Re: Supporting stylistic sets

["समीर सिंह Sameer Singh" <lumarzeli30@gmail.com>]

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>
> You are thinking about one particular use case.  There might be
> others.


What might be the other use cases?

Btw, is it always the case that, when using a particular font, users
> will want to apply the same stylistic-set feature to all of the
> characters from the font that have alternative glyphs?  If not, then
> font-level feature sets are not going to solve that, and we will need
> to be able to specify this for each character individually.
>

There are different stylistic-set features for different glyphs.
For example in FiraCode to change "a" there is cv01, for "g" cv02 etc.
or am I misunderstanding the question? (most likely)

On Sat, Sep 24, 2022 at 12:25 PM Eli Zaretskii <eliz@gnu.org> wrote:

> > From: समीर सिंह Sameer Singh <lumarzeli30@gmail.com>
> > Date: Sat, 24 Sep 2022 10:13:47 +0530
> > Cc: emacs-devel@gnu.org
> >
> >  That means all text that uses the font will use that stylistic-set.
> >  Is that good enough?  What if you want to have the same font with and
> >  without a specific stylistic-set in the same document?.
> >
> > Isn't the point of stylistic-set is that if you don't like a particular
> glyph of a font you can interchange it for
> > another, therefore I don't
> > see why someone would have the same font with and without the
> stylistic-set in the same document.
>
> You are thinking about one particular use case.  There might be
> others.
>
> > For example: Tiro Bangla had set the stylistic set because the users
> could not agree how the হ্+ন and হ্+ণ
> > conjuncts should look[1].
> > It is the case for FiraCode too, simple variations of glyphs which the
> user can switch out according to their
> > preference.
>
> If we want to support the use case of "just change the appearance of a
> particular character", then a much simpler implementation would be to
> use the existing character-composition machinery.  Specifically:
>
>   . add a suitable entry to composition-function-table, with a regexp
>     that matches the characters you want to affect
>   . provide a new variable that can be used to specify which, if any,
>     stylistic feature to use for each character (this could be a
>     char-table, for example)
>   . modify hbfont_shape to consult the above variable and apply the
>     requested features to the affected character(s)
>
> Btw, is it always the case that, when using a particular font, users
> will want to apply the same stylistic-set feature to all of the
> characters from the font that have alternative glyphs?  If not, then
> font-level feature sets are not going to solve that, and we will need
> to be able to specify this for each character individually.
>
> >  And if the font is not the default face's font, it means you need to
> >  setup a special face for using it anyway.
> >
> > You mean for scripts like Bangla, Devanagari etc?
> > For them defining their font-spec wouldn't work?
>
> I meant that the way to use a special font in Emacs, for ASCII
> characters, is to define a special face that uses that font.
>

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