typst/library/src/layout/place.rs
2023-01-22 13:18:30 +01:00

126 lines
3.4 KiB
Rust

use crate::prelude::*;
/// # Place
/// Place content at an absolute position.
///
/// Placed content will not affect the position of other content. Place is
/// always relative to its parent container and will be in the foreground of all
/// other content in the container. Page margins will be respected.
///
///
/// ## Example
/// ```
/// #set page(height: 60pt)
/// Hello, world!
///
/// #place(
/// top + right,
/// square(
/// width: 10pt,
/// stroke: 1pt + blue
/// ),
/// )
/// ```
///
/// ## Parameters
/// - alignment: Axes<Option<GenAlign>> (positional)
/// Relative to which position in the parent container to place the content.
///
/// When an axis of the page is `{auto}` sized, all alignments relative to that
/// axis will be ignored, instead, the item will be placed in the origin of the
/// axis.
///
/// - body: Content (positional, required)
/// The content to place.
///
/// - dx: Rel<Length> (named)
/// The horizontal displacement of the placed content.
///
/// ### Example
/// ```
/// #set align(center)
///
/// #box(
/// width: 80pt,
/// height: 80pt,
/// {
/// for i in range(18) {
/// let amount = i * 4pt
/// place(dx: amount, dy: amount)[A]
/// }
/// }
/// )
/// ```
///
/// - dy: Rel<Length> (named)
/// The vertical displacement of the placed content.
///
/// ## Category
/// layout
#[func]
#[capable(Layout, Behave)]
#[derive(Debug, Hash)]
pub struct PlaceNode(pub Content, bool);
#[node]
impl PlaceNode {
fn construct(_: &Vm, args: &mut Args) -> SourceResult<Content> {
let aligns = args.find()?.unwrap_or(Axes::with_x(Some(GenAlign::Start)));
let dx = args.named("dx")?.unwrap_or_default();
let dy = args.named("dy")?.unwrap_or_default();
let body = args.expect::<Content>("body")?;
let out_of_flow = aligns.y.is_some();
Ok(Self(body.moved(Axes::new(dx, dy)).aligned(aligns), out_of_flow).pack())
}
fn field(&self, name: &str) -> Option<Value> {
match name {
"body" => Some(Value::Content(self.0.clone())),
_ => None,
}
}
}
impl Layout for PlaceNode {
fn layout(
&self,
vt: &mut Vt,
styles: StyleChain,
regions: Regions,
) -> SourceResult<Fragment> {
let out_of_flow = self.out_of_flow();
// The pod is the base area of the region because for absolute
// placement we don't really care about the already used area.
let pod = {
let finite = regions.base.map(Abs::is_finite);
let expand = finite & (regions.expand | out_of_flow);
Regions::one(regions.base, regions.base, expand)
};
let mut frame = self.0.layout(vt, styles, pod)?.into_frame();
// If expansion is off, zero all sizes so that we don't take up any
// space in our parent. Otherwise, respect the expand settings.
let target = regions.expand.select(regions.first, Size::zero());
frame.resize(target, Align::LEFT_TOP);
Ok(Fragment::frame(frame))
}
}
impl PlaceNode {
/// Whether this node wants to be placed relative to its its parent's base
/// origin. Instead of relative to the parent's current flow/cursor
/// position.
pub fn out_of_flow(&self) -> bool {
self.1
}
}
impl Behave for PlaceNode {
fn behaviour(&self) -> Behaviour {
Behaviour::Ignorant
}
}