RE: [CSS21] [css3-text] Text decoration behavior

Take a look at the attached document in Firefox. There are many levels of lines. In IE7 we see just one underline.

I believe that we need to change the 'text-decoration' wording in CSS 2.1 to read something like:

    "..., but should use the same baseline and thickness on each line."

We might also indicate that the same decoration should not be applied twice. When a user applies underline, overline and line-through it is okay to change the line on an element. However, it appears to be weird when multiple underlines, overlines, and line-through instances can be applied to the same text.





From: Steve Zilles [mailto:szilles@adobe.com]
Sent: Tuesday, March 04, 2008 1:19 PM
To: fantasai; Paul Nelson (ATC)
Cc: www-style@w3.org
Subject: Re: [CSS21] [css3-text] Text decoration behavior

As I understand the intent of this provision within the specification of 'text-decoration', it is to insure that for an element, the same styling is applied to the whole element, whether or not it has sub-elements; whether or not it fits on one line or many. It further says that the natures of the sub-elements (a.k.a. descendants) can be considered in deciding when the styling to be applied is chosen. So, see comments inline below.

At 12:42 PM 3/4/2008, fantasai wrote:

CCing www-style...

Paul Nelson (ATC) wrote:

Spec is ambiguous
In determining the position of and thickness of text decoration lines,
user agents may consider the font sizes of and dominant baselines of
descendants, but must use the same baseline and thickness on each line.
"on each line" - of text, each element?

Append "for a given element" right before the first comma.

And, add "of that element" before the second comma.


 The term
"line" at the end of the sentence refers to "line" in the "line box"
sense, not in the text decoration sense. I.e. all text decoration
lines in line box L that are generated by the 'text-decoration' value
on element E must be drawn with the same color, thickness, and position
with respect to element E's primary baseline.

It's possible "on each line" should be "throughout each line" so that
it's clear averaging can take place on a per-line basis. If not, we may
need to clarify that it can't. I'd check with Michel Suignard if you can.

I think that "on each line" should instead be "throughout the element" because I do not believe the 'text-decoration' should change when the window is resized causing an element that was on one line to move to two lines. It might be reasonable to add, after "element" above, "and on each line in which the element appears". This latter addition would make clear that the same position is used on every line, although that is implied by "throughout the element".



~fantasai

         Steve
=====================================
Steve Zilles
115 Lansberry Court,
Los Gatos, CA 95032-4710
steve@zilles.org