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Re: [CSS21] Issues with inline formatting model (particularly 10.8)

From: Anton Prowse <prowse@moonhenge.net>
Date: Mon, 31 Aug 2009 21:25:40 +0200
Message-ID: <4A9C23B4.5020101@moonhenge.net>
To: Bert Bos <bert@w3.org>
CC: "www-style@w3.org" <www-style@w3.org>
Bert Bos wrote:
> On Sunday 01 March 2009, Anton Prowse wrote:
>> 10.8.1, 'line-height' property
>> (http://www.w3.org/TR/CSS21/visudet.html#propdef-line-height) :
>>
>>    # When an element contains text that is rendered in more than one
>>    # font, user agents may determine the 'line-height' value
>> according to # the largest font size.
>>    #
>>    # Generally, when there is only one value of 'line-height' for all
>>    # inline boxes in a paragraph (and no tall images), the above will
>>    # ensure that baselines of successive lines are exactly
>> 'line-height' # apart.
>>
>>
>> Issue 9a:  s/Generally/for example/
>
> No, "generally" is correct, "for example" would not be right.
>
Indeed, "for example" was wrong.  (David Baron pointed this out before.[1])

However, I dislike(*) the word "generally" in specifications because it
is unclear whether it is being used in its mathematical sense ("always")
or in its colloquial sense ("usually").  Perhaps the latter is more
natural for most readers.

(*) Generally speaking, at least ;-)


>> Issue 9b:  s/tall images/inline replaced elements/
>
> To be even more precise, the images referred to are inline replaced
> elements whose height and vertical alignment are such that their margin
> boxes fall completely within the line box height established by the
> surrounding elements.

Certainly.  I too was trying to avoid getting bogged down in details;
for me, the jarring thing is the word "images" rather than the word
"tall" (which I felt could be taken as read and hence omitted).  I guess
we differ about which details should be explicit when generalizing
the "usual" behaviour!

> But I'm not sure it is necessary to be very precise in this paragraph.
> It tries to give an intuition for what 'line-height' is roughly meant
> to do, without getting lost in details.
>
Sure.  What I had hoped to highlight was that the current sentence seems
to me to give special status to images, which both my (incorrect) "for
example" and my "inline replaced elements" were calculated to remove.

> The sentence doesn't get worse by replacing "tall images" with "inline
> replaced elements" but it doesn't get better either. I don't think a
> change is necessary.

To me it does get better because it avoids me stopping to decide whether
the reason for omitting other replaced inlines is because their
behaviour differs from images in this case (false) or because they are
represented here by images (true).  However, as you say, provided one
takes the intended interpretation of "generally", the paragraph is
clearly nothing more than a sketch of why line-height is so called.
Hence I can live with keeping "images"!

[1] http://lists.w3.org/Archives/Public/www-style/2009May/0191.html

Cheers,
Anton Prowse
http://dev.moonhenge.net
Received on Monday, 31 August 2009 19:27:38 GMT

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