Private Use areas (was: Re: Thoughts on working with the Emoji Subcommittee (was ...))

[Peter Constable via Unicode]

Layout engines that support CJK vertical layout do not rely on the 'vert' feature to rotate glyphs for CJK ideographs, but rather rotate the glyph 90° and switch to using vertical glyph metrics. The 'vert' feature is used to substitute vertical alternate glyphs as needed, such as for punctuation that isn't automatically rotated (and would probably need a differently-positioned alternate in any case).

Cf. UAX 50.


Peter

-----Original Message-----
From: Unicode <unicode-bounces at unicode.org> On Behalf Of Richard Wordingham via Unicode
Sent: Tuesday, August 21, 2018 3:02 AM
To: unicode at unicode.org
Subject: Re: Private Use areas (was: Re: Thoughts on working with the Emoji Subcommittee (was ...))

On Tue, 21 Aug 2018 08:53:18 +0800
via Unicode <unicode at unicode.org> wrote:

> On 2018-08-21 08:04, Mark E. Shoulson via Unicode wrote:

> > Still, maybe it
> > doesn't really matter much: your special-purpose font can treat any 
> > codepoint any way it likes, right?

> Not all properties come from the font. For example a Zhuang character 
> PUA font, which supplements CJK ideographs, does not rotate characters 
> 90 degrees, when change from RTL to vertical display of text.

Isn't that supposed to be treated by an OpenType feature such as 'vert'?  Or does the rendering stack get in the way?

However, one might need reflowing text to be about 40% WJ.

Richard.