[iip] Incorrect segmentation for styling initials (#94)

r12a has just created a new issue for https://github.com/w3c/iip:

== Incorrect segmentation for styling initials ==
Because of the problems associated with grapheme cluster boundaries (see above), first-letter selection in CSS doesn't work well for conjuncts. For example, Chrome, IE and Edge fail to style the whole conjunct in क्शण when using ::first-letter in a selector, and styles only the क्. This is problematic for many words in a script such as Devanagari, and forces the content author to use explicit spans rather than the proper mechanism for selecting initial letter.

<a href="https://w3c.github.io/ilreq/#h_indic_orthographic_syllable_boundaries">Indian Layout Requirements</a> provides a grammar for indian orthographic syllable boundaries which works for Devanagari, and CSS uses the concept of <a href="https://drafts.csswg.org/css-text-3/#typographic-character-unit">'typographic character unit'</a>, rather than grapheme cluster, in its specs with the explanation that these cases are beyond the scope of the grapheme cluster concept and that implementations should provide appropriate support. In addition, a modification to the concept of grapheme cluster is <a href="https://www.unicode.org/reports/tr29/proposed.html#Rule_Constraints">currently in development</a> at the Unicode Consortium, which is likely to resolve the problem for a script like Devanagari.

In addition, the alignment of styled initial-letter character glyphs with the rest of the text is not clearly specified or implemented.

See requirements at: <a href="https://w3c.github.io/ilreq/#h_initial_letter_styling">Indic Layout Requirements</a>

Relevant tests:

    <li><a href="https://www.w3.org/International/tests/repo/results/first-letter#devanagari">Selectors 3, first-letter</a></li>

Please view or discuss this issue at https://github.com/w3c/iip/issues/94 using your GitHub account

Received on Wednesday, 5 February 2020 05:57:54 UTC