Add a preference to allow using the dark variant of a theme if available

data/org.x.editor.gschema.xml.in

@@ -41,6 +41,12 @@
       <description>A custom font that will be used for the editing area. This will only take effect if the "Use Default Font" option is turned off.</description>
     </key>
 
+    <key name="prefer-dark-theme" type="b">
+      <default>false</default>
+      <summary>Prefer Dark Theme</summary>
+      <description>Whether xed should prefer the dark variation of the current Gtk theme if available.</description>
+    </key>
+
     <key name="scheme" type="s">
       <default>'tango'</default>
       <summary>Style Scheme</summary>

xed/resources/ui/xed-preferences-dialog.ui

@@ -1118,6 +1118,22 @@
                         <property name="position">0</property>
                       </packing>
                     </child>
+                    <child>
+                      <object class="GtkCheckButton" id="prefer_dark_theme_checkbutton">
+                        <property name="label" translatable="yes">Use dark theme variant (if available)</property>
+                        <property name="visible">True</property>
+                        <property name="can_focus">True</property>
+                        <property name="receives_default">False</property>
+                        <property name="margin_left">12</property>
+                        <property name="xalign">0</property>
+                        <property name="draw_indicator">True</property>
+                      </object>
+                      <packing>
+                        <property name="expand">False</property>
+                        <property name="fill">False</property>
+                        <property name="position">1</property>
+                      </packing>
+                    </child>
                     <child>
                       <object class="GtkHBox" id="hbox115">
                         <property name="visible">True</property>
@@ -1216,7 +1232,7 @@
                       <packing>
                         <property name="expand">True</property>
                         <property name="fill">True</property>
-                        <property name="position">1</property>
+                        <property name="position">2</property>
                       </packing>
                     </child>
                   </object>

xed/xed-app.c

@@ -80,6 +80,7 @@ struct _XedAppPrivate
 
     GObject *settings;
     GSettings *window_settings;
+    GSettings *editor_settings;
 
     PeasExtensionSet *extensions;
 
@@ -168,6 +169,7 @@ xed_app_dispose (GObject *object)
     XedApp *app = XED_APP (object);
 
     g_clear_object (&app->priv->window_settings);
+    g_clear_object (&app->priv->editor_settings);
     g_clear_object (&app->priv->settings);
     g_clear_object (&app->priv->page_setup);
     g_clear_object (&app->priv->print_settings);
@@ -209,6 +211,18 @@ extension_removed (PeasExtensionSet *extensions,
     peas_extension_call (exten, "deactivate");
 }
 
+static void
+set_initial_theme_style (XedApp *app)
+{
+    if (g_settings_get_boolean (app->priv->editor_settings, XED_SETTINGS_PREFER_DARK_THEME))
+    {
+        GtkSettings *gtk_settings;
+
+        gtk_settings = gtk_settings_get_default ();
+        g_object_set (G_OBJECT (gtk_settings), "gtk-application-prefer-dark-theme", TRUE, NULL);
+    }
+}
+
 static void
 xed_app_startup (GApplication *application)
 {
@@ -248,6 +262,9 @@ xed_app_startup (GApplication *application)
    /* Load settings */
    app->priv->settings = xed_settings_new ();
    app->priv->window_settings = g_settings_new ("org.x.editor.state.window");
+   app->priv->editor_settings = g_settings_new ("org.x.editor.preferences.editor");
+
+   set_initial_theme_style (app);
 
    /*
     * We use the default gtksourceview style scheme manager so that plugins

xed/xed-preferences-dialog.c

@@ -89,6 +89,7 @@ struct _XedPreferencesDialogPrivate
     GtkWidget *font_hbox;
 
     /* Style Scheme */
+    GtkWidget *prefer_dark_theme_checkbutton;
     GtkListStore *schemes_treeview_model;
     GtkWidget *schemes_treeview;
     GtkWidget *install_scheme_button;
@@ -1050,6 +1051,12 @@ setup_font_colors_page (XedPreferencesDialog *dlg)
 {
     setup_font_colors_page_font_section (dlg);
     setup_font_colors_page_style_scheme_section (dlg);
+
+    g_settings_bind (dlg->priv->editor,
+                     XED_SETTINGS_PREFER_DARK_THEME,
+                     dlg->priv->prefer_dark_theme_checkbutton,
+                     "active",
+                     G_SETTINGS_BIND_GET | G_SETTINGS_BIND_SET);
 }
 
 static void
@@ -1127,6 +1134,7 @@ xed_preferences_dialog_init (XedPreferencesDialog *dlg)
     dlg->priv->default_font_checkbutton = GTK_WIDGET (gtk_builder_get_object (builder, "default_font_checkbutton"));
     dlg->priv->font_button = GTK_WIDGET (gtk_builder_get_object (builder, "font_button"));
     dlg->priv->font_hbox = GTK_WIDGET (gtk_builder_get_object (builder, "font_hbox"));
+    dlg->priv->prefer_dark_theme_checkbutton = GTK_WIDGET (gtk_builder_get_object (builder, "prefer_dark_theme_checkbutton"));
     dlg->priv->schemes_treeview = GTK_WIDGET (gtk_builder_get_object (builder, "schemes_treeview"));
     dlg->priv->install_scheme_button = GTK_WIDGET (gtk_builder_get_object (builder, "install_scheme_button"));
     dlg->priv->uninstall_scheme_button = GTK_WIDGET (gtk_builder_get_object (builder, "uninstall_scheme_button"));

xed/xed-settings.c

@@ -176,6 +176,20 @@ on_editor_font_changed (GSettings   *settings,
     g_free (font);
 }
 
+static void
+on_prefer_dark_theme_changed (GSettings   *settings,
+                              const gchar *key,
+                              XedSettings *xs)
+{
+    GtkSettings *gtk_settings;
+    gboolean prefer_dark_theme;
+
+    prefer_dark_theme = g_settings_get_boolean (xs->priv->editor, XED_SETTINGS_PREFER_DARK_THEME);
+    gtk_settings = gtk_settings_get_default ();
+
+    g_object_set (G_OBJECT (gtk_settings), "gtk-application-prefer-dark-theme", prefer_dark_theme, NULL);
+}
+
 static void
 on_scheme_changed (GSettings   *settings,
                    const gchar *key,
@@ -375,6 +389,8 @@ xed_settings_init (XedSettings *xs)
                       G_CALLBACK (on_use_default_font_changed), xs);
     g_signal_connect (xs->priv->editor, "changed::editor-font",
                       G_CALLBACK (on_editor_font_changed), xs);
+    g_signal_connect (xs->priv->editor, "changed::prefer-dark-theme",
+                      G_CALLBACK (on_prefer_dark_theme_changed), xs);
     g_signal_connect (xs->priv->editor, "changed::scheme",
                       G_CALLBACK (on_scheme_changed), xs);
     g_signal_connect (xs->priv->editor, "changed::auto-save",

xed/xed-settings.h

@@ -55,19 +55,10 @@ struct _XedSettingsClass
     GObjectClass parent_class;
 };
 
-// typedef enum {
-//     XED_TOOLBAR_SYSTEM = 0,
-//     XED_TOOLBAR_ICONS,
-//     XED_TOOLBAR_ICONS_AND_TEXT,
-//     XED_TOOLBAR_ICONS_BOTH_HORIZ
-// } XedToolbarSetting;
-
 GType xed_settings_get_type (void) G_GNUC_CONST;
 
 GObject *xed_settings_new (void);
 
-// XedLockdownMask    xed_settings_get_lockdown            (XedSettings *xs);
-
 gchar *xed_settings_get_system_font (XedSettings *xs);
 
 /* Utility functions */
@@ -81,6 +72,7 @@ void xed_settings_set_list (GSettings    *settings,
 /* key constants */
 #define XED_SETTINGS_USE_DEFAULT_FONT           "use-default-font"
 #define XED_SETTINGS_EDITOR_FONT                "editor-font"
+#define XED_SETTINGS_PREFER_DARK_THEME          "prefer-dark-theme"
 #define XED_SETTINGS_SCHEME                     "scheme"
 #define XED_SETTINGS_CREATE_BACKUP_COPY         "create-backup-copy"
 #define XED_SETTINGS_AUTO_SAVE                  "auto-save"