feat: pdf.artifact element

8 files changed, 92 insertions, 74 deletions

diff --git a/crates/typst-layout/src/pages/finalize.rs b/crates/typst-layout/src/pages/finalize.rs
index 543dbb0c..b16d9569 100644
--- a/crates/typst-layout/src/pages/finalize.rs
+++ b/crates/typst-layout/src/pages/finalize.rs
@@ -1,10 +1,7 @@
 use typst_library::diag::SourceResult;
 use typst_library::engine::Engine;
-use typst_library::foundations::{Content, NativeElement};
-use typst_library::introspection::{ManualPageCounter, SplitLocator, Tag};
-use typst_library::layout::{
-    ArtifactKind, ArtifactMarker, Frame, FrameItem, Page, Point,
-};
+use typst_library::introspection::{ManualPageCounter, Tag};
+use typst_library::layout::{Frame, FrameItem, Page, Point};
 
 use super::LayoutedPage;
 
@@ -13,7 +10,6 @@ use super::LayoutedPage;
 /// physical page number, which is unknown during parallel layout.
 pub fn finalize(
     engine: &mut Engine,
-    locator: &mut SplitLocator,
     counter: &mut ManualPageCounter,
     tags: &mut Vec<Tag>,
     LayoutedPage {
@@ -49,12 +45,10 @@ pub fn finalize(
     // important as it affects the relative ordering of introspectable elements
     // and thus how counters resolve.
     if let Some(background) = background {
-        let tag = ArtifactMarker::new(ArtifactKind::Page).pack();
-        push_tagged(engine, locator, &mut frame, Point::zero(), background, tag);
+        frame.push_frame(Point::zero(), background);
     }
     if let Some(header) = header {
-        let tag = ArtifactMarker::new(ArtifactKind::Header).pack();
-        push_tagged(engine, locator, &mut frame, Point::with_x(margin.left), header, tag);
+        frame.push_frame(Point::with_x(margin.left), header);
     }
 
     // Add the inner contents.
@@ -63,8 +57,7 @@ pub fn finalize(
     // Add the "after" marginals.
     if let Some(footer) = footer {
         let y = frame.height() - footer.height();
-        let tag = ArtifactMarker::new(ArtifactKind::Footer).pack();
-        push_tagged(engine, locator, &mut frame, Point::new(margin.left, y), footer, tag);
+        frame.push_frame(Point::new(margin.left, y), footer);
     }
     if let Some(foreground) = foreground {
         frame.push_frame(Point::zero(), foreground);
@@ -79,25 +72,3 @@ pub fn finalize(
 
     Ok(Page { frame, fill, numbering, supplement, number })
 }
-
-fn push_tagged(
-    engine: &mut Engine,
-    locator: &mut SplitLocator,
-    frame: &mut Frame,
-    mut pos: Point,
-    inner: Frame,
-    mut tag: Content,
-) {
-    // TODO: use general PDF Tagged/Artifact element that wraps some content and
-    // is also available to the user.
-    let key = typst_utils::hash128(&tag);
-    let loc = locator.next_location(engine.introspector, key);
-    tag.set_location(loc);
-    frame.push(pos, FrameItem::Tag(Tag::Start(tag)));
-
-    let height = inner.height();
-    frame.push_frame(pos, inner);
-
-    pos.y += height;
-    frame.push(pos, FrameItem::Tag(Tag::End(loc, key)));
-}
diff --git a/crates/typst-layout/src/pages/mod.rs b/crates/typst-layout/src/pages/mod.rs
index a64fee4b..14dc0f3f 100644
--- a/crates/typst-layout/src/pages/mod.rs
+++ b/crates/typst-layout/src/pages/mod.rs
@@ -123,19 +123,17 @@ fn layout_pages<'a>(
             Item::Run(..) => {
                 let layouted = runs.next().unwrap()?;
                 for layouted in layouted {
-                    let page =
-                        finalize(engine, locator, &mut counter, &mut tags, layouted)?;
+                    let page = finalize(engine, &mut counter, &mut tags, layouted)?;
                     pages.push(page);
                 }
             }
-            Item::Parity(parity, initial, page_locator) => {
+            Item::Parity(parity, initial, locator) => {
                 if !parity.matches(pages.len()) {
                     continue;
                 }
 
-                let layouted =
-                    layout_blank_page(engine, page_locator.relayout(), *initial)?;
-                let page = finalize(engine, locator, &mut counter, &mut tags, layouted)?;
+                let layouted = layout_blank_page(engine, locator.relayout(), *initial)?;
+                let page = finalize(engine, &mut counter, &mut tags, layouted)?;
                 pages.push(page);
             }
             Item::Tags(items) => {
diff --git a/crates/typst-layout/src/pages/run.rs b/crates/typst-layout/src/pages/run.rs
index 6d2d29da..23360838 100644
--- a/crates/typst-layout/src/pages/run.rs
+++ b/crates/typst-layout/src/pages/run.rs
@@ -13,6 +13,7 @@ use typst_library::layout::{
     VAlignment,
 };
 use typst_library::model::Numbering;
+use typst_library::pdf::ArtifactKind;
 use typst_library::routines::{Pair, Routines};
 use typst_library::text::{LocalName, TextElem};
 use typst_library::visualize::Paint;
@@ -200,6 +201,11 @@ fn layout_page_run_impl(
 
     // Layout marginals.
     let mut layouted = Vec::with_capacity(fragment.len());
+
+    let header = header.as_ref().map(|h| h.clone().artifact(ArtifactKind::Header));
+    let footer = footer.as_ref().map(|f| f.clone().artifact(ArtifactKind::Footer));
+    let background = background.as_ref().map(|b| b.clone().artifact(ArtifactKind::Page));
+
     for inner in fragment {
         let header_size = Size::new(inner.width(), margin.top - header_ascent);
         let footer_size = Size::new(inner.width(), margin.bottom - footer_descent);
@@ -210,9 +216,9 @@ fn layout_page_run_impl(
             fill: fill.clone(),
             numbering: numbering.clone(),
             supplement: supplement.clone(),
-            header: layout_marginal(header, header_size, Alignment::BOTTOM)?,
-            footer: layout_marginal(footer, footer_size, Alignment::TOP)?,
-            background: layout_marginal(background, full_size, mid)?,
+            header: layout_marginal(&header, header_size, Alignment::BOTTOM)?,
+            footer: layout_marginal(&footer, footer_size, Alignment::TOP)?,
+            background: layout_marginal(&background, full_size, mid)?,
             foreground: layout_marginal(foreground, full_size, mid)?,
             margin,
             binding,
diff --git a/crates/typst-library/src/foundations/content.rs b/crates/typst-library/src/foundations/content.rs
index 278d4940..8cd46f0d 100644
--- a/crates/typst-library/src/foundations/content.rs
+++ b/crates/typst-library/src/foundations/content.rs
@@ -22,6 +22,7 @@ use crate::foundations::{
 use crate::introspection::Location;
 use crate::layout::{AlignElem, Alignment, Axes, Length, MoveElem, PadElem, Rel, Sides};
 use crate::model::{Destination, EmphElem, LinkElem, StrongElem};
+use crate::pdf::{ArtifactElem, ArtifactKind};
 use crate::text::UnderlineElem;
 
 /// A piece of document content.
@@ -534,6 +535,12 @@ impl Content {
             .pack()
             .spanned(span)
     }
+
+    /// Link the content somewhere.
+    pub fn artifact(self, kind: ArtifactKind) -> Self {
+        let span = self.span();
+        ArtifactElem::new(self).with_kind(kind).pack().spanned(span)
+    }
 }
 
 #[scope]
diff --git a/crates/typst-library/src/layout/page.rs b/crates/typst-library/src/layout/page.rs
index b6fa5d0b..98afbd06 100644
--- a/crates/typst-library/src/layout/page.rs
+++ b/crates/typst-library/src/layout/page.rs
@@ -10,7 +10,7 @@ use crate::foundations::{
     cast, elem, Args, AutoValue, Cast, Construct, Content, Dict, Fold, NativeElement,
     Set, Smart, Value,
 };
-use crate::introspection::{Introspector, Locatable};
+use crate::introspection::Introspector;
 use crate::layout::{
     Abs, Alignment, FlushElem, Frame, HAlignment, Length, OuterVAlignment, Ratio, Rel,
     Sides, SpecificAlignment,
@@ -451,28 +451,6 @@ impl PagebreakElem {
     }
 }
 
-// HACK: this should probably not be an element
-#[derive(Copy)]
-#[elem(Construct, Locatable)]
-pub struct ArtifactMarker {
-    #[internal]
-    #[required]
-    pub kind: ArtifactKind,
-}
-
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
-pub enum ArtifactKind {
-    Header,
-    Footer,
-    Page,
-}
-
-impl Construct for ArtifactMarker {
-    fn construct(_: &mut Engine, args: &mut Args) -> SourceResult<Content> {
-        bail!(args.span, "cannot be constructed manually");
-    }
-}
-
 /// A finished document with metadata and page frames.
 #[derive(Debug, Default, Clone)]
 pub struct PagedDocument {
diff --git a/crates/typst-library/src/pdf/accessibility.rs b/crates/typst-library/src/pdf/accessibility.rs
new file mode 100644
index 00000000..586e2cbb
--- /dev/null
+++ b/crates/typst-library/src/pdf/accessibility.rs
@@ -0,0 +1,54 @@
+use typst_macros::{cast, elem};
+
+use crate::diag::SourceResult;
+use crate::engine::Engine;
+use crate::foundations::{Content, Packed, Show, StyleChain};
+use crate::introspection::Locatable;
+
+// TODO: docs
+
+/// Mark content as a PDF artifact.
+/// TODO: also use to mark html elements with `aria-hidden="true"`?
+#[elem(Locatable, Show)]
+pub struct ArtifactElem {
+    #[default(ArtifactKind::Other)]
+    pub kind: ArtifactKind,
+
+    /// The content to underline.
+    #[required]
+    pub body: Content,
+}
+
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
+pub enum ArtifactKind {
+    /// Page header artifacts.
+    Header,
+    /// Page footer artifacts.
+    Footer,
+    /// Other page artifacts.
+    Page,
+    /// Other artifacts.
+    #[default]
+    Other,
+}
+
+cast! {
+    ArtifactKind,
+    self => match self {
+        ArtifactKind::Header => "header".into_value(),
+        ArtifactKind::Footer => "footer".into_value(),
+        ArtifactKind::Page => "page".into_value(),
+        ArtifactKind::Other => "other".into_value(),
+    },
+    "header" => Self::Header,
+    "footer" => Self::Footer,
+    "page" => Self::Page,
+    "other" => Self::Other,
+}
+
+impl Show for Packed<ArtifactElem> {
+    #[typst_macros::time(name = "underline", span = self.span())]
+    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        Ok(self.body.clone())
+    }
+}
diff --git a/crates/typst-library/src/pdf/mod.rs b/crates/typst-library/src/pdf/mod.rs
index 786a3637..835cc69f 100644
--- a/crates/typst-library/src/pdf/mod.rs
+++ b/crates/typst-library/src/pdf/mod.rs
@@ -1,7 +1,9 @@
 //! PDF-specific functionality.
 
+mod accessibility;
 mod embed;
 
+pub use self::accessibility::*;
 pub use self::embed::*;
 
 use crate::foundations::{Module, Scope};
@@ -11,5 +13,6 @@ pub fn module() -> Module {
     let mut pdf = Scope::deduplicating();
     pdf.start_category(crate::Category::Pdf);
     pdf.define_elem::<EmbedElem>();
+    pdf.define_elem::<ArtifactElem>();
     Module::new("pdf", pdf)
 }
diff --git a/crates/typst-pdf/src/tags.rs b/crates/typst-pdf/src/tags.rs
index ae15674f..d6415ade 100644
--- a/crates/typst-pdf/src/tags.rs
+++ b/crates/typst-pdf/src/tags.rs
@@ -1,5 +1,4 @@
 use std::cell::OnceCell;
-use std::ops::Deref;
 
 use krilla::annotation::Annotation;
 use krilla::page::Page;
@@ -9,8 +8,8 @@ use krilla::tagging::{
 };
 use typst_library::foundations::{Content, StyleChain};
 use typst_library::introspection::Location;
-use typst_library::layout::{ArtifactKind, ArtifactMarker};
 use typst_library::model::{HeadingElem, OutlineElem, OutlineEntry};
+use typst_library::pdf::{ArtifactElem, ArtifactKind};
 
 use crate::convert::GlobalContext;
 
@@ -18,7 +17,7 @@ pub(crate) struct Tags {
     /// The intermediary stack of nested tag groups.
     pub(crate) stack: Vec<(Location, Tag, Vec<TagNode>)>,
     pub(crate) placeholders: Vec<OnceCell<Node>>,
-    pub(crate) in_artifact: Option<(Location, ArtifactMarker)>,
+    pub(crate) in_artifact: Option<(Location, ArtifactKind)>,
 
     /// The output.
     pub(crate) tree: Vec<TagNode>,
@@ -161,8 +160,8 @@ impl Tags {
 /// at the end of the last page.
 pub(crate) fn restart(gc: &mut GlobalContext, surface: &mut Surface) {
     // TODO: somehow avoid empty marked-content sequences
-    if let Some((_, marker)) = gc.tags.in_artifact {
-        start_artifact(gc, surface, marker.kind);
+    if let Some((_, kind)) = gc.tags.in_artifact {
+        start_artifact(gc, surface, kind);
     } else if let Some((_, _, nodes)) = gc.tags.stack.last_mut() {
         let id = surface.start_tagged(ContentTag::Other);
         nodes.push(TagNode::Leaf(id));
@@ -200,12 +199,13 @@ pub(crate) fn handle_start(
 
     let loc = elem.location().unwrap();
 
-    if let Some(marker) = elem.to_packed::<ArtifactMarker>() {
+    if let Some(artifact) = elem.to_packed::<ArtifactElem>() {
         if !gc.tags.stack.is_empty() {
             surface.end_tagged();
         }
-        start_artifact(gc, surface, marker.kind);
-        gc.tags.in_artifact = Some((loc, *marker.deref()));
+        let kind = artifact.kind(StyleChain::default());
+        start_artifact(gc, surface, kind);
+        gc.tags.in_artifact = Some((loc, kind));
         return;
     }
 
@@ -282,5 +282,6 @@ fn artifact_type(kind: ArtifactKind) -> ArtifactType {
         ArtifactKind::Header => ArtifactType::Header,
         ArtifactKind::Footer => ArtifactType::Footer,
         ArtifactKind::Page => ArtifactType::Page,
+        ArtifactKind::Other => ArtifactType::Other,
     }
 }