typst/library/src/layout/place.rs
2022-11-03 13:35:39 +01:00

57 lines
1.9 KiB
Rust

use super::AlignNode;
use crate::prelude::*;
/// Place content at an absolute position.
#[derive(Debug, Hash)]
pub struct PlaceNode(pub Content);
#[node(LayoutBlock)]
impl PlaceNode {
fn construct(_: &mut 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")?;
Ok(Self(body.moved(Axes::new(dx, dy)).aligned(aligns)).pack())
}
}
impl LayoutBlock for PlaceNode {
fn layout_block(
&self,
world: Tracked<dyn World>,
regions: &Regions,
styles: StyleChain,
) -> SourceResult<Vec<Frame>> {
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 frames = self.0.layout_block(world, &pod, styles)?;
// 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());
frames[0].resize(target, Align::LEFT_TOP);
Ok(frames)
}
}
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.0
.downcast::<AlignNode>()
.map_or(false, |node| node.aligns.y.is_some())
}
}