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Equivalence between tts:textDecoration="none" and "noUnderline noLineThrough noOverline". #1138
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What would be a possible interpretation that is not equivalent? |
... so, you agree that |
Reviewing CSS2.1 [1], XSL-FO 1.1 [2][3], and CSS Text Decoration Module Level 3 [4], I see that the
So, given that we don't support As an FYI, I've posted a related question as an issue on [4], about which see w3c/csswg-drafts#4188. [1] https://www.w3.org/TR/2011/REC-CSS2-20110607/text.html#decoration |
Without feeling that I know the answer to this issue, a question it raises for me is how the special inheritance of individual values is affected by setting Example 1: inherit with unspecified value, where initial value applies<span tts:textDecoration="underline lineThrough overline">
<span tts:color="lime">lime text with underline and line through and overline</span>
</span> Example 2: inherit with specified value the same as the initial value<span tts:textDecoration="underline lineThrough overline">
<span tts:color="lime" tts:textDecoration="none">lime text with underline and line through and overline?</span>
</span> Example 3: explicit override using component valuesFor reference, the following example is clear to me at the moment: <span tts:textDecoration="underline lineThrough overline">
<span tts:color="lime" tts:textDecoration="noUnderline noLineThrough noOverline">lime text with no underline and no line through and no overline</span>
</span> |
@nigelmegitt as TTML has defined it, the inner span inherits the computed tuple (underline, lineThrough, overline) in all three examples; in example 2, the inner span's computed tuple is (noUnderline, noLineThrough, noOverline), and the same holds for example 3; |
@skynavga right, that means that there is exact equivalence between a specified value of |
I am not sure how this works since A perhaps subtle difference is that |
Added to TPAC Agenda, https://www.w3.org/wiki/TimedText/tpac2019#Topics. |
The Timed Text Working Group just discussed
The full IRC log of that discussion<cyril> Topic: Equivalence between tts:textDecoration="none" and "noUnderline noLineThrough noOverline" #1138<cyril> github: https://github.com//issues/1138 <cyril> nigel: in practice right now they are the same <cyril> cyril: in this case, example 2 and 3 should give the same result? <cyril> nigel: yes <cyril> ... but if this was CSS it wouldn't be the same <cyril> ... example 2 the textDecoration would be displayed <cyril> ... example 3 is not possible in CSS because there are no values equivalent to no* <cyril> ... you just can't do it <cyril> ... once underlined has been applied at a parent level, you cannot un-apply it <cyril> glenn: in TTML, it does punch a hole <cyril> pal: is none identical to specifying the 3 no* <cyril> glenn: yes <cyril> cyril: at least we need a note that none here behaves differently from none in CSS <cyril> glenn: the no versions are also different <cyril> cyril: because you can undo them and not in CSS <cyril> glenn: yes <cyril> ... this is a feature where we are diverging from CSS <cyril> ... that does not mean you cannot map TTML to CSS <cyril> pal: it is not inherited in CSS <cyril> nigel: the only way to get rid of the text decoration is to use an inline block <cyril> nigel: we need a note to explain that none is equivalent to no* <cyril> ... and in the semantic derivation that there are differences (inheritance behavior <cyril> glenn: we could put it directly in the text decoration definition <cyril> pal: 2 different notes: TTML-level and CSS/TTML difference <cyril> SUMMARY: we agree with having 2 notes, and let the editor decide where they go |
Clarify semantics of tts:textDecoration value 'none' (#1138).
The specification does not conclusively state the equivalence between
tts:textDecoration="none"
andtts:textDecoration="noUnderline noLineThrough noOverline"
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