Add Layer widget

src/ui/widgets.rs

@@ -2,6 +2,7 @@ pub mod background;
 pub mod border;
 pub mod empty;
 pub mod join;
+pub mod layer;
 pub mod list;
 pub mod padding;
 pub mod rules;

src/ui/widgets/layer.rs

@@ -0,0 +1,33 @@
+use async_trait::async_trait;
+use toss::frame::{Frame, Size};
+
+use super::{BoxedWidget, Widget};
+
+pub struct Layer {
+    layers: Vec<BoxedWidget>,
+}
+
+impl Layer {
+    pub fn new(layers: Vec<BoxedWidget>) -> Self {
+        Self { layers }
+    }
+}
+
+#[async_trait]
+impl Widget for Layer {
+    fn size(&self, frame: &mut Frame, max_width: Option<u16>, max_height: Option<u16>) -> Size {
+        let mut max_size = Size::ZERO;
+        for layer in &self.layers {
+            let size = layer.size(frame, max_width, max_height);
+            max_size.width = max_size.width.max(size.width);
+            max_size.height = max_size.height.max(size.height);
+        }
+        max_size
+    }
+
+    async fn render(self: Box<Self>, frame: &mut Frame) {
+        for layer in self.layers {
+            layer.render(frame).await;
+        }
+    }
+}