[NTG-context] Re: rendering arabic diacritics

["Hamid,Idris" <Idris.Hamid@ColoState.EDU>]

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------ Original Message ------
From "Hans Hagen" <j.hagen@xs4all.nl<mailto:j.hagen@xs4all.nl>>
To "ntg-context@ntg.nl<mailto:ntg-context@ntg.nl>" <ntg-context@ntg.nl<mailto:ntg-context@ntg.nl>>
Date 5/9/2024 6:29:40 AM
Subject [NTG-context] Re: rendering arabic diacritics

** Caution: EXTERNAL Sender **

On 5/9/2024 2:17 PM, Hamid,Idris wrote:
Hi Seyal,

See below:

------ Original Message ------
From "Hans Hagen" <j.hagen@xs4all.nl<mailto:j.hagen@xs4all.nl> <mailto:j.hagen@xs4all.nl>>
To "seyal.zavira@gmail.com<mailto:seyal.zavira@gmail.com> <mailto:seyal.zavira@gmail.com>"
<seyal.zavira@gmail.com<mailto:seyal.zavira@gmail.com> <mailto:seyal.zavira@gmail.com>>; "mailing list
for ConTeXt users" <ntg-context@ntg.nl<mailto:ntg-context@ntg.nl> <mailto:ntg-context@ntg.nl>>
Date 5/9/2024 3:31:45 AM
Subject [NTG-context] Re: rendering arabic diacritics

** Caution: EXTERNAL Sender **
On 5/9/2024 10:03 AM, seyal.zavira@gmail.com<mailto:seyal.zavira@gmail.com>
<mailto:seyal.zavira@gmail.com> wrote:
Hi all,
when i want to use the linked font for arabic texts it doesn't render
diacritics properly
i doesn't have problem with this font in inkscape or libreoffice
what featureset should i apply?
font link:
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1hCcv6wqWjd-5GEKnaowh8E8YVbTgGqQr%2Fview%3Fusp%3Dsharing&data=05%7C02%7CIdris.Hamid%40ColoState.EDU%7Cc8b63025b08545aa636308dc70244f52%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C638508548453863256%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=a2qMEGD0wo%2FhM6oNJ7AvfFyRPMEJuu0bFeceX4PPnsg%3D&reserved=0<https://drive.google.com/file/d/1hCcv6wqWjd-5GEKnaowh8E8YVbTgGqQr/view?usp=sharing> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1hCcv6wqWjd-5GEKnaowh8E8YVbTgGqQr%2Fview%3Fusp%3Dsharing&data=05%7C02%7CIdris.Hamid%40ColoState.EDU%7Cc8b63025b08545aa636308dc70244f52%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C638508548453873437%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=%2FLAHOebc2kdBEl4rBsEnp7gV4f6ZpXMWNt4FoUptSus%3D&reserved=0<https://drive.google.com/file/d/1hCcv6wqWjd-5GEKnaowh8E8YVbTgGqQr/view?usp=sharing>>
this is my MWE:
\definefontfeature [arabis]
[mode=node,language=dflt,script=arab,
init=yes,medi=yes,fina=yes,isol=yes,
liga=yes,dlig=yes,rlig=yes,clig=yes,
mark=yes,mkmk=yes,kern=yes,curs=yes]
\definefont [Ahang] [file:Ahang-Regular.otf*arabis at 18pt]
\setupalign[r2l]
\starttext
{\Ahang تَشْكِيل كَسْرَة}
\stoptext
\definefont [Ahang] [file:Ahang-Regular.otf*arabic at 18pt]
but there is an issue with widths, ill send you a patch to test

The provided "*arabic" featureset should suffice for this font. Also
TEXpage is useful for this kind of MWE:

\definefont [Ahang] [file:Ahang-Regular.otf*arabic at 18pt]
\setupalign[r2l]
\startTEXpage[offset=1em]
{\Ahang تَشْكِيل كَسْرَة}
\stopTEXpage

In prehistoric ConTeXt version

2023.09.26 18:19

the diacritics look fine in both ConTeXt and unicode editor MS Notepad.

So if there is something wrong, it must be in a more recent version.

For comparison: Before applying Hans' patch, could you kindly send your
pdf of the MWE that shows the error? Mine is attached.
Ahang-Regular has no width settings for the marks so we need to zero
them. Tahrir_Regular has widths but these we explictly need to zero with
a pseudo feature then. (What are the assumptions when we do arabic? That
marks are to have zero width?)

Yes, marks should have zero-width but Uniscribe (and Harbuzz?/its successor?) provide support for legacy fonts with non-zero width.

But sometimes font designers imitate legacy behavior..

So it used to be often the case that a font with diacritics that worked in Uniscribe etc. (e.g., Deja Vu Arabic) would show marks with widths in ConTeXt.

In order to be more helpful, I should update to the latest beta, run some tests, and get current on the status of these matters..

Idris
--
Idris Samawi Hamid, Professor
Department of Philosophy
Colorado State University
Fort Collins, CO 80523

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