[xsct 1.9] Fix issue #32 by adding linear brightness parameter (PR #33)

Add second argument: Linear brightness

Usage:
```sh
./xsct 4000 0.5 && ./xsct
```

Fixes #32 .

Author: zvezdochiot

CHANGELOG

@@ -1,5 +1,8 @@
 PROJECT: https://github.com/faf0/sct
 
+1.9: zvezdochiot on 15 Dec 2022
+* Add [brightness] - linear brightness {0.0 .. 1.0}
+
 1.8.1: Ionic and faf0 on 27 Jul 2022
 * Allow Makefile default settings to be overridden by environment variables; patch
 contributed by Ionic

Makefile

@@ -7,7 +7,7 @@ MAN ?= $(PREFIX)/share/man/man1
 INSTALL ?= install
 
 PROG = xsct
-SRCS = xsct.c
+SRCS = src/xsct.c
 
 LIBS = -lX11 -lXrandr -lm
 

README.md

@@ -80,14 +80,18 @@ gcc -Wall -Wextra -Werror -pedantic -std=c99 -O2 -I /usr/X11R6/include xsct.c -o
 
 Provided that xsct binary is located in your `$PATH`, execute it using the following command:
 ~~~sh
-xsct 3700
+xsct 3700 0.9
 ~~~
 
-The first parameter (`3700` above) represents the color temperature.  
+The first parameter (`3700` above) represents the color temperature.
 
-If `xsct` is called with parameter 0, the color temperature is set to `6500`.  
+The second parameter (`0.9` above) represents the brightness. The values are in the range `[0.0, 1.0]`.
 
-If `xsct` is called without parameters, the current display temperature is estimated.
+If `xsct` is called with parameter 0, the color temperature is set to `6500`.
+
+If `xsct` is called with the color temperature parameter only, the brightness is set to `1.0`.
+
+If `xsct` is called without parameters, the current display temperature and brightness are estimated.
 
 The following options, which can be specified before the optional temperature parameter, are supported:
 - `-h`, `--help`: display the help page
@@ -98,7 +102,7 @@ The following options, which can be specified before the optional temperature pa
 
 Test xsct using the following command:
 ~~~sh
-xsct 3700 && xsct
+xsct 3700 0.9 && xsct
 ~~~
 
 # Resources

xsct.c src/xsct.c

@@ -4,70 +4,46 @@
  * Public domain, do as you wish.
  */
 
-#include <X11/Xatom.h>
-#include <X11/Xlib.h>
-#include <X11/Xproto.h>
-#include <X11/extensions/Xrandr.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <math.h>
+#include "xsct.h"
 
 static void usage(char * pname)
 {
-    printf("Xsct (1.8)\n"
-           "Usage: %s [options] [temperature]\n"
+    printf("Xsct (%s)\n"
+           "Usage: %s [options] [temperature] [brightness]\n"
            "\tIf the argument is 0, xsct resets the display to the default temperature (6500K)\n"
-           "\tIf no arguments are passed, xsct estimates the current display temperature\n"
+           "\tIf no arguments are passed, xsct estimates the current display temperature and brightness\n"
            "Options:\n"
            "\t-h, --help \t xsct will display this usage information\n"
            "\t-v, --verbose \t xsct will display debugging information\n"
            "\t-d, --delta\t xsct will shift temperature by the temperature value\n"
            "\t-s, --screen N\t xsct will only select screen specified by given zero-based index\n"
-           "\t-c, --crtc N\t xsct will only select CRTC specified by given zero-based index\n", pname);
+           "\t-c, --crtc N\t xsct will only select CRTC specified by given zero-based index\n", XSCT_VERSION, pname);
 }
 
-#define TEMPERATURE_NORM    6500
-#define TEMPERATURE_ZERO    700
-#define GAMMA_MULT          65535.0
-// Approximation of the `redshift` table from
-// https://github.com/jonls/redshift/blob/04760afe31bff5b26cf18fe51606e7bdeac15504/src/colorramp.c#L30-L273
-// without limits:
-// GAMMA = K0 + K1 * ln(T - T0)
-// Red range (T0 = TEMPERATURE_ZERO)
-// Green color
-#define GAMMA_K0GR          -1.47751309139817
-#define GAMMA_K1GR          0.28590164772055
-// Blue color
-#define GAMMA_K0BR          -4.38321650114872
-#define GAMMA_K1BR          0.6212158769447
-// Blue range  (T0 = TEMPERATURE_NORM - TEMPERATURE_ZERO)
-// Red color
-#define GAMMA_K0RB          1.75390204039018
-#define GAMMA_K1RB          -0.1150805671482
-// Green color
-#define GAMMA_K0GB          1.49221604915144
-#define GAMMA_K1GB          -0.07513509588921
-
 static double DoubleTrim(double x, double a, double b)
 {
     double buff[3] = {a, x, b};
     return buff[ (int)(x > a) + (int)(x > b) ];
 }
 
-static int get_sct_for_screen(Display *dpy, int screen, int icrtc, int fdebug)
+static struct temp_status get_sct_for_screen(Display *dpy, int screen, int icrtc, int fdebug)
 {
     Window root = RootWindow(dpy, screen);
     XRRScreenResources *res = XRRGetScreenResourcesCurrent(dpy, root);
 
-    int temp = 0, n, c;
+    int n, c;
     double t = 0.0;
-    double gammar = 0.0, gammag = 0.0, gammab = 0.0, gammam = 1.0, gammad = 0.0;
+    double gammar = 0.0, gammag = 0.0, gammab = 0.0, gammad = 0.0;
+    struct temp_status temp;
+    temp.temp = 0;
+    temp.brightness = 1.0;
 
     n = res->ncrtc;
-    int icrtc_specified = icrtc >= 0 && icrtc < n;
-    for (c = icrtc_specified ? icrtc : 0; c < (icrtc_specified ? icrtc + 1 : n); c++)
+    if ((icrtc >= 0) && (icrtc < n))
+        n = 1;
+    else
+        icrtc = 0;
+    for (c = icrtc; c < (icrtc + n); c++)
     {
         RRCrtc crtcxid;
         int size;
@@ -82,14 +58,17 @@ static int get_sct_for_screen(Display *dpy, int screen, int icrtc, int fdebug)
         XRRFreeGamma(crtc_gamma);
     }
     XFree(res);
-    gammam = (gammar > gammag) ? gammar : gammag;
-    gammam = (gammab > gammam) ? gammab : gammam;
-    if (gammam > 0.0)
+    temp.brightness = (gammar > gammag) ? gammar : gammag;
+    temp.brightness = (gammab > temp.brightness) ? gammab : temp.brightness;
+    if (temp.brightness > 0.0 && n > 0)
     {
-        gammar /= gammam;
-        gammag /= gammam;
-        gammab /= gammam;
-        if (fdebug > 0) fprintf(stderr, "DEBUG: Gamma: %f, %f, %f\n", gammar, gammag, gammab);
+        gammar /= temp.brightness;
+        gammag /= temp.brightness;
+        gammab /= temp.brightness;
+        temp.brightness /= n;
+        temp.brightness /= BRIGHTHESS_DIV;
+        temp.brightness = DoubleTrim(temp.brightness, 0.0, 1.0);
+        if (fdebug > 0) fprintf(stderr, "DEBUG: Gamma: %f, %f, %f, brightness: %f\n", gammar, gammag, gammab, temp.brightness);
         gammad = gammab - gammar;
         if (gammad < 0.0)
         {
@@ -107,34 +86,37 @@ static int get_sct_for_screen(Display *dpy, int screen, int icrtc, int fdebug)
             t = exp((gammag + 1.0 - gammad - (GAMMA_K0GB + GAMMA_K0RB)) / (GAMMA_K1GB + GAMMA_K1RB)) + (TEMPERATURE_NORM - TEMPERATURE_ZERO);
         }
     }
+    else
+        temp.brightness = DoubleTrim(temp.brightness, 0.0, 1.0);
 
-    temp = (int)(t + 0.5);
+    temp.temp = (int)(t + 0.5);
 
     return temp;
 }
 
-static void sct_for_screen(Display *dpy, int screen, int icrtc, int temp, int fdebug)
+static void sct_for_screen(Display *dpy, int screen, int icrtc, struct temp_status temp, int fdebug)
 {
-    double t = 0.0, g = 0.0, gammar, gammag, gammab;
+    double t = 0.0, b = 1.0, g = 0.0, gammar, gammag, gammab;
     int n, c;
     Window root = RootWindow(dpy, screen);
     XRRScreenResources *res = XRRGetScreenResourcesCurrent(dpy, root);
 
-    t = (double)temp;
-    if (temp < TEMPERATURE_NORM)
+    t = (double)temp.temp;
+    b = DoubleTrim(temp.brightness, 0.0, 1.0);
+    if (temp.temp < TEMPERATURE_NORM)
     {
         gammar = 1.0;
-        if (temp < TEMPERATURE_ZERO)
-        {
-            gammag = 0.0;
-            gammab = 0.0;
-        }
-        else
+        if (temp.temp > TEMPERATURE_ZERO)
         {
             g = log(t - TEMPERATURE_ZERO);
             gammag = DoubleTrim(GAMMA_K0GR + GAMMA_K1GR * g, 0.0, 1.0);
             gammab = DoubleTrim(GAMMA_K0BR + GAMMA_K1BR * g, 0.0, 1.0);
         }
+        else
+        {
+            gammag = 0.0;
+            gammab = 0.0;
+        }
     }
     else
     {
@@ -143,10 +125,13 @@ static void sct_for_screen(Display *dpy, int screen, int icrtc, int temp, int fd
         gammag = DoubleTrim(GAMMA_K0GB + GAMMA_K1GB * g, 0.0, 1.0);
         gammab = 1.0;
     }
-    if (fdebug > 0) fprintf(stderr, "DEBUG: Gamma: %f, %f, %f\n", gammar, gammag, gammab);
+    if (fdebug > 0) fprintf(stderr, "DEBUG: Gamma: %f, %f, %f, brightness: %f\n", gammar, gammag, gammab, b);
     n = res->ncrtc;
-    int icrtc_specified = icrtc >= 0 && icrtc < n;
-    for (c = icrtc_specified ? icrtc : 0; c < (icrtc_specified ? icrtc + 1 : n); c++)
+    if ((icrtc >= 0) && (icrtc < n))
+        n = 1;
+    else
+        icrtc = 0;
+    for (c = icrtc; c < (icrtc + n); c++)
     {
         int size, i;
         RRCrtc crtcxid;
@@ -158,7 +143,7 @@ static void sct_for_screen(Display *dpy, int screen, int icrtc, int temp, int fd
 
         for (i = 0; i < size; i++)
         {
-            g = GAMMA_MULT * (double)i / (double)size;
+            g = GAMMA_MULT * b * (double)i / (double)size;
             crtc_gamma->red[i] = (unsigned short int)(g * gammar + 0.5);
             crtc_gamma->green[i] = (unsigned short int)(g * gammag + 0.5);
             crtc_gamma->blue[i] = (unsigned short int)(g * gammab + 0.5);
@@ -173,8 +158,9 @@ static void sct_for_screen(Display *dpy, int screen, int icrtc, int temp, int fd
 
 int main(int argc, char **argv)
 {
-    int i, screen, screens, temp;
+    int i, screen, screens;
     int screen_specified, screen_first, screen_last, crtc_specified;
+    struct temp_status temp;
     int fdebug = 0, fdelta = 0, fhelp = 0;
     Display *dpy = XOpenDisplay(NULL);
 
@@ -187,9 +173,10 @@ int main(int argc, char **argv)
     screens = XScreenCount(dpy);
     screen_first = 0;
     screen_last = screens - 1;
-    temp = -1;
     screen_specified = -1;
     crtc_specified = -1;
+    temp.temp = DELTA_MIN;
+    temp.brightness = -1.0;
     for (i = 1; i < argc; i++)
     {
         if ((strcmp(argv[i],"-h") == 0) || (strcmp(argv[i],"--help") == 0)) fhelp = 1;
@@ -217,7 +204,8 @@ int main(int argc, char **argv)
                 fhelp = 1;
             }
         }
-        else if (temp == -1) temp = atoi(argv[i]);
+        else if (temp.temp == DELTA_MIN) temp.temp = atoi(argv[i]);
+        else if (temp.brightness < 0.0) temp.brightness = atof(argv[i]);
         else
         {
             fprintf(stderr, "ERROR! Unknown parameter: %s\n!", argv[i]);
@@ -235,33 +223,34 @@ int main(int argc, char **argv)
     }
     else
     {
+        if (temp.brightness < 0.0) temp.brightness = 1.0;
         if (screen_specified >= 0)
         {
             screen_first = screen_specified;
             screen_last = screen_specified;
         }
-        if ((temp < 0) && (fdelta == 0))
+        if ((temp.temp < 0) && (fdelta == 0))
         {
             // No arguments, so print estimated temperature for each screen
             for (screen = screen_first; screen <= screen_last; screen++)
             {
                 temp = get_sct_for_screen(dpy, screen, crtc_specified, fdebug);
-                printf("Screen %d: temperature ~ %d\n", screen, temp);
+                printf("Screen %d: temperature ~ %d %f\n", screen, temp.temp, temp.brightness);
             }
         }
         else
         {
             if (fdelta == 0)
             {
                 // Set temperature to given value or default for a value of 0
-                if (temp == 0)
+                if (temp.temp == 0)
                 {
-                    temp = TEMPERATURE_NORM;
+                    temp.temp = TEMPERATURE_NORM;
                 }
-                else if (temp < TEMPERATURE_ZERO)
+                else if (temp.temp < TEMPERATURE_ZERO)
                 {
                     fprintf(stderr, "WARNING! Temperatures below %d cannot be displayed.\n", TEMPERATURE_ZERO);
-                    temp = TEMPERATURE_ZERO;
+                    temp.temp = TEMPERATURE_ZERO;
                 }
                 for (screen = screen_first; screen <= screen_last; screen++)
                 {
@@ -273,11 +262,12 @@ int main(int argc, char **argv)
                 // Delta mode: Shift temperature of each screen by given value
                 for (screen = screen_first; screen <= screen_last; screen++)
                 {
-                    int tempd = temp + get_sct_for_screen(dpy, screen, crtc_specified, fdebug);
-                    if (tempd < TEMPERATURE_ZERO)
+                    struct temp_status tempd = get_sct_for_screen(dpy, screen, crtc_specified, fdebug);
+                    tempd.temp += temp.temp;
+                    if (tempd.temp < TEMPERATURE_ZERO)
                     {
                         fprintf(stderr, "WARNING! Temperatures below %d cannot be displayed.\n", TEMPERATURE_ZERO);
-                        tempd = TEMPERATURE_ZERO;
+                        tempd.temp = TEMPERATURE_ZERO;
                     }
                     sct_for_screen(dpy, screen, crtc_specified, tempd, fdebug);
                 }

src/xsct.h

@@ -0,0 +1,57 @@
+/*
+ * xsct - X11 set color temperature
+ *
+ * Public domain, do as you wish.
+ */
+
+#include <X11/Xatom.h>
+#include <X11/Xlib.h>
+#include <X11/Xproto.h>
+#include <X11/extensions/Xrandr.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+#ifndef __XSCT_H
+#define __XSCT_H
+
+#define XSCT_VERSION "1.9"
+
+#define TEMPERATURE_NORM    6500
+#define TEMPERATURE_ZERO    700
+#define GAMMA_MULT          65535.0
+// Approximation of the `redshift` table from
+// https://github.com/jonls/redshift/blob/04760afe31bff5b26cf18fe51606e7bdeac15504/src/colorramp.c#L30-L273
+// without limits:
+// GAMMA = K0 + K1 * ln(T - T0)
+// Red range (T0 = TEMPERATURE_ZERO)
+// Green color
+#define GAMMA_K0GR          -1.47751309139817
+#define GAMMA_K1GR          0.28590164772055
+// Blue color
+#define GAMMA_K0BR          -4.38321650114872
+#define GAMMA_K1BR          0.6212158769447
+// Blue range  (T0 = TEMPERATURE_NORM - TEMPERATURE_ZERO)
+// Red color
+#define GAMMA_K0RB          1.75390204039018
+#define GAMMA_K1RB          -0.1150805671482
+// Green color
+#define GAMMA_K0GB          1.49221604915144
+#define GAMMA_K1GB          -0.07513509588921
+#define BRIGHTHESS_DIV      65470.988
+#define DELTA_MIN           -1000000
+
+struct temp_status
+{
+    int temp;
+    double brightness;
+};
+
+static void usage(char * pname);
+static double DoubleTrim(double x, double a, double b);
+static struct temp_status get_sct_for_screen(Display *dpy, int screen, int icrtc, int fdebug);
+static void sct_for_screen(Display *dpy, int screen, int icrtc, struct temp_status temp, int fdebug);
+
+#endif /* __XSCT_H */