Re: [Devel] Re: [Kannada] Re: Problem with freetype rendering of an Indic opentype font

[Owen Taylor]

On Sun, 2003-09-07 at 17:51, Lars Knoll wrote:
> On Sunday 07 September 2003 23:37, Arun Sharma wrote:
> > On Thu, Sep 04, 2003 at 10:24:10PM +0200, Werner LEMBERG wrote:
> > > > I see a problem with the freetype rendering of this unicode string:
> > > >
> > > > "0xcb7 0xccd"
> > > >
> > > > Using Microsoft tunga.ttf (A kannada font that ships with Windows
> > > > XP).  In fact, the problem manifests itself with all other
> > > > consonants too, including 0xcb7.
> > >
> > > I don't have time to investigate but it seems to me that some
> > > contextual shaping is happening.  If this is true it is not a problem
> > > of FreeType 2 (which doesn't support OpenType directly for the moment)
> > > but rather a problem one level higher where Indic scripts are handled,
> > > probably within the Pango library.  Owen?
> 
> I did some investigations and the problem seems to lie within the freetype 1 
> open type code used by Qt and pango. The font uses chain substitutions to 
> achieve correct rendering of this combination and these seem to work 
> incorrectly. Up do now I didn't find time to dig into this in more detail.

I just recently applied a patch to Pango for Chain Context substitutions
that apparently was needed for Kannada - 

http://people.redhat.com/otaylor/opentype-patches/pango-26-chain-format3

(from Kailash C. Chowksey.) Could that fix the problem here? (That patch
is in Pango-1.2.5)

http://bugzilla.gnome.org/show_bug.cgi?id=118592 also comes up for
tunga.ttf, though we haven't come up with a final patch for that.

Regards,
                                                Owen