[HarfBuzz] Disabling OT features for ranges

[Lóránt Pintér]

Hi,  

I'm trying to disable some OpenType features while shaping. I'm trying to shape "VAV VAV" and disable kerning for the first three characters.

If I don't set any features, kerning is on for the whole string: OK, this is what I expect
If I set "+kern[4:7]", I get what I want: the first "VAV" is not kerned, the second is: OK
If I set "-kern[0:3]", I get kerning disabled for the whole string: NOT what I expect
If I set "+kern", "-kern[0:3]", I get kerning disabled for the whole string: NOT what I expect
If I set "+kern[0:8]", "-kern[0:3]", I get what I want: the first "VAV" is not kerned, the second is: OK

So "+/-kern[x:y]" disables the kerning for the rest of the input unless I specify the whole range with "+kern[0:end]" first. I find it a bit contra-intuitive. Is this how it should work?  

--  
Lóránt Pintér
Developer at Prezi (http://prezi.com)


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