gdctl: Allow setting color mode

This allows configuring a monitor to enter BT.2100 a.k.a. HDR mode.

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

doc/man/gdctl.rst

@@ -134,6 +134,12 @@ MONITOR OPTIONS
 
   Set the mode of the monitor.
 
+``--color-mode``, ``-c``
+
+  Set the color mode of the monitor. Available color modes are ``default`` and
+  ``bt2100``.
+
+
 EXAMPLES
 --------
 

tools/gdctl

@@ -296,6 +296,7 @@ class Monitor:
     properties: dict
     current_mode: MonitorMode | None
     preferred_mode: MonitorMode | None
+    color_mode: ColorMode | None
 
     @classmethod
     def from_variant(cls, variant):
@@ -320,6 +321,7 @@ class Monitor:
         )
 
         display_name = properties.get("display-name", None)
+        color_mode = properties.get("color-mode", None)
 
         return cls(
             connector=connector,
@@ -331,6 +333,7 @@ class Monitor:
             current_mode=current_mode,
             preferred_mode=preferred_mode,
             display_name=display_name,
+            color_mode=color_mode,
         )
 
 
@@ -715,6 +718,9 @@ def create_logical_monitor(monitors_state, layout_mode, logical_monitor_args):
                 )
 
         monitor.mode = mode
+        monitor.color_mode = ColorMode.maybe_from_string(
+            monitor_args.get("color_mode", None)
+        )
 
         monitors.append(monitor)
 
@@ -836,10 +842,17 @@ def print_config(config):
             )
             print_data(
                 level=4,
-                is_last=True,
+                is_last=not monitor.color_mode,
                 lines=lines,
                 data=f"Mode: {monitor.mode.name}",
             )
+            if monitor.color_mode:
+                print_data(
+                    level=4,
+                    is_last=True,
+                    lines=lines,
+                    data=f"Color mode: {monitor.color_mode}",
+                )
 
         index += 1
 
@@ -1076,15 +1089,23 @@ class Config:
     layout_mode: LayoutMode
 
     def generate_monitor_tuples(self, monitors):
-        return [
+        tuples = []
+        for monitor in monitors:
+            options = {}
+            if monitor.color_mode:
+                options["color-mode"] = GLib.Variant(
+                    "u", monitor.color_mode.value
+                )
+
             # Variant type: (ssa{sv})
-            (
-                monitor.connector,
-                monitor.mode.name,
-                {},
+            tuples.append(
+                (
+                    monitor.connector,
+                    monitor.mode.name,
+                    options,
+                )
             )
-            for monitor in monitors
-        ]
+        return tuples
 
     def generate_logical_monitor_tuples(self):
         tuples = []
@@ -1232,6 +1253,11 @@ class TransformCompleter(NamedEnumCompleter):
         super().__init__(Transform)
 
 
+class ColorModeCompleter(NamedEnumCompleter):
+    def __init__(self):
+        super().__init__(ColorMode)
+
+
 if __name__ == "__main__":
     parser = GdctlParser(
         description="Display control utility",
@@ -1333,6 +1359,14 @@ if __name__ == "__main__":
         help="Monitor mode",
         type=str,
     ).completer = MonitorModeCompleter()
+    monitor_parser.add_argument(
+        "--color-mode",
+        "-c",
+        action=AppendToSubGroup,
+        help="Color mode",
+        choices=[str(color_mode) for color_mode in list(ColorMode)],
+        type=str,
+    ).completer = ColorModeCompleter()
     logical_monitor_parser.add_argument(
         "--primary",
         "-p",