[HarfBuzz] Indic support in Harfbuzz
emader at icu-project.org
Tue Dec 15 08:36:15 PST 2009
प्रविण सातपुते wrote:
> 2009/12/14 Eric Mader <emader at icu-project.org
> <mailto: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 <mailto:behdad at behdad.org>> wrote:
> >> 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 integrated.
> >>> Can you check if Jonathan's code can still be
> integrated in harfbuzz?
> >> 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?
I didn't do this implementation, so I don't know how much testing was done.
> 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.
I agree that there should be a single OpenSource layout engine that the
whole OpenSource community uses. That is, as I understand it, the goal
Given that Microsoft will continue to use Uniscribe, I think it's
important to make sure that all the fonts that work on Windows work w/
HarfBuzz and visa versa. This is what users will expect, and it seems to
me to be a reasonable expectation. Plus, it will mean that there are a
lot more fonts available on OpenSource platforms. ;-)
> Pravin S
More information about the HarfBuzz