4 files changed, 107 insertions, 9 deletions

diff --git a/native/src/layout.rs b/native/src/layout.rs
index 0a744346..e945706b 100644
--- a/native/src/layout.rs
+++ b/native/src/layout.rs
@@ -1,3 +1,4 @@
+//! Position your widgets properly.
 mod limits;
 mod node;
 
@@ -8,6 +9,9 @@ pub use node::Node;
 
 use crate::{Point, Rectangle, Vector};
 
+/// The bounds of a [`Node`] and its children, using absolute coordinates.
+///
+/// [`Node`]: struct.Node.html
 #[derive(Debug, Clone, Copy)]
 pub struct Layout<'a> {
     position: Point,
@@ -28,6 +32,14 @@ impl<'a> Layout<'a> {
         }
     }
 
+    /// Gets the bounds of the [`Layout`].
+    ///
+    /// The returned [`Rectangle`] describes the position and size of a
+    /// [`Node`].
+    ///
+    /// [`Layout`]: struct.Layout.html
+    /// [`Rectangle`]: struct.Rectangle.html
+    /// [`Node`]: struct.Node.html
     pub fn bounds(&self) -> Rectangle {
         let bounds = self.node.bounds();
 
@@ -39,6 +51,10 @@ impl<'a> Layout<'a> {
         }
     }
 
+    /// Returns an iterator over the [`Layout`] of the children of a [`Node`].
+    ///
+    /// [`Layout`]: struct.Layout.html
+    /// [`Node`]: struct.Node.html
     pub fn children(&'a self) -> impl Iterator<Item = Layout<'a>> {
         self.node.children().iter().map(move |node| {
             Layout::with_offset(
diff --git a/native/src/layout/flex.rs b/native/src/layout/flex.rs
index 7a2b0d70..bc90553e 100644
--- a/native/src/layout/flex.rs
+++ b/native/src/layout/flex.rs
@@ -1,3 +1,4 @@
+//! Distribute elements using a flex-based layout.
 // This code is heavily inspired by the [`druid`] codebase.
 //
 // [`druid`]: https://github.com/xi-editor/druid
@@ -20,9 +21,13 @@ use crate::{
     Align, Element, Size,
 };
 
+/// The main axis of a flex layout.
 #[derive(Debug)]
 pub enum Axis {
+    /// The horizontal axis
     Horizontal,
+
+    /// The vertical axis
     Vertical,
 }
 
@@ -49,7 +54,12 @@ impl Axis {
     }
 }
 
-// TODO: Remove `Message` type parameter
+/// Computes the flex layout with the given axis and limits, applying spacing,
+/// padding and alignment to the items as needed.
+///
+/// It returns a new layout [`Node`].
+///
+/// [`Node`]: ../struct.Node.html
 pub fn resolve<Message, Renderer>(
     axis: Axis,
     renderer: &Renderer,
@@ -57,7 +67,7 @@ pub fn resolve<Message, Renderer>(
     padding: f32,
     spacing: f32,
     align_items: Align,
-    children: &[Element<'_, Message, Renderer>],
+    items: &[Element<'_, Message, Renderer>],
 ) -> Node
 where
     Renderer: crate::Renderer,
@@ -65,14 +75,14 @@ where
     let limits = limits.pad(padding);
 
     let mut total_non_fill =
-        spacing as f32 * (children.len() as i32 - 1).max(0) as f32;
+        spacing as f32 * (items.len() as i32 - 1).max(0) as f32;
     let mut fill_sum = 0;
     let mut cross = axis.cross(limits.min());
 
-    let mut nodes: Vec<Node> = Vec::with_capacity(children.len());
-    nodes.resize(children.len(), Node::default());
+    let mut nodes: Vec<Node> = Vec::with_capacity(items.len());
+    nodes.resize(items.len(), Node::default());
 
-    for (i, child) in children.iter().enumerate() {
+    for (i, child) in items.iter().enumerate() {
         let fill_factor = match axis {
             Axis::Horizontal => child.width(),
             Axis::Vertical => child.height(),
@@ -97,7 +107,7 @@ where
     let available = axis.main(limits.max());
     let remaining = (available - total_non_fill).max(0.0);
 
-    for (i, child) in children.iter().enumerate() {
+    for (i, child) in items.iter().enumerate() {
         let fill_factor = match axis {
             Axis::Horizontal => child.width(),
             Axis::Vertical => child.height(),
diff --git a/native/src/layout/limits.rs b/native/src/layout/limits.rs
index af269acd..2705a47d 100644
--- a/native/src/layout/limits.rs
+++ b/native/src/layout/limits.rs
@@ -1,5 +1,6 @@
 use crate::{Length, Size};
 
+/// A set of size constraints for layouting.
 #[derive(Debug, Clone, Copy)]
 pub struct Limits {
     min: Size,
@@ -8,12 +9,17 @@ pub struct Limits {
 }
 
 impl Limits {
+    /// No limits
     pub const NONE: Limits = Limits {
         min: Size::ZERO,
         max: Size::INFINITY,
         fill: Size::INFINITY,
     };
 
+    /// Creates new [`Limits`] with the given minimum and maximum [`Size`].
+    ///
+    /// [`Limits`]: struct.Limits.html
+    /// [`Size`]: ../struct.Size.html
     pub fn new(min: Size, max: Size) -> Limits {
         Limits {
             min,
@@ -22,14 +28,25 @@ impl Limits {
         }
     }
 
+    /// Returns the minimum [`Size`] of the [`Limits`].
+    ///
+    /// [`Limits`]: struct.Limits.html
+    /// [`Size`]: ../struct.Size.html
     pub fn min(&self) -> Size {
         self.min
     }
 
+    /// Returns the maximum [`Size`] of the [`Limits`].
+    ///
+    /// [`Limits`]: struct.Limits.html
+    /// [`Size`]: ../struct.Size.html
     pub fn max(&self) -> Size {
         self.max
     }
 
+    /// Applies a width constraint to the current [`Limits`].
+    ///
+    /// [`Limits`]: struct.Limits.html
     pub fn width(mut self, width: Length) -> Limits {
         match width {
             Length::Shrink => {
@@ -51,6 +68,9 @@ impl Limits {
         self
     }
 
+    /// Applies a height constraint to the current [`Limits`].
+    ///
+    /// [`Limits`]: struct.Limits.html
     pub fn height(mut self, height: Length) -> Limits {
         match height {
             Length::Shrink => {
@@ -72,6 +92,9 @@ impl Limits {
         self
     }
 
+    /// Applies a minimum width constraint to the current [`Limits`].
+    ///
+    /// [`Limits`]: struct.Limits.html
     pub fn min_width(mut self, min_width: u32) -> Limits {
         self.min.width =
             self.min.width.max(min_width as f32).min(self.max.width);
@@ -79,6 +102,9 @@ impl Limits {
         self
     }
 
+    /// Applies a maximum width constraint to the current [`Limits`].
+    ///
+    /// [`Limits`]: struct.Limits.html
     pub fn max_width(mut self, max_width: u32) -> Limits {
         self.max.width =
             self.max.width.min(max_width as f32).max(self.min.width);
@@ -86,6 +112,19 @@ impl Limits {
         self
     }
 
+    /// Applies a minimum height constraint to the current [`Limits`].
+    ///
+    /// [`Limits`]: struct.Limits.html
+    pub fn min_height(mut self, min_height: u32) -> Limits {
+        self.min.height =
+            self.min.height.max(min_height as f32).min(self.max.height);
+
+        self
+    }
+
+    /// Applies a maximum height constraint to the current [`Limits`].
+    ///
+    /// [`Limits`]: struct.Limits.html
     pub fn max_height(mut self, max_height: u32) -> Limits {
         self.max.height =
             self.max.height.min(max_height as f32).max(self.min.height);
@@ -93,10 +132,17 @@ impl Limits {
         self
     }
 
+    /// Shrinks the current [`Limits`] to account for the given padding.
+    ///
+    /// [`Limits`]: struct.Limits.html
     pub fn pad(&self, padding: f32) -> Limits {
         self.shrink(Size::new(padding * 2.0, padding * 2.0))
     }
 
+    /// Shrinks the current [`Limits`] by the given [`Size`].
+    ///
+    /// [`Limits`]: struct.Limits.html
+    /// [`Size`]: ../struct.Size.html
     pub fn shrink(&self, size: Size) -> Limits {
         let min = Size::new(
             (self.min().width - size.width).max(0.0),
@@ -116,6 +162,9 @@ impl Limits {
         Limits { min, max, fill }
     }
 
+    /// Removes the minimum width constraint for the current [`Limits`].
+    ///
+    /// [`Limits`]: struct.Limits.html
     pub fn loose(&self) -> Limits {
         Limits {
             min: Size::ZERO,
@@ -124,6 +173,10 @@ impl Limits {
         }
     }
 
+    /// Computes the resulting [`Size`] that fits the [`Limits`] given the
+    /// intrinsic size of some content.
+    ///
+    /// [`Limits`]: struct.Limits.html
     pub fn resolve(&self, intrinsic_size: Size) -> Size {
         Size::new(
             intrinsic_size
diff --git a/native/src/layout/node.rs b/native/src/layout/node.rs
index 64ebf2d0..ed1cd3da 100644
--- a/native/src/layout/node.rs
+++ b/native/src/layout/node.rs
@@ -1,16 +1,25 @@
 use crate::{Align, Rectangle, Size};
 
+/// The bounds of an element and its children.
 #[derive(Debug, Clone, Default)]
 pub struct Node {
-    pub bounds: Rectangle,
+    pub(crate) bounds: Rectangle,
     children: Vec<Node>,
 }
 
 impl Node {
+    /// Creates a new [`Node`] with the given [`Size`].
+    ///
+    /// [`Node`]: struct.Node.html
+    /// [`Size`]: ../struct.Size.html
     pub fn new(size: Size) -> Self {
         Self::with_children(size, Vec::new())
     }
 
+    /// Creates a new [`Node`] with the given [`Size`] and children.
+    ///
+    /// [`Node`]: struct.Node.html
+    /// [`Size`]: ../struct.Size.html
     pub fn with_children(size: Size, children: Vec<Node>) -> Self {
         Node {
             bounds: Rectangle {
@@ -23,19 +32,29 @@ impl Node {
         }
     }
 
+    /// Returns the [`Size`] of the [`Node`].
+    ///
+    /// [`Node`]: struct.Node.html
+    /// [`Size`]: ../struct.Size.html
     pub fn size(&self) -> Size {
         Size::new(self.bounds.width, self.bounds.height)
     }
 
+    /// Returns the bounds of the [`Node`].
+    ///
+    /// [`Node`]: struct.Node.html
     pub fn bounds(&self) -> Rectangle {
         self.bounds
     }
 
+    /// Returns the children of the [`Node`].
+    ///
+    /// [`Node`]: struct.Node.html
     pub fn children(&self) -> &[Node] {
         &self.children
     }
 
-    pub fn align(
+    pub(crate) fn align(
         &mut self,
         horizontal_alignment: Align,
         vertical_alignment: Align,