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use super::{HorizontalAlign, ParNode};
use crate::prelude::*;
/// Align content along the layouting axes.
#[derive(Debug, Hash)]
pub struct AlignNode {
/// How to align the content horizontally and vertically.
pub aligns: Axes<Option<GenAlign>>,
/// The content to be aligned.
pub child: Content,
}
#[node(Layout)]
impl AlignNode {
fn construct(_: &Vm, args: &mut Args) -> SourceResult<Content> {
let aligns: Axes<Option<GenAlign>> = args.find()?.unwrap_or_default();
let body: Content = args.expect("body")?;
if let Axes { x: Some(x), y: None } = aligns {
if !body.has::<dyn Layout>() || body.has::<dyn Inline>() {
return Ok(body.styled(ParNode::ALIGN, HorizontalAlign(x)));
}
}
Ok(body.aligned(aligns))
}
}
impl Layout for AlignNode {
fn layout(
&self,
world: Tracked<dyn World>,
styles: StyleChain,
regions: &Regions,
) -> SourceResult<Fragment> {
// The child only needs to expand along an axis if there's no alignment.
let mut pod = regions.clone();
pod.expand &= self.aligns.as_ref().map(Option::is_none);
// Align paragraphs inside the child.
let mut map = StyleMap::new();
if let Some(align) = self.aligns.x {
map.set(ParNode::ALIGN, HorizontalAlign(align));
}
// Layout the child.
let mut fragment = self.child.layout(world, styles.chain(&map), &pod)?;
for (region, frame) in regions.iter().zip(&mut fragment) {
// Align in the target size. The target size depends on whether we
// should expand.
let target = regions.expand.select(region, frame.size());
let aligns = self
.aligns
.map(|align| align.resolve(styles))
.unwrap_or(Axes::new(Align::Left, Align::Top));
frame.resize(target, aligns);
}
Ok(fragment)
}
}
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