[alreq] Inline elements break cursive shaping (#222)

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

== Inline elements break cursive shaping ==
When elements surround part of a cursive run of text, and apply styling, the results often break the cursive joins. (See the results of trying to colour individual letters in the illustration below – successful on the left, unsuccessful on the right.)


After some <a href="https://github.com/w3c/csswg-drafts/issues/698">discussion</a>, the CSS spec requires the following:

   <li>Markup alone around part of a joined up sequence must not disturb the joining behaviour.</li>
   <li>Styling that doesn't affect the characters, such as text-decoration, must not break the joins.</li>
   <li>Styling that does affect the shape of the characters should not break the joins, however the result is not well defined for complex glyph arrangements such as ligatures where the markup occurs between characters that make up the ligature.</li>
   <li>Non-zero margins, padding, and borders, will break the join, as will isolation boundaries.</li>

See the <a href="https://w3c.github.io/i18n-tests/results/css-text-shaping">tests and results</a> for a range of different styling effects.

<span class="fail">Safari</span> breaks cursive joining as soon as markup appears around a character, and so obviously fails for any type of styling application, too.

<span class="partial">Firefox</span>, Chrome, and <span class="partial">Edge</span> keep joins for styling that doesn't affect the shape of the characters (eg. text-decoration), and keeps it for colour changes, however they fail for changes in font-weight, font-style, and font-size, as well as for markup such as `em` and `b` tags.

<span class="issue">It would be useful to decide on the potential impact of the failures described here, so as to prioritise the issue. Is the inability to surround/style parts of a word a significant issue? It may be problematic when defining a term (using `dfn`) if the term is only part of the run of letters between spaces, eg. after the definite article.</span>

Please view or discuss this issue at https://github.com/w3c/alreq/issues/222 using your GitHub account

Received on Sunday, 2 February 2020 16:35:26 UTC