[gnome-shell/wip/exalm/dark-3] background: Support dark wallpapers

[Alexander Mikhaylenko <alexm src gnome org>]

commit ab493e24aa4e830970d2fafb10df53983bcc90a3
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Sat Nov 27 17:53:14 2021 +0500

    background: Support dark wallpapers
    
    See https://gitlab.gnome.org/GNOME/gnome-control-center/-/merge_requests/1174

 js/ui/background.js | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)
---
diff --git a/js/ui/background.js b/js/ui/background.js
index 1f7c5e5720..ee4c370184 100644
--- a/js/ui/background.js
+++ b/js/ui/background.js
@@ -111,6 +111,10 @@ const SECONDARY_COLOR_KEY = 'secondary-color';
 const COLOR_SHADING_TYPE_KEY = 'color-shading-type';
 const BACKGROUND_STYLE_KEY = 'picture-options';
 const PICTURE_URI_KEY = 'picture-uri';
+const PICTURE_URI_DARK_KEY = 'picture-uri-dark';
+
+const INTERFACE_SCHEMA = 'org.gnome.desktop.interface';
+const COLOR_SCHEME_KEY = 'color-scheme';
 
 var FADE_ANIMATION_TIME = 1000;
 
@@ -227,15 +231,19 @@ var Background = GObject.registerClass({
     Signals: { 'loaded': {}, 'bg-changed': {} },
 }, class Background extends Meta.Background {
     _init(params) {
-        params = Params.parse(params, { monitorIndex: 0,
-                                        layoutManager: Main.layoutManager,
-                                        settings: null,
-                                        file: null,
-                                        style: null });
+        params = Params.parse(params, {
+            monitorIndex: 0,
+            layoutManager: Main.layoutManager,
+            settings: null,
+            interfaceSettings: null,
+            file: null,
+            style: null
+        });
 
         super._init({ meta_display: global.display });
 
         this._settings = params.settings;
+        this._interfaceSettings = params.interfaceSettings;
         this._file = params.file;
         this._style = params.style;
         this._monitorIndex = params.monitorIndex;
@@ -262,6 +270,10 @@ var Background = GObject.registerClass({
         this._settingsChangedSignalId =
             this._settings.connect('changed', this._emitChangedSignal.bind(this));
 
+        this._colorSchemeChangedSignalId =
+            this._interfaceSettings.connect('changed::%s'.format(COLOR_SCHEME_KEY),
+                this._emitChangedSignal.bind(this));
+
         this._load();
     }
 
@@ -290,6 +302,10 @@ var Background = GObject.registerClass({
             this._settings.disconnect(this._settingsChangedSignalId);
         this._settingsChangedSignalId = 0;
 
+        if (this._colorSchemeChangedSignalId !== 0)
+            this._interfaceSettings.disconnect(this._colorSchemeChangedSignalId);
+        this._colorSchemeChangedSignalId = 0;
+
         if (this._changedIdleId) {
             GLib.source_remove(this._changedIdleId);
             this._changedIdleId = 0;
@@ -546,6 +562,8 @@ var BackgroundSource = class BackgroundSource {
         this._monitorsChangedId =
             monitorManager.connect('monitors-changed',
                                    this._onMonitorsChanged.bind(this));
+
+        this._interfaceSettings = new Gio.Settings({ schema_id: INTERFACE_SCHEMA });
     }
 
     _onMonitorsChanged() {
@@ -576,7 +594,12 @@ var BackgroundSource = class BackgroundSource {
         } else {
             style = this._settings.get_enum(BACKGROUND_STYLE_KEY);
             if (style != GDesktopEnums.BackgroundStyle.NONE) {
-                let uri = this._settings.get_string(PICTURE_URI_KEY);
+                let uri;
+                let colorScheme = this._interfaceSettings.get_enum('color-scheme');
+                if (colorScheme === 1) // GDesktopEnums.ColorScheme.PREFER_DARK
+                    uri = this._settings.get_string(PICTURE_URI_DARK_KEY);
+                else
+                    uri = this._settings.get_string(PICTURE_URI_KEY);
                 file = Gio.File.new_for_commandline_arg(uri);
             }
         }
@@ -593,6 +616,7 @@ var BackgroundSource = class BackgroundSource {
                 monitorIndex,
                 layoutManager: this._layoutManager,
                 settings: this._settings,
+                interfaceSettings: this._interfaceSettings,
                 file,
                 style,
             });