Add Padding widget

src/ui/widgets.rs

@@ -3,6 +3,7 @@ pub mod border;
 pub mod empty;
 pub mod join;
 pub mod list;
+pub mod padding;
 pub mod rules;
 pub mod text;
 

src/ui/widgets/padding.rs

@@ -0,0 +1,73 @@
+use async_trait::async_trait;
+use toss::frame::{Frame, Pos, Size};
+
+use super::{BoxedWidget, Widget};
+
+pub struct Padding {
+    inner: BoxedWidget,
+    left: u16,
+    right: u16,
+    top: u16,
+    bottom: u16,
+}
+
+impl Padding {
+    pub fn new<W: Into<BoxedWidget>>(inner: W) -> Self {
+        Self {
+            inner: inner.into(),
+            left: 0,
+            right: 0,
+            top: 0,
+            bottom: 0,
+        }
+    }
+
+    pub fn left(mut self, amount: u16) -> Self {
+        self.left = amount;
+        self
+    }
+
+    pub fn right(mut self, amount: u16) -> Self {
+        self.right = amount;
+        self
+    }
+
+    pub fn top(mut self, amount: u16) -> Self {
+        self.top = amount;
+        self
+    }
+
+    pub fn bottom(mut self, amount: u16) -> Self {
+        self.bottom = amount;
+        self
+    }
+}
+
+#[async_trait]
+impl Widget for Padding {
+    fn size(&self, frame: &mut Frame, max_width: Option<u16>, max_height: Option<u16>) -> Size {
+        let horizontal = self.left + self.right;
+        let vertical = self.top + self.bottom;
+
+        let max_width = max_width.map(|w| w.saturating_sub(horizontal));
+        let max_height = max_height.map(|h| h.saturating_sub(vertical));
+
+        let size = self.inner.size(frame, max_width, max_height);
+
+        size + Size::new(horizontal, vertical)
+    }
+
+    async fn render(self: Box<Self>, frame: &mut Frame) {
+        let size = frame.size();
+
+        let inner_pos = Pos::new(self.left.into(), self.top.into());
+        let inner_size = Size::new(
+            size.width.saturating_sub(self.left + self.right),
+            size.height.saturating_sub(self.top + self.bottom),
+        );
+
+        frame.push(inner_pos, inner_size);
+        self.inner.render(frame).await;
+        frame.pop();
+    }
+}