[HarfBuzz] Overlap of vocal with thai text

[Vignesh Raman]

Hi Konstantin,

Thanks for your pointers. Unfortunately I'm forced to use Qt 4.7.4 due
to a customer issue.

I was wondering which harfbuzz code Qt will use
a) qt-everywhere-opensource-src-4.7.4/src/3rdparty/harfbuzz/src/ or
b)  harfbuzz-0.9.38 (If I install this version)

I also see that freetype is required by Qt and this call some
functionality of harfbuzz to render thai fonts correctly.

Please correct me if I'm wrong.

Thanks & Regards,
Vignesh,

On Thu, Feb 26, 2015 at 1:55 AM, Konstantin Ritt <ritt.ks at gmail.com> wrote:
> 2015-02-24 13:58 GMT+04:00 Vignesh Raman <rvignesh.raman at gmail.com>:
>>
>> Hi,
>>
>> In one of the test using qt harfbuzz the font "ซ้ำ" is rendered as
>> http://postimg.org/image/77eo3ekbb/bfc768ce/
>>
>> There was a similar issue reported in
>> https://bugreports.qt.io/browse/QTBUG-21206.
>>
>> I applied the harfbuzz thai patches from,
>>
>> http://linux.thai.net/websvn/wsvn/software.qt/trunk/qt-everywhere-opensource-4.7.0/?#ad73b806583aa98bb601f6b456fa92491
>>
>> Also I applied the patch,
>> Fix isolated Thai SARA AM handling -
>> 44f415aafaf7eec56b31468a58e0ca768bbc082d
>>
>> But the issue was still not resolved.
>>
>> I checked in harfbuzz-0.9.38,
>> ./hb-view --annotate Tahoma.ttf "ซ้ำ" > thai1.png
>>
>> The text rendered properly (There is no overlap of vocal as shown in
>> previous image)
>> http://postimg.org/image/h62uhsu29/dab679e6/
>>
>
> You need Qt 5.5 (where HB-NG is the preferred shaper engine) or Qt 5.4
> configured with -qt-harfbuzz.
> Plz re-open QTBUG-21206 if the issue still reproducible with 5.5.
>
>>
>>
>> My questions
>> 1) From above two test can we confirm that harfbuzz-0.9.38 renders the
>> thai text correctly and qt harfbuzz is not rendering correctly?
>
>
> yes
>
>>
>> 2) Is there a way to test thai characters/text with
>> qt-everywhere-opensource-src-4.7.4/src/3rdparty/harfbuzz ?
>
>
> no. use Qt>=5.4
>
>>
>> 3) Is this a know issue with qt harfbuzz ?
>
>
> didn't you just point to QTBUG-21206? so I'd say it is a known issue for old
> Qt.
>
>
> Regards,
> Konstantin
>



-- 
Regards,
Vignesh.