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|
use super::prelude::*;
/// `align`: Configure the alignment along the layouting axes.
pub fn align(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
let mut x = args.named("horizontal")?;
let mut y = args.named("vertical")?;
for Spanned { v, span } in args.all::<Spanned<Align>>() {
match v.axis() {
None | Some(SpecAxis::Horizontal) if x.is_none() => x = Some(v),
None | Some(SpecAxis::Vertical) if y.is_none() => y = Some(v),
_ => bail!(span, "unexpected argument"),
}
}
let body = args.expect::<Template>("body")?;
Ok(Value::Template(Template::from_block(move |style| {
let mut style = style.clone();
if let Some(x) = x {
style.par_mut().align = x;
}
body.pack(&style).aligned(x, y)
})))
}
/// A node that aligns its child.
#[derive(Debug, Hash)]
pub struct AlignNode {
/// The node to be aligned.
pub child: PackedNode,
/// How to align the node horizontally and vertically.
pub aligns: Spec<Option<Align>>,
}
impl Layout for AlignNode {
fn layout(
&self,
ctx: &mut LayoutContext,
regions: &Regions,
) -> Vec<Constrained<Rc<Frame>>> {
// Along axes with specified alignment, the child doesn't need to expand.
let mut pod = regions.clone();
pod.expand.x &= self.aligns.x.is_none();
pod.expand.y &= self.aligns.y.is_none();
let mut frames = self.child.layout(ctx, &pod);
for (Constrained { item: frame, cts }, (current, _)) in
frames.iter_mut().zip(regions.iter())
{
let canvas = Size::new(
if regions.expand.x { current.w } else { frame.size.w },
if regions.expand.y { current.h } else { frame.size.h },
);
let aligns = self.aligns.unwrap_or(Spec::new(Align::Left, Align::Top));
let offset = Point::new(
aligns.x.resolve(Length::zero() .. canvas.w - frame.size.w),
aligns.y.resolve(Length::zero() .. canvas.h - frame.size.h),
);
let frame = Rc::make_mut(frame);
frame.size = canvas;
frame.baseline += offset.y;
for (point, _) in &mut frame.elements {
*point += offset;
}
cts.expand = regions.expand;
cts.exact = current.to_spec().map(Some);
}
frames
}
}
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