height line boxes for  
>>>> the
>>>>    # purposes of determining the positions of any elements inside of
>>>>    # them, and must be treated as not existing for any other purpose.
>>>>
>>>> While the condition "no inline elements with non-zero margins,  
>>>> padding,
>>>> or borders" probably has quirks-mode difference too (and should be
>>>> specced), if you are testing the current prose to see if the above
>>>> <span> contributes to line height, I'd suggest the test be written in
>>>> this way:
>>>>
>>>>    | div { line-height: 0} span { padding:1px 0; line-height: normal }
>>>>    | <div id=test>x<span></span></div><div id=ref>x</div>
>>>>    | <div id=s_ref>x<span>x</span></div>
>>>>
>>>> The 'x' at the beginning ensures that the tests don't go into the
>>>> "zero-height line boxes" situation.
>>>>
>>>> Ditto for all others.
>>>
>>> I think this is intentional. We could add tests with "x" in as well,
>>> though, if that still makes the quirk kick in.
>>>
>>> Do you have a test case demonstrating quirks-mode differences in "no
>>> inline elements with non-zero margins, padding, or borders"?
>>
>> (By the way, the CSS 2.1 propose here should really be "non-zero
>> horizontal margins/paddings/borders/" as you have observed.)
>>
>> Well, your test case:
>>
>>    # span { margin:0 1px }
>>    # <div id=test><span></span></div>
>>    # <div id=ref></div><div id=s_ref>x</div>
>>
>> shows that :) (whether non-zero margins matter only in standards mode).
>>
>> What I am saying here is that if you compare this test with
>>
>>    | div { line-height: 0;} span { margin:0 1px; line-height: normal; }
>>    | <div id=test>x<span></span></div>
>>    | <div id=ref>x</div><div id=s_ref>x<span>x</span></div>
>>
>> you'll see that Firefox passes the former but not the latter. That is,
>> the <span> in "<div id=test>x<span></span></div>" does contribute to
>> line height (in a buggy way). This is probably an edgy bug Gecko has,
>> but the point is that the result could be differnt.
>>
>> In other words, I guess the best option is to spec the quirk about
>> "zero-height line boxes" and include both test cases.

Please see https://www.w3.org/Bugs/Public/show_bug.cgi?id=20055

>>
>>
>> Cheers,
>> Kenny
>
> So are there any links to any testcase?

The spec http://quirks.spec.whatwg.org/ has links to tests in the margin.

The discussion above is about  
http://w3c-test.org/quirks-mode/tests/js/line-height-calculation.html

The tests are currently maintained at https://dvcs.w3.org/hg/quirks-mode

-- 
Simon Pieters
Opera Software
Received on Friday, 1 March 2013 15:40:07 GMT

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