compositor: add icc_profile weston.ini option for outputs

This adds "icc_profile" key support in [output] sections for backends
headless, x11, wayland, and drm, and also for remoted and pipewire
outputs FWIW. On the other hand, RDP-backend does not use output
sections from weston.ini, and fbdev-backend does not deserve anything
new (it wouldn't support color management anyway due to no GL-renderer).

This allows one to configure an ICC v2 or v4 file to be used as an
output profile. However, color-lcms does not actually use output
profiles yet, so trying this will fail until support is implemented.

The parent_winsys_profile argument is reserved for using the color
profile from a parent window system where applicable, if nothing else is
set in weston.ini. None of the nested backends provide an output color
profile yet. It is more of a reminder of a missing feature than a
serious implementation.

Note: cms-static Weston plugin uses the exact same weston.ini key for
loading VCGT from ICC profiles. If "color-management" option is set to
false, this new use of "icc_profile" is disabled and the old behavior
with cms-static is kept.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

compositor/main.c

@@ -126,6 +126,7 @@ struct wet_compositor {
 	struct wl_list child_process_list;
 	pid_t autolaunch_pid;
 	bool autolaunch_watch;
+	bool use_color_manager;
 };
 
 static FILE *weston_logfile = NULL;
@@ -1095,6 +1096,7 @@ static int
 weston_compositor_init_config(struct weston_compositor *ec,
 			      struct weston_config *config)
 {
+	struct wet_compositor *compositor = to_wet_compositor(ec);
 	struct xkb_rule_names xkb_names;
 	struct weston_config_section *s;
 	int repaint_msec;
@@ -1143,6 +1145,8 @@ weston_compositor_init_config(struct weston_compositor *ec,
 	if (color_management) {
 		if (weston_compositor_load_color_manager(ec) < 0)
 			return -1;
+		else
+			compositor->use_color_manager = true;
 	}
 
 	/* weston.ini [libinput] */
@@ -1302,6 +1306,48 @@ wet_output_set_transform(struct weston_output *output,
 	return 0;
 }
 
+static int
+wet_output_set_color_profile(struct weston_output *output,
+			     struct weston_config_section *section,
+			     struct weston_color_profile *parent_winsys_profile)
+{
+	struct wet_compositor *compositor = to_wet_compositor(output->compositor);
+	struct weston_color_profile *cprof;
+	char *icc_file = NULL;
+	bool ok;
+
+	if (!compositor->use_color_manager)
+		return 0;
+
+	if (section) {
+		weston_config_section_get_string(section, "icc_profile",
+						 &icc_file, NULL);
+	}
+
+	if (icc_file) {
+		cprof = weston_compositor_load_icc_file(output->compositor,
+							icc_file);
+		free(icc_file);
+	} else if (parent_winsys_profile) {
+		cprof = weston_color_profile_ref(parent_winsys_profile);
+	} else {
+		return 0;
+	}
+
+	if (!cprof)
+		return -1;
+
+	ok = weston_output_set_color_profile(output, cprof);
+	if (!ok) {
+		weston_log("Error: failed to set color profile '%s' for output %s\n",
+			   weston_color_profile_get_description(cprof),
+			   output->name);
+	}
+
+	weston_color_profile_unref(cprof);
+	return ok ? 0 : -1;
+}
+
 static void
 allow_content_protection(struct weston_output *output,
 			struct weston_config_section *section)
@@ -1366,6 +1412,9 @@ wet_configure_windowed_output_from_config(struct weston_output *output,
 		return -1;
 	}
 
+	if (wet_output_set_color_profile(output, section, NULL) < 0)
+		return -1;
+
 	if (api->output_set_size(output, width, height) < 0) {
 		weston_log("Cannot configure output \"%s\" using weston_windowed_output_api.\n",
 			   output->name);
@@ -1806,6 +1855,9 @@ drm_backend_output_configure(struct weston_output *output,
 		return -1;
 	}
 
+	if (wet_output_set_color_profile(output, section, NULL) < 0)
+		return -1;
+
 	weston_config_section_get_string(section,
 					 "gbm-format", &gbm_format, NULL);
 
@@ -2305,6 +2357,9 @@ drm_backend_remoted_output_configure(struct weston_output *output,
 		return -1;
 	};
 
+	if (wet_output_set_color_profile(output, section, NULL) < 0)
+		return -1;
+
 	weston_config_section_get_string(section, "gbm-format", &gbm_format,
 					 NULL);
 	api->set_gbm_format(output, gbm_format);
@@ -2456,6 +2511,9 @@ drm_backend_pipewire_output_configure(struct weston_output *output,
 		return -1;
 	}
 
+	if (wet_output_set_color_profile(output, section, NULL) < 0)
+		return -1;
+
 	weston_config_section_get_string(section, "seat", &seat, "");
 
 	api->set_seat(output, seat);

man/weston.ini.man

@@ -545,6 +545,14 @@ An integer, 1 by default, typically configured as 2 or higher when needed,
 denoting the scaling multiplier for the output.
 .RE
 .TP 7
+.BI "icc_profile=" file
+If option
+.B color-management
+is true, load the given ICC file as the output color profile. This works only
+on DRM, headless, wayland, and x11 backends, and for remoting and pipewire
+outputs.
+.RE
+.TP 7
 .BI "seat=" name
 The logical seat name that this output should be associated with. If this
 is set then the seat's input will be confined to the output that has the seat