[HarfBuzz] glyph advance difference between coretext and ot backend

[Jonathan Kew]

On 31/7/12 19:29, Behdad Esfahbod wrote:
> Interesting.  I'll take a look.

It might be worth calling CTFontGetUnitsPerEm to see what Core Text 
considers the em-square of the font to be. ISTR that I've seen cases 
where Core Graphics, at least, "normalizes" the em-units of certain 
fonts that aren't using a "typical" size; I'm not sure if that carries 
through to Core Text metrics as well, but it might be a factor here...

JK

>
> 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
>>> _______________________________________________
>>> HarfBuzz mailing list
>>> HarfBuzz at lists.freedesktop.org
>>> http://lists.freedesktop.org/mailman/listinfo/harfbuzz
>>
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