Re: Physical keyboard events

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 29 Oct 2024 00:15:22 +0100
> From: Cecilio Pardo <cpardo@imayhem.com>
> 
> Hello,
> 
> I'm planning to implement physical key press/release events for emacs.
> I would add a new element to 'enum event_kind', that in turn would
> send a new input event. This input event will be bound in
> 'special-event-map' so that it will not modify the normal flow of
> keyboard input. Platform dependent code would send these events
> on key press and release.

I hope these new events will not be sent at all times, only when some
optional variable is set (similar to track-mouse, perhaps).  I
wouldn't want Emacs to start processing press/release events on Shift
or Ctrl unless a Lisp program needs that, and I don't think we want to
change our processing of keyboard such that instead of a single
keypress with modifiers we need to process multiple key-press and
key-release events when the user simply types on the keyboard.

Physical keys also raise the issue of supporting input methods,
keyboard layout switches, etc.

> Then a lisp fuction can be bound to this on the special-event-map, to
> implement the detection of:
> 
> - double/triple tap on Shift, Control, Alt, etc
> - Long presses on Shift, Control, Alt, etc.
> 
> This actions could be bound to commands, or could add a modififer
> (Super, Hyper) to next commands.
> 
> And make Tetris independent of the keyboard repeat rate :)
> 
> Has something like this been discussed before, so I can check?

No, I don't think so, although we get feature requests for something
like that from time to time.

However, on what systems and which Emacs configurations will it be
possible to provide such a feature?

Thanks.