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/**
* get-luminosity — Determine how bright it is in your room
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "linearise.h"
#include <stddef.h>
#include <stdio.h>
#include <stdint.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <pthread.h>
static Display* restrict display;
static double get_brightness(int screen)
{
auto Window root = XRootWindow(display, screen);
auto long width = (long)XDisplayWidth(display, screen);
auto long height = (long)XDisplayHeight(display, screen);
auto XImage* restrict image = XGetImage(display, root, 0, 0, width, height, AllPlanes, ZPixmap);
register double sum = 0;
register unsigned char* restrict pixels;
register unsigned char* restrict end;
if (image == NULL)
return -1;
pixels = (unsigned char*)(image->data);
end = pixels + width * height * 4;
while (pixels != end)
{
sum += LINEAR_MAP[*pixels++];
sum += LINEAR_MAP[*pixels++];
sum += LINEAR_MAP[*pixels++];
pixels++;
}
XDestroyImage(image);
return sum / (double)(height * width * 3);
}
int main(void)
{
int screen, screens;
if (display = XOpenDisplay(NULL), display == NULL)
return 1;
screens = (size_t)ScreenCount(display);
for (screen = 0; screen < screens; screen++)
fprintf(stderr, "%lf\n", get_brightness(screen));
XCloseDisplay(display);
return 0;
}
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