Repository: typst/typst
File: crates/typst/src/layout/layout.rs (Rust)

Code before:
///     block(width: size.width, text),
///   )
///   This text is #height high with
///   the current page width: \
///   #text
/// ])
/// ```
///
/// If the `layout` call is placed inside a box with a width of `{800pt}` and a
/// height of `{400pt}`, then the specified function will be given the parameter
/// `{(width: 800pt, height: 400pt)}`. If it is placed directly into the page, it
/// receives the page's dimensions minus its margins. This is mostly useful in
/// combination with [measurement]($measure).
///
/// You can also use this function to resolve [`ratio`] to fixed lengths. This
/// might come in handy if you're building your own layout abstractions.
///
/// ```example
/// #layout(size => {
///   let half = 50% * size.width
///   [Half a page is #half wide.]
/// })
/// ```
///
/// Note that the provided width or height will be infinite in case the
/// corresponding page dimension is set to `{auto}`.
///
/// Moreover, this function also provides [context]($context) to its argument,
/// so you don't need to use it in combination with the `context` keyword.
#[func]
pub fn layout(
    /// The call span of this function.
    span: Span,
    /// A function to call with the outer container's size. Its return value is
    /// displayed in the document.
    ///
    /// The container's size is given as a [dictionary] with the keys `width`
    /// and `height`.
    ///
    /// This function is called once for each time the content returned by
    /// `layout` appears in the document. This makes it possible to generate
    /// content that depends on the dimensions of its container.
    func: Func,
) -> Content {
    LayoutElem::new(func).pack().spanned(span)
}

/// Executes a `layout` call.
#[elem(Locatable, LayoutMultiple)]
struct LayoutElem {
    /// The function to call with the outer container's (or page's) size.

Review comment (suggestion):
I think this might be a slight bit better (not 100% sure):

```suggestion
/// Note that the width or height provided by `layout` will be infinite if the
/// corresponding page dimension is set to `{auto}`.
```

Code after:
/// #let text = lorem(30)
/// #layout(size => [
///   #let (height,) = measure(
///     block(width: size.width, text),
///   )
///   This text is #height high with
///   the current page width: \
///   #text
/// ])
/// ```
///
/// If the `layout` call is placed inside a box with a width of `{800pt}` and a
/// height of `{400pt}`, then the specified function will be given the argument
/// `{(width: 800pt, height: 400pt)}`. If it is placed directly into the page, it
/// receives the page's dimensions minus its margins. This is mostly useful in
/// combination with [measurement]($measure).
///
/// You can also use this function to resolve [`ratio`] to fixed lengths. This
/// might come in handy if you're building your own layout abstractions.
///
/// ```example
/// #layout(size => {
///   let half = 50% * size.width
///   [Half a page is #half wide.]
/// })
/// ```
///
/// Note that the width or height provided by `layout` will be infinite if the
/// corresponding page dimension is set to `{auto}`.
#[func]
pub fn layout(
    /// The call span of this function.
    span: Span,
    /// A function to call with the outer container's size. Its return value is
    /// displayed in the document.
    ///
    /// The container's size is given as a [dictionary] with the keys `width`
    /// and `height`.
    ///
    /// This function is called once for each time the content returned by
    /// `layout` appears in the document. This makes it possible to generate
    /// content that depends on the dimensions of its container.
    func: Func,
) -> Content {
    LayoutElem::new(func).pack().spanned(span)
}

/// Executes a `layout` call.
#[elem(Locatable, LayoutMultiple)]
struct LayoutElem {
    /// The function to call with the outer container's (or page's) size.