Rename overlay::Content trait to Overlay

The `Overlay` struct is now `overlay::Element`.

native/src/overlay/content.rs

@@ -1,34 +0,0 @@
-use crate::{layout, Clipboard, Event, Hasher, Layout, Point, Size};
-
-pub trait Content<Message, Renderer>
-where
-    Renderer: crate::Renderer,
-{
-    fn layout(
-        &self,
-        renderer: &Renderer,
-        bounds: Size,
-        position: Point,
-    ) -> layout::Node;
-
-    fn draw(
-        &self,
-        renderer: &mut Renderer,
-        defaults: &Renderer::Defaults,
-        layout: Layout<'_>,
-        cursor_position: Point,
-    ) -> Renderer::Output;
-
-    fn hash_layout(&self, state: &mut Hasher, position: Point);
-
-    fn on_event(
-        &mut self,
-        _event: Event,
-        _layout: Layout<'_>,
-        _cursor_position: Point,
-        _messages: &mut Vec<Message>,
-        _renderer: &Renderer,
-        _clipboard: Option<&dyn Clipboard>,
-    ) {
-    }
-}

native/src/overlay/element.rs

@@ -0,0 +1,145 @@
+pub use crate::Overlay;
+
+use crate::{layout, Clipboard, Event, Hasher, Layout, Point, Size, Vector};
+use std::rc::Rc;
+
+#[allow(missing_debug_implementations)]
+pub struct Element<'a, Message, Renderer> {
+    position: Point,
+    overlay: Box<dyn Overlay<Message, Renderer> + 'a>,
+}
+
+impl<'a, Message, Renderer> Element<'a, Message, Renderer>
+where
+    Renderer: crate::Renderer,
+{
+    pub fn new(
+        position: Point,
+        overlay: Box<dyn Overlay<Message, Renderer> + 'a>,
+    ) -> Self {
+        Self { position, overlay }
+    }
+
+    pub fn translate(mut self, translation: Vector) -> Self {
+        self.position = self.position + translation;
+        self
+    }
+
+    pub fn map<B>(self, f: Rc<dyn Fn(Message) -> B>) -> Element<'a, B, Renderer>
+    where
+        Message: 'a,
+        Renderer: 'a,
+        B: 'static,
+    {
+        Element {
+            position: self.position,
+            overlay: Box::new(Map::new(self.overlay, f)),
+        }
+    }
+
+    pub fn layout(&self, renderer: &Renderer, bounds: Size) -> layout::Node {
+        self.overlay.layout(renderer, bounds, self.position)
+    }
+
+    pub fn draw(
+        &self,
+        renderer: &mut Renderer,
+        defaults: &Renderer::Defaults,
+        layout: Layout<'_>,
+        cursor_position: Point,
+    ) -> Renderer::Output {
+        self.overlay
+            .draw(renderer, defaults, layout, cursor_position)
+    }
+
+    pub fn hash_layout(&self, state: &mut Hasher) {
+        self.overlay.hash_layout(state, self.position);
+    }
+
+    pub fn on_event(
+        &mut self,
+        event: Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        messages: &mut Vec<Message>,
+        renderer: &Renderer,
+        clipboard: Option<&dyn Clipboard>,
+    ) {
+        self.overlay.on_event(
+            event,
+            layout,
+            cursor_position,
+            messages,
+            renderer,
+            clipboard,
+        )
+    }
+}
+
+struct Map<'a, A, B, Renderer> {
+    content: Box<dyn Overlay<A, Renderer> + 'a>,
+    mapper: Rc<dyn Fn(A) -> B>,
+}
+
+impl<'a, A, B, Renderer> Map<'a, A, B, Renderer> {
+    pub fn new(
+        content: Box<dyn Overlay<A, Renderer> + 'a>,
+        mapper: Rc<dyn Fn(A) -> B + 'static>,
+    ) -> Map<'a, A, B, Renderer> {
+        Map { content, mapper }
+    }
+}
+
+impl<'a, A, B, Renderer> Overlay<B, Renderer> for Map<'a, A, B, Renderer>
+where
+    Renderer: crate::Renderer,
+{
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        bounds: Size,
+        position: Point,
+    ) -> layout::Node {
+        self.content.layout(renderer, bounds, position)
+    }
+
+    fn on_event(
+        &mut self,
+        event: Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        messages: &mut Vec<B>,
+        renderer: &Renderer,
+        clipboard: Option<&dyn Clipboard>,
+    ) {
+        let mut original_messages = Vec::new();
+
+        self.content.on_event(
+            event,
+            layout,
+            cursor_position,
+            &mut original_messages,
+            renderer,
+            clipboard,
+        );
+
+        original_messages
+            .drain(..)
+            .for_each(|message| messages.push((self.mapper)(message)));
+    }
+
+    fn draw(
+        &self,
+        renderer: &mut Renderer,
+        defaults: &Renderer::Defaults,
+        layout: Layout<'_>,
+        cursor_position: Point,
+    ) -> Renderer::Output {
+        self.content
+            .draw(renderer, defaults, layout, cursor_position)
+    }
+
+    fn hash_layout(&self, state: &mut Hasher, position: Point) {
+        self.content.hash_layout(state, position);
+    }
+}

native/src/overlay/menu.rs

@@ -70,8 +70,8 @@ where
         self,
         position: Point,
         target_height: f32,
-    ) -> overlay::Overlay<'a, Message, Renderer> {
-        overlay::Overlay::new(
+    ) -> overlay::Element<'a, Message, Renderer> {
+        overlay::Element::new(
             position,
             Box::new(Overlay::new(self, target_height)),
         )
@@ -149,7 +149,7 @@ where
     }
 }
 
-impl<'a, Message, Renderer> overlay::Content<Message, Renderer>
+impl<'a, Message, Renderer> crate::Overlay<Message, Renderer>
     for Overlay<'a, Message, Renderer>
 where
     Renderer: self::Renderer,