[NTG-context] ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[NTG-context] ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[Felix]

https://pastebin.com/245uwYj4

I have this setup for my fonts, called myfonts.

I assume that `\definefontfeature [default] [default] [trep=yes,dlig=yes,itlc=yes]` will affect every single font that goes into my preamble (Forgive me if I seem incompetent, I am a beginner at ConTeXt)

I have dlig and trep on so that works with single quotations like don't have a directional quote, and so that I get the Times New Roman ligatures via dlig and not just liga. itlc is enabled since I read some documentation and they sometimes mention enabling it

is there some stuff like the extrafeatures option or anything that you would recommend i enable? might there be options for extrakerns that would be seen as something that one should enable? 

also, how can I see all the options available? dlig is something I discovered by accident that was not in the options list in the documentation. 

i use the latest version of ConTeXt LMTX on Windows
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[NTG-context] Re: ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[Marcus Vinicius Mesquita]

Hi, Felix


In linux, to find the GSUB/GPOS features of a opentype face you can
use the command

otfinfo -f fontname.ttf

otfinfo is part of the lcdf-typetools package

Regards

Marcus Vinicius

Marcus Vinicius

On Thu, Sep 5, 2024 at 6:02 PM Felix <fm117575@students.panola.edu> wrote:
>
> https://pastebin.com/245uwYj4
>
> I have this setup for my fonts, called myfonts.
>
> I assume that `\definefontfeature [default] [default] [trep=yes,dlig=yes,itlc=yes]` will affect every single font that goes into my preamble (Forgive me if I seem incompetent, I am a beginner at ConTeXt)
>
> I have dlig and trep on so that works with single quotations like don't have a directional quote, and so that I get the Times New Roman ligatures via dlig and not just liga. itlc is enabled since I read some documentation and they sometimes mention enabling it
>
> is there some stuff like the extrafeatures option or anything that you would recommend i enable? might there be options for extrakerns that would be seen as something that one should enable?
>
> also, how can I see all the options available? dlig is something I discovered by accident that was not in the options list in the documentation.
>
> i use the latest version of ConTeXt LMTX on Windows
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
>
> maillist : ntg-context@ntg.nl / https://mailman.ntg.nl/mailman3/lists/ntg-context.ntg.nl
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> ___________________________________________________________________________________



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[NTG-context] Re: ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[Hans Hagen]

On 9/6/2024 12:02 AM, Marcus Vinicius Mesquita wrote:
> Hi, Felix
> 
> 
> In linux, to find the GSUB/GPOS features of a opentype face you can
> use the command
> 
> otfinfo -f fontname.ttf
> 
> otfinfo is part of the lcdf-typetools package
context always shipped with this:

mtxrun --script font --info --all --list --pattern=pagella*

which also can generate the font database.

Hans

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[NTG-context] Re: ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[Wolfgang Schuster]

Felix  schrieb am 05.09.2024 um 22:58:
> https://pastebin.com/245uwYj4
> 
> I have this setup for my fonts, called myfonts.
> 
> I assume that `\definefontfeature [default] [default] [trep=yes,dlig=yes,itlc=yes]` will affect every single font that goes into my preamble (Forgive me if I seem incompetent, I am a beginner at ConTeXt)

It is applied to all fonts which use the "default" feature set and which 
enabled after you made the changes.

In the following example only pagella uses the "trep" feature because 
modern was loaded before the settings was added to the default feature set.

%%%% begin example
\starttext

\setupbodyfont[modern]

a'b

\definefontfeature [default] [default] [trep=yes]

\setupbodyfont[pagella]

a'b

\stoptext
%%%% end example

To be on the save side create custom feature set where you add 
additional settings and apply these to your fonts.

%%%% begin example
\definefontfeature [MyFeatures] [default] [trep=yes]

\definefontfamily [OldTimes] [rm] [Times New Roman]
\definefontfamily [NewTimes] [rm] [Times New Roman] [features=MyFeatures]

\starttext

\setupbodyfont[OldTimes]

a'b

\setupbodyfont[NewTimes]

a'b

\stoptext
%%%% end example

> I have dlig and trep on so that works with single quotations like don't have a directional quote, and so that I get the Times New Roman ligatures via dlig and not just liga. itlc is enabled since I read some documentation and they sometimes mention enabling it

It shouldn't be necessary to add "itlc" anymore to get italic correction 
for \em etc.

> is there some stuff like the extrafeatures option or anything that you would recommend i enable? might there be options for extrakerns that would be seen as something that one should enable?
> 
> also, how can I see all the options available? dlig is something I discovered by accident that was not in the options list in the documentation.

Unless you know the effect of a feature you shouldn't add or enable it.

You even have to know what is supported by the fonts in your document 
which can differ between certain versions of a font, take Times New 
Roman which is included with Windows as an example.

1. For a long time ligatures weren't supported by the font at all and 
the first mention of the support it is from 2022.

2. The font uses the "dlig" feature to enable the f ligatures even 
though the normal tag for it is "liga". My guess why they made this 
decision is backwards compatibility with existing document to avoid them 
from using these ligatures.

3. You shouldn't enable "dlig" by default for all fonts because the 
results of the feature can vastly for the fonts which provide it, take 
the following two fonts as example.

%%%% begin example
\definefontfeature [discretionary-ligatures] [dlig=yes]

\starttext

\startbuffer[pagella]
\starttabulate[|||]
\NC \type{----} \EQ ---- \NC\NR
\NC \type{--}   \EQ --   \NC\NR
\NC \type{!`}   \EQ !`   \NC\NR
\NC \type{!‘}   \EQ !‘   \NC\NR
\NC \type{?`}   \EQ ?`   \NC\NR
\NC \type{?‘}   \EQ ?‘   \NC\NR
\NC \type{,,}   \EQ ,,   \NC\NR
\NC \type{‘‘}   \EQ ‘‘   \NC\NR
\NC \type{’’}   \EQ ’’   \NC\NR
\NC \type{---}  \EQ ---  \NC\NR
\stoptabulate
\stopbuffer

\setupbodyfont[pagella]

\start \nohyphencollapsing
\getbuffer[pagella]
\stop

\start \nohyphencollapsing \feature[+][discretionary-ligatures]
\getbuffer[pagella]
\stop

\startbuffer[dejavuserif]
\starttabulate[|||]
\NC \type{ſt} \EQ ſt \NC\NR
\NC \type{st} \EQ st \NC\NR
\stoptabulate
\stopbuffer

\setupbodyfont[dejavu]

\start
\getbuffer[dejavuserif]
\stop

\start \feature[+][discretionary-ligatures]
\getbuffer[dejavuserif]
\stop

\stoptext
%%%% end example

The only additional features which can be added without problems are 
"expansion" and "protrusion" because until you enable them with 
\setupalign nothing changes in your document.

Wolfgang
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[NTG-context] Re: ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[Felix]

Hello Wolfgang, so if I follow your code examp,e what if I were to edit my code to be like this:

\definefontfeature[generalfeatures][default][
    kern=yes, % enables kerning
    extrakerns=yes, % enables extra kerning
    trep=yes, % Enables single and double quotes to show up correctly in text, perhaps does more
    liga=yes, % Enables ligatures.
    itlc=yes, % Activates italic correction.
    mark=yes, % Used for positioning diacritical marks (accents, dots, etc.) relative to base characters.
    mkmk=yes, % positions diacritical marks relative to other marks
    locl=yes,
    ccmp=yes, % Composes multiple characters into a single glyph or breaks down ligatures.
    mode=node,
    protrusion=yes,
    expansion=yes,
    language=dflt,
]

\definefontfamily [myfonts] [rm]        [Times New Roman] [features=generalfeatures,dlig=yes,cpsp=yes,% dlig enables times new roman ligatures, and cpsp is used by tnr, not aptos]
\definefontfamily [myfonts] [ss]        [Aptos]           [features=generalfeatures,]
\definetypeface   [myfonts] [mm] [math] [stixtwo]         [features=generalfeatures,]

\setupbodyfont[myfonts,12pt]

do you think this code is flawed?

Also, do you think you could explain how locl and extrakerns works? do I need to have kern=yes for it to enable? how can I test if extrakerns Is working? when I just have kern=yes enable, and then enable extra, a pdf that has a paragraph using both in code looks the same. locl is something I'm completely unsure about.
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[NTG-context] Re: ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[Felix]

\definefontfamily [myfonts] [rm]        [Times New Roman] [features=generalfeatures,dlig=yes,cpsp=yes,] % dlig enables times new roman ligatures, and cpsp is used by tnr, not aptos

is the correct code
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[NTG-context] Re: ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[Felix]

Hans, hello. I have a question regarding a new version of my font setup in context:

\definefontfeature[generalfeatures][default][
    kern=yes, % enables kerning
    extrakerns=yes, % enables extra kerning
    trep=yes, % Enables single and double quotes to show up correctly in text, perhaps does more
    liga=yes, % Enables ligatures.
    itlc=yes, % Activates italic correction.
    mark=yes, % Used for positioning diacritical marks (accents, dots, etc.) relative to base characters.
    mkmk=yes, % positions diacritical marks relative to other marks
    locl=yes,
    ccmp=yes, % Composes multiple characters into a single glyph or breaks down ligatures.
    mode=node,
    protrusion=yes,
    expansion=yes,
    language=dflt,
]

\definefontfamily [myfonts] [rm]        [Times New Roman] [features=generalfeatures,dlig=yes,cpsp=yes,] % dlig enables times new roman ligatures, and cpsp is used by tnr, not aptos
\definefontfamily [myfonts] [ss]        [Aptos]           [features=generalfeatures,]
\definetypeface   [myfonts] [mm] [math] [stixtwo]         [features=generalfeatures,]

\setupbodyfont[myfonts,12pt]

1. is extrakerns setup correctly? how can I tell if extrakerns will work? Since only kerns shows up in the OpenType features for TNR and Aptos. I wonder if it is like trep, which seems to be a context option for fonts.

2. What exactly does locl do if in tnr and aptos the option supports the latin script? (aptos also supports cyrl, and tnr also supports arab)

3. mode=node. I see that base is also an option in the settings sig page in context wiki, and ChatGPT told me node is the more 'complete', accurate, glyph based option that is typographically better, but takes more time to produce when used in a doc. Is this the case?
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[NTG-context] Re: ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[Wolfgang Schuster]

Felix schrieb am 13.09.2024 um 08:02:
> Hello Wolfgang, so if I follow your code examp,e what if I were to edit my code to be like this:
>
> \definefontfeature[generalfeatures][default][
>      kern=yes, % enables kerning
>      extrakerns=yes, % enables extra kerning
>      trep=yes, % Enables single and double quotes to show up correctly in text, perhaps does more
>      liga=yes, % Enables ligatures.
>      itlc=yes, % Activates italic correction.
>      mark=yes, % Used for positioning diacritical marks (accents, dots, etc.) relative to base characters.
>      mkmk=yes, % positions diacritical marks relative to other marks
>      locl=yes,
>      ccmp=yes, % Composes multiple characters into a single glyph or breaks down ligatures.
>      mode=node,
>      protrusion=yes,
>      expansion=yes,
>      language=dflt,
> ]
>
> \definefontfamily [myfonts] [rm]        [Times New Roman] [features=generalfeatures,dlig=yes,cpsp=yes,% dlig enables times new roman ligatures, and cpsp is used by tnr, not aptos]
> \definefontfamily [myfonts] [ss]        [Aptos]           [features=generalfeatures,]
> \definetypeface   [myfonts] [mm] [math] [stixtwo]         [features=generalfeatures,]
>
> \setupbodyfont[myfonts,12pt]
>
> do you think this code is flawed?

Stay with the following basic setups and add only expansion or 
protrusion when you use the features in your document, otherwise there 
is no need for them.

\definefontfeature [times] [default] [trep=yes,dlig=yes]
\definefontfeature [aptos] [default] [trep=yes]

\definefontfamily [myfonts] [rm]        [Times New Roman] [features=times]
\definefontfamily [myfonts] [ss]        [Aptos] [features=aptos]
\definefontfamily [myfonts] [tt]        [Aptos Mono] [features=none]
\definetypeface   [myfonts] [mm] [math] [stixtwo]

\setupbodyfont[myfonts,12pt]

\starttext
\samplefile{lorem}
\stoptext

> Also, do you think you could explain how locl and extrakerns works? do I need to have kern=yes for it to enable? how can I test if extrakerns Is working? when I just have kern=yes enable, and then enable extra, a pdf that has a paragraph using both in code looks the same. locl is something I'm completely unsure about.

1. Many features above are part of the default set.

2. When you don't know what the effect of an opentype feature is (look 
at https://www.preusstype.com/techdata/features.php for a few examples) 
don't enable it because you can get an unexpected output in your 
document. It is also important to know what your font makes with the 
feature because like I previously mentioned Times New Roman uses dlig to 
produce standard ligatures which isn't what you expect here.

Wolfgang

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[NTG-context] Re: ConTeXt beginner, What should I enable within font features? And how do I see all the options possible?

[Henning Hraban Ramm]

Am 13.09.24 um 16:21 schrieb Wolfgang Schuster:
> 2. When you don't know what the effect of an opentype feature is (look 
> at https://www.preusstype.com/techdata/features.php for a few examples) 

Also this list:
https://en.wikipedia.org/wiki/List_of_typographic_features

Hraban

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