1 files changed, 101 insertions, 0 deletions
diff --git a/src/geom/sides.rs b/src/geom/sides.rs
new file mode 100644
index 00000000..770fad58
--- /dev/null
+++ b/src/geom/sides.rs
@@ -0,0 +1,101 @@
+use super::*;
+
+/// A container with left, top, right and bottom components.
+#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
+pub struct Sides<T> {
+    /// The value for the left side.
+    pub left: T,
+    /// The value for the top side.
+    pub top: T,
+    /// The value for the right side.
+    pub right: T,
+    /// The value for the bottom side.
+    pub bottom: T,
+}
+
+impl<T> Sides<T> {
+    /// Create a new box from four sizes.
+    pub fn new(left: T, top: T, right: T, bottom: T) -> Self {
+        Self { left, top, right, bottom }
+    }
+
+    /// Create an instance with all four components set to the same `value`.
+    pub fn uniform(value: T) -> Self
+    where
+        T: Clone,
+    {
+        Self {
+            left: value.clone(),
+            top: value.clone(),
+            right: value.clone(),
+            bottom: value,
+        }
+    }
+}
+
+impl Sides<Linear> {
+    /// Evaluate the linear values in this container.
+    pub fn eval(self, size: Size) -> Sides<Length> {
+        Sides {
+            left: self.left.eval(size.width),
+            top: self.top.eval(size.height),
+            right: self.right.eval(size.width),
+            bottom: self.bottom.eval(size.height),
+        }
+    }
+}
+
+impl Sides<Length> {
+    /// A size with `left` and `right` summed into `width`, and `top` and
+    /// `bottom` summed into `height`.
+    pub fn size(self) -> Size {
+        Size::new(self.left + self.right, self.top + self.bottom)
+    }
+}
+
+impl<T> Get<Side> for Sides<T> {
+    type Component = T;
+
+    fn get(self, side: Side) -> T {
+        match side {
+            Side::Left => self.left,
+            Side::Top => self.top,
+            Side::Right => self.right,
+            Side::Bottom => self.bottom,
+        }
+    }
+
+    fn get_mut(&mut self, side: Side) -> &mut T {
+        match side {
+            Side::Left => &mut self.left,
+            Side::Top => &mut self.top,
+            Side::Right => &mut self.right,
+            Side::Bottom => &mut self.bottom,
+        }
+    }
+}
+
+/// The four sides of objects.
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum Side {
+    /// The left side.
+    Left,
+    /// The top side.
+    Top,
+    /// The right side.
+    Right,
+    /// The bottom side.
+    Bottom,
+}
+
+impl Side {
+    /// The opposite side.
+    pub fn inv(self) -> Self {
+        match self {
+            Self::Left => Self::Right,
+            Self::Top => Self::Bottom,
+            Self::Right => Self::Left,
+            Self::Bottom => Self::Top,
+        }
+    }
+}