dropdown: Add on change callback

crates/story/src/dropdown_story.rs

@@ -61,8 +61,11 @@ impl DropdownStory {
             Country::new("Ecuador", "EC"),
         ];
 
-        let country_dropdown =
+        let country_dropdown = cx.new_view(|cx| {
-            cx.new_view(|cx| Dropdown::new("dropdown-country", countries, Some(6), cx));
+            Dropdown::new("dropdown-country", countries, Some(6), cx).on_change(|value, _cx| {
+                println!("Country changed: {:?}", value);
+            })
+        });
 
         let furits = vec![
             "Apple",
@@ -73,8 +76,11 @@ impl DropdownStory {
             "Watermelon",
             "Avocado",
         ];
-        let furit_dropdown =
+        let furit_dropdown = cx.new_view(|cx| {
-            cx.new_view(|cx| Dropdown::string_list("dropdown-furits", furits, None, cx));
+            Dropdown::string_list("dropdown-furits", furits, None, cx).on_change(|value, _cx| {
+                println!("Furit changed: {:?}", value);
+            })
+        });
 
         cx.new_view(|cx| Self {
             country_dropdown,

crates/ui/src/dropdown.rs

@@ -154,11 +154,16 @@ where
         self.selected_index = ix;
 
         if let Some(view) = self.dropdown.upgrade() {
-            cx.update_view(&view, |view, _| {
+            cx.update_view(&view, |view, cx| {
-                view.selected_value = self
+                let selected_value = self
                     .selected_index
                     .and_then(|ix| self.delegate.get(ix))
                     .map(|item| item.value().clone());
+
+                if let Some(on_change) = &view.on_change {
+                    on_change(&selected_value, cx);
+                }
+                view.selected_value = selected_value;
                 view.open = false;
             });
         }
@@ -179,6 +184,9 @@ pub struct Dropdown<D: DropdownDelegate + 'static> {
     placeholder: SharedString,
     title_prefix: Option<SharedString>,
     selected_value: Option<<D::Item as DropdownItem>::Value>,
+    on_change: Option<
+        Box<dyn Fn(&Option<<D::Item as DropdownItem>::Value>, &mut WindowContext) + 'static>,
+    >,
 }
 
 impl<D> Dropdown<D>
@@ -208,6 +216,7 @@ where
             open: false,
             cleanable: true,
             title_prefix: None,
+            on_change: None,
         };
         this.update_selected_value(cx);
         this
@@ -240,6 +249,14 @@ where
         self
     }
 
+    pub fn on_change(
+        mut self,
+        on_change: impl Fn(&Option<<D::Item as DropdownItem>::Value>, &mut WindowContext) + 'static,
+    ) -> Self {
+        self.on_change = Some(Box::new(on_change));
+        self
+    }
+
     pub fn set_selected_index(
         &mut self,
         selected_index: Option<usize>,

crates/ui/src/radio.rs

@@ -90,7 +90,7 @@ impl RenderOnce for Radio {
                 self.on_click.filter(|_| !self.disabled),
                 |this, on_click| {
                     this.on_click(move |_event, cx| {
-                        (on_click)(&!self.selected, cx);
+                        on_click(&!self.selected, cx);
                     })
                 },
             )