[NTG-context] tlig feature sometimes does not work

Mohammad Hossein Bateni bateni at gmail.com
Sat Mar 13 01:13:30 CET 2021


Any idea why the ligature {U+647 and U+654 => U+6C0} does not kick in?

On Fri, Mar 12, 2021 at 7:11 PM Mohammad Hossein Bateni <bateni at gmail.com>
wrote:

> That's bad.  It seems, I forgot to add the fallbacks properly.  I will
> reach out to the designer to add those chars.
>
> On Fri, Mar 12, 2021 at 12:32 PM Hans Hagen <j.hagen at xs4all.nl> wrote:
>
>> On 3/11/2021 2:05 AM, Mohammad Hossein Bateni wrote:
>> > Hi,
>> >
>> > Since most fonts do not have the standard tex ligatures built in, I
>> tend
>> > to add them when I load the fonts.  Once in a while, I run into fonts
>> > where this does not work.
>> >
>> > See the attached tex/pdf files.  I basically load the font as follows:
>> >
>> > \definefontfeature[tf][arabic][tlig=yes]
>> > \definedfont[dejavusansmono*tf]
>> >
>> > This works fine for DejaVuSansMono and for one Farsi font I use
>> > (
>> https://github.com/rastikerdar/vazir-font/blob/master/dist/Vazir-Regular.ttf
>> > <
>> https://github.com/rastikerdar/vazir-font/blob/master/dist/Vazir-Regular.ttf>)
>>
>> > but not for this other Farsi font
>> > (
>> https://github.com/aminabedi68/Mikhak/blob/master/Font/ttf/Mikhak-Medium.ttf
>> > <
>> https://github.com/aminabedi68/Mikhak/blob/master/Font/ttf/Mikhak-Medium.ttf>).
>>
>> > Perhaps this is because the last font is not standard, but
>> > TrueType/OpenType standard is sometimes up for interpretation.
>> >
>> > I see two strange symptoms here:
>> >
>> > \showotfcomposition displays the tlig feature differently for the last
>> > font.  It appears in the "extra" list, not in "basic".  Why is that?
>> > What does this mean anyway?
>>
>> The font doesn't have endash and emdash so there is nothing to construct
>> from the double -
>>
>> \starttext
>>      \definedfont[file:Mikhak-Medium.ttf*default] foo--bar
>>      [\char"2013]
>>      [\char"2014]
>> \stoptext
>>
>> Just ask the author to add these characters and you're fine.
>>
>> Hans
>>
>> -----------------------------------------------------------------
>>                                            Hans Hagen | PRAGMA ADE
>>                Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>>         tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
>> -----------------------------------------------------------------
>>
>
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