minimal intel_backlight

from pathlib import Path
from tkinter import Button, Tk
from tkinter.ttk import Scale

BASE = Path("/sys/class/backlight/intel_backlight")
BRIGHTNESS = BASE / "brightness"
MAX_BRIGHTNESS = int(BASE.joinpath("max_brightness").read_text())


def set(percent: float):
    value = MAX_BRIGHTNESS / 100 * float(percent)
    BRIGHTNESS.write_text(str(int(value)))


def get() -> float:
    return int(BRIGHTNESS.read_text()) / MAX_BRIGHTNESS * 100


def gui() -> Tk:
    root = Tk()
    Scale(root, value=get(), from_=0, to=100, command=set).pack()
    Button(root, text="Close", command=root.destroy).pack()
    return root


if __name__ == "__main__":
    gui().mainloop()