implement save as.. menu item

src/app/browser/window/action/save_as.rs

@@ -0,0 +1,64 @@
+use gtk::{
+    gio::SimpleAction,
+    glib::uuid_string_random,
+    prelude::{ActionExt, ToVariant},
+};
+
+// Defaults
+
+/// C-compatible variant type
+const DEFAULT_STATE: i32 = -1;
+
+/// [SimpleAction](https://docs.gtk.org/gio/class.SimpleAction.html) wrapper for `Save As` action of `Window` group
+pub struct SaveAs {
+    pub gobject: SimpleAction,
+}
+
+impl SaveAs {
+    // Constructors
+
+    /// Create new `Self`
+    pub fn new() -> Self {
+        Self {
+            gobject: SimpleAction::new_stateful(
+                &uuid_string_random(),
+                None,
+                &DEFAULT_STATE.to_variant(),
+            ),
+        }
+    }
+
+    // Actions
+
+    /// Change action [state](https://docs.gtk.org/gio/method.SimpleAction.set_state.html)
+    /// * set `DEFAULT_STATE` on `None`
+    pub fn change_state(&self, state: Option<i32>) {
+        self.gobject.change_state(
+            &match state {
+                Some(value) => value,
+                None => DEFAULT_STATE,
+            }
+            .to_variant(),
+        )
+    }
+
+    // Events
+
+    /// Define callback function for
+    /// [SimpleAction::activate](https://docs.gtk.org/gio/signal.SimpleAction.activate.html) signal
+    pub fn connect_activate(&self, callback: impl Fn(Option<i32>) + 'static) {
+        self.gobject.connect_activate(move |this, _| {
+            let state = this
+                .state()
+                .expect("State value required")
+                .get::<i32>()
+                .expect("Parameter type does not match `i32`");
+
+            callback(if state == DEFAULT_STATE {
+                None
+            } else {
+                Some(state)
+            })
+        });
+    }
+}