Re: Grapheme clusters and east asian width

From: Asmus Freytag (t) <asmus-inc_at_ix.netcom.com>
Date: Wed, 16 Sep 2015 14:14:11 -0700

Hello,   

Is there any guidance on how to combine the information given by grapheme clusters and the east asian width property to do fixed-width layouts in terminal emulators ?  

For example if we have:  

U+AC01 ( 각 ) HANGUL SYLLABLE GAG

This will delimit a single grapheme cluster with east asian width W and hence 2 columns in a tty. However if we have it as the sequence:

U+1100 ( ᄀ ) HANGUL CHOSEONG KIYEOK
U+1161 ( ᅡ ) HANGUL JUNGSEONG A
U+11A8 ( ᆨ ) HANGUL JONGSEONG KIYEOK



This will delimit a single grapheme cluster, but if I try to add up their east asian widths (W, N, N), this would result in 4 columns.

No, this is a misreading of "N".

"N" doesn't mean "narrow" but "neutral" - that is, the width is given by other consideration.

In this case, the width is zero, because these code points are "conjoining" jamos, so in a sequence of them, they are supposed to "conjoin" into a single shape, in this case equivalent to U+AC01.


Look at combining marks, for example, they all have "N" as a value, but that does not mean they are suddenly supposed to take up a display position on their own.

A./
Received on Wed Sep 16 2015 - 16:15:21 CDT