Hi,
Just took some time to bake a helper command to adjust the laptop's screen brightness, so as that I can easily adjust it in Emacs in a tiling window environment.
The code is inspired (well, almost copied from) by `text-scale-adjust`:
```elisp
(defun w/screen-brightness-adjust (inc)
"Adjust the screen brightness by INC*10%.
INC may be passed as a numeric prefix argument.
The actual adjustment made depends on the final component of the
key-binding used to invoke the command, with all modifiers removed:
+, = Increase the height of the default face by one step
- Decrease the height of the default face by one step
After adjusting, continue to read input events and further adjust
the screen brightness as long as the input event read
\(with all modifiers removed) is one of the above characters.
"
(interactive "p")
(let ((ev last-command-event)
(echo-keystrokes nil))
(let* ((base (event-basic-type ev))
(step (* inc 10))
(cmd (format "brightnessctl set %s%d%%%s" ; +10% or 10%-
(if (or (= ?+ base)
(= ?= base))
"+"
"")
step
(if (= ?- base) "-" ""))))
(shell-command cmd)
(message "Use +,- for further adjustment by %d%%" step)
(set-transient-map
(let ((map (make-sparse-keymap)))
(dolist (mods '(() (control)))
(dolist (key '(?- ?+ ?=)) ;; = is often unshifted +.
(define-key map (vector (append mods (list key)))
(lambda () (interactive)
(w/screen-brightness-adjust (abs inc))))))
map)))))
```