xscreenfilter/xscreenfilter.c at main · caph1993/xscreenfilter · GitHub

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/*
xscreenfilter. A command line tool for setting window birghtness and temperature in linux systems.

Compilation dependencies: sudo apt install libxrandr-dev libx11-dev
Compilation instructions: gcc -I/usr/local/include -L/usr/local/lib xscreenfilter.c -o xscreenfilter -lXrandr -lX11

Assign to hotkeys for best experience.

Author:
 - Carlos Pinzón, caph1993@gmail.com

Credits to:
 - https://flak.tedunangst.com/post/sct-set-color-temperature
 - https://github.com/mgudemann/sct
*/
#include <X11/Xlib.h>
#include <X11/Xproto.h>
#include <X11/Xatom.h>
#include <X11/extensions/Xrandr.h>

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

/* cribbed from redshift, but truncated with 500K steps */
static const struct { float r; float g; float b; } whitepoints[] = {
        { 1.00000000,  0.18172716,  0.00000000, }, /* 1000K */
        { 1.00000000,  0.42322816,  0.00000000, },
        { 1.00000000,  0.54360078,  0.08679949, },
        { 1.00000000,  0.64373109,  0.28819679, },
        { 1.00000000,  0.71976951,  0.42860152, },
        { 1.00000000,  0.77987699,  0.54642268, },
        { 1.00000000,  0.82854786,  0.64816570, },
        { 1.00000000,  0.86860704,  0.73688797, },
        { 1.00000000,  0.90198230,  0.81465502, },
        { 1.00000000,  0.93853986,  0.88130458, },
        { 1.00000000,  0.97107439,  0.94305985, },
        { 1.00000000,  1.00000000,  1.00000000, }, /* 6500K */
        { 0.95160805,  0.96983355,  1.00000000, },
        { 0.91194747,  0.94470005,  1.00000000, },
        { 0.87906581,  0.92357340,  1.00000000, },
        { 0.85139976,  0.90559011,  1.00000000, },
        { 0.82782969,  0.89011714,  1.00000000, },
        { 0.80753191,  0.87667891,  1.00000000, },
        { 0.78988728,  0.86491137,  1.00000000, }, /* 10000K */
        { 0.77442176,  0.85453121,  1.00000000, },
};

int
main(int argc, char **argv)
{
	Display *dpy = XOpenDisplay(NULL);
	int screen = DefaultScreen(dpy);
	Window root = RootWindow(dpy, screen);

	XRRScreenResources *res = XRRGetScreenResourcesCurrent(dpy, root);

  char *filename = "/.xscreenfilter";
  char *home_dir = getenv("HOME");
  char *filepath = malloc(strlen(home_dir) + strlen(filename) + 1);
  strncpy(filepath, home_dir, strlen(home_dir) + 1);
  strncat(filepath, filename, strlen(filename) + 1);
  //printf("%s\n", filepath);


	int temp = 6500;
	double brightness = 1.0;

	FILE *fpRead;
	fpRead = fopen(filepath, "r");
	if(fpRead){
		fscanf(fpRead, "%d %lf", &temp, &brightness);
	}

	if (argc > 1){
		int tempArg = atoi(argv[1]);
		if(argv[1][0]=='+' || argv[1][0]=='-') temp+=tempArg;
		else temp = tempArg;
	} else temp = 6500;

  if (argc > 2){
    double brightnessArg = atof(argv[2]);
		if(argv[1][0]=='+' || argv[1][0]=='-') brightness+=brightnessArg;
		else brightness = brightnessArg;
  } else brightness = 1.0;

	if (temp < 1000) temp = 1000;
	if (temp > 6500) temp = 6500;
  if (brightness < 0.1) brightness = 0.1;
  if (brightness > 1.0) brightness = 1.0;

	FILE *fpWrite;
	fpWrite = fopen(filepath, "w");
	//printf("%d\n", !!fpWrite);
	if(fpWrite){
		fprintf(fpWrite, "%d %lf\n", temp, brightness);
	}


	temp -= 1000;
	double ratio = temp % 500 / 500.0;
	#define AVG(c) whitepoints[temp / 500].c * (1 - ratio) + whitepoints[temp / 500 + 1].c * ratio
	double gammar = brightness * (AVG(r));
	double gammag = brightness * (AVG(g));
	double gammab = brightness * (AVG(b));

	int num_crtcs = res->ncrtc;
	for (int c = 0; c < res->ncrtc; c++) {
		int crtcxid = res->crtcs[c];
		XRRCrtcInfo *crtc_info = XRRGetCrtcInfo(dpy, res, crtcxid);

		int size = XRRGetCrtcGammaSize(dpy, crtcxid);

		XRRCrtcGamma *crtc_gamma = XRRAllocGamma(size);

		for (int i = 0; i < size; i++) {
			double g = 65535.0 * i / size;
			crtc_gamma->red[i] = g * gammar;
			crtc_gamma->green[i] = g * gammag;
			crtc_gamma->blue[i] = g * gammab;
		}
		XRRSetCrtcGamma(dpy, crtcxid, crtc_gamma);

		XFree(crtc_gamma);
	}
}