Re: Bigger fringe bitmaps

[Eli Zaretskii]

> From: Yuri D'Elia <wavexx@thregr.org>
> Date: Thu, 17 Mar 2022 08:43:44 +0100
> 
> No comment on the idea of potentially using characters in the fringe?

I did comment on that.  To repeat: it could be a useful new feature,
but I don't think it should be _the_ solution for showing stuff on the
fringes on hidpi terminals; we should be able to produce legible
display of the bitmaps on those terminals.

> I find the idea appealing somehow, even ignoring hidpi issues, simply
> because "it's just more text".

Yes, it could be a good feature.  Patches are welcome.

> I like the idea of using 🢱 (or ⤶⤷) for wrapped text, 🮗 as a
> end-of-buffer, and so on. Easily scaled, and nicely antialiased.

You disregard the issue of which fonts support what characters in the
relevant Unicode blocks.  E.g., on my system, 🢱 is shown as "tofu", as
I evidently don't have a font for that codepoint.  Solving this in the
limited fringe screen estate will need some non-trivial ideas.  And
what about 'half-width' or 'minimal' fringe-styles?

I don't want to discourage someone who wants to work on this new
feature, but my point is that adding it will need some non-trivial
design and implementation decisions, and that's even before we talk
about the details in internals (fringe bitmaps are a special kind of
image in the Emacs display code).  Like I said, patches are welcome,
but let's not pretend that adding this is a trivial job.

> Especially the fact that this would potentially mean an usable fringe
> mode on character displays that can be toggled, so that you don't need
> to provide an alternate signaling mechanism if you rely on the fringe to
> show makers (like gud).

I don't think I follow.  Emacs doesn't support fringes on TTY
displays, so what do you mean by "usable fringe mode on character
displays"?

> - a bitmap
> - a character symbol for character displays (where the font family has
>   to be the same throughout the display and thus can be more limited in
>   choice)

This is already supported, see overlay-arrow-string.  Or do you mean
something else?