Re: Changing font weight with buffer-face-mode-invoke

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 26 Jun 2024 20:54:53 +0000
> From: Heime <heimeborgia@protonmail.com>
> Cc: help-gnu-emacs@gnu.org
> 
> Could there be support functions (font-height-list :family family) and 
> (font-weight-list :family family) so they can be used with
> 
> (buffer-face-mode-invoke 
>   `(:family ,face-family :height ,face-height :weight ,face-weight) t)

They were never needed, and I don't really understand why you'd need
them.  So no, such functions are not planned.

> As the height and weight are customarily asked by users wanting to change
> font.

Users are not asked about these attributes, certainly not
"customarily", not in Emacs.  In fact, users are not supposed to be
bothered by that at all, they just need to specify the family/families
of font(s) they want to use, and Emacs will do the rest automatically.

IOW, I think you are talking about a problem that doesn't exist for
most Emacs users.  I understand that you decided for some reason to
write some peculiar program that allows selection of these attributes
interactively, and I'm prepared to help you find the related Emacs
functionalities for that program.  But the problem you are trying to
solve is largely an academic one, because the resulting font will be
largely not useful in Emacs, as you will discover next.  Emacs was not
designed to support selection of fonts by fine-tuning their weight,
slant, and other similar attributes, so specifying such fonts works in
some cases but doesn't work in others.