[webkit-reviews] review requested: [Bug 16131] ZWNJ - Display non-printing, invisible character : [Attachment 51179] Removed style changes and presentation form check from patch

[bugzilla-daemon at webkit.org]

David Yonge-Mallo <davinci at chromium.org> has asked  for review:
Bug 16131: ZWNJ - Display non-printing, invisible character
https://bugs.webkit.org/show_bug.cgi?id=16131

Attachment 51179: Removed style changes and presentation form check from patch
https://bugs.webkit.org/attachment.cgi?id=51179&action=review

------- Additional Comments from David Yonge-Mallo <davinci at chromium.org>
I've removed the stylistic changes from the patch.  I only made them so the
style checker would stop outputting errors.

You're right that presentation forms should not be subject to shaping if web
sites follow the rules, but some (I don't know how many) don't.  This is
particularly true for sites in Persian and Urdu, some of which use the
presentation forms to force the display of certain glyphs which look better
than the standard Arabic glyphs for those languages (especially ye and
he-jimi).  I can include a test case, but it would contain what is essentially
incorrect Unicode.  Rather than handle bad Unicode for backwards compatibility
reasons, it's better to have correct language detection and have WebKit choose
the right "pretty" glyphs.  So, I've dropped the representation form check from
the patch.

This goes beyond the scope of the bug as originally described, but ZWNJ and ZWJ
are not handled correctly in the complex text font path.  On Mac, the ZWJ acts
like ZWNJ.  On Linux, the joining behaviour is correct, but the glyphs are
displayed.  I'll file a separate bug for those.