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|
//! Aligning nodes in their parent container.
use super::prelude::*;
use super::ParNode;
/// Align a node along the layouting axes.
#[derive(Debug, Hash)]
pub struct AlignNode {
/// How to align the node horizontally and vertically.
pub aligns: Spec<Option<Align>>,
/// The node to be aligned.
pub child: LayoutNode,
}
#[class]
impl AlignNode {
fn construct(_: &mut EvalContext, args: &mut Args) -> TypResult<Template> {
let aligns: Spec<_> = args.find().unwrap_or_default();
let body: LayoutNode = args.expect("body")?;
Ok(Template::block(body.aligned(aligns)))
}
}
impl Layout for AlignNode {
fn layout(
&self,
ctx: &mut LayoutContext,
regions: &Regions,
styles: StyleChain,
) -> Vec<Constrained<Arc<Frame>>> {
// The child only needs to expand along an axis if there's no alignment.
let mut pod = regions.clone();
pod.expand &= self.aligns.map_is_none();
// Align paragraphs inside the child.
let mut passed = StyleMap::new();
if let Some(align) = self.aligns.x {
passed.set(ParNode::ALIGN, align);
}
// Layout the child.
let mut frames = self.child.layout(ctx, &pod, passed.chain(&styles));
for ((current, base), Constrained { item: frame, cts }) in
regions.iter().zip(&mut frames)
{
// Align in the target size. The target size depends on whether we
// should expand.
let target = regions.expand.select(current, frame.size);
let default = Spec::new(Align::Left, Align::Top);
let aligns = self.aligns.unwrap_or(default);
Arc::make_mut(frame).resize(target, aligns);
// Set constraints.
cts.expand = regions.expand;
cts.base = base.filter(cts.base.map_is_some());
cts.exact = current.filter(regions.expand | cts.exact.map_is_some());
}
frames
}
}
dynamic! {
Align: "alignment",
}
dynamic! {
Spec<Align>: "2d alignment",
}
castable! {
Spec<Option<Align>>,
Expected: "1d or 2d alignment",
@align: Align => {
let mut aligns = Spec::default();
aligns.set(align.axis(), Some(*align));
aligns
},
@aligns: Spec<Align> => aligns.map(Some),
}
|
