update example

Author: xarvic

druid/examples/menu.rs

@@ -74,22 +74,29 @@ fn build_menu() -> Menu<AppState> {
         )
         .entry(
             MenuItem::new("1 Selected")
-                .on_activate(|_, data: &mut AppState, _|if data.value == 1 {data.value = 0} else {data.value = 1})
-                .selected_if(|data: &AppState, _|data.value == 1)
+                .radio_item(1, Some(0))
+                .lens(AppState::value)
         )
         .entry(
             MenuItem::new("2 Selected")
-                .on_activate(|_, data: &mut AppState, _|if data.value == 2 {data.value = 0} else {data.value = 2})
-                .selected_if(|data: &AppState, _|data.value == 2)
+                .radio_item(2, Some(0))
+                .lens(AppState::value)
         )
         .entry(
+            // Implementing the radio item from hand
             MenuItem::new("3 Selected")
                 .on_activate(|_, data: &mut AppState, _|if data.value == 3 {data.value = 0} else {data.value = 3})
                 .selected_if(|data: &AppState, _|data.value == 3)
         )
         .separator()
         .entry(
             MenuItem::new("CheckBox")
+                .toggle_data()
+                .lens(AppState::option)
+        )
+        .entry(
+            // Implementing the CheckBox from hand
+            MenuItem::new("Manual CheckBox")
                 .on_activate(|_, data: &mut AppState, _|data.option = !data.option)
                 .selected_if(|data: &AppState, _|data.option)
         )

druid/src/menu/mod.rs

@@ -638,6 +638,23 @@ impl<T: Data> MenuItem<T> {
         self.on_activate(move |ctx, _data, _env| ctx.submit_command(cmd.clone()))
     }
 
+    /// Turns this `MenuItem` into a `RadioButton`
+    ///
+    /// When selected this MenuItem will set the provided value as data.
+    /// If data is equal to the provided value the Item is selected otherwise not.
+    pub fn radio_item(self, value: T, unselect: Option<T>) -> Self where T: PartialEq {
+        let value2 = value.clone();
+        self
+            .on_activate(move |_, data: &mut T, _|{
+                if data != value {
+                    *data = value.clone();
+                } else if let Some(value) = unselect.clone() {
+                    *data = value;
+                }
+            })
+            .selected_if(move |data, _|data == value2)
+    }
+
     /// Provide a hotkey for activating this menu item.
     ///
     /// This is equivalent to
@@ -723,6 +740,18 @@ impl<T: Data> MenuItem<T> {
     }
 }
 
+impl MenuItem<bool> {
+    /// Turns the MenuItem into a CheckBox.
+    ///
+    /// this is a convenience method which sets the `on_activate` and `selected_if` callbacks
+    /// to behave like a `CheckBox`.
+    pub fn toggle_data(self) -> Self {
+        self
+            .on_activate(|_, data, _|*data = !*data)
+            .selected_if(|data, _|*data)
+    }
+}
+
 impl<T: Data> MenuVisitor<T> for Menu<T> {
     fn activate(&mut self, ctx: &mut MenuEventCtx, id: MenuItemId, data: &mut T, env: &Env) {
         for child in &mut self.children {