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 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 -----------------------------------------------------------------

Umm... the fallbacks are correct. My conclusion is that tlig does not work when the character is not in the font itself. Is that the case? Is this a bug or a feature? \starttext \definefontfallback[fall][dejavusansmono][0-0xfffff][check=yes,force=no] \definefontsynonym[Test][file:Mikhak-Medium.ttf][fallbacks=fall] \definefontfeature[tf][arabic][tlig=yes] \definedfont[Test*tf] foo--bar [\char"2013] [\char"2014] \stoptext On Fri, Mar 12, 2021 at 7:13 PM Mohammad Hossein Bateni wrote:

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 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 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 -----------------------------------------------------------------

Added some notes to the wiki: https://wiki.contextgarden.net/Featuresets#Open-type_features On Sat, Mar 13, 2021 at 3:12 AM Hans Hagen wrote:

On 3/13/2021 2:01 AM, Mohammad Hossein Bateni wrote:

...

Umm... the fallbacks are correct. My conclusion is that tlig does not work when the character is not in the font itself. Is that the case? Is this a bug or a feature?

\starttext

\definefontfallback[fall][dejavusansmono][0-0xfffff][check=yes,force=no]

...

\definefontsynonym[Test][file:Mikhak-Medium.ttf][fallbacks=fall] \definefontfeature[tf][arabic][tlig=yes] \definedfont[Test*tf] foo--bar [\char"2013] [\char"2014] \stoptext

... or a misunderdstanding:

\starttext

\definefontfallback[myfallback][dejavuserif*default][0x02d,0x2013,0x2014][check=yes,force=yes]

\definefontsynonym[mytestfont][file:Mikhak-Medium.ttf][fallbacks=myfallback] \definedfont[mytestfont*arabic] foo--ofo---oof [\char"002D] [\char"2013] [\char"2014] \stoptext

for a ligature to be made all the glyphs involved have to come from the same font

I think you should wikify this (also because the font once complete is a nice one to use in examples),

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 -----------------------------------------------------------------