typst/crates/typst-pdf/src/link.rs

use krilla::action::{Action, LinkAction};
use krilla::annotation::{Annotation, LinkAnnotation, Target};
use krilla::destination::XyzDestination;
use krilla::geom::Rect;
use typst_library::layout::{Abs, Point, Position, Size};
use typst_library::model::Destination;

use crate::convert::{FrameContext, GlobalContext};
use crate::tags::TagNode;
use crate::util::{AbsExt, PointExt};

pub(crate) fn handle_link(
    fc: &mut FrameContext,
    gc: &mut GlobalContext,
    alt: Option<String>,
    dest: &Destination,
    size: Size,
) {
    let mut min_x = Abs::inf();
    let mut min_y = Abs::inf();
    let mut max_x = -Abs::inf();
    let mut max_y = -Abs::inf();

    let pos = Point::zero();

    // Compute the bounding box of the transformed link.
    for point in [
        pos,
        pos + Point::with_x(size.x),
        pos + Point::with_y(size.y),
        pos + size.to_point(),
    ] {
        let t = point.transform(fc.state().transform());
        min_x.set_min(t.x);
        min_y.set_min(t.y);
        max_x.set_max(t.x);
        max_y.set_max(t.y);
    }

    let x1 = min_x.to_f32();
    let x2 = max_x.to_f32();
    let y1 = min_y.to_f32();
    let y2 = max_y.to_f32();

    let rect = Rect::from_ltrb(x1, y1, x2, y2).unwrap();

    // TODO: Support quad points.

    let target = match dest {
        Destination::Url(u) => {
            Target::Action(Action::Link(LinkAction::new(u.to_string())))
        }
        Destination::Position(p) => match pos_to_target(gc, *p) {
            Some(target) => target,
            None => return,
        },
        Destination::Location(loc) => {
            if let Some(nd) = gc.loc_to_names.get(loc) {
                // If a named destination has been registered, it's already guaranteed to
                // not point to an excluded page.
                Target::Destination(krilla::destination::Destination::Named(nd.clone()))
            } else {
                let pos = gc.document.introspector.position(*loc);
                match pos_to_target(gc, pos) {
                    Some(target) => target,
                    None => return,
                }
            }
        }
    };

    let placeholder = gc.tags.reserve_placeholder();
    gc.tags.push(TagNode::Placeholder(placeholder));

    fc.push_annotation(
        placeholder,
        Annotation::new_link(LinkAnnotation::new(rect, None, target), alt),
    );
}

fn pos_to_target(gc: &mut GlobalContext, pos: Position) -> Option<Target> {
    let page_index = pos.page.get() - 1;
    let index = gc.page_index_converter.pdf_page_index(page_index)?;

    let dest = XyzDestination::new(index, pos.point.to_krilla());
    Some(Target::Destination(krilla::destination::Destination::Xyz(dest)))
}