bug#74214: 30.0.92; Feature request - Support fringe bitmaps of width > 16 pixel

bug#74214: 30.0.92; Feature request - Support fringe bitmaps of width > 16 pixel

[Daniel Mendler via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Dear Emacs devs,

on high resolution displays, fringe bitmaps of 8 or even 16 pixel are
quite small. The function `define-fringe-bitmap' requires the bitmap
width to be an integer from 1 to 16. I would like to request to lift
this restriction, maybe allowing widths up to 64 or even larger. The
fringe itself is already allowed to be larger, e.g., the following is
supported, but the bitmaps cannot take advantage of the larger fringe:

(setq-local left-fringe-width 64
            right-fringe-width 64)

Thank you!

In GNU Emacs 30.0.92 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.18.2, Xaw scroll bars) of 2024-10-26

bug#74214: 30.0.92; Feature request - Support fringe bitmaps of width > 16 pixel

[Eli Zaretskii]

> Date: Tue, 05 Nov 2024 18:11:24 +0100
> From:  Daniel Mendler via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Dear Emacs devs,
> 
> on high resolution displays, fringe bitmaps of 8 or even 16 pixel are
> quite small. The function `define-fringe-bitmap' requires the bitmap
> width to be an integer from 1 to 16. I would like to request to lift
> this restriction, maybe allowing widths up to 64 or even larger. The
> fringe itself is already allowed to be larger, e.g., the following is
> supported, but the bitmaps cannot take advantage of the larger fringe:
> 
> (setq-local left-fringe-width 64
>             right-fringe-width 64)

This is not easy.  For some history, see bug#37755 and bug#37689.

Po Lu, ISTR that we established at some point that there were some
technical difficulties to implementing scaling of fringe bitmaps, but
I cannot find the relevant discussion.  Do you happen to remember the
details?  Or am I dreaming and we never talked about this?