[HarfBuzz] Fwd: Re: Script itemization in Firefox

[Behdad Esfahbod]

Forwarding to the list as it looks like Jonathan's reply never made it to the
list.

-------- Original Message --------
Subject: Re: Script itemization in Firefox
Date: Thu, 3 Nov 2011 12:37:04 +0000
From: Jonathan Kew <jfkthame at googlemail.com>
To: Behdad Esfahbod <behdad at behdad.org>
CC: Harfbuzz <harfbuzz at lists.freedesktop.org>

Hi Behdad,

The script itemization is pretty closely based on code from ICU, just adapted
a little to our needs. See
http://mxr.mozilla.org/mozilla-central/source/gfx/thebes/gfxScriptItemizer.cpp.

IIRC, we break text into direction runs before doing script itemization, so
that the script itemizer works *within*, not across, bidi runs. This means
that Sc=Common characters at the beginning of a direction run will be grouped
with what follows, rather than what precedes. I'd guess that's more likely to
be useful in general, and it would explain better handling of your tatweel
example.

JK

On 2 Nov 2011, at 23:02, Behdad Esfahbod wrote:

> Hi Jonathan,
> 
> Can you elaborate on the script itemization algorithm in Firefox?  Whatever it
> is, it's doing a much better job than Pango is doing.  See:
> 
>  https://bugzilla.gnome.org/show_bug.cgi?id=662313
> 
> Thanks,
> behdad