Port 'Menu' demo to Vala

src/Menu/main.vala

@@ -0,0 +1,60 @@
+#! /usr/bin/env -S vala workbench.vala --pkg libadwaita-1
+
+public void main () {
+    var label = (Gtk.Label) workbench.builder.get_object ("label");
+
+    var text_group = new SimpleActionGroup ();
+    label.insert_action_group ("text", text_group);
+
+    var text_state = new HashTable<string, Variant> (str_hash, str_equal);
+    text_state.insert ("italic", false);
+    text_state.insert ("bold", false);
+    text_state.insert ("foreground", "green");
+
+    var italic_action = new SimpleAction.stateful ("italic", null, new Variant.boolean (false));
+    italic_action.notify["state"].connect (() => {
+        text_state.replace ("italic", italic_action.state.get_boolean ());
+        label.attributes = (state_to_attr (text_state));
+    });
+    text_group.add_action (italic_action);
+
+    var bold_action = new SimpleAction.stateful ("bold", null, new Variant.boolean (false));
+    bold_action.notify["state"].connect (() => {
+        text_state.replace ("bold", bold_action.state.get_boolean ());
+        label.attributes = (state_to_attr (text_state));
+    });
+    text_group.add_action (bold_action);
+
+    var color_action = new SimpleAction.stateful ("color", new VariantType ("s"), new Variant.string ("green"));
+    color_action.notify["state"].connect (() => {
+        text_state.replace ("foreground", color_action.state.get_string ());
+        label.attributes = (state_to_attr (text_state));
+    });
+    text_group.add_action (color_action);
+}
+
+// Helper function to create a PangoAttrList from text_state
+private Pango.AttrList state_to_attr (HashTable<string, Variant> state) {
+    string attr_string = "";
+    GenericArray<string> attrs = new GenericArray<string> ();
+
+    Variant? bold_variant = state.lookup ("bold");
+    if (bold_variant != null && bold_variant.get_boolean ()) {
+        attrs.add (@"0 -1 weight bold");
+    }
+
+    Variant? italic_variant = state.lookup ("italic");
+    if (italic_variant != null && italic_variant.get_boolean ()) {
+        attrs.add (@"0 -1 style italic");
+    }
+
+    string color = state.lookup ("foreground").get_string ();
+    if (color != null) {
+        attrs.add (@"0 -1 foreground $color");
+    }
+
+    foreach (string arr_attrb in attrs) {
+        attr_string += arr_attrb + ", ";
+    }
+    return Pango.AttrList.from_string (attr_string);
+}