nightlight: Implement schedule mode 'always' (#408)

This is more user-friendly than having to tweak the start and stop times.

Author: misch7

data/org.cinnamon.settings-daemon.plugins.color.gschema.xml.in.in

@@ -2,6 +2,7 @@
   <enum id="schedule_mode">
     <value value="0" nick="auto"/>
     <value value="1" nick="manual"/>
+    <value value="2" nick="always"/>
   </enum>
   <schema gettext-domain="@GETTEXT_PACKAGE@" id="org.cinnamon.settings-daemon.plugins.color" path="/org/cinnamon/settings-daemon/plugins/color/">
     <key name="recalibrate-display-threshold" type="u">
@@ -27,7 +28,7 @@
     <key name="night-light-schedule-mode" enum="schedule_mode">
       <default>'auto'</default>
       <summary>Set the way start and stop times are determined</summary>
-      <description>Setting to 'auto' will use the system timezone to determine sunrise and sunset. Using 'manual' mode allows specifying exact start and stop times (night-light-schedule-from and -to).</description>
+      <description>Setting to 'auto' will use the system timezone to determine sunrise and sunset. Using 'manual' mode allows specifying exact start and stop times (night-light-schedule-from and -to). The 'always' mode keeps the selected color temperature of your display permanently on.</description>
     </key>
     <key name="night-light-schedule-from" type="d">
       <default>20.00</default>

plugins/color/csd-night-light.c

@@ -62,7 +62,8 @@ enum {
 
 enum {
         NIGHT_LIGHT_SCHEDULE_AUTO = 0,
-        NIGHT_LIGHT_SCHEDULE_MANUAL = 1
+        NIGHT_LIGHT_SCHEDULE_MANUAL = 1,
+        NIGHT_LIGHT_SCHEDULE_ALWAYS_ON = 2
 };
 
 #define CSD_NIGHT_LIGHT_SCHEDULE_TIMEOUT      5       /* seconds */
@@ -274,13 +275,26 @@ night_light_recheck (CsdNightLight *self)
                 return;
         }
 
-        /* calculate the position of the sun */
-        if (g_settings_get_enum (self->settings, "night-light-schedule-mode") == NIGHT_LIGHT_SCHEDULE_AUTO) {
+        /* schedule-mode */
+        switch (g_settings_get_enum (self->settings, "night-light-schedule-mode")) {
+        case NIGHT_LIGHT_SCHEDULE_ALWAYS_ON:
+                /* just set the temperature to night light */
+                temperature = g_settings_get_uint (self->settings, "night-light-temperature");
+                g_debug ("night light mode always on, using temperature of %uK",
+                         temperature);
+                csd_night_light_set_active (self, TRUE);
+                csd_night_light_set_temperature (self, temperature);
+                return;
+        case NIGHT_LIGHT_SCHEDULE_AUTO:
+                /* calculate the position of the sun */
                 update_cached_sunrise_sunset (self);
                 if (self->cached_sunrise > 0.f && self->cached_sunset > 0.f) {
                         schedule_to = self->cached_sunrise;
                         schedule_from = self->cached_sunset;
                 }
+                break;
+        default:
+                break;
         }
 
         /* fall back to manual settings */