Introduce `Layer` trait

2 files changed, 11 insertions, 1 deletions

diff --git a/native/src/renderer.rs b/native/src/renderer.rs
index a16df72b..29a091a4 100644
--- a/native/src/renderer.rs
+++ b/native/src/renderer.rs
@@ -25,7 +25,7 @@ mod null;
 #[cfg(debug_assertions)]
 pub use null::Null;
 
-use crate::{layout, Element};
+use crate::{layout, Element, Rectangle};
 
 /// A component that can take the state of a user interface and produce an
 /// output for its users.
@@ -56,4 +56,11 @@ pub trait Renderer: Sized {
     ) -> layout::Node {
         element.layout(self, limits)
     }
+
+    fn overlay(
+        &mut self,
+        base: Self::Output,
+        overlay: Self::Output,
+        overlay_bounds: Rectangle,
+    ) -> Self::Output;
 }
diff --git a/native/src/renderer/null.rs b/native/src/renderer/null.rs
index 5fd3627b..bd6aca29 100644
--- a/native/src/renderer/null.rs
+++ b/native/src/renderer/null.rs
@@ -22,6 +22,9 @@ impl Null {
 impl Renderer for Null {
     type Output = ();
     type Defaults = ();
+
+    fn overlay(&mut self, _base: (), _overlay: (), _overlay_bounds: Rectangle) {
+    }
 }
 
 impl column::Renderer for Null {