typst/src/library/transform.rs

112 lines
3.1 KiB
Rust

//! Affine transformations on nodes.
use super::prelude::*;
use crate::geom::Transform;
/// Transform a node without affecting layout.
#[derive(Debug, Hash)]
pub struct TransformNode<T: TransformKind> {
/// Transformation to apply to the contents.
pub kind: T,
/// The node whose contents should be transformed.
pub child: PackedNode,
}
#[class]
impl<T: TransformKind> TransformNode<T> {
/// The origin of the transformation.
pub const ORIGIN: Spec<Option<Align>> = Spec::default();
fn construct(_: &mut EvalContext, args: &mut Args) -> TypResult<Template> {
Ok(Template::inline(Self {
kind: T::construct(args)?,
child: args.expect("body")?,
}))
}
fn set(args: &mut Args, styles: &mut StyleMap) -> TypResult<()> {
styles.set_opt(Self::ORIGIN, args.named("origin")?);
Ok(())
}
}
impl<T: TransformKind> Layout for TransformNode<T> {
fn layout(
&self,
ctx: &mut LayoutContext,
regions: &Regions,
styles: StyleChain,
) -> Vec<Constrained<Arc<Frame>>> {
let origin = styles.get(Self::ORIGIN).unwrap_or(Align::CENTER_HORIZON);
let matrix = self.kind.matrix();
let mut frames = self.child.layout(ctx, regions, styles);
for Constrained { item: frame, .. } in &mut frames {
let Spec { x, y } = origin.zip(frame.size).map(|(o, s)| o.resolve(s));
let transform = Transform::translation(x, y)
.pre_concat(matrix)
.pre_concat(Transform::translation(-x, -y));
Arc::make_mut(frame).transform(transform);
}
frames
}
}
/// Kinds of transformations.
pub trait TransformKind: Debug + Hash + Sized + Sync + Send + 'static {
fn construct(args: &mut Args) -> TypResult<Self>;
fn matrix(&self) -> Transform;
}
/// A translation on the X and Y axes.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub struct Move(pub Length, pub Length);
impl TransformKind for Move {
fn construct(args: &mut Args) -> TypResult<Self> {
let tx = args.named("x")?.unwrap_or_default();
let ty = args.named("y")?.unwrap_or_default();
Ok(Self(tx, ty))
}
fn matrix(&self) -> Transform {
Transform::translation(self.0, self.1)
}
}
/// A rotational transformation.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub struct Rotate(pub Angle);
impl TransformKind for Rotate {
fn construct(args: &mut Args) -> TypResult<Self> {
Ok(Self(
args.named("angle")?.or_else(|| args.find()).unwrap_or_default(),
))
}
fn matrix(&self) -> Transform {
Transform::rotation(self.0)
}
}
/// A scale transformation.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub struct Scale(pub Relative, pub Relative);
impl TransformKind for Scale {
fn construct(args: &mut Args) -> TypResult<Self> {
let all = args.find();
let sx = args.named("x")?.or(all).unwrap_or(Relative::one());
let sy = args.named("y")?.or(all).unwrap_or(Relative::one());
Ok(Self(sx, sy))
}
fn matrix(&self) -> Transform {
Transform::scale(self.0, self.1)
}
}