Re: master 3b41141708: Expose the name of an event's input device to Lisp

[Po Lu]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> For instance, I have a pedal that's a USB HID thingie.  Amusingly
> enough, stomping on the pedal gives me a "b" event.  The key "b",
> indistinguishable from a "b" from the keyboard.

Exactly.  This is partly the sort of use case I designed this feature
for.

> So if I could somehow say
>
> (keymap-set global-mode-map "[device footpad]-b" 'do-something)
>
> that would be ideal.

Oh yes, that would be good as well.  We could have the ability to bind
keys to individual devices.

I could imagine a different API that didn't put the device name into the
name of the key, though: there could be a system for making keymaps
"device-local", or even better device-specific bindings in a keymap:

  (keymap-set global-mode-map "b" #'do-something "name of footpad")

And the "name of footpad" can reasonably be system dependent, since the
user will be making such a customization, and he can look in the output
of `xinput list' (or the system's input preferences.)

We could also have a system like:

  (keymap-set global-mode-map "<wheel-down>"
              #'pixel-scroll-precision-interpolate 'mouse)

Where the last part doesn't have to be window system dependent, as long
as it's one of the values documented in `device-class'.

This is likely to make some things mysterious, so it will probably need
adjustment to the `describe-keymap' output.