Re: [css-text-decor-3] determining position and thickness of line decorations

On 03/24/2013 09:39 PM, L. David Baron wrote:
> specifies
> the following for determining the thickness of decorations:
>    # CSS does not define the thickness of line decorations. In
>    # determining the thickness of text decoration lines, user agents
>    # may consider the font sizes, faces, and weights of descendants
>    # to provide an appropriately averaged thickness.
> I think this "may consider" is a bad suggestion, and I would prefer
> that CSS specify that descendants do not affect the thickness.
> I think this attempt to determine a useful underline for a single
> element is more likely to be harmful than helpful because it will
> lead to underlines being inconsistent between elements.  And I
> believe consistency of underlines between different underlined
> elements is important in many designs.  For example, if one item
> within a list (horizontal or vertical) or links contains some
> superscripted text, I believe authors would expect it to have the
> same style of underline as the other links.
> I'm also hesitant to break invariants that you get basically the
> same thing if you split a single inline into multiple inlines -- an
> invariant that I expect editing tools assume in a number of cases.
> I believe these same invariants apply to the rules for positioning,
> where the specification is substantially more complicated.  I
> disagree with the entire premise of the rules, which I think are, as
> with thickness, likely to lead (in the cases where the rules matter
> at all) to ransom-note style underlining, which I believe designers
> dislike.
> While these rules improve certain complex cases, I belive they hurt
> more common cases, and they also add substantial complexity to the
> specification.

Ok, what you're asking for would be a significant change from what 2.1
specifies, which is, I quote:

   # 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.

It's also quite different from the examples and illustrations in
CSS3 Text that have been there since before I inherited the spec.

I think I'm okay with requiring a consistent thickness as determined
by the decorating element. However, I'm not really a fan of drawing
underlines across a subscript, and I don't think that's what designers
want, either. I guess it would be appropriate to ignore them in the
positioning if they are being skipped however (via 'text-decoration-skip'),
so I'll update the spec to say that.


Received on Tuesday, 7 May 2013 02:12:46 UTC