Add Background widget

src/widgets/background.rs

@@ -0,0 +1,71 @@
+use async_trait::async_trait;
+use crossterm::style::ContentStyle;
+
+use crate::{AsyncWidget, Frame, Pos, Size, Widget};
+
+pub struct Background<I> {
+    inner: I,
+    style: ContentStyle,
+}
+
+impl<I> Background<I> {
+    pub fn new(inner: I) -> Self {
+        Self {
+            inner,
+            style: ContentStyle::default(),
+        }
+    }
+
+    pub fn style(mut self, style: ContentStyle) -> Self {
+        self.style = style;
+        self
+    }
+
+    fn fill(&self, frame: &mut Frame) {
+        let size = frame.size();
+        for dy in 0..size.height {
+            for dx in 0..size.width {
+                frame.write(Pos::new(dx.into(), dy.into()), (" ", self.style));
+            }
+        }
+    }
+}
+
+impl<E, I> Widget<E> for Background<I>
+where
+    I: Widget<E>,
+{
+    fn size(
+        &self,
+        frame: &mut Frame,
+        max_width: Option<u16>,
+        max_height: Option<u16>,
+    ) -> Result<Size, E> {
+        self.inner.size(frame, max_width, max_height)
+    }
+
+    fn draw(self, frame: &mut Frame) -> Result<(), E> {
+        self.fill(frame);
+        self.inner.draw(frame)
+    }
+}
+
+#[async_trait]
+impl<E, I> AsyncWidget<E> for Background<I>
+where
+    I: AsyncWidget<E> + Send + Sync,
+{
+    async fn size(
+        &self,
+        frame: &mut Frame,
+        max_width: Option<u16>,
+        max_height: Option<u16>,
+    ) -> Result<Size, E> {
+        self.inner.size(frame, max_width, max_height).await
+    }
+
+    async fn draw(self, frame: &mut Frame) -> Result<(), E> {
+        self.fill(frame);
+        self.inner.draw(frame).await
+    }
+}