sway/commands/output: Add command to set color profile

This makes it possible to render output buffers in a different color
space, by specifying an ICC profile for the output.

include/sway/commands.h

@@ -283,6 +283,7 @@ sway_cmd input_cmd_xkb_variant;
 
 sway_cmd output_cmd_adaptive_sync;
 sway_cmd output_cmd_background;
+sway_cmd output_cmd_color_profile;
 sway_cmd output_cmd_disable;
 sway_cmd output_cmd_dpms;
 sway_cmd output_cmd_enable;

include/sway/config.h

@@ -7,6 +7,7 @@
 #include <wlr/interfaces/wlr_switch.h>
 #include <wlr/types/wlr_tablet_tool.h>
 #include <wlr/util/box.h>
+#include <wlr/render/color.h>
 #include <xkbcommon/xkbcommon.h>
 #include <xf86drmMode.h>
 #include "../include/config.h"
@@ -285,6 +286,8 @@ struct output_config {
 	int max_render_time; // In milliseconds
 	int adaptive_sync;
 	enum render_bit_depth render_bit_depth;
+	bool set_color_transform;
+	struct wlr_color_transform *color_transform;
 
 	char *background;
 	char *background_option;

include/sway/output.h

@@ -66,6 +66,8 @@ struct sway_output {
 		struct wl_signal disable;
 	} events;
 
+	struct wlr_color_transform *color_transform;
+
 	struct timespec last_presentation;
 	uint32_t refresh_nsec;
 	int max_render_time; // In milliseconds

sway/commands/output.c

@@ -10,6 +10,7 @@ static const struct cmd_handler output_handlers[] = {
 	{ "adaptive_sync", output_cmd_adaptive_sync },
 	{ "background", output_cmd_background },
 	{ "bg", output_cmd_background },
+	{ "color_profile", output_cmd_color_profile },
 	{ "disable", output_cmd_disable },
 	{ "dpms", output_cmd_dpms },
 	{ "enable", output_cmd_enable },

sway/commands/output/color_profile.c

@@ -0,0 +1,103 @@
+#define _XOPEN_SOURCE 700
+#include <fcntl.h>
+#include <strings.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <wlr/render/color.h>
+#include "sway/commands.h"
+#include "sway/config.h"
+
+static bool read_file_into_buf(const char *path, void **buf, size_t *size) {
+	/* Why not use fopen/fread directly? glibc will succesfully open directories,
+	 * not just files, and supports seeking on them. Instead, we directly
+	 * work with file descriptors and use the more consistent open/fstat/read. */
+	int fd = open(path, O_RDONLY | O_NOCTTY | O_CLOEXEC);
+	if (fd == -1) {
+		return false;
+	}
+	char *b = NULL;
+	struct stat info;
+	if (fstat(fd, &info) == -1) {
+		goto fail;
+	}
+	// only regular files, to avoid issues with e.g. opening pipes
+	if (!S_ISREG(info.st_mode)) {
+		goto fail;
+	}
+	off_t s = info.st_size;
+	if (s <= 0) {
+		goto fail;
+	}
+	b = calloc(1, s);
+	if (!b) {
+		goto fail;
+	}
+	size_t nread = 0;
+	while (nread < (size_t)s) {
+		size_t to_read = (size_t)s - nread;
+		ssize_t r = read(fd, b + nread, to_read);
+		if ((r == -1 && errno != EINTR) || r == 0) {
+			goto fail;
+		}
+		nread += (size_t)r;
+	}
+	close(fd);
+	*buf = b;
+	*size = (size_t)s;
+	return true; // success
+fail:
+	free(b);
+	close(fd);
+	return false;
+}
+
+struct cmd_results *output_cmd_color_profile(int argc, char **argv) {
+	if (!config->handler_context.output_config) {
+		return cmd_results_new(CMD_FAILURE, "Missing output config");
+	}
+	if (!argc) {
+		return cmd_results_new(CMD_INVALID, "Missing color_profile first argument.");
+	}
+
+	if (strcmp(*argv, "srgb") == 0) {
+		wlr_color_transform_unref(config->handler_context.output_config->color_transform);
+		config->handler_context.output_config->color_transform = NULL;
+		config->handler_context.output_config->set_color_transform = true;
+
+		config->handler_context.leftovers.argc = argc - 1;
+		config->handler_context.leftovers.argv = argv + 1;
+	} else if (strcmp(*argv, "icc") == 0) {
+		if (argc < 2) {
+			return cmd_results_new(CMD_INVALID,
+				"Invalid color profile specification: icc type requires a file");
+		}
+		void *data = NULL;
+		size_t size = 0;
+		if (!read_file_into_buf(argv[1], &data, &size)) {
+			return cmd_results_new(CMD_FAILURE,
+				"Failed to load color profile: could not read ICC file");
+		}
+
+		struct wlr_color_transform *tmp =
+			wlr_color_transform_init_linear_to_icc(data, size);
+		if (!tmp) {
+			free(data);
+			return cmd_results_new(CMD_FAILURE,
+				"Failed to load color profile: failed to initialize transform from ICC");
+		}
+		free(data);
+
+		wlr_color_transform_unref(config->handler_context.output_config->color_transform);
+		config->handler_context.output_config->color_transform = tmp;
+		config->handler_context.output_config->set_color_transform = true;
+
+		config->handler_context.leftovers.argc = argc - 2;
+		config->handler_context.leftovers.argv = argv + 2;
+	} else {
+		return cmd_results_new(CMD_INVALID,
+			"Invalid color profile specification: first argument should be icc|srgb");
+	}
+
+	return NULL;
+}
+

sway/config/output.c

@@ -75,6 +75,8 @@ struct output_config *new_output_config(const char *name) {
 	oc->max_render_time = -1;
 	oc->adaptive_sync = -1;
 	oc->render_bit_depth = RENDER_BIT_DEPTH_DEFAULT;
+	oc->set_color_transform = false;
+	oc->color_transform = NULL;
 	oc->power = -1;
 	return oc;
 }
@@ -190,6 +192,14 @@ static void merge_output_config(struct output_config *dst, struct output_config
 	if (src->render_bit_depth != RENDER_BIT_DEPTH_DEFAULT) {
 		dst->render_bit_depth = src->render_bit_depth;
 	}
+	if (src->set_color_transform) {
+		if (src->color_transform) {
+			wlr_color_transform_ref(src->color_transform);
+		}
+		wlr_color_transform_unref(dst->color_transform);
+		dst->set_color_transform = true;
+		dst->color_transform = src->color_transform;
+	}
 	if (src->background) {
 		free(dst->background);
 		dst->background = strdup(src->background);
@@ -556,6 +566,13 @@ static bool finalize_output_config(struct output_config *oc, struct sway_output
 		output->max_render_time = oc->max_render_time;
 	}
 
+	if (oc && oc->set_color_transform) {
+		if (oc->color_transform) {
+			wlr_color_transform_ref(oc->color_transform);
+		}
+		wlr_color_transform_unref(output->color_transform);
+		output->color_transform = oc->color_transform;
+	}
 	return true;
 }
 
@@ -996,6 +1013,7 @@ void free_output_config(struct output_config *oc) {
 	free(oc->name);
 	free(oc->background);
 	free(oc->background_option);
+	wlr_color_transform_unref(oc->color_transform);
 	free(oc);
 }
 

sway/desktop/output.c

@@ -269,7 +269,10 @@ static int output_repaint_timer_handler(void *data) {
 		return 0;
 	}
 
-	wlr_scene_output_commit(output->scene_output, NULL);
+	struct wlr_scene_output_state_options opts = {
+		.color_transform = output->color_transform,
+	};
+	wlr_scene_output_commit(output->scene_output, &opts);
 	return 0;
 }
 

sway/meson.build

@@ -202,6 +202,7 @@ sway_sources = files(
 	'commands/output/toggle.c',
 	'commands/output/transform.c',
 	'commands/output/unplug.c',
+	'commands/output/color_profile.c',
 
 	'tree/arrange.c',
 	'tree/container.c',

sway/sway-output.5.scd

@@ -178,6 +178,18 @@ must be separated by one space. For example:
 	updated to work with different bit depths. This command is experimental,
 	and may be removed or changed in the future.
 
+*output* <name> color_profile srgb|[icc <file>]
+	Sets the color profile for an output. The default is _srgb_. <file> should be a
+	path to a display ICC profile.
+
+	Not all renderers support this feature; currently it only works with the
+	the Vulkan renderer works. Even where supported, the application of the
+	color profile may be inaccurate.
+
+	This command is experimental, and may be removed or changed in the future. It
+	may have no effect or produce unexpected output when used together with future
+	HDR support features.
+
 # SEE ALSO
 
 *sway*(5) *sway-input*(5)

sway/tree/output.c

@@ -279,6 +279,7 @@ void output_destroy(struct sway_output *output) {
 	list_free(output->workspaces);
 	list_free(output->current.workspaces);
 	wl_event_source_remove(output->repaint_timer);
+	wlr_color_transform_unref(output->color_transform);
 	free(output);
 }