[HarfBuzz] Inconsistent shaping across systems

[Behdad Esfahbod]

On 15-08-17 08:51 AM, Simon Cozens wrote:
> More details at https://github.com/simoncozens/sile/issues/164 , but in
> a nutshell, using Noto Sans CJK JP and TTB direction, Ubuntu 12 gives:
> 
> $ md5sum  ~/.fonts/NotoSansCJKjp-Light.otf
> f269c193b1ef0b739030d56386670c3f  /home/simon/.fonts/NotoSansCJKjp-Light.otf
> $ hb-shape --direction=ttb ~/.fonts/NotoSansCJKjp-Light.otf '世界'
> [gid9861=0 at -500,-880+0,-1000|gid27506=1 at -500,-880+0,-1000]
> 
> and OS X (not using CoreText) gives
> 
> $ md5sum ~/Library/Fonts/NotoSansCJKjp-Light.otf
> f269c193b1ef0b739030d56386670c3f  ~/Library/Fonts/NotoSansCJKjp-Light.otf
> $ hb-shape --direction=ttb ~/Library/Fonts/NotoSansCJKjp-Light.otf '世界'
> [gid9861=0 at -500,-894+0,-1000|gid27506=1 at -500,-894+0,-1000]

This is quite probably a rounding issue happening in hb-ft.  I've seen it on
Mac before.

Try with --font-funcs=ot.  Our ot font funcs currently don't fully implement
all funcs.  And don't support VORG table, but then again, neither does FreeType.

behdad