Bug 255710

Summary:	Upright text in vertical lines doesn't segment correctly
Product:	WebKit	Reporter:	Fuqiao Xue <xfq.free>
Component:	Layout and Rendering	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	bfulgham, mmaxfield, simon.fraser, webkit-bug-importer, zalan
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified

Description Fuqiao Xue 2023-04-20 00:20:03 PDT

WebKit doesn't tailor grapheme cluster rules to take into account full orthographic syllables represented as conjuncts, upright characters in vertical lines of text don't break correctly.

See requirements at: https://w3c.github.io/ilreq/#h_vertical_arrangements_of_characters , but add to those the points made in https://w3c.github.io/i18n-drafts/questions/qa-indic-graphemes.en.html

Tests & results:
When devanagari characters are rendered upright in vertical text, orthographic syllables containing conjuncts are kept together: https://github.com/w3c/text_direction_tests/issues/10

An attempt has been made to keep conjuncts together, but pre-base consonants are rendered alone.

Comment 1 Radar WebKit Bug Importer 2023-04-27 00:21:19 PDT

<rdar://problem/108594541>