update size macro, add docs to layout module

hui/src/layout.rs

@@ -46,6 +46,7 @@ pub struct Alignment2d {
 }
 
 impl Alignment2d {
+  /// Create a new `Alignment2d` with the same alignment for both axes
   #[inline]
   pub const fn all(alignment: Alignment) -> Self {
     Self {
@@ -76,6 +77,9 @@ impl From<Alignment> for Alignment2d {
   }
 }
 
+/// Represents a single size dimension of an UI element.\
+/// Can be either a static size in pixels, a fraction the parent size or auto-calculated\
+/// (Meaning of `auto` is entirely dependent on the element).
 #[derive(Default, Debug, Clone, Copy, PartialEq)]
 pub enum UiSize {
   #[default]
@@ -83,6 +87,9 @@ pub enum UiSize {
   Auto,
   /// Size as a ratio of parent size\
   /// Valid range: 0.0-1.0 (0-100%)
+  ///
+  /// Out of range values are allowed, but are not guaranteed to work as expected\
+  /// (especially with negative values)
   Fraction(f32),
   /// Static size in pixels
   Static(f32),
@@ -121,31 +128,61 @@ impl From<UiSize> for UiSize2d {
 
 //TODO?: add `UiSize2d` from `(Into<UiSize>, Into<UiSize>)` or Into<UiSize> conversion
 
-/// Create a `UiSize` or `UiSize2d` from a literal
+/// Constructs a `UiSize` or `UiSize2d` from a literal or expression
+///
 /// # Syntax:
 /// - `auto` - `UiSize::Auto`
 /// - `x` - `UiSize::Static(x)`
-/// - `x%` - `UiSize::Fraction(x / 100.)`
+/// - `x%` - `UiSize::Fraction(x / 100.)` *(literal only)*
+/// - `x/` - `UiSize::Fraction(x)`
 ///
-/// If two values are provided, it creates a `UiSize2d` with the first value as width and the second as height
+/// ...where `x` is a literal, identifier or an expression wrapped in parentheses
+///
+/// # Note:
+/// - If a single argument is provided, it creates a `UiSize` using the rules specified above\
+/// - If two arguments are provided, it creates a `UiSize2d` with the first value as width and the second as height\
+///   Example: `size!(100, 50%)` creates a `UiSize2d` with width `100` (`UiSize::Static(100.)`) and height `50%` (`UiSize::Fraction(0.5)`)
+/// - `%` syntax is only valid for literals (`50%`), not expressions or identidiers.\
+///   Use `/` instead (`(0.5 * x)/`, `x/`), but be aware of the different range (0.0-1.0) \
+/// - Expressions must be wrapped in parentheses (for example: `(x + 5)`).\
+///   This does not apply to single identifiers (`x`) or literals (`5`)
 #[macro_export]
 macro_rules! size {
   (auto) => {
     $crate::layout::UiSize::Auto
   };
+
   ($x:literal) => {
     $crate::layout::UiSize::Static($x as f32)
   };
   ($x:literal %) => {
     $crate::layout::UiSize::Fraction($x as f32 / 100.)
   };
-  ($x:literal , $y:tt $($ys:tt)?) => {
+  ($x:literal /) => {
+    $crate::layout::UiSize::Fraction($x as f32)
+  };
+
+  ($x:ident) => {
+    $crate::layout::UiSize::Static($x as f32)
+  };
+  ($x:ident /) => {
+    $crate::layout::UiSize::Fraction($x as f32)
+  };
+
+  (($x:expr)) => {
+    $crate::layout::UiSize::Static(($x) as f32)
+  };
+  (($x:expr) /) => {
+    $crate::layout::UiSize::Fraction(($x) as f32)
+  };
+
+  ($x:tt , $y:tt $($ys:tt)?) => {
     $crate::layout::UiSize2d {
       width: $crate::layout::size!($x),
       height: $crate::layout::size!($y $($ys)?),
     }
   };
-  ($x:literal $($xs:tt)? , $y:tt $($ys:tt)?) => {
+  ($x:tt $($xs:tt)? , $y:tt $($ys:tt)?) => {
     $crate::layout::UiSize2d {
       width: $crate::layout::size!($x $($xs)?),
       height: $crate::layout::size!($y $($ys)?),
@@ -154,16 +191,33 @@ macro_rules! size {
 }
 pub use size;
 
+/// Represents the direction of the layout\
+/// (for example, the direction of a container's children)\
+///
+/// - `Vertical` - Children are laid out from top to bottom\
+/// - `Horizontal` - Children are laid out from left to right
 #[derive(Default, Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub enum UiDirection {
+  /// Children are laid out from top to bottom
   #[default]
   Vertical,
+  /// Children are laid out from left to right
   Horizontal,
 }
 
+/// Represents the layout information required to measure, layout and render an element.\
+/// Includes the position, maximum size, direction of the layout and other information
 pub struct LayoutInfo {
-  ///Not availabe during measuring step
+  /// Screen-space coordinates of the top-left corner of the element.\
+  /// Use this value during the layout step to render the element
+  ///
+  /// Not available during the measure step (will be set to zero)
   pub position: Vec2,
+
+  /// Maximum size the element is allowed to take up
   pub max_size: Vec2,
+
+  /// Current direction of the layout\
+  /// (Usually matches direction of the parent container)
   pub direction: UiDirection,
 }