[HarfBuzz] Language-specific forms in Scheherazade [was: Fwd: Re: Questions regarding hb_language_t]

Jonathan Kew jfkthame at googlemail.com
Mon Dec 16 04:00:15 PST 2013

Hi Bob & Lorna,

I'm hearing reports that the language-sensitive forms (such as the 
Sindhi and Urdu variants of Eastern Arabic-indic digits, and variants of 
Meem and Heh; maybe one or two others, I forget exactly) that we had in 
Scheherazade are not working as expected in the 2.0 font.

Looking briefly at the GSUB lookups, I don't see the language-specific 
lookups I'd expect. In the 1.x font, it looks like we handled this 
within the 'calt' feature (which is a little odd - I'd have expected it 
in 'locl' - but perhaps we had a good reason for it at the time, I 
forget). But in the newer font this functionality seems to be missing.

The attached testcase (assumes both old and new fonts are present in the 
same directory) shows an example of the failure when viewed in Firefox 
(with either OpenType or Graphite rendering), although it's also been 
observed in HarfBuzz separately from Firefox.


-------- Original Message --------
Subject: Re: [HarfBuzz] Questions regarding hb_language_t
Date: Sun, 15 Dec 2013 19:23:07 -0500
From: Behdad Esfahbod <behdad at behdad.org>
To: Ariel Malka <ariel at chronotext.org>, roozbeh at google.com
CC: Khaled Hosny <khaledhosny at eglug.org>, 
harfbuzz at lists.freedesktop.org,  Jonathan Kew <jfkthame at googlemail.com>

I can reproduce your results with Scheherazade-R.ttf, even when specifically
asking for the ot shaper instead of graphite2.  I have a local font file
called ScheherazadeRegOT.ttf that does work.  No idea what's going on, 

On 13-12-15 06:57 PM, Ariel Malka wrote:
> Thank you all for the advices...
> I tried Urdu ("ur"), without success.
> Regarding the fonts:
> For the Cyrillic test: I used DejaVuSerif.tff v2.34
> For the Arabic test: I used Scheherazade-R.ttf v2.010
> FWIW, the "critical code" is here:
> 1. http://goo.gl/LGw95n
> 2. http://goo.gl/lJaSVs
> On Mon, Dec 16, 2013 at 1:36 AM, Behdad Esfahbod <behdad at behdad.org
> <mailto:behdad at behdad.org>> wrote:
>     On 13-12-15 06:21 PM, Ariel Malka wrote:
>     >
>     > Should I activate some "special features" beyond hb_script_t and
>     hb_language_t?
>     Nope.  Seems to be working to me.  Depends on the specific fonts you are
>     using.
>     --
>     behdad
>     http://behdad.org/


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