[HarfBuzz] GSUB for vertical layouts (CJK)

[Grigori Goronzy]

On 05/30/2011 07:39 PM, Behdad Esfahbod wrote:
> Right.  Default features for vertical is still missing.  That's about 10 lines
> of code.  I'll fix it today hopefully.
> 

Well, I enabled the `vert' feature with --features and also specified
script and language. Actually it _does_ work this way, but only for
regular, single OpenType fonts. At first, I tested it with Microsoft's
Meiryo font. This font is shipped as a TrueType collection of several
fonts and it looks like this isn't handled correctly by Harfbuzz. After
extracting a single font out of the TTC with FontForge, substitution
works as expected, although the conversion messes up positioning somehow
(a FontForge bug, I hope).

Another font I tested that normally is available in a single file per
font, Matisse Pro, doesn't show any such irregularities and everything
looks great--positioning and substitutions. Enabling `vrt2' makes it use
vertical only for CJK characters. Very nice!

It appears that Harfbuzz doesn't find any tables/fonts at all inside a
TTC and thus doesn't really do anything. The `main' program that dumps
some table info just shows this with Meiryo:

> Opened font file /home/greg/.fonts/meiryo.ttc: 9533888 bytes long
> TrueType Collection of OpenType fonts
> 0 font(s) found in file

Best regards,
Grigori