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Re: [css3-text] Adjacent and nested underlines (was Allow control of text-decoration width

From: Aryeh Gregor <Simetrical+w3c@gmail.com>
Date: Sun, 10 Apr 2011 16:54:56 -0400
Message-ID: <BANLkTimbfFLMMBUWNP1PfP0U_SVHoc6xMQ@mail.gmail.com>
To: Koji Ishii <kojiishi@gluesoft.co.jp>
Cc: fantasai <fantasai.lists@inkedblade.net>, "www-style@w3.org" <www-style@w3.org>
On Sun, Apr 10, 2011 at 4:49 AM, Koji Ishii <kojiishi@gluesoft.co.jp> wrote:
> I'm worried Eric's hack[1] might stop working as browsers implement smarter thickness/position, because it becomes more likely that multiple underlines are not painted over for different font/size. Is drawing multiple underlines to the same text important? If not, could we change the semantics of such case to "keep the same position and thickness, but re-apply color and style"?

The use-case I can think of offhand is if you want to underline a
superscript or subscript for some reason, like

    1<sup><u>o</u></sup>

(which is maybe used in French or something?).  Then if the text
happens to be underlined for some other reason, like

    <u>1<sup><u>o</u></sup></u>

I guess you do actually want both underlines to be drawn in this case,
because they're logically separate.  This is what the current spec
requires, and it's what Gecko and Opera do.

IE9 draws a single underline to be drawn under both of them, contrary
to the current spec.  I guess you could argue that it's just deciding
for some reason to place the superscript's underline at the same place
as the outer underline, but it's a stretch.  It does make some sense,
despite being against the spec.

WebKit here draws one underline under the "o", at the correct height
for the superscript, without extending the underline from under the
"1" at all, which seems undesirable across the board as well as being
against the spec.


For my use-case I'd only really care that

    <u>1</u><sup><u>o</u></sup>

renders the same as

    <u>1<sup>o</sup></u>

which it doesn't per spec and Gecko/Opera, but does per IE/WebKit.  If
they can render differently, then there's no reasonable way to
un-underline safely except by sticking in <span
style="text-decoration: cancel-underline">, which is not only long and
ugly but has bad back-compat and doesn't work with non-CSS UAs at all.

I'm not sure whether my use-case is enough to trump the extra
flexibility that the current spec allows, with the possibility of
multiple underlines under a single character.  Half the major
rendering engines don't allow that anyway -- has there been any
pressure on them to change?  I really think IE's approach is simplest
to understand and looks nicest.
Received on Sunday, 10 April 2011 20:55:43 GMT

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