Re: Increase default `line-spacing' to 0.05, 0.10 or 0.15 [proposal]

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Fri, 7 May 2021 13:43:56 -0500
> Cc: rms@gnu.org, emacs-devel@gnu.org
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > IMO, we should provide both local and global settings.
> 
> So how about this menu structure:
> 
> Options -> Set Line Height -> In this buffer -> 100 %
>                                              -> 110 %
>                                              -> ...
>                                              -> 160 %
>                            -> Global setting -> 100 %
>                                              -> 110 %
>                                              -> ...
>                                              -> 160 %
 
First, "Line Height" sounds like incorrect name to me.  Both Emacs and
other editors out there call this "Line Spacing", so why not use just
that (without the "Set" part)?

And second, 7 predefined values sounds too much.  I think we should
have 3 predefined possibilities: 1, 1.5, and 2, and one more asking
the user to provide the value.

On the implementation side, I'm not sure I understand how do you
intend to implement these values: 110% of what?  Line spacing is
eventually a pixel value; you can, of course, compute it in percents
of the font size, but then the nominal spacing will not have the 100%
or 1.0 value, right?  So how do you intend to convert the value in the
menu into the actual line-spacing value?