[HarfBuzz] disabling Arabic shaping when direction is vertical

Behdad Esfahbod behdad at behdad.org
Thu Apr 23 12:17:49 PDT 2015

On 15-04-23 04:47 AM, Jonathan Kew wrote:
> On 28/11/14 21:50, Behdad Esfahbod wrote:
>> On 14-09-23 04:20 AM, Behdad Esfahbod wrote:
>>> On 14-09-15 05:40 PM, Jonathan Kew wrote:
>>>>> Hi Behdad,
>>>>> If the harfbuzz buffer direction is vertical (TTB or BTT), I think we should
>>>>> refrain from doing Arabic shaping.[1]
>>>>> We could do this, for example, by adding an early return such as
>>>>>    if (unlikely (HB_DIRECTION_IS_VERTICAL (buffer->props.direction)))
>>>>>      return;
>>>>> in setup_masks_arabic(), so that the shaping analysis and setting of
>>>>> per-glyph
>>>>> features doesn't happen. WDYT?
>>> I can agree to that.  In that case, lets also not collect the features.
>> Bringing this back up so we fix.
> Ping. :)
> I just submitted https://github.com/behdad/harfbuzz/pull/100 with a trivial
> patch for this... please see what you think, and fix as appropriate. Thanks!

Thanks.  Counter proposal: how about changing the shaper-switch to route to
default shaper if direction is vertical?  That's much less intrusive.
Probably should do for Indic as well.


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