[HarfBuzz] Future of HarfBuzz

Behdad Esfahbod behdad at behdad.org
Tue Apr 14 11:59:46 PDT 2009

On 04/10/2009 07:04 PM, Damjan Georgievski wrote:
> Hi all,


> I have a question about the future of HarfBuzz in Qt and Pango.


> Is the plan still for HarfBuzz to be a common implementation of
> OpenType layout in both Qt and Pango?

Yes.  And more than that.  In the future, OpenOffice.org, Firefox, Webkit, etc 
are expected to use HarfBuzz directly.

> Is HarfBuzz used in Qt at all?


> I have also opened this bug, which hasn't seen any activity
> http://bugs.freedesktop.org/show_bug.cgi?id=17636 (implement OpenType
> "locale" feature)
> Is HarfBuzz even the correct project to have that RFE, since I really
> need it in Qt?

Yes and no.  The current HarfBuzz code is comprised of two parts: the layout 
engine and the shaping engine.  Pango only uses the layout engine from 
HarfBuzz currently, and has its own shaping engine.  The layout engine doesn't 
need any change to support "locl".  The shaping engine in HarfBuzz is used by 
Qt, and that would need to be changed to support "locl".

My grand plan for HarfBuzz is to:

   1) Rewrite the layout engine to use mmap()ed files.  I hacked on this for a 
while two years ago, but didn't have time to finish it.  The good news is that 
I'm back on it now.

   2) Merge the shaping engine with Pango's, picking and choosing the best of 

   3) Design a friendly API on the top.  The current API is IMO a mess and 
unnecessarily complex in some parts.

Hope that helps,


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