[HarfBuzz] Itemising Japanese scripts

[Simon Cozens]

On 25/04/2016 07:22, Khaled Hosny wrote:
> This leaves Han which has its own OpenType tag and that is what I have
> been seeing most. So I wounder what other application do, should I try
> something clever like see what scripts/features/lookups are in the font
> and decide to merge the scripts if it is safe (i.e. merging or not should
> have no effect on features applied), or should I just leave the current
> behaviour and not worry about it?

Just merge them. From an OpenType perspective, Japanese is boring.
Japanese characters are treated as discrete, independent units except in
extreme cases, (e.g. Kazuraki which uses ligatures to attempt to
replicate a hand-written look) so there should not be any OpenType
interactions between characters. I remember Paul Hunt saying that when
they developed Kazuraki they had to rewrite chunks of their OpenType
shaper to deal with it, as it was such a special case.

*Even if* there are OpenType interactions, these should take place
within the context of a Japanese font which has both kana and kanji
sets, so merging would be the right thing to do.

The real fun you're going to have is getting the layout correct, but you
can look at my code for how to implement that. :-)