[HarfBuzz] Indic support in Harfbuzz
pravin.d.s at gmail.com
Mon Dec 14 19:47:55 PST 2009
2009/12/14 Eric Mader <emader at icu-project.org>
> Jonathan Kew wrote:
> > On 14 Dec 2009, at 16:26, kevin & siji wrote:
> >> On Mon, Dec 14, 2009 at 12:39 PM, Behdad Esfahbod <behdad at behdad.org>
> >> On 12/13/2009 11:03 PM, Parag Nemade wrote:
> >>> Hi Behdad,
> >>> On Friday 11 December 2009 01:57 PM, Jonathan Kew wrote:
> >>>> On 10 Dec 2009, at 21:29, Parag Nemade wrote:
> >>>>> Hi,
> >>>>> I would like to know whether current harfbuzz code can be used
> for testing the rendering of Indic scripts?
> >>>> Not easily, I think. A little while ago, I started work on Indic
> support (initially concentrating on the "new" Devanagari standard as used in
> Vista/Windows7), but AFAIK I don't think Behdad has committed any of that
> code to the repository yet. At that time, there were still some changes
> happening in the internal shaper/features APIs. I've been busy in other
> areas for the past few weeks, so have not been pressing to get this
> >>> Can you check if Jonathan's code can still be integrated in
> >> It's not. Will get to it this week.
> >> Is it worth reinventing the wheel? Is it not possible to use the code
> from ICU or Pango? Already a bunch of complex script rendering engines (ICU,
> Pango, Uniscribe) has made the Indic rendering scene a mess. Currently fonts
> should have separate ligature rules according to different rendering engine
> behaviours to create a single expected result universally.
> > AFAIK, neither ICU nor Pango code has support for the new Indic script
> tags and shaping behavior, so we'd need to adapt/extend/rewrite/something
> for that. And the shaping code interacts closely with the glyph buffer and
> with the feature controls, all stuff that differs between engines. So "use
> the code from ICU or Pango" is nowhere near as straightforward as it sounds.
> We may do that, but it would still need considerable work.
> ICU has code to support 'dev2'.
does ICU code rendering matches with Uniscribe?
> > In view of all that, I decided to experiment with writing a 'dev2' shaper
> directly from the spec, to see how that would work out (and to learn more
> about the details of the new spec, in the process). If we decide in the end
> that the old Pango or ICU code is preferable, that's fine. I'm not
> particularly interested in reinventing any wheels, if the old wheels can be
> upgraded to meet today's need, but it was not immediately clear to me
> whether that would actually be any easier or lead to a better result.
> > JK
> Microsoft has claimed that the Indic specs needed to be rewritten
> because the old specs weren't sufficient to implement all the required
> behavior for all the scripts. I don't know the details, but I'm inclined
> to believe them.
All the effort on harfbuzz are going on to make a unified rendering engine
and that is must things today. And it is better to try to match it with
Uniscribe (i guess it is with latest OT specs). so after that users should
not complain again fonts is working on Linux but not on windows/windows
fonts not working on linux. All opensource community can put effort in
fixing issues only at one place not like bug for ICU, pango etc.
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