Init: set accent color from portal

lib/Init.vala

@@ -7,6 +7,7 @@ namespace Granite {
     private static bool initialized = false;
     private static Gtk.CssProvider? base_provider = null;
     private static Gtk.CssProvider? dark_provider = null;
+    private static Gtk.CssProvider? accent_provider = null;
     private static Gtk.CssProvider? app_provider = null;
 
     /**
@@ -41,12 +42,28 @@ namespace Granite {
             set_provider_for_display (display, gtk_settings.gtk_application_prefer_dark_theme);
         });
 
+        var granite_settings = Granite.Settings.get_default ();
+        granite_settings.notify["accent-color"].connect (() => {
+            set_accent_for_display (display, granite_settings.accent_color);
+        });
+
         set_provider_for_display (display, gtk_settings.gtk_application_prefer_dark_theme);
+        set_accent_for_display (display, granite_settings.accent_color);
 
         var icon_theme = Gtk.IconTheme.get_for_display (display);
         icon_theme.add_resource_path ("/io/elementary/granite");
     }
 
+    private static void set_accent_for_display (Gdk.Display display, string accent_color) {
+        if (accent_provider == null) {
+            accent_provider = new Gtk.CssProvider ();
+        }
+
+        Gtk.StyleContext.remove_provider_for_display (display, accent_provider);
+        accent_provider.load_from_string ("@define-color accent_color %s;".printf (accent_color));
+        Gtk.StyleContext.add_provider_for_display (display, accent_provider, Gtk.STYLE_PROVIDER_PRIORITY_THEME);
+    }
+
     private static void set_provider_for_display (Gdk.Display display, bool prefer_dark_style) {
         if (app_provider == null) {
             var base_path = Application.get_default ().resource_base_path;

lib/Styles/Index-dark.scss

@@ -43,6 +43,7 @@ $warning-color: $BANANA_100;
 $warning-icon-color: $BANANA_500;
 
 // Common styles
+@import '_exported.scss';
 @import '_label.scss';
 @import '_osd.scss';
 

lib/Styles/Index.scss

@@ -43,6 +43,7 @@ $warning_color: $BANANA_900;
 $warning-icon-color: mix($BANANA_500, $BANANA_700, $weight: 50%);
 
 // Common styles
+@import '_exported.scss';
 @import '_label.scss';
 @import '_osd.scss';
 

lib/Styles/_exported.scss

@@ -0,0 +1,8 @@
+// These are defined as GtkCSS variables, so are accessible and overridable
+// inside of apps. While internal sass variables are considered private API,
+// these exported GtkCSS variables should be considered public API.
+
+@define-color base_color #{"" + bg_color(1)};
+@define-color bg_color #{"" + bg_color(2)};
+@define-color fg_color #{"" + $fg-color};
+@define-color highlight_color #{"" + $highlight_color};

lib/Styles/_label.scss

@@ -1,3 +1,11 @@
+.accent {
+    color: #{'mix(@accent_color, @fg_color, 0.27)'};
+
+    &:backdrop {
+        color: inherit;
+    }
+}
+
 .title-1 {
     font-size: 24pt;
     font-weight: 700;

lib/Widgets/Settings.vala

@@ -36,6 +36,25 @@ namespace Granite {
             LIGHT
         }
 
+        private string? _accent_color = null;
+
+        /**
+         * The theme accent color chosen by the user
+         * @since 7.5.0
+         */
+        [Version (since = "7.5.0")]
+        public string accent_color {
+            get {
+                if (_accent_color == null) {
+                    setup_accent_color ();
+                }
+                return (_accent_color);
+            }
+            private set {
+                _accent_color = value;
+            }
+        }
+
         private ColorScheme? _prefers_color_scheme = null;
 
         /**
@@ -96,6 +115,38 @@ namespace Granite {
             }
         }
 
+        private void setup_accent_color () {
+            try {
+                portal = Portal.Settings.get ();
+
+                var variant = portal.read (
+                    "org.freedesktop.appearance",
+                    "accent-color"
+                ).get_variant ();
+
+                accent_color = parse_color (variant);
+
+                portal.setting_changed.connect ((scheme, key, value) => {
+                    if (scheme == "org.freedesktop.appearance" && key == "accent-color") {
+                        accent_color = parse_color (value);
+                    }
+                });
+            } catch (Error e) {
+                warning (e.message);
+
+                // Set a default in case we can't get from system
+                accent_color = "#3689e6";
+            }
+        }
+
+        private string parse_color (GLib.Variant color) {
+            double red, green, blue;
+            color.get ("(ddd)", out red, out green, out blue);
+
+            Gdk.RGBA rgba = {(float) red, (float) green, (float) blue, 1};
+            return rgba.to_string ();
+        }
+
         private void setup_prefers_color_scheme () {
             try {
                 portal = Portal.Settings.get ();

meson.build

@@ -49,7 +49,7 @@ libgranite_deps = [
     gio_os_dep,
     dependency('glib-2.0', version: '>=' + glib_min_version),
     dependency('gobject-2.0', version: '>=' + glib_min_version),
-    dependency('gtk4', version: '>=4.4'),
+    dependency('gtk4', version: '>=4.12'),
 ]
 
 icons_dir = join_paths(