Advanced Automatic Brightness on Macbook running Arch Linux

README.md

Compile screensy:

gcc -O3 -I/usr/include/cairo/ -lX11 -lcairo screensy.cpp -o screensy

I have to run to be able to write brightness changes:

sudo setpci -v -H1 -s 00:01.00 BRIDGE_CONTROL=0

Then run:

sudo python auto_brightness.py

auto_brightness.py

#!/usr/bin/env python

# add keyboard brightness
import os
import time
from datetime import datetime
from PIL import Image
import numpy as np


SCREEN_BRIGHTNESS_FILE = "/home/pascal/screen_brightness.png"

HIGH_SCREEN_BRIGHTNESS_CUTOFF = 70
MAX_AVG_RGB = 255

def write(n):
    with open("/sys/class/backlight/gmux_backlight/brightness", "w") as f:
        #print("new", n)
        f.write(str(int(n)))


def get_screen_brightness():
    im = Image.open(SCREEN_BRIGHTNESS_FILE)
    im_arr = np.fromstring(im.tobytes(), dtype=np.uint8)
    im_arr = im_arr.reshape((im.size[1], im.size[0], 3))
    crop = im_arr[-100:, -100:, :]
    return crop.mean()


with open("/sys/class/backlight/gmux_backlight/max_brightness") as f:
    max_v = int(f.read())

print("running brightness, did you run with root?")
prev_check = time.time()
while True:
    os.system("/home/pascal/screensy " + SCREEN_BRIGHTNESS_FILE)
    with open("/sys/devices/platform/applesmc.768/light") as f:
        backlight = int(f.read()[1:-1].split(",")[0])
    sb = get_screen_brightness()
    print(sb, backlight)
    new_value = max_v
    # if v < 10:
    #     # do not do comparison constantly
    #     hour = datetime.now().hour
    #     if hour > 20 or hour < 8:
    #         new_value = 100
    #     else:
    #         new_value = 300
    # if new_value == max_v and sb > HIGH_SCREEN_BRIGHTNESS_CUTOFF:
    new_value = (1 - (sb / MAX_AVG_RGB)) * 0.8 * new_value + (0.2) * new_value
    new_value = new_value if backlight > 10 else 0.3 * new_value
    print(new_value)
    write(new_value)
    time.sleep(0.5)

screensy.cpp

/*
    Adapted by Pascal van Kooten
    -----------------------------------------------
    Grabs a screenshot of the root window.

    Usage   : ./scr_tool <display> <output file>
    Example : ./scr_tool :0 /path/to/output.png

    Author: S Bozdag <selcuk.bozdag@gmail.com>
*/

#include <assert.h>
#include <stdio.h>
#include <cairo.h>
#include <cairo-xlib.h>
#include <X11/Xlib.h>

int max(int a, int b) {
  if (a > b) {
    return a;
  } else {
    return b;
  }
}

int min(int a, int b) {
  if (a < b) {
    return a;
  } else {
    return b;
  }
}

int main(int argc, char** argv) {
    Display *disp;
    Window root;
    cairo_surface_t *surface;
    int scr;
    // mouse related
    Bool query_result;
    int root_x, root_y;
    int win_x, win_y;
    unsigned int mask_return;
    Window window_returned;
    /* The only checkpoint only concerns about the number of parameters, see "Usage" */
    if( argc != 2) {
        fprintf(stderr, "Usage: screensy <output file> \n");
        return 1;
    }
    /* try to connect to display, exit if it's NULL */
    disp = XOpenDisplay( NULL );
    if( disp == NULL ){
        fprintf(stderr, "Given display cannot be found, exiting: %s\n" , argv[1]);
        return 1;
    }
    scr = DefaultScreen(disp);
    root = DefaultRootWindow(disp);

    // mouse stuff, eventually we would even prefer a fast screenshot around mouse position / active window in i3
    // query_result = XQueryPointer(disp, root, &window_returned,
    //                        &window_returned, &root_x, &root_y, &win_x, &win_y,
    //                        &mask_return);

    // printf("Mouse is at (%d,%d)\n", root_x, root_y);
    /* get the root surface on given display */
    surface = cairo_xlib_surface_create(disp, root, DefaultVisual(disp, scr),
                                        100,
                                        1000);
    // cairo_xlib_surface_set_size(surface, 100, 1000);
    /* right now, the tool only outputs PNG images */
    cairo_surface_write_to_png( surface, argv[1] );
    /* free the memory*/
    cairo_surface_destroy(surface);
    /* return with success */
    return 0;
}