DisplayConfig: Advertise monitor color standard support

It'll be used to allow Settings to know whether it can enable HDR or
not.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4192>

data/dbus-interfaces/org.gnome.Mutter.DisplayConfig.xml

@@ -393,11 +393,16 @@
 	                              Variable Refresh Rate is active (absence
 	                              of this means unknown)
 	    - "is-for-lease" (b): whether the monitor is for lease or not
+	    - "supported-color-modes" (au): list of supported color modes
 
         Possible mode flags:
 	  1 : preferred mode
 	  2 : current mode
 
+        Available color modes:
+          0 : default
+          1 : BT.2100
+
 
 	@logical_monitors represent current logical monitor configuration
 

src/backends/meta-monitor-manager.c

@@ -2002,6 +2002,23 @@ request_persistent_confirmation (MetaMonitorManager *manager)
 #define LOGICAL_MONITOR_FORMAT "(iidub" LOGICAL_MONITOR_MONITORS_FORMAT "a{sv})"
 #define LOGICAL_MONITORS_FORMAT "a" LOGICAL_MONITOR_FORMAT
 
+static GVariant *
+generate_color_modes_variant (MetaMonitor *monitor)
+{
+  GVariantBuilder builder;
+  GList *l;
+
+  g_variant_builder_init (&builder, G_VARIANT_TYPE ("au"));
+  for (l = meta_monitor_get_supported_color_modes (monitor); l; l = l->next)
+    {
+      MetaColorMode color_mode = GPOINTER_TO_INT (l->data);
+
+      g_variant_builder_add (&builder, "u", color_mode);
+    }
+
+  return g_variant_builder_end (&builder);
+}
+
 static gboolean
 meta_monitor_manager_handle_get_current_state (MetaDBusDisplayConfig *skeleton,
                                                GDBusMethodInvocation *invocation,
@@ -2159,6 +2176,10 @@ meta_monitor_manager_handle_get_current_state (MetaDBusDisplayConfig *skeleton,
                              "is-for-lease",
                              g_variant_new_boolean (is_for_lease));
 
+      g_variant_builder_add (&monitor_properties_builder, "{sv}",
+                             "supported-color-modes",
+                             generate_color_modes_variant (monitor));
+
       g_variant_builder_add (&monitors_builder, MONITOR_FORMAT,
                              monitor_spec->connector,
                              monitor_spec->vendor,

src/tests/gdctl/show-properties

@@ -12,10 +12,11 @@ Monitors:
 │  │       └──Properties: (2)
 │  │           ├──is-current ⇒  yes
 │  │           └──is-preferred ⇒  yes
-│  └──Properties: (3)
+│  └──Properties: (4)
 │      ├──is-builtin ⇒  no
 │      ├──display-name ⇒  MetaProduct's Inc. 14"
-│      └──is-for-lease ⇒  no
+│      ├──is-for-lease ⇒  no
+│      └──supported-color-modes ⇒  [0]
 └──Monitor DP-2 (MetaProduct's Inc. 13")
    ├──Vendor: MetaProduct's Inc.
    ├──Product: MetaMonitor
@@ -29,10 +30,11 @@ Monitors:
    │       └──Properties: (2)
    │           ├──is-current ⇒  yes
    │           └──is-preferred ⇒  yes
-   └──Properties: (3)
+   └──Properties: (4)
        ├──is-builtin ⇒  no
        ├──display-name ⇒  MetaProduct's Inc. 13"
-       └──is-for-lease ⇒  no
+       ├──is-for-lease ⇒  no
+       └──supported-color-modes ⇒  [0]
 
 Logical monitors:
 ├──Logical monitor #1

src/tests/gdctl/show-verbose

@@ -30,10 +30,11 @@ Monitors:
 │  │       ├──Preferred scale: 1.0
 │  │       ├──Supported scales: [1.0, 1.25, 1.5, 1.7475727796554565]
 │  │       └──Properties: (0)
-│  └──Properties: (3)
+│  └──Properties: (4)
 │      ├──is-builtin ⇒  no
 │      ├──display-name ⇒  MetaProduct's Inc. 14"
-│      └──is-for-lease ⇒  no
+│      ├──is-for-lease ⇒  no
+│      └──supported-color-modes ⇒  [0]
 └──Monitor DP-2 (MetaProduct's Inc. 13")
    ├──Vendor: MetaProduct's Inc.
    ├──Product: MetaMonitor
@@ -65,10 +66,11 @@ Monitors:
    │       ├──Preferred scale: 1.0
    │       ├──Supported scales: [1.0]
    │       └──Properties: (0)
-   └──Properties: (3)
+   └──Properties: (4)
        ├──is-builtin ⇒  no
        ├──display-name ⇒  MetaProduct's Inc. 13"
-       └──is-for-lease ⇒  no
+       ├──is-for-lease ⇒  no
+       └──supported-color-modes ⇒  [0]
 
 Logical monitors:
 ├──Logical monitor #1