Re: Shaping Hangul text with U+115F and/or U+1160

2013/3/18 Konstantin Ritt <ritt.ks_at_gmail.com>:
> Hi Philippe,
>
> thanks for your reply.
> I was confused by http://www.unicode.org/faq/unsup_char.html , which states
>> All default-ignorable characters should be rendered as completely invisible (and non advancing, i.e. "zero width"), if not explicitly supported in rendering.
> Do I understand correctly that, if the choseong filler is used when
> there's no leading consonnent before a medial vowel, it should be
> rendered as visible; otherwise become non-advancing
> (similarly, if the jungseong filler is used to replace a missing
> medial or final vowel, it should be rendered as visible; otherwise
> become non-advancing) ?

The important part of the statement is "if not explicitly supported in
rendering". But Hangul syllabic clusters are standardized and should
be supported in all renderers. This means that fillers cannot be
ignored, and this these fillers have a visible impact in the
rendering.

> i.e. <U+115F>, or <U+1161, U+1160>, or <U+115F, U+112B> -- should the
> fillers be rendered as non-advancing?

The renderer should create a single syllabic cluster by grouping the
vowel filler with the previous consonnant, and grouping the leading
consonnant filler with the following vowel. So there will be two
clusters.

But :

- the editor will generally now allow you to place the edit caret
between a the leading consonnant filler and the following vowel, and
it you place the caret after these two characters and press backspace,
it may delete both characters at once, or just leave the leading
consonnant filler alone (creating a defective Hangul syllable) ;

- in that case, the defective standalone consonnant filler not
followed by a vowel **may** be rendered with a visible glyph in the
editor (i.e. not zero-width and advancing, showing for example a
dotted square), but it will still be default-ignorable in searches.

For the same reason, an isolated vowel not following a leading
consonnant or leading consonnant filler may be rendered as defective
(i.e. not zero-width and advancing, showing the vowel on top of a
dotted square to sibily mark the fact that it is missing a leading
consonnant before it; that vowel will thne become advancing, even that
vowel is normally not advancing when rendering Hangul clusters).

Not also that the Hangul script **may** also be rendered using only
linear jamos (especially in small font sizes or when the display
resolution is poor). In that case the individual jamaos will ALL be
advancing (but Hangul fillers should not be shown if they combine
correctly with the necessary letter with which they should be
encoded).

Note finally that Hangul clusters are almost always encoded in
documents in precomposed forms (NFC : see the Unicode standard about
how normalisation operates in Hangul), so Hangul fillers will almost
never occur, except in defective syllables (note finally that, in text
editors, the dotted square may be shown, but it will remain blank and
invisible in rendered documents and these fillers, even if they are
used in a defective way, should remain zero-width).
Received on Mon Mar 18 2013 - 11:28:14 CDT