wip: Content and Widget traits

crates/tek_core/src/engine/component.rs

@@ -15,3 +15,97 @@ pub trait ExitableComponent<E>: Exit + Component<E> where E: Engine {
 }
 
 impl<E: Engine, C: Component<E> + Exit> ExitableComponent<E> for C {}
+
+pub trait Widget {
+    type Engine: Engine;
+    fn layout (&self, to: <<Self as Widget>::Engine as Engine>::Area) ->
+        Perhaps<<<Self as Widget>::Engine as Engine>::Area>;
+    fn render (&self, to: &mut Self::Engine) ->
+        Perhaps<<<Self as Widget>::Engine as Engine>::Area>;
+}
+impl<E: Engine> Widget for Box<dyn Widget<Engine = E>> {
+    type Engine = E;
+    fn layout (&self, to: E::Area) -> Perhaps<E::Area> {
+        (**self).layout(to)
+    }
+    fn render (&self, to: &mut E) -> Perhaps<E::Area> {
+        (**self).render(to)
+    }
+}
+impl<E: Engine> Widget for &dyn Widget<Engine = E> {
+    type Engine = E;
+    fn layout (&self, to: E::Area)  -> Perhaps<E::Area> {
+        (*self).layout(to)
+    }
+    fn render (&self, to: &mut E) -> Perhaps<E::Area> {
+        (*self).render(to)
+    }
+}
+impl<E: Engine> Widget for &mut dyn Widget<Engine = E> {
+    type Engine = E;
+    fn layout (&self, to: E::Area) -> Perhaps<E::Area> {
+        (**self).layout(to)
+    }
+    fn render (&self, to: &mut E) -> Perhaps<E::Area> {
+        (**self).render(to)
+    }
+}
+impl<E: Engine, W: Widget<Engine = E>> Widget for Arc<W> {
+    type Engine = E;
+    fn layout (&self, to: E::Area) -> Perhaps<E::Area> {
+        self.as_ref().layout(to)
+    }
+    fn render (&self, to: &mut E) -> Perhaps<E::Area> {
+        self.as_ref().render(to)
+    }
+}
+impl<E: Engine, W: Widget<Engine = E>> Widget for Mutex<W> {
+    type Engine = E;
+    fn layout (&self, to: E::Area) -> Perhaps<E::Area> {
+        self.lock().unwrap().layout(to)
+    }
+    fn render (&self, to: &mut E) -> Perhaps<E::Area> {
+        self.lock().unwrap().render(to)
+    }
+}
+impl<E: Engine, W: Widget<Engine = E>> Widget for RwLock<W> {
+    type Engine = E;
+    fn layout (&self, to: E::Area) -> Perhaps<E::Area> {
+        self.read().unwrap().layout(to)
+    }
+    fn render (&self, to: &mut E) -> Perhaps<E::Area> {
+        self.read().unwrap().render(to)
+    }
+}
+impl<E: Engine, W: Widget<Engine = E>> Widget for Option<W> {
+    type Engine = E;
+    fn layout (&self, to: E::Area) -> Perhaps<E::Area> {
+        Ok(self.as_ref().map(|widget|widget.layout(to)).transpose()?.flatten())
+    }
+    fn render (&self, to: &mut E) -> Perhaps<E::Area> {
+        Ok(self.as_ref().map(|widget|widget.render(to)).transpose()?.flatten())
+    }
+}
+
+pub trait Content {
+    type Engine: Engine;
+    fn content (&self) -> impl Widget<Engine = <Self as Content>::Engine>;
+}
+//impl<E> Content<E> for () where E: Engine {
+    //fn content (&self) -> impl Widget<E> {
+        //()
+    //}
+//}
+impl<W> Widget for W where W: Content {
+    type Engine = <Self as Content>::Engine;
+    fn layout (&self, to: <<Self as Content>::Engine as Engine>::Area) 
+        -> Perhaps<<<Self as Content>::Engine as Engine>::Area>
+    {
+        self.content().layout(to)
+    }
+    fn render (&self, to: &mut <Self as Content>::Engine)
+        -> Perhaps<<<Self as Content>::Engine as Engine>::Area>
+    {
+        self.content().render(to)
+    }
+}