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|
use crate::prelude::*;
/// Places content at an absolute position.
///
/// Placed content will not affect the position of other content. Place is
/// always relative to its parent container and will be in the foreground of all
/// other content in the container. Page margins will be respected.
///
///
/// # Example
/// ```example
/// #set page(height: 60pt)
/// Hello, world!
///
/// #place(
/// top + right,
/// square(
/// width: 20pt,
/// stroke: 2pt + blue
/// ),
/// )
/// ```
#[elem(Layout, Behave)]
pub struct PlaceElem {
/// Relative to which position in the parent container to place the content.
///
/// Cannot be `{auto}` if `float` is `{false}` and must be either
/// `{auto}`, `{top}`, or `{bottom}` if `float` is `{true}`.
///
/// When an axis of the page is `{auto}` sized, all alignments relative to
/// that axis will be ignored, instead, the item will be placed in the
/// origin of the axis.
#[positional]
#[default(Smart::Custom(Align::START))]
pub alignment: Smart<Align>,
/// Whether the placed element has floating layout.
///
/// Floating elements are positioned at the top or bottom of the page,
/// displacing in-flow content.
///
/// ```example
/// #set page(height: 150pt)
/// #let note(where, body) = place(
/// center + where,
/// float: true,
/// clearance: 6pt,
/// rect(body),
/// )
///
/// #lorem(10)
/// #note(bottom)[Bottom 1]
/// #note(bottom)[Bottom 2]
/// #lorem(40)
/// #note(top)[Top]
/// #lorem(10)
/// ```
pub float: bool,
/// The amount of clearance the placed element has in a floating layout.
#[default(Em::new(1.5).into())]
#[resolve]
pub clearance: Length,
/// The horizontal displacement of the placed content.
///
/// ```example
/// #set page(height: 100pt)
/// #for i in range(16) {
/// let amount = i * 4pt
/// place(center, dx: amount - 32pt, dy: amount)[A]
/// }
/// ```
pub dx: Rel<Length>,
/// The vertical displacement of the placed content.
pub dy: Rel<Length>,
/// The content to place.
#[required]
pub body: Content,
}
impl Layout for PlaceElem {
#[tracing::instrument(name = "PlaceElem::layout", skip_all)]
fn layout(
&self,
vt: &mut Vt,
styles: StyleChain,
regions: Regions,
) -> SourceResult<Fragment> {
// The pod is the base area of the region because for absolute
// placement we don't really care about the already used area.
let base = regions.base();
let float = self.float(styles);
let alignment = self.alignment(styles);
if float
&& alignment
.map_or(false, |align| matches!(align.y(), None | Some(VAlign::Horizon)))
{
bail!(self.span(), "floating placement must be `auto`, `top`, or `bottom`");
} else if !float && alignment.is_auto() {
return Err("automatic positioning is only available for floating placement")
.hint("you can enable floating placement with `place(float: true, ..)`")
.at(self.span());
}
let child = self.body().aligned(alignment.unwrap_or_else(|| Align::CENTER));
let pod = Regions::one(base, Axes::splat(false));
let frame = child.layout(vt, styles, pod)?.into_frame();
Ok(Fragment::frame(frame))
}
}
impl Behave for PlaceElem {
fn behaviour(&self) -> Behaviour {
Behaviour::Ignorant
}
}
|
