typst/src/library/heading.rs

72 lines
2.1 KiB
Rust

//! Document-structuring section headings.
use super::prelude::*;
use super::{FontFamily, TextNode};
/// A section heading.
#[derive(Debug, Hash)]
pub struct HeadingNode {
/// The logical nesting depth of the section, starting from one. In the
/// default style, this controls the text size of the heading.
pub level: usize,
/// The node that produces the heading's contents.
pub child: PackedNode,
}
#[properties]
impl HeadingNode {
/// The heading's font family.
pub const FAMILY: Smart<FontFamily> = Smart::Auto;
/// The fill color of text in the heading. Just the surrounding text color
/// if `auto`.
pub const FILL: Smart<Paint> = Smart::Auto;
}
impl Construct for HeadingNode {
fn construct(_: &mut EvalContext, args: &mut Args) -> TypResult<Node> {
Ok(Node::block(Self {
child: args.expect("body")?,
level: args.named("level")?.unwrap_or(1),
}))
}
}
impl Set for HeadingNode {
fn set(args: &mut Args, styles: &mut StyleMap) -> TypResult<()> {
styles.set_opt(Self::FAMILY, args.named("family")?);
styles.set_opt(Self::FILL, args.named("fill")?);
Ok(())
}
}
impl Layout for HeadingNode {
fn layout(
&self,
ctx: &mut LayoutContext,
regions: &Regions,
styles: StyleChain,
) -> Vec<Constrained<Rc<Frame>>> {
let upscale = (1.6 - 0.1 * self.level as f64).max(0.75);
let mut passed = StyleMap::new();
passed.set(TextNode::STRONG, true);
passed.set(TextNode::SIZE, Relative::new(upscale).into());
if let Smart::Custom(family) = styles.get_ref(Self::FAMILY) {
passed.set(
TextNode::FAMILY_LIST,
std::iter::once(family)
.chain(styles.get_ref(TextNode::FAMILY_LIST))
.cloned()
.collect(),
);
}
if let Smart::Custom(fill) = styles.get(Self::FILL) {
passed.set(TextNode::FILL, fill);
}
self.child.layout(ctx, regions, passed.chain(&styles))
}
}