[iip] Break anywhere fails on conjuncts (#78)

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

== Break anywhere fails on conjuncts ==
<code class="kw" translate="no">line-break:anywhere</code> causes lines to break inside words. It should break lines on grapheme cluster boundaries for all consonant clusters apart from the 3 special conjuncts. Chrome doesn't support the anywhere value. <span class="pass">Firefox</span> and <span class="pass">Safari</span> behave as expected.</p>
<p>The exceptions are the sequences <span class="charExample" translate="no"><span class="ex" lang="ta">க்ஷ</span> <span class="trans">k͓ʂ</span></span>, and <span class="charExample" translate="no"><span class="ex" lang="ta">ஶ்ரீ</span> <span class="trans">ʃ͓ɾī</span></span> / <span class="charExample" translate="no"><span class="ex" lang="ta">ஸ்ரீ</span> <span class="trans">s͓ɾī</span></span> (which are synonyms). These sequences should not be broken during line breaking. Correct line breaking of these conjunct-forming sequences are not  supported by default by Unicode grapheme clusters (which split them in two), and requires the application of tailored rules.

Test: Apply the strings ரிக்ஷா  ஸ்ரீநகர் <a href="https://w3c.github.io/i18n-tests/css-text/interactive/int-line-break-000">to this </a>interactive test.

<span class="partial">Firefox</span> is ok for shri and for ksha without a vowel-sign, but  in ரிக்ஷா leaves க் on previous line, still shaped for half a conjunct. <span class="partial">Safari</span> is ok for shri in HTML, but leaves ஸ் behind in textarea; for ksha, in textarea leaves க் behind, in HTML initially moves whole word to next line, then puts ரி back at end of line as you decrease the window width.

Similar results are produced for <code class="kw" translate="no">word-break: break-all</code>, except that Chrome supports this property and value.  <span class="fail">Chrome</span> wraps ஸ்ரீந as a single unit and ரிக்ஷா as a unit.

The impact of this is advanced, although it would be good to fix it.

Please view or discuss this issue at https://github.com/w3c/iip/issues/78 using your GitHub account

Received on Tuesday, 4 February 2020 18:30:43 UTC