Set accent color based on wallpaper

src/PantheonAccountsServicePlugin.vala

@@ -1,5 +1,6 @@
 [DBus (name = "io.elementary.pantheon.AccountsService")]
 private interface PantheonShell.Pantheon.AccountsService : Object {
+    public abstract int prefers_accent_color { get; set; }
     public abstract int prefers_color_scheme { get; set; }
 }
 

src/Views/Appearance.vala

@@ -37,6 +37,47 @@ public class PantheonShell.Appearance : Gtk.Grid {
 
     private Granite.Widgets.ModeButton text_size_modebutton;
 
+    private enum AccentColor {
+        NO_PREFERENCE,
+        RED,
+        ORANGE,
+        YELLOW,
+        GREEN,
+        MINT,
+        BLUE,
+        PURPLE,
+        PINK,
+        BROWN,
+        GRAY;
+
+        public string to_string () {
+            switch (this) {
+                case RED:
+                    return "strawberry";
+                case ORANGE:
+                    return "orange";
+                case YELLOW:
+                    return "banana";
+                case GREEN:
+                    return "lime";
+                case MINT:
+                    return "mint";
+                case BLUE:
+                    return "blueberry";
+                case PURPLE:
+                    return "grape";
+                case PINK:
+                    return "bubblegum";
+                case BROWN:
+                    return "cocoa";
+                case GRAY:
+                    return "slate";
+            }
+
+            return "auto";
+        }
+    }
+
     construct {
         column_spacing = 12;
         halign = Gtk.Align.CENTER;
@@ -248,13 +289,15 @@ public class PantheonShell.Appearance : Gtk.Grid {
 
             ((GLib.DBusProxy) pantheon_act).g_properties_changed.connect ((changed, invalid) => {
                 var color_scheme = changed.lookup_value ("PrefersColorScheme", new VariantType ("i"));
-                switch ((Granite.Settings.ColorScheme) color_scheme.get_int32 ()) {
-                    case Granite.Settings.ColorScheme.DARK:
-                        prefer_dark_radio.active = true;
-                        break;
-                    default:
-                        prefer_default_radio.active = true;
-                        break;
+                if (color_scheme != null) {
+                    switch ((Granite.Settings.ColorScheme) color_scheme.get_int32 ()) {
+                        case Granite.Settings.ColorScheme.DARK:
+                            prefer_dark_radio.active = true;
+                            break;
+                        default:
+                            prefer_default_radio.active = true;
+                            break;
+                    }
                 }
             });
 
@@ -311,36 +354,39 @@ public class PantheonShell.Appearance : Gtk.Grid {
             var accent_label = new Gtk.Label (_("Accent:"));
             accent_label.halign = Gtk.Align.END;
 
-            var blueberry_button = new ColorButton ("blueberry");
+            var blueberry_button = new PrefersAccentColorButton (pantheon_act, AccentColor.BLUE);
             blueberry_button.tooltip_text = _("Blueberry");
 
-            var mint_button = new ColorButton ("mint", blueberry_button);
+            var mint_button = new PrefersAccentColorButton (pantheon_act, AccentColor.MINT, blueberry_button);
             mint_button.tooltip_text = _("Mint");
 
-            var lime_button = new ColorButton ("lime", blueberry_button);
+            var lime_button = new PrefersAccentColorButton (pantheon_act, AccentColor.GREEN, blueberry_button);
             lime_button.tooltip_text = _("Lime");
 
-            var banana_button = new ColorButton ("banana", blueberry_button);
+            var banana_button = new PrefersAccentColorButton (pantheon_act, AccentColor.YELLOW, blueberry_button);
             banana_button.tooltip_text = _("Banana");
 
-            var orange_button = new ColorButton ("orange", blueberry_button);
+            var orange_button = new PrefersAccentColorButton (pantheon_act, AccentColor.ORANGE, blueberry_button);
             orange_button.tooltip_text = _("Orange");
 
-            var strawberry_button = new ColorButton ("strawberry", blueberry_button);
+            var strawberry_button = new PrefersAccentColorButton (pantheon_act, AccentColor.RED, blueberry_button);
             strawberry_button.tooltip_text = _("Strawberry");
 
-            var bubblegum_button = new ColorButton ("bubblegum", blueberry_button);
+            var bubblegum_button = new PrefersAccentColorButton (pantheon_act, AccentColor.PINK, blueberry_button);
             bubblegum_button.tooltip_text = _("Bubblegum");
 
-            var grape_button = new ColorButton ("grape", blueberry_button);
+            var grape_button = new PrefersAccentColorButton (pantheon_act, AccentColor.PURPLE, blueberry_button);
             grape_button.tooltip_text = _("Grape");
 
-            var cocoa_button = new ColorButton ("cocoa", blueberry_button);
+            var cocoa_button = new PrefersAccentColorButton (pantheon_act, AccentColor.BROWN, blueberry_button);
             cocoa_button.tooltip_text = _("Cocoa");
 
-            var slate_button = new ColorButton ("slate", blueberry_button);
+            var slate_button = new PrefersAccentColorButton (pantheon_act, AccentColor.GRAY, blueberry_button);
             slate_button.tooltip_text = _("Slate");
 
+            var auto_button = new PrefersAccentColorButton (pantheon_act, AccentColor.NO_PREFERENCE, blueberry_button);
+            auto_button.tooltip_text = _("Automatic based on wallpaper");
+
             var accent_grid = new Gtk.Grid ();
             accent_grid.column_spacing = 6;
             accent_grid.add (blueberry_button);
@@ -353,6 +399,7 @@ public class PantheonShell.Appearance : Gtk.Grid {
             accent_grid.add (grape_button);
             accent_grid.add (cocoa_button);
             accent_grid.add (slate_button);
+            accent_grid.add (auto_button);
 
             var accent_info = new Gtk.Label (_("Used across the system by default. Apps can always use their own accent color.")) {
                 margin_bottom = 18,
@@ -382,15 +429,16 @@ public class PantheonShell.Appearance : Gtk.Grid {
         });
     }
 
-    private class ColorButton : Gtk.RadioButton {
-        public string color_name { get; construct; }
+    private class PrefersAccentColorButton : Gtk.RadioButton {
+        public AccentColor color { get; construct; }
+        public Pantheon.AccountsService? pantheon_act { get; construct; default = null; }
 
         private static GLib.Settings interface_settings;
-        private static string current_accent;
 
-        public ColorButton (string _color_name, Gtk.RadioButton? group_member = null) {
+        public PrefersAccentColorButton (Pantheon.AccountsService? pantheon_act, AccentColor color, Gtk.RadioButton? group_member = null) {
             Object (
-                color_name: _color_name,
+                pantheon_act: pantheon_act,
+                color: color,
                 group: group_member
             );
         }
@@ -399,22 +447,27 @@ public class PantheonShell.Appearance : Gtk.Grid {
             interface_settings = new GLib.Settings (INTERFACE_SCHEMA);
 
             var current_stylesheet = interface_settings.get_string (STYLESHEET_KEY);
-            current_accent = current_stylesheet.replace (STYLESHEET_PREFIX, "");
         }
 
         construct {
             unowned Gtk.StyleContext context = get_style_context ();
-            context.add_class ("color-button");
-            context.add_class (color_name);
+            context.add_class (Granite.STYLE_CLASS_COLOR_BUTTON);
+            context.add_class (color.to_string ());
 
             realize.connect (() => {
-                active = current_accent == color_name;
+                active = color == pantheon_act.prefers_accent_color;
 
                 toggled.connect (() => {
-                    interface_settings.set_string (
-                        STYLESHEET_KEY,
-                        STYLESHEET_PREFIX + color_name
-                    );
+                    if (color != AccentColor.NO_PREFERENCE) {
+                        interface_settings.set_string (
+                            STYLESHEET_KEY,
+                            STYLESHEET_PREFIX + color.to_string ()
+                        );
+                    }
+
+                    if (((GLib.DBusProxy) pantheon_act).get_cached_property ("PrefersAccentColor") != null) {
+                        pantheon_act.prefers_accent_color = color;
+                    }
                 });
             });
         }