[NTG-context] italic correction after math

Hans Hagen pragma at wxs.nl
Wed Feb 14 10:34:49 CET 2018


On 2/14/2018 10:22 AM, Ulrike Fischer wrote:
> Am Tue, 13 Feb 2018 19:21:21 +0100 schrieb Hans Hagen:
> 
> 
>>> But xits is in this case not lying about the italic. The cal-P has a
>>> large overhang and one would like to take this somehow into account.
>>
>> well, how should math (or whatever) know what comes after it ...
> 
> I wasn't looking for a completly automatic solution. Only something
> that lets me retrieve the correct kern and insert it (or suppress it
> if needed)

these things are always tricky and e.g. math-text boundaries can be
obscured by for instance boxing and so ... sometimes lua offers a way 
out but even then there are limits

>> only when it binds with a character
> ..
>> maybe inserting a zerowidthjoiner character helps
>>
>> $ .... \Uchar"200D$
> 
> Looks good. And for the record: \strut works the other way round and
> suppress the kern.

Yes, because a zwj is a real character and can be used to fool the mechanism

>>> Btw: I found in the luatex manuel the options
>>>      \mathoption nocharitalic 1
>>> but it seems to do nothing (the example in the manual show imho
>>> identical output).
> 
>> these flags are just for testing (the mathoption ones will go away
>> eventually which is why we use \mathoption) .. there are other
>> \math*mode etc parameters
> 
> It would be good to mention this in the manual. It is rather
> confusing to see examples that claim to show the effect of some
> setting and then do nothing.
actually there can be an effect but one that is effectively zero: it can 
be that a italic kern is injected and then removed as in traditional ... 
these effects really depend on the font and character properties

(in a similar fashion an example exposing some property and 
demonstrating some trick can fail when a font gets updated)

Hans

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