Re: Physical keyboard events

[Alan Mackenzie <acm@muc.de>]

Hello, Cecilio.

On Tue, Oct 29, 2024 at 00:15:22 +0100, Cecilio Pardo wrote:
> 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.

> 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.

I envisage these leading to trouble.

For example, my KVM box intercepts a sufficiently rapid double press on
(either) Control key, and then expects a CR to switch computers, or ESC
to cancel (and maybe there are other keys I don't know about).

I quite frequently start typing a command by pressing the Control key,
then change my mind and let it go again.  I might sometimes hold that
key while trying to decide what I want to do.  The same surely applies
to Meta as well.

To make this work on a tty would involve fancy work on the keyboard
layout if it's even possible.  On a Linux console, it might even need
enhancements to the kernel.

I'm not sure binding our shift keys to commands, or even prefixes, is a
good idea.

> 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?

-- 
Alan Mackenzie (Nuremberg, Germany).