[HarfBuzz] disabling Arabic shaping when direction is vertical

[Jonathan Kew]

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!