mirror of
https://github.com/typst/typst
synced 2025-05-18 19:15:29 +08:00
75 lines
2.6 KiB
Rust
75 lines
2.6 KiB
Rust
use super::prelude::*;
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use super::AlignNode;
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/// `place`: Place content at an absolute position.
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pub fn place(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
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let aligns = args.find().unwrap_or(Spec::new(Some(Align::Left), None));
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let tx = args.named("dx")?.unwrap_or_default();
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let ty = args.named("dy")?.unwrap_or_default();
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let body: Template = args.expect("body")?;
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Ok(Value::Template(Template::from_block(move |style| {
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PlacedNode {
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child: body.pack(style).moved(Point::new(tx, ty)).aligned(aligns),
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}
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})))
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}
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/// A node that places its child absolutely.
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#[derive(Debug, Hash)]
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pub struct PlacedNode {
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/// The node to be placed.
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pub child: PackedNode,
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}
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impl PlacedNode {
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/// Whether this node wants to be placed relative to its its parent's base
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/// origin. instead of relative to the parent's current flow/cursor
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/// position.
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pub fn out_of_flow(&self) -> bool {
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self.child
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.downcast::<AlignNode>()
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.map_or(false, |node| node.aligns.y.is_some())
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}
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}
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impl Layout for PlacedNode {
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fn layout(
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&self,
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ctx: &mut LayoutContext,
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regions: &Regions,
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) -> Vec<Constrained<Rc<Frame>>> {
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let out_of_flow = self.out_of_flow();
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// The pod is the base area of the region because for absolute
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// placement we don't really care about the already used area (current).
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let pod = {
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let finite = regions.base.map(Length::is_finite);
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let expand = finite & (regions.expand | out_of_flow);
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Regions::one(regions.base, regions.base, expand)
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};
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let mut frames = self.child.layout(ctx, &pod);
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let Constrained { item: frame, cts } = &mut frames[0];
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// If expansion is off, zero all sizes so that we don't take up any
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// space in our parent. Otherwise, respect the expand settings.
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let target = regions.expand.select(regions.current, Size::zero());
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Rc::make_mut(frame).resize(target, Align::LEFT_TOP);
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// Place relative to parent's base origin by offsetting our elements by
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// the negative cursor position.
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if out_of_flow {
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let offset = (regions.current - regions.base).to_point();
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Rc::make_mut(frame).translate(offset);
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}
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// Set base constraint because our pod size is base and exact
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// constraints if we needed to expand or offset.
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*cts = Constraints::new(regions.expand);
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cts.base = regions.base.map(Some);
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cts.exact = regions.current.filter(regions.expand | out_of_flow);
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frames
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}
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}
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