From 16149d7c2577c5aa0e8228fa0be9327a641cfa75 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20=C3=85dahl?= <jadahl@gmail.com>
Date: Sat, 4 Dec 2021 00:31:43 +0100
Subject: [PATCH] color-manager: Keep track of temperature

It will be used to generate gamma look up tables depending on
temperature.

The temperature comes from org.gnome.SettingsDaemon.Color and
depends on the current night light state.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2165>
---
 src/backends/meta-color-manager.c | 34 +++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/src/backends/meta-color-manager.c b/src/backends/meta-color-manager.c
index face6abe2..9ba58565b 100644
--- a/src/backends/meta-color-manager.c
+++ b/src/backends/meta-color-manager.c
@@ -55,6 +55,8 @@
 #include "meta-dbus-gsd-color.h"
 #include "meta-dbus-gsd-power-screen.h"
 
+#define DEFAULT_TEMPERATURE 6500 /* Kelvin */
+
 enum
 {
   PROP_0,
@@ -83,6 +85,11 @@ typedef struct _MetaColorManagerPrivate
   MetaDbusSettingsDaemonPowerScreen *gsd_power_screen;
 
   gboolean is_ready;
+
+  /* The temperature (in Kelvin) adjustment to apply to the color LUTs;
+   * used to shift the screen towards red for Night Light.
+   */
+  unsigned int temperature;
 } MetaColorManagerPrivate;
 
 G_DEFINE_TYPE_WITH_PRIVATE (MetaColorManager, meta_color_manager, G_TYPE_OBJECT)
@@ -218,6 +225,28 @@ cd_client_connect_cb (GObject      *source_object,
   priv->is_ready = TRUE;
 }
 
+static void
+on_temperature_changed (MetaDbusSettingsDaemonColor *gsd_color,
+                        GParamSpec                  *pspec,
+                        MetaColorManager            *color_manager)
+{
+  MetaColorManagerPrivate *priv =
+    meta_color_manager_get_instance_private (color_manager);
+  unsigned int temperature;
+
+  temperature = meta_dbus_settings_daemon_color_get_temperature (gsd_color);
+  if (priv->temperature == temperature)
+    return;
+
+  if (temperature < 1000 || temperature > 10000)
+    {
+      g_warning ("Invalid temperature from gsd-color: %u K", temperature);
+      return;
+    }
+
+  priv->temperature = temperature;
+}
+
 static void
 on_gsd_color_ready (GObject      *source_object,
                     GAsyncResult *res,
@@ -243,6 +272,10 @@ on_gsd_color_ready (GObject      *source_object,
   meta_topic (META_DEBUG_COLOR,
               "Connection to org.gnome.SettingsDaemon.Color established");
   priv->gsd_color = gsd_color;
+
+  g_signal_connect (gsd_color, "notify::temperature",
+                    G_CALLBACK (on_temperature_changed),
+                    color_manager);
 }
 
 static void
@@ -283,6 +316,7 @@ meta_color_manager_constructed (GObject *object)
   priv->lcms_context = cmsCreateContext (NULL, NULL);
 
   priv->cancellable = g_cancellable_new ();
+  priv->temperature = DEFAULT_TEMPERATURE;
 
   priv->cd_client = cd_client_new ();
   cd_client_connect (priv->cd_client, priv->cancellable, cd_client_connect_cb,