[HarfBuzz] Overlap of vocal with thai text

[Vignesh Raman]

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/


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?
2) Is there a way to test thai characters/text with
qt-everywhere-opensource-src-4.7.4/src/3rdparty/harfbuzz ?
3) Is this a know issue with qt harfbuzz ?

Any pointers is appreciated. Thanks.

-- 
Regards,
Vignesh.