Allow selection of X screen to apply adjustments to.

README

@@ -42,6 +42,7 @@ have reasonable defaults.
      		vidmode). Default is randr. In some cases one of the
      		methods will not work. In that case you may be able to
      		use the other method.
+  -s SCREEN	X screen to apply adjustments to.
   -t DAY:NIGHT	Color temperature to set at daytime/night.
   -v		Verbose output.
 

src/randr.c

@@ -122,17 +122,35 @@ randr_crtc_set_temperature(xcb_connection_t *conn, xcb_randr_crtc_t crtc,
 }
 
 int
-randr_set_temperature(int temp, float gamma[3])
+randr_set_temperature(int screen_num, int temp, float gamma[3])
 {
 	xcb_generic_error_t *error;
 
 	/* Open X server connection */
-	xcb_connection_t *conn = xcb_connect(NULL, NULL);
+	int preferred_screen;
+	xcb_connection_t *conn = xcb_connect(NULL, &preferred_screen);
 
-	/* Get first screen */
+	if (screen_num < 0) screen_num = preferred_screen;
+
+	/* Get screen */
 	const xcb_setup_t *setup = xcb_get_setup(conn);
 	xcb_screen_iterator_t iter = xcb_setup_roots_iterator(setup);
-	xcb_screen_t *screen = iter.data;
+	xcb_screen_t *screen = NULL;
+
+	for (int i = 0; iter.rem > 0; i++) {
+		if (i == screen_num) {
+			screen = iter.data;
+			break;
+		}
+		xcb_screen_next(&iter);
+	}
+
+	if (screen == NULL) {
+		fprintf(stderr, "Screen %i could not be found.\n",
+			screen_num);
+		xcb_disconnect(conn);
+		return -1;
+	}
 
 	/* Get list of CRTCs for the screen */
 	xcb_randr_get_screen_resources_current_cookie_t res_cookie =

src/randr.h

@@ -21,6 +21,6 @@
 #define _REDSHIFT_RANDR_H
 
 int randr_check_extension();
-int randr_set_temperature(int temp, float gamma[3]);
+int randr_set_temperature(int screen_num, int temp, float gamma[3]);
 
 #endif /* ! _REDSHIFT_RANDR_H */

src/redshift.c

@@ -62,6 +62,7 @@
 	"  -h\t\tDisplay this help message\n" \
 	"  -l LAT:LON\tYour current location\n" \
 	"  -m METHOD\tMethod to use to set color temperature (randr or vidmode)\n" \
+	"  -s SCREEN\tX screen to apply adjustments to\n" \
 	"  -t DAY:NIGHT\tColor temperature to set at daytime/night\n" \
 	"  -v\t\tVerbose output\n"
 
@@ -88,11 +89,12 @@ main(int argc, char *argv[])
 	int temp_night = DEFAULT_NIGHT_TEMP;
 	float gamma[3] = { DEFAULT_GAMMA, DEFAULT_GAMMA, DEFAULT_GAMMA };
 	int use_randr = 1;
+	int screen_num = -1;
 	int verbose = 0;
 	char *s;
 
 	int opt;
-	while ((opt = getopt(argc, argv, "g:hl:m:t:v")) != -1) {
+	while ((opt = getopt(argc, argv, "g:hl:m:s:t:v")) != -1) {
 		switch (opt) {
 		case 'g':
 			s = strchr(optarg, ':');
@@ -140,6 +142,9 @@ main(int argc, char *argv[])
 				exit(EXIT_FAILURE);
 			}
 			break;
+		case 's':
+			screen_num = atoi(optarg);
+			break;
 		case 't':
 			s = strchr(optarg, ':');
 			if (s == NULL) {
@@ -249,9 +254,10 @@ main(int argc, char *argv[])
 		if (r < 0) {
 			use_randr = 0;
 		} else {
-			r = randr_set_temperature(temp, gamma);
+			r = randr_set_temperature(screen_num, temp, gamma);
 			if (r < 0) {
-				fprintf(stderr, "Unable to set color temperature with RANDR,"
+				fprintf(stderr, "Unable to set color"
+					" temperature with RANDR,"
 					" trying VidMode...\n");
 				use_randr = 0;
 			}
@@ -262,14 +268,15 @@ main(int argc, char *argv[])
 		/* Check VidMode extension */
 		r = vidmode_check_extension();
 		if (r < 0) {
-			fprintf(stderr, "Missing needed extension to set gamma ramp"
-				"(RANDR or VidMode).\n");
+			fprintf(stderr, "Missing needed extension"
+				" to set gamma ramp (RANDR or VidMode).\n");
 			exit(EXIT_FAILURE);
 		}
 
-		r = vidmode_set_temperature(temp, gamma);
+		r = vidmode_set_temperature(screen_num, temp, gamma);
 		if (r < 0) {
-			fprintf(stderr, "Unable to set color temperature with VidMode.\n");
+			fprintf(stderr, "Unable to set color temperature"
+				" with VidMode.\n");
 			exit(EXIT_FAILURE);
 		}
 	}

src/vidmode.c

@@ -56,7 +56,7 @@ vidmode_check_extension()
 }
 
 int
-vidmode_set_temperature(int temp, float gamma[3])
+vidmode_set_temperature(int screen_num, int temp, float gamma[3])
 {
 	int r;
 
@@ -67,9 +67,11 @@ vidmode_set_temperature(int temp, float gamma[3])
 		return -1;
 	}
 
-	/* Request size of gamma ramps for screen 0 */
+	if (screen_num < 0) screen_num = DefaultScreen(dpy);
+
+	/* Request size of gamma ramps */
 	int gamma_ramp_size;
-	r = XF86VidModeGetGammaRampSize(dpy, 0, &gamma_ramp_size);
+	r = XF86VidModeGetGammaRampSize(dpy, screen_num, &gamma_ramp_size);
 	if (!r) {
 		fprintf(stderr, "XF86VidModeGetGammaRampSize failed.\n");
 		XCloseDisplay(dpy);
@@ -95,7 +97,8 @@ vidmode_set_temperature(int temp, float gamma[3])
 		       temp, gamma);
 
 	/* Set new gamma ramps */
-	r = XF86VidModeSetGammaRamp(dpy, 0, gamma_ramp_size, gamma_r, gamma_g, gamma_b);
+	r = XF86VidModeSetGammaRamp(dpy, screen_num, gamma_ramp_size,
+				    gamma_r, gamma_g, gamma_b);
 	if (!r) {
 		fprintf(stderr, "XF86VidModeSetGammaRamp failed.\n");
 		XCloseDisplay(dpy);

src/vidmode.h

@@ -21,6 +21,6 @@
 #define _REDSHIFT_VIDMODE_H
 
 int vidmode_check_extension();
-int vidmode_set_temperature(int temp, float gamma[3]);
+int vidmode_set_temperature(int screen_num, int temp, float gamma[3]);
 
 #endif /* ! _REDSHIFT_VIDMODE_H */