[HarfBuzz] glyph advance difference between coretext and ot backend

[Behdad Esfahbod]

Interesting.  I'll take a look.

On 07/31/2012 01:49 PM, Rolf Langenhuijzen wrote:
> I did a similar test with 2 fonts and it was different between the two.. could it be some internal font thing that is causing this?
> 
> OSX:
> hb-shape --shapers=coretext "/dev/fonts/MaiolaPro-Regular.otf" ABC
> [A=0+670|B=1+565|C=2+640]
> 
> hb-shape --shapers=ot "/dev/fonts/MaiolaPro-Regular.otf" ABC
> [A=0+660|B=1+555|C=2+630]
> 
> hb-shape --shapers=ot "/dev/Whitney-Book-Pro.otf" ABC
> [A=0+691|B=1+547|C=2+638]
> 
> hb-shape --shapers=coretext "/dev/Whitney-Book-Pro.otf" ABC
> [A=0+691|B=1+547|C=2+638]
> 
> I tried on Ubuntu: 
> hb-shape --shapers=ot "MaiolaPro-Regular.otf" ABC
> [A=0+660|B=1+555|C=2+630]
> 
> So the same as on OSX, not the same as with coretext as you are getting…
> 
> Regards,
> Rolf
> 
> On Jul 31, 2012, at 12:42 PM, Dohyun Kim wrote:
> 
>> Hi,
>>
>> I have compiled harfbuzz-ng on Mac OS X Lion.
>> While testing some fonts, I encounterd a strange mismatch between
>> coretext and ot backends:
>>
>> $ ./hb-shape --shapers=coretext /System/Library/Fonts/AppleGothic.ttf ABC
>> [gid41=0+726|gid42=1+644|gid43=2+685]
>>
>> $ ./hb-shape --shapers=ot /System/Library/Fonts/AppleGothic.ttf ABC
>> [gid41=0+743|gid42=1+659|gid43=2+701]
>>
>> The Units Per Em of AppleGothic is 1000.
>> However, ot backend under Mac seems to consider upem as 1024 and
>> increase glyph widths in proportion, resulting in incorrect glyph positions.
>>
>> BTW, ot backend on ubuntu machine gives the same result as coretext under Mac.
>>
>> Best,
>> -- 
>> Dohyun Kim
>> College of Law, Dongguk University
>> Seoul, Republic of Korea
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