WIP [no ci] tag table headers

skip-checks:true

# Please enter the commit message for your changes. Lines starting
# with '#' will be kept; you may remove them yourself if you want to.
# An empty message aborts the commit.
#
# Date:      Wed May 28 17:47:35 2025 +0200
#
# On branch pdf-accessibility
# Your branch and 'origin/pdf-accessibility' have diverged,
# and have 11 and 5 different commits each, respectively.
#
# Changes to be committed:
#	modified:   crates/typst-ide/src/jump.rs
#	modified:   crates/typst-layout/src/flow/distribute.rs
#	modified:   crates/typst-layout/src/modifiers.rs
#	modified:   crates/typst-library/src/foundations/content.rs
#	modified:   crates/typst-library/src/layout/frame.rs
#	modified:   crates/typst-library/src/model/bibliography.rs
#	modified:   crates/typst-library/src/model/footnote.rs
#	modified:   crates/typst-library/src/model/link.rs
#	modified:   crates/typst-library/src/model/outline.rs
#	modified:   crates/typst-library/src/model/reference.rs
#	modified:   crates/typst-pdf/src/convert.rs
#	modified:   crates/typst-pdf/src/link.rs
#	modified:   crates/typst-render/src/lib.rs
#	modified:   crates/typst-svg/src/lib.rs
#	modified:   tests/src/run.rs
#

Cargo.lock

@@ -1367,7 +1367,6 @@ dependencies = [
 [[package]]
 name = "krilla"
 version = "0.4.0"
-source = "git+https://github.com/LaurenzV/krilla?rev=20c14fe#20c14fefee5002566b3d6668b338bbe2168784e7"
 dependencies = [
  "base64",
  "bumpalo",
@@ -1395,7 +1394,6 @@ dependencies = [
 [[package]]
 name = "krilla-svg"
 version = "0.1.0"
-source = "git+https://github.com/LaurenzV/krilla?rev=20c14fe#20c14fefee5002566b3d6668b338bbe2168784e7"
 dependencies = [
  "flate2",
  "fontdb",

Cargo.toml

@@ -73,8 +73,8 @@ image = { version = "0.25.5", default-features = false, features = ["png", "jpeg
 indexmap = { version = "2", features = ["serde"] }
 infer = { version = "0.19.0", default-features = false }
 kamadak-exif = "0.6"
-krilla = { git = "https://github.com/LaurenzV/krilla", rev = "20c14fe", default-features = false, features = ["raster-images", "comemo", "rayon"] }
-krilla-svg = { git = "https://github.com/LaurenzV/krilla", rev = "20c14fe" }
+krilla = { path = "../krilla/crates/krilla", default-features = false, features = ["raster-images", "comemo", "rayon"] }
+krilla-svg = { path = "../krilla/crates/krilla-svg" }
 kurbo = "0.11"
 libfuzzer-sys = "0.4"
 lipsum = "0.9"

crates/typst-cli/src/args.rs

@@ -246,6 +246,13 @@ pub struct CompileArgs {
     #[arg(long = "pdf-standard", value_delimiter = ',')]
     pub pdf_standard: Vec<PdfStandard>,
 
+    /// By default, even when not producing a `PDF/UA-1` document, a tagged PDF
+    /// document is written to provide a baseline of accessibility. In some
+    /// circumstances (for example when trying to reduce the size of a document)
+    /// it can be desirable to disable tagged PDF.
+    #[arg(long = "disable-pdf-tags")]
+    pub disable_pdf_tags: bool,
+
     /// The PPI (pixels per inch) to use for PNG export.
     #[arg(long = "ppi", default_value_t = 144.0)]
     pub ppi: f32,
@@ -506,6 +513,9 @@ pub enum PdfStandard {
     /// PDF/A-4e.
     #[value(name = "a-4e")]
     A_4e,
+    /// PDF/UA-1.
+    #[value(name = "ua-1")]
+    Ua_1,
 }
 
 display_possible_values!(PdfStandard);

crates/typst-cli/src/compile.rs

@@ -65,6 +65,8 @@ pub struct CompileConfig {
     pub open: Option<Option<String>>,
     /// A list of standards the PDF should conform to.
     pub pdf_standards: PdfStandards,
+    /// Whether to write PDF (accessibility) tags.
+    pub disable_pdf_tags: bool,
     /// A path to write a Makefile rule describing the current compilation.
     pub make_deps: Option<PathBuf>,
     /// The PPI (pixels per inch) to use for PNG export.
@@ -150,6 +152,7 @@ impl CompileConfig {
             output_format,
             pages,
             pdf_standards,
+            disable_pdf_tags: args.disable_pdf_tags,
             creation_timestamp: args.world.creation_timestamp,
             make_deps: args.make_deps.clone(),
             ppi: args.ppi,
@@ -291,6 +294,7 @@ fn export_pdf(document: &PagedDocument, config: &CompileConfig) -> SourceResult<
         timestamp,
         page_ranges: config.pages.clone(),
         standards: config.pdf_standards.clone(),
+        disable_tags: config.disable_pdf_tags,
     };
     let buffer = typst_pdf::pdf(document, &options)?;
     config
@@ -773,6 +777,7 @@ impl From<PdfStandard> for typst_pdf::PdfStandard {
             PdfStandard::A_4 => typst_pdf::PdfStandard::A_4,
             PdfStandard::A_4f => typst_pdf::PdfStandard::A_4f,
             PdfStandard::A_4e => typst_pdf::PdfStandard::A_4e,
+            PdfStandard::Ua_1 => typst_pdf::PdfStandard::Ua_1,
         }
     }
 }

crates/typst-layout/src/flow/distribute.rs

@@ -93,7 +93,7 @@ impl Item<'_, '_> {
             Self::Frame(frame, _) => {
                 frame.size().is_zero()
                     && frame.items().all(|(_, item)| {
-                        matches!(item, FrameItem::Link(_, _) | FrameItem::Tag(_))
+                        matches!(item, FrameItem::Link(..) | FrameItem::Tag(_))
                     })
             }
             Self::Placed(_, placed) => !placed.float,

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,

crates/typst-library/src/foundations/content.rs

@@ -16,12 +16,13 @@ use crate::diag::{SourceResult, StrResult};
 use crate::engine::Engine;
 use crate::foundations::{
     elem, func, scope, ty, Context, Dict, Element, Fields, IntoValue, Label,
-    NativeElement, Recipe, RecipeIndex, Repr, Selector, Str, Style, StyleChain, Styles,
-    Value,
+    NativeElement, Recipe, RecipeIndex, Repr, Selector, Show, Str, Style, StyleChain,
+    Styles, Value,
 };
-use crate::introspection::Location;
+use crate::introspection::{Locatable, 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.
@@ -503,8 +504,12 @@ impl Content {
     }
 
     /// Link the content somewhere.
-    pub fn linked(self, dest: Destination) -> Self {
-        self.styled(LinkElem::set_current(Some(dest)))
+    pub fn linked(self, dest: Destination, alt: Option<EcoString>) -> Self {
+        let span = self.span();
+        LinkMarker::new(self, dest.clone(), alt)
+            .pack()
+            .spanned(span)
+            .styled(LinkElem::set_current(Some(dest)))
     }
 
     /// Set alignments for this content.
@@ -533,6 +538,12 @@ 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]
@@ -980,6 +991,24 @@ pub trait PlainText {
     fn plain_text(&self, text: &mut EcoString);
 }
 
+/// An element that associates the body of a link with the destination.
+#[elem(Show, Locatable)]
+pub struct LinkMarker {
+    /// The content.
+    #[required]
+    pub body: Content,
+    #[required]
+    pub dest: Destination,
+    #[required]
+    pub alt: Option<EcoString>,
+}
+
+impl Show for Packed<LinkMarker> {
+    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        Ok(self.body.clone())
+    }
+}
+
 /// An error arising when trying to access a field of content.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
 pub enum FieldAccessError {

crates/typst-library/src/html/mod.rs

@@ -8,6 +8,7 @@ pub use self::dom::*;
 use ecow::EcoString;
 
 use crate::foundations::{elem, Content, Module, Scope};
+use crate::introspection::Locatable;
 
 /// Create a module with all HTML definitions.
 pub fn module() -> Module {
@@ -40,7 +41,7 @@ pub fn module() -> Module {
 ///   A div with _Typst content_ inside!
 /// ]
 /// ```
-#[elem(name = "elem")]
+#[elem(name = "elem", Locatable)]
 pub struct HtmlElem {
     /// The element's tag.
     #[required]

crates/typst-library/src/layout/grid/mod.rs

@@ -13,6 +13,7 @@ use crate::foundations::{
     cast, elem, scope, Array, CastInfo, Content, Context, Fold, FromValue, Func,
     IntoValue, NativeElement, Packed, Reflect, Resolve, Show, Smart, StyleChain, Value,
 };
+use crate::introspection::Locatable;
 use crate::layout::{
     Alignment, BlockElem, Length, OuterHAlignment, OuterVAlignment, Rel, Sides, Sizing,
 };
@@ -136,7 +137,7 @@ use crate::visualize::{Paint, Stroke};
 ///
 /// Furthermore, strokes of a repeated grid header or footer will take
 /// precedence over regular cell strokes.
-#[elem(scope, Show)]
+#[elem(scope, Locatable, Show)]
 pub struct GridElem {
     /// The column sizes.
     ///
@@ -462,7 +463,7 @@ impl TryFrom<Content> for GridItem {
 /// If `repeat` is set to `true`, the header will be repeated across pages. For
 /// an example, refer to the [`table.header`]($table.header) element and the
 /// [`grid.stroke`]($grid.stroke) parameter.
-#[elem(name = "header", title = "Grid Header")]
+#[elem(name = "header", title = "Grid Header", Locatable)]
 pub struct GridHeader {
     /// Whether this header should be repeated across pages.
     #[default(true)]
@@ -490,7 +491,7 @@ pub struct GridHeader {
 /// itself on every page of the table.
 ///
 /// No other grid cells may be placed after the footer.
-#[elem(name = "footer", title = "Grid Footer")]
+#[elem(name = "footer", title = "Grid Footer", Locatable)]
 pub struct GridFooter {
     /// Whether this footer should be repeated across pages.
     #[default(true)]
@@ -657,7 +658,7 @@ pub struct GridVLine {
 /// which allows you, for example, to apply styles based on a cell's position.
 /// Refer to the examples of the [`table.cell`]($table.cell) element to learn
 /// more about this.
-#[elem(name = "cell", title = "Grid Cell", Show)]
+#[elem(name = "cell", title = "Grid Cell", Locatable, Show)]
 pub struct GridCell {
     /// The cell's body.
     #[required]

crates/typst-library/src/layout/hide.rs

@@ -1,6 +1,7 @@
 use crate::diag::SourceResult;
 use crate::engine::Engine;
 use crate::foundations::{elem, Content, Packed, Show, StyleChain};
+use crate::introspection::Locatable;
 
 /// Hides content without affecting layout.
 ///
@@ -14,7 +15,7 @@ use crate::foundations::{elem, Content, Packed, Show, StyleChain};
 /// Hello Jane \
 /// #hide[Hello] Joe
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct HideElem {
     /// The content to hide.
     #[required]

crates/typst-library/src/layout/repeat.rs

@@ -1,6 +1,7 @@
 use crate::diag::SourceResult;
 use crate::engine::Engine;
 use crate::foundations::{elem, Content, NativeElement, Packed, Show, StyleChain};
+use crate::introspection::Locatable;
 use crate::layout::{BlockElem, Length};
 
 /// Repeats content to the available space.
@@ -24,7 +25,7 @@ use crate::layout::{BlockElem, Length};
 ///   Berlin, the 22nd of December, 2022
 /// ]
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct RepeatElem {
     /// The content to repeat.
     #[required]

crates/typst-library/src/math/mod.rs

@@ -28,6 +28,7 @@ use typst_utils::singleton;
 use unicode_math_class::MathClass;
 
 use crate::foundations::{elem, Content, Module, NativeElement, Scope};
+use crate::introspection::Locatable;
 use crate::layout::{Em, HElem};
 use crate::text::TextElem;
 
@@ -109,7 +110,7 @@ pub fn module() -> Module {
 pub trait Mathy {}
 
 /// A math alignment point: `&`, `&&`.
-#[elem(title = "Alignment Point", Mathy)]
+#[elem(title = "Alignment Point", Mathy, Locatable)]
 pub struct AlignPointElem {}
 
 impl AlignPointElem {
@@ -136,7 +137,7 @@ impl AlignPointElem {
 ///
 /// $x loves y and y loves 5$
 /// ```
-#[elem(Mathy)]
+#[elem(Mathy, Locatable)]
 pub struct ClassElem {
     /// The class to apply to the content.
     #[required]

crates/typst-library/src/math/root.rs

@@ -1,6 +1,7 @@
 use typst_syntax::Span;
 
 use crate::foundations::{elem, func, Content, NativeElement};
+use crate::introspection::Locatable;
 use crate::math::Mathy;
 
 /// A square root.
@@ -22,7 +23,7 @@ pub fn sqrt(
 /// ```example
 /// $ root(3, x) $
 /// ```
-#[elem(Mathy)]
+#[elem(Mathy, Locatable)]
 pub struct RootElem {
     /// Which root of the radicand to take.
     #[positional]

crates/typst-library/src/model/bibliography.rs

@@ -873,7 +873,8 @@ impl<'a> Generator<'a> {
                         renderer.display_elem_child(elem, &mut None, false)?;
                     if let Some(location) = first_occurrences.get(item.key.as_str()) {
                         let dest = Destination::Location(*location);
-                        content = content.linked(dest);
+                        // TODO: accept user supplied alt text
+                        content = content.linked(dest, None);
                     }
                     StrResult::Ok(content)
                 })
@@ -1008,7 +1009,8 @@ impl ElemRenderer<'_> {
         if let Some(hayagriva::ElemMeta::Entry(i)) = elem.meta {
             if let Some(location) = (self.link)(i) {
                 let dest = Destination::Location(location);
-                content = content.linked(dest);
+                // TODO: accept user supplied alt text
+                content = content.linked(dest, None);
             }
         }
 

crates/typst-library/src/model/cite.rs

@@ -43,7 +43,7 @@ use crate::text::{Lang, Region, TextElem};
 /// This function indirectly has dedicated syntax. [References]($ref) can be
 /// used to cite works from the bibliography. The label then corresponds to the
 /// citation key.
-#[elem(Synthesize)]
+#[elem(Locatable, Synthesize)]
 pub struct CiteElem {
     /// The citation key that identifies the entry in the bibliography that
     /// shall be cited, as a label.

crates/typst-library/src/model/emph.rs

@@ -4,6 +4,7 @@ use crate::foundations::{
     elem, Content, NativeElement, Packed, Show, StyleChain, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::text::{ItalicToggle, TextElem};
 
 /// Emphasizes content by toggling italics.
@@ -29,7 +30,7 @@ use crate::text::{ItalicToggle, TextElem};
 /// This function also has dedicated syntax: To emphasize content, simply
 /// enclose it in underscores (`_`). Note that this only works at word
 /// boundaries. To emphasize part of a word, you have to use the function.
-#[elem(title = "Emphasis", keywords = ["italic"], Show)]
+#[elem(title = "Emphasis", keywords = ["italic"], Locatable, Show)]
 pub struct EmphElem {
     /// The content to emphasize.
     #[required]

crates/typst-library/src/model/enum.rs

@@ -10,6 +10,7 @@ use crate::foundations::{
     Styles, TargetElem,
 };
 use crate::html::{attr, tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{Alignment, BlockElem, Em, HAlignment, Length, VAlignment, VElem};
 use crate::model::{
     ListItemLike, ListLike, Numbering, NumberingPattern, ParElem, ParbreakElem,
@@ -71,7 +72,7 @@ use crate::model::{
 /// Enumeration items can contain multiple paragraphs and other block-level
 /// content. All content that is indented more than an item's marker becomes
 /// part of that item.
-#[elem(scope, title = "Numbered List", Show)]
+#[elem(scope, title = "Numbered List", Locatable, Show)]
 pub struct EnumElem {
     /// Defines the default [spacing]($enum.spacing) of the enumeration. If it
     /// is `{false}`, the items are spaced apart with
@@ -271,7 +272,7 @@ impl Show for Packed<EnumElem> {
 }
 
 /// An enumeration item.
-#[elem(name = "item", title = "Numbered List Item")]
+#[elem(name = "item", title = "Numbered List Item", Locatable)]
 pub struct EnumItem {
     /// The item's number.
     #[positional]

crates/typst-library/src/model/figure.rs

@@ -473,7 +473,7 @@ impl Outlinable for Packed<FigureElem> {
 ///   caption: [A rectangle],
 /// )
 /// ```
-#[elem(name = "caption", Synthesize, Show)]
+#[elem(name = "caption", Locatable, Synthesize, Show)]
 pub struct FigureCaption {
     /// The caption's position in the figure. Either `{top}` or `{bottom}`.
     ///

crates/typst-library/src/model/footnote.rs

@@ -147,7 +147,8 @@ impl Show for Packed<FootnoteElem> {
         let sup = SuperElem::new(num).pack().spanned(span);
         let loc = loc.variant(1);
         // Add zero-width weak spacing to make the footnote "sticky".
-        Ok(HElem::hole().pack() + sup.linked(Destination::Location(loc)))
+        // TODO: accept user supplied alt text
+        Ok(HElem::hole().pack() + sup.linked(Destination::Location(loc), None))
     }
 }
 
@@ -192,7 +193,7 @@ cast! {
 /// page run is a sequence of pages without an explicit pagebreak in between).
 /// For this reason, set and show rules for footnote entries should be defined
 /// before any page content, typically at the very start of the document.
-#[elem(name = "entry", title = "Footnote Entry", Show, ShowSet)]
+#[elem(name = "entry", title = "Footnote Entry", Locatable, Show, ShowSet)]
 pub struct FootnoteEntry {
     /// The footnote for this entry. Its location can be used to determine
     /// the footnote counter state.
@@ -296,7 +297,8 @@ impl Show for Packed<FootnoteEntry> {
         let sup = SuperElem::new(num)
             .pack()
             .spanned(span)
-            .linked(Destination::Location(loc))
+            // TODO: accept user supplied alt text
+            .linked(Destination::Location(loc), None)
             .located(loc.variant(1));
 
         Ok(Content::sequence([

crates/typst-library/src/model/link.rs

@@ -9,7 +9,7 @@ use crate::foundations::{
     StyleChain, Styles, TargetElem,
 };
 use crate::html::{attr, tag, HtmlElem};
-use crate::introspection::Location;
+use crate::introspection::{Locatable, Location};
 use crate::layout::Position;
 use crate::text::TextElem;
 
@@ -38,8 +38,11 @@ use crate::text::TextElem;
 /// # Syntax
 /// This function also has dedicated syntax: Text that starts with `http://` or
 /// `https://` is automatically turned into a link.
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct LinkElem {
+    /// A text describing the link.
+    pub alt: Option<EcoString>,
+
     /// The destination the link points to.
     ///
     /// - To link to web pages, `dest` should be a valid URL string. If the URL
@@ -123,12 +126,13 @@ impl Show for Packed<LinkElem> {
                 body
             }
         } else {
+            let alt = self.alt(styles);
             match &self.dest {
-                LinkTarget::Dest(dest) => body.linked(dest.clone()),
+                LinkTarget::Dest(dest) => body.linked(dest.clone(), alt),
                 LinkTarget::Label(label) => {
                     let elem = engine.introspector.query_label(*label).at(self.span())?;
                     let dest = Destination::Location(elem.location().unwrap());
-                    body.clone().linked(dest)
+                    body.linked(dest, alt)
                 }
             }
         })

crates/typst-library/src/model/list.rs

@@ -7,6 +7,7 @@ use crate::foundations::{
     Smart, StyleChain, Styles, TargetElem, Value,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{BlockElem, Em, Length, VElem};
 use crate::model::{ParElem, ParbreakElem};
 use crate::text::TextElem;
@@ -42,7 +43,7 @@ use crate::text::TextElem;
 /// followed by a space to create a list item. A list item can contain multiple
 /// paragraphs and other block-level content. All content that is indented
 /// more than an item's marker becomes part of that item.
-#[elem(scope, title = "Bullet List", Show)]
+#[elem(scope, title = "Bullet List", Locatable, Show)]
 pub struct ListElem {
     /// Defines the default [spacing]($list.spacing) of the list. If it is
     /// `{false}`, the items are spaced apart with
@@ -178,7 +179,7 @@ impl Show for Packed<ListElem> {
 }
 
 /// A bullet list item.
-#[elem(name = "item", title = "Bullet List Item")]
+#[elem(name = "item", title = "Bullet List Item", Locatable)]
 pub struct ListItem {
     /// The item's body.
     #[required]

crates/typst-library/src/model/outline.rs

@@ -2,6 +2,7 @@ use std::num::NonZeroUsize;
 use std::str::FromStr;
 
 use comemo::{Track, Tracked};
+use ecow::eco_format;
 use smallvec::SmallVec;
 use typst_syntax::Span;
 use typst_utils::{Get, NonZeroExt};
@@ -17,8 +18,8 @@ use crate::introspection::{
     Counter, CounterKey, Introspector, Locatable, Location, Locator, LocatorLink,
 };
 use crate::layout::{
-    Abs, Axes, BlockBody, BlockElem, BoxElem, Dir, Em, Fr, HElem, Length, Region, Rel,
-    RepeatElem, Sides,
+    Abs, Axes, BlockBody, BlockElem, BoxElem, Dir, Em, Fr, HElem, Length, PageElem,
+    Region, Rel, RepeatElem, Sides,
 };
 use crate::math::EquationElem;
 use crate::model::{Destination, HeadingElem, NumberingPattern, ParElem, Refable};
@@ -272,6 +273,7 @@ impl Show for Packed<OutlineElem> {
         let depth = self.depth(styles).unwrap_or(NonZeroUsize::MAX);
 
         // Build the outline entries.
+        let mut entries = vec![];
         for elem in elems {
             let Some(outlinable) = elem.with::<dyn Outlinable>() else {
                 bail!(span, "cannot outline {}", elem.func().name());
@@ -280,10 +282,13 @@ impl Show for Packed<OutlineElem> {
             let level = outlinable.level();
             if outlinable.outlined() && level <= depth {
                 let entry = OutlineEntry::new(level, elem);
-                seq.push(entry.pack().spanned(span));
+                entries.push(entry.pack().spanned(span));
             }
         }
 
+        // Wrap the entries into a marker for pdf tagging.
+        seq.push(OutlineBody::new(Content::sequence(entries)).pack());
+
         Ok(Content::sequence(seq))
     }
 }
@@ -306,6 +311,19 @@ impl LocalName for Packed<OutlineElem> {
     const KEY: &'static str = "outline";
 }
 
+/// Only used to mark
+#[elem(Locatable, Show)]
+pub struct OutlineBody {
+    #[required]
+    body: Content,
+}
+
+impl Show for Packed<OutlineBody> {
+    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        Ok(self.body.clone())
+    }
+}
+
 /// Defines how an outline is indented.
 #[derive(Debug, Clone, PartialEq, Hash)]
 pub enum OutlineIndent {
@@ -364,7 +382,7 @@ pub trait Outlinable: Refable {
 /// With show-set and show rules on outline entries, you can richly customize
 /// the outline's appearance. See the
 /// [section on styling the outline]($outline/#styling-the-outline) for details.
-#[elem(scope, name = "entry", title = "Outline Entry", Show)]
+#[elem(scope, name = "entry", title = "Outline Entry", Locatable, Show)]
 pub struct OutlineEntry {
     /// The nesting level of this outline entry. Starts at `{1}` for top-level
     /// entries.
@@ -417,8 +435,19 @@ impl Show for Packed<OutlineEntry> {
         let context = Context::new(None, Some(styles));
         let context = context.track();
 
+        // TODO: prefix should be wrapped in a `Lbl` structure element
         let prefix = self.prefix(engine, context, span)?;
-        let inner = self.inner(engine, context, span)?;
+        let body = self.body().at(span)?;
+        let page = self.page(engine, context, span)?;
+        let alt = {
+            // TODO: accept user supplied alt text
+            let prefix = prefix.as_ref().map(|p| p.plain_text()).unwrap_or_default();
+            let body = body.plain_text();
+            let page_str = PageElem::local_name_in(styles);
+            let page_nr = page.plain_text();
+            eco_format!("{prefix} \"{body}\", {page_str} {page_nr}")
+        };
+        let inner = self.inner(context, span, body, page)?;
         let block = if self.element.is::<EquationElem>() {
             let body = prefix.unwrap_or_default() + inner;
             BlockElem::new()
@@ -430,7 +459,7 @@ impl Show for Packed<OutlineEntry> {
         };
 
         let loc = self.element_location().at(span)?;
-        Ok(block.linked(Destination::Location(loc)))
+        Ok(block.linked(Destination::Location(loc), Some(alt)))
     }
 }
 
@@ -565,9 +594,10 @@ impl OutlineEntry {
     #[func(contextual)]
     pub fn inner(
         &self,
-        engine: &mut Engine,
         context: Tracked<Context>,
         span: Span,
+        body: Content,
+        page: Content,
     ) -> SourceResult<Content> {
         let styles = context.styles().at(span)?;
 
@@ -588,7 +618,7 @@ impl OutlineEntry {
             seq.push(TextElem::packed("\u{202B}"));
         }
 
-        seq.push(self.body().at(span)?);
+        seq.push(body);
 
         if rtl {
             // "Pop Directional Formatting"
@@ -613,7 +643,7 @@ impl OutlineEntry {
         // Add the page number. The word joiner in front ensures that the page
         // number doesn't stand alone in its line.
         seq.push(TextElem::packed("\u{2060}"));
-        seq.push(self.page(engine, context, span)?);
+        seq.push(page);
 
         Ok(Content::sequence(seq))
     }

crates/typst-library/src/model/par.rs

@@ -93,7 +93,7 @@ use crate::model::Numbering;
 /// let $a$ be the smallest of the
 /// three integers. Then, we ...
 /// ```
-#[elem(scope, title = "Paragraph")]
+#[elem(scope, title = "Paragraph", Locatable)]
 pub struct ParElem {
     /// The spacing between lines.
     ///

crates/typst-library/src/model/reference.rs

@@ -343,7 +343,8 @@ fn show_reference(
         content = supplement + TextElem::packed("\u{a0}") + content;
     }
 
-    Ok(content.linked(Destination::Location(loc)))
+    // TODO: accept user supplied alt text
+    Ok(content.linked(Destination::Location(loc), None))
 }
 
 /// Turn a reference into a citation.

crates/typst-library/src/model/strong.rs

@@ -4,6 +4,7 @@ use crate::foundations::{
     elem, Content, NativeElement, Packed, Show, StyleChain, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::text::{TextElem, WeightDelta};
 
 /// Strongly emphasizes content by increasing the font weight.
@@ -24,7 +25,7 @@ use crate::text::{TextElem, WeightDelta};
 /// simply enclose it in stars/asterisks (`*`). Note that this only works at
 /// word boundaries. To strongly emphasize part of a word, you have to use the
 /// function.
-#[elem(title = "Strong Emphasis", keywords = ["bold", "weight"], Show)]
+#[elem(title = "Strong Emphasis", keywords = ["bold", "weight"], Locatable, Show)]
 pub struct StrongElem {
     /// The delta to apply on the font weight.
     ///

crates/typst-library/src/model/table.rs

@@ -1,6 +1,8 @@
 use std::num::{NonZeroU32, NonZeroUsize};
 use std::sync::Arc;
 
+use ecow::EcoString;
+use typst_macros::Cast;
 use typst_utils::NonZeroExt;
 
 use crate::diag::{bail, HintedStrResult, HintedString, SourceResult};
@@ -10,7 +12,7 @@ use crate::foundations::{
     TargetElem,
 };
 use crate::html::{attr, tag, HtmlAttrs, HtmlElem, HtmlTag};
-use crate::introspection::Locator;
+use crate::introspection::{Locatable, Locator};
 use crate::layout::grid::resolve::{table_to_cellgrid, Cell, CellGrid, Entry};
 use crate::layout::{
     show_grid_cell, Abs, Alignment, BlockElem, Celled, GridCell, GridFooter, GridHLine,
@@ -121,7 +123,7 @@ use crate::visualize::{Paint, Stroke};
 ///   [Robert], b, a, b,
 /// )
 /// ```
-#[elem(scope, Show, LocalName, Figurable)]
+#[elem(scope, Locatable, Show, LocalName, Figurable)]
 pub struct TableElem {
     /// The column sizes. See the [grid documentation]($grid) for more
     /// information on track sizing.
@@ -237,6 +239,9 @@ pub struct TableElem {
     #[default(Celled::Value(Sides::splat(Some(Abs::pt(5.0).into()))))]
     pub inset: Celled<Sides<Option<Rel<Length>>>>,
 
+    // TODO: docs
+    pub summary: Option<EcoString>,
+
     /// The contents of the table cells, plus any extra table lines specified
     /// with the [`table.hline`]($table.hline) and
     /// [`table.vline`]($table.vline) elements.
@@ -357,15 +362,40 @@ fn show_cellgrid_html(grid: CellGrid, styles: StyleChain) -> Content {
 
 impl Show for Packed<TableElem> {
     fn show(&self, engine: &mut Engine, styles: StyleChain) -> SourceResult<Content> {
-        Ok(if TargetElem::target_in(styles).is_html() {
+        let elem = if TargetElem::target_in(styles).is_html() {
             // TODO: This is a hack, it is not clear whether the locator is actually used by HTML.
             // How can we find out whether locator is actually used?
             let locator = Locator::root();
             show_cellgrid_html(table_to_cellgrid(self, engine, locator, styles)?, styles)
         } else {
-            BlockElem::multi_layouter(self.clone(), engine.routines.layout_table).pack()
+            let children = self
+                .children
+                .iter()
+                .map(|c| match c.clone() {
+                    TableChild::Header(header) => {
+                        let mut header = header.unpack();
+                        header.children = header
+                            .children
+                            .into_iter()
+                            .map(|item| match item {
+                                TableItem::Cell(cell) => {
+                                    let mut cell = cell.unpack();
+                                    cell.push_header_scope(Smart::Custom(TableHeaderScope::Column));
+                                    TableItem::Cell(Packed::new(cell))
                                 }
-        .spanned(self.span()))
+                                item => item,
+                            })
+                            .collect();
+                        TableChild::Header(Packed::new(header))
+                    }
+                    child => child,
+                })
+                .collect();
+            let mut table = self.clone().unpack();
+            table.children = children;
+            BlockElem::multi_layouter(Packed::new(table), engine.routines.layout_table).pack()
+        };
+        Ok(elem.spanned(self.span()))
     }
 }
 
@@ -531,7 +561,7 @@ impl TryFrom<Content> for TableItem {
 ///   [7.34], [57],  [2],
 /// )
 /// ```
-#[elem(name = "header", title = "Table Header")]
+#[elem(name = "header", title = "Table Header", Locatable)]
 pub struct TableHeader {
     /// Whether this header should be repeated across pages.
     #[default(true)]
@@ -561,7 +591,7 @@ pub struct TableHeader {
 /// totals, or other information that should be visible on every page.
 ///
 /// No other table cells may be placed after the footer.
-#[elem(name = "footer", title = "Table Footer")]
+#[elem(name = "footer", title = "Table Footer", Locatable)]
 pub struct TableFooter {
     /// Whether this footer should be repeated across pages.
     #[default(true)]
@@ -604,7 +634,7 @@ pub struct TableFooter {
 ///   [19:00], [Day 1 Attendee Mixer],
 /// )
 /// ```
-#[elem(name = "hline", title = "Table Horizontal Line")]
+#[elem(name = "hline", title = "Table Horizontal Line", Locatable)]
 pub struct TableHLine {
     /// The row above which the horizontal line is placed (zero-indexed).
     /// Functions identically to the `y` field in [`grid.hline`]($grid.hline.y).
@@ -649,7 +679,7 @@ pub struct TableHLine {
 /// use the [table's `stroke`]($table.stroke) field or [`table.cell`'s
 /// `stroke`]($table.cell.stroke) field instead if the line you want to place is
 /// part of all your tables' designs.
-#[elem(name = "vline", title = "Table Vertical Line")]
+#[elem(name = "vline", title = "Table Vertical Line", Locatable)]
 pub struct TableVLine {
     /// The column before which the horizontal line is placed (zero-indexed).
     /// Functions identically to the `x` field in [`grid.vline`]($grid.vline).
@@ -770,7 +800,7 @@ pub struct TableVLine {
 ///   [Vikram], [49], [Perseverance],
 /// )
 /// ```
-#[elem(name = "cell", title = "Table Cell", Show)]
+#[elem(name = "cell", title = "Table Cell", Locatable, Show)]
 pub struct TableCell {
     /// The cell's body.
     #[required]
@@ -806,6 +836,9 @@ pub struct TableCell {
     #[fold]
     pub stroke: Sides<Option<Option<Arc<Stroke>>>>,
 
+    // TODO: feature gate
+    pub header_scope: Smart<TableHeaderScope>,
+
     /// Whether rows spanned by this cell can be placed in different pages.
     /// When equal to `{auto}`, a cell spanning only fixed-size rows is
     /// unbreakable, while a cell spanning at least one `{auto}`-sized row is
@@ -843,3 +876,10 @@ impl From<Content> for TableCell {
         value.unpack::<Self>().unwrap_or_else(Self::new)
     }
 }
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Cast)]
+pub enum TableHeaderScope {
+    Both,
+    Column,
+    Row,
+}

crates/typst-library/src/model/terms.rs

@@ -7,6 +7,7 @@ use crate::foundations::{
     Styles, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{Em, HElem, Length, Sides, StackChild, StackElem, VElem};
 use crate::model::{ListItemLike, ListLike, ParElem, ParbreakElem};
 use crate::text::TextElem;
@@ -27,7 +28,7 @@ use crate::text::TextElem;
 /// # Syntax
 /// This function also has dedicated syntax: Starting a line with a slash,
 /// followed by a term, a colon and a description creates a term list item.
-#[elem(scope, title = "Term List", Show)]
+#[elem(scope, title = "Term List", Locatable, Show)]
 pub struct TermsElem {
     /// Defines the default [spacing]($terms.spacing) of the term list. If it is
     /// `{false}`, the items are spaced apart with
@@ -205,7 +206,7 @@ impl Show for Packed<TermsElem> {
 }
 
 /// A term list item.
-#[elem(name = "item", title = "Term List Item")]
+#[elem(name = "item", title = "Term List Item", Locatable)]
 pub struct TermItem {
     /// The term described by the list item.
     #[required]

crates/typst-library/src/pdf/accessibility.rs

@@ -0,0 +1,222 @@
+use ecow::EcoString;
+use typst_macros::{cast, elem, Cast};
+
+use crate::diag::SourceResult;
+use crate::engine::Engine;
+use crate::foundations::{Content, Packed, Show, StyleChain};
+use crate::introspection::Locatable;
+
+// TODO: docs
+#[elem(Locatable, Show)]
+pub struct PdfTagElem {
+    #[default(PdfTagKind::NonStruct)]
+    pub kind: PdfTagKind,
+
+    /// An alternate description.
+    pub alt: Option<EcoString>,
+    /// Exact replacement for this structure element and its children.
+    pub actual_text: Option<EcoString>,
+    /// The expanded form of an abbreviation/acronym.
+    pub expansion: Option<EcoString>,
+
+    /// The content to underline.
+    #[required]
+    pub body: Content,
+}
+
+impl Show for Packed<PdfTagElem> {
+    #[typst_macros::time(name = "pdf.tag", span = self.span())]
+    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        Ok(self.body.clone())
+    }
+}
+
+// TODO: docs
+/// PDF structure elements
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum PdfTagKind {
+    // grouping elements
+    /// (Part)
+    Part,
+    /// (Article)
+    Art,
+    /// (Section)
+    Sect,
+    /// (Division)
+    Div,
+    /// (Block quotation)
+    BlockQuote,
+    /// (Caption)
+    Caption,
+    /// (Table of contents)
+    TOC,
+    /// (Table of contents item)
+    TOCI,
+    /// (Index)
+    Index,
+    /// (Nonstructural element)
+    NonStruct,
+    /// (Private element)
+    Private,
+
+    // paragraph like elements
+    /// (Heading)
+    H { title: Option<EcoString> },
+    /// (Heading level 1)
+    H1 { title: Option<EcoString> },
+    /// (Heading level 2)
+    H2 { title: Option<EcoString> },
+    /// (Heading level 3)
+    H4 { title: Option<EcoString> },
+    /// (Heading level 4)
+    H3 { title: Option<EcoString> },
+    /// (Heading level 5)
+    H5 { title: Option<EcoString> },
+    /// (Heading level 6)
+    H6 { title: Option<EcoString> },
+    /// (Paragraph)
+    P,
+
+    // list elements
+    /// (List)
+    L { numbering: ListNumbering },
+    /// (List item)
+    LI,
+    /// (Label)
+    Lbl,
+    /// (List body)
+    LBody,
+
+    // table elements
+    /// (Table)
+    Table,
+    /// (Table row)
+    TR,
+    /// (Table header)
+    TH { scope: TableHeaderScope },
+    /// (Table data cell)
+    TD,
+    /// (Table header row group)
+    THead,
+    /// (Table body row group)
+    TBody,
+    /// (Table footer row group)
+    TFoot,
+
+    // inline elements
+    /// (Span)
+    Span,
+    /// (Quotation)
+    Quote,
+    /// (Note)
+    Note,
+    /// (Reference)
+    Reference,
+    /// (Bibliography Entry)
+    BibEntry,
+    /// (Code)
+    Code,
+    /// (Link)
+    Link,
+    /// (Annotation)
+    Annot,
+
+    /// (Ruby)
+    Ruby,
+    /// (Ruby base text)
+    RB,
+    /// (Ruby annotation text)
+    RT,
+    /// (Ruby punctuation)
+    RP,
+
+    /// (Warichu)
+    Warichu,
+    /// (Warichu text)
+    WT,
+    /// (Warichu punctuation)
+    WP,
+
+    /// (Figure)
+    Figure,
+    /// (Formula)
+    Formula,
+    /// (Form)
+    Form,
+}
+
+cast! {
+    PdfTagKind,
+    self => match self {
+        PdfTagKind::Part => "part".into_value(),
+        _ => todo!(),
+    },
+    "part" => Self::Part,
+    // TODO
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum ListNumbering {
+    /// No numbering.
+    None,
+    /// Solid circular bullets.
+    Disc,
+    /// Open circular bullets.
+    Circle,
+    /// Solid square bullets.
+    Square,
+    /// Decimal numbers.
+    Decimal,
+    /// Lowercase Roman numerals.
+    LowerRoman,
+    /// Uppercase Roman numerals.
+    UpperRoman,
+    /// Lowercase letters.
+    LowerAlpha,
+    /// Uppercase letters.
+    UpperAlpha,
+}
+
+/// The scope of a table header cell.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum TableHeaderScope {
+    /// The header cell refers to the row.
+    Row,
+    /// The header cell refers to the column.
+    Column,
+    /// The header cell refers to both the row and the column.
+    Both,
+}
+
+/// Mark content as a PDF artifact.
+/// TODO: maybe generalize this and use it to mark html elements with `aria-hidden="true"`?
+#[elem(Locatable, Show)]
+pub struct ArtifactElem {
+    /// The artifact kind.
+    #[default(ArtifactKind::Other)]
+    pub kind: ArtifactKind,
+
+    /// The content that is an artifact.
+    #[required]
+    pub body: Content,
+}
+
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash, Cast)]
+pub enum ArtifactKind {
+    /// Page header artifacts.
+    Header,
+    /// Page footer artifacts.
+    Footer,
+    /// Other page artifacts.
+    Page,
+    /// Other artifacts.
+    #[default]
+    Other,
+}
+
+impl Show for Packed<ArtifactElem> {
+    #[typst_macros::time(name = "pdf.artifact", span = self.span())]
+    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        Ok(self.body.clone())
+    }
+}

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 +13,7 @@ pub fn module() -> Module {
     let mut pdf = Scope::deduplicating();
     pdf.start_category(crate::Category::Pdf);
     pdf.define_elem::<EmbedElem>();
+    pdf.define_elem::<PdfTagElem>();
+    pdf.define_elem::<ArtifactElem>();
     Module::new("pdf", pdf)
 }

crates/typst-library/src/text/deco.rs

@@ -3,6 +3,7 @@ use smallvec::smallvec;
 use crate::diag::SourceResult;
 use crate::engine::Engine;
 use crate::foundations::{elem, Content, Packed, Show, Smart, StyleChain};
+use crate::introspection::Locatable;
 use crate::layout::{Abs, Corners, Length, Rel, Sides};
 use crate::text::{BottomEdge, BottomEdgeMetric, TextElem, TopEdge, TopEdgeMetric};
 use crate::visualize::{Color, FixedStroke, Paint, Stroke};
@@ -13,7 +14,7 @@ use crate::visualize::{Color, FixedStroke, Paint, Stroke};
 /// ```example
 /// This is #underline[important].
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct UnderlineElem {
     /// How to [stroke] the line.
     ///
@@ -99,7 +100,7 @@ impl Show for Packed<UnderlineElem> {
 /// ```example
 /// #overline[A line over text.]
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct OverlineElem {
     /// How to [stroke] the line.
     ///
@@ -191,7 +192,7 @@ impl Show for Packed<OverlineElem> {
 /// ```example
 /// This is #strike[not] relevant.
 /// ```
-#[elem(title = "Strikethrough", Show)]
+#[elem(title = "Strikethrough", Locatable, Show)]
 pub struct StrikeElem {
     /// How to [stroke] the line.
     ///
@@ -268,7 +269,7 @@ impl Show for Packed<StrikeElem> {
 /// ```example
 /// This is #highlight[important].
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct HighlightElem {
     /// The color to highlight the text with.
     ///

crates/typst-library/src/text/raw.rs

@@ -20,6 +20,7 @@ use crate::foundations::{
     PlainText, Show, ShowSet, Smart, StyleChain, Styles, Synthesize, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{BlockBody, BlockElem, Em, HAlignment};
 use crate::loading::{DataSource, Load};
 use crate::model::{Figurable, ParElem};
@@ -78,6 +79,7 @@ use crate::World;
     scope,
     title = "Raw Text / Code",
     Synthesize,
+    Locatable,
     Show,
     ShowSet,
     LocalName,
@@ -636,7 +638,7 @@ fn format_theme_error(error: syntect::LoadingError) -> LoadError {
 /// It allows you to access various properties of the line, such as the line
 /// number, the raw non-highlighted text, the highlighted text, and whether it
 /// is the first or last line of the raw block.
-#[elem(name = "line", title = "Raw Text / Code Line", Show, PlainText)]
+#[elem(name = "line", title = "Raw Text / Code Line", Locatable, Show, PlainText)]
 pub struct RawLine {
     /// The line number of the raw line inside of the raw block, starts at 1.
     #[required]

crates/typst-library/src/text/shift.rs

@@ -6,6 +6,7 @@ use crate::foundations::{
     elem, Content, NativeElement, Packed, SequenceElem, Show, StyleChain, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{Em, Length};
 use crate::text::{variant, SpaceElem, TextElem, TextSize};
 use crate::World;
@@ -18,7 +19,7 @@ use crate::World;
 /// ```example
 /// Revenue#sub[yearly]
 /// ```
-#[elem(title = "Subscript", Show)]
+#[elem(title = "Subscript", Locatable, Show)]
 pub struct SubElem {
     /// Whether to prefer the dedicated subscript characters of the font.
     ///
@@ -84,7 +85,7 @@ impl Show for Packed<SubElem> {
 /// ```example
 /// 1#super[st] try!
 /// ```
-#[elem(title = "Superscript", Show)]
+#[elem(title = "Superscript", Locatable, Show)]
 pub struct SuperElem {
     /// Whether to prefer the dedicated superscript characters of the font.
     ///

crates/typst-library/src/visualize/image/mod.rs

@@ -21,6 +21,7 @@ use crate::foundations::{
     cast, elem, func, scope, Bytes, Cast, Content, Derived, NativeElement, Packed, Show,
     Smart, StyleChain,
 };
+use crate::introspection::Locatable;
 use crate::layout::{BlockElem, Length, Rel, Sizing};
 use crate::loading::{DataSource, Load, LoadSource, Loaded, Readable};
 use crate::model::Figurable;
@@ -44,7 +45,7 @@ use crate::text::LocalName;
 ///   ],
 /// )
 /// ```
-#[elem(scope, Show, LocalName, Figurable)]
+#[elem(scope, Locatable, Show, LocalName, Figurable)]
 pub struct ImageElem {
     /// A [path]($syntax/#paths) to an image file or raw bytes making up an
     /// image in one of the supported [formats]($image.format).

crates/typst-pdf/src/convert.rs

@@ -2,7 +2,6 @@ use std::collections::{BTreeMap, HashMap, HashSet};
 use std::num::NonZeroU64;
 
 use ecow::{eco_format, EcoVec};
-use krilla::annotation::Annotation;
 use krilla::configure::{Configuration, ValidationError, Validator};
 use krilla::destination::{NamedDestination, XyzDestination};
 use krilla::embed::EmbedError;
@@ -14,7 +13,7 @@ use krilla::{Document, SerializeSettings};
 use krilla_svg::render_svg_glyph;
 use typst_library::diag::{bail, error, SourceDiagnostic, SourceResult};
 use typst_library::foundations::{NativeElement, Repr};
-use typst_library::introspection::Location;
+use typst_library::introspection::{Location, Tag};
 use typst_library::layout::{
     Abs, Frame, FrameItem, GroupItem, PagedDocument, Size, Transform,
 };
@@ -25,11 +24,12 @@ use typst_syntax::Span;
 
 use crate::embed::embed_files;
 use crate::image::handle_image;
-use crate::link::handle_link;
+use crate::link::{handle_link, LinkAnnotation};
 use crate::metadata::build_metadata;
 use crate::outline::build_outline;
 use crate::page::PageLabelExt;
 use crate::shape::handle_shape;
+use crate::tags::{self, Tags};
 use crate::text::handle_text;
 use crate::util::{convert_path, display_font, AbsExt, TransformExt};
 use crate::PdfOptions;
@@ -46,7 +46,7 @@ pub fn convert(
         xmp_metadata: true,
         cmyk_profile: None,
         configuration: options.standards.config,
-        enable_tagging: false,
+        enable_tagging: !options.disable_tags,
         render_svg_glyph_fn: render_svg_glyph,
     };
 
@@ -54,6 +54,7 @@ pub fn convert(
     let page_index_converter = PageIndexConverter::new(typst_document, options);
     let named_destinations =
         collect_named_destinations(typst_document, &page_index_converter);
+
     let mut gc = GlobalContext::new(
         typst_document,
         options,
@@ -66,6 +67,7 @@ pub fn convert(
 
     document.set_outline(build_outline(&gc));
     document.set_metadata(build_metadata(&gc));
+    document.set_tag_tree(gc.tags.build_tree());
 
     finish(document, gc, options.standards.config)
 }
@@ -115,9 +117,7 @@ fn convert_pages(gc: &mut GlobalContext, document: &mut Document) -> SourceResul
 
             surface.finish();
 
-            for annotation in fc.annotations {
-                page.add_annotation(annotation);
-            }
+            tags::add_annotations(gc, &mut page, fc.link_annotations);
         }
     }
 
@@ -171,14 +171,14 @@ impl State {
 /// Context needed for converting a single frame.
 pub(crate) struct FrameContext {
     states: Vec<State>,
-    annotations: Vec<Annotation>,
+    link_annotations: Vec<LinkAnnotation>,
 }
 
 impl FrameContext {
     pub(crate) fn new(size: Size) -> Self {
         Self {
             states: vec![State::new(size)],
-            annotations: vec![],
+            link_annotations: Vec::new(),
         }
     }
 
@@ -198,8 +198,18 @@ impl FrameContext {
         self.states.last_mut().unwrap()
     }
 
-    pub(crate) fn push_annotation(&mut self, annotation: Annotation) {
-        self.annotations.push(annotation);
+    pub(crate) fn get_link_annotation(
+        &mut self,
+        link_id: tags::LinkId,
+    ) -> Option<&mut LinkAnnotation> {
+        self.link_annotations
+            .iter_mut()
+            .rev()
+            .find(|annot| annot.id == link_id)
+    }
+
+    pub(crate) fn push_link_annotation(&mut self, annotation: LinkAnnotation) {
+        self.link_annotations.push(annotation);
     }
 }
 
@@ -225,6 +235,8 @@ pub(crate) struct GlobalContext<'a> {
     /// The languages used throughout the document.
     pub(crate) languages: BTreeMap<Lang, usize>,
     pub(crate) page_index_converter: PageIndexConverter,
+    /// Tagged PDF context.
+    pub(crate) tags: Tags,
 }
 
 impl<'a> GlobalContext<'a> {
@@ -244,6 +256,8 @@ impl<'a> GlobalContext<'a> {
             image_spans: HashSet::new(),
             languages: BTreeMap::new(),
             page_index_converter,
+
+            tags: Tags::new(),
         }
     }
 }
@@ -278,8 +292,9 @@ pub(crate) fn handle_frame(
             FrameItem::Image(image, size, span) => {
                 handle_image(gc, fc, image, *size, surface, *span)?
             }
-            FrameItem::Link(d, s) => handle_link(fc, gc, d, *s),
-            FrameItem::Tag(_) => {}
+            FrameItem::Link(dest, size) => handle_link(fc, gc, dest, *size),
+            FrameItem::Tag(Tag::Start(elem)) => tags::handle_start(gc, elem),
+            FrameItem::Tag(Tag::End(loc, _)) => tags::handle_end(gc, *loc),
         }
 
         fc.pop();
@@ -294,7 +309,7 @@ pub(crate) fn handle_group(
     fc: &mut FrameContext,
     group: &GroupItem,
     surface: &mut Surface,
-    context: &mut GlobalContext,
+    gc: &mut GlobalContext,
 ) -> SourceResult<()> {
     fc.push();
     fc.state_mut().pre_concat(group.transform);
@@ -310,10 +325,12 @@ pub(crate) fn handle_group(
         .and_then(|p| p.transform(fc.state().transform.to_krilla()));
 
     if let Some(clip_path) = &clip_path {
+        let mut handle = tags::start_marked(gc, surface);
+        let surface = handle.surface();
         surface.push_clip_path(clip_path, &krilla::paint::FillRule::NonZero);
     }
 
-    handle_frame(fc, &group.frame, None, surface, context)?;
+    handle_frame(fc, &group.frame, None, surface, gc)?;
 
     if clip_path.is_some() {
         surface.pop();
@@ -576,6 +593,16 @@ fn convert_error(
             "{prefix} missing document date";
             hint: "set the date of the document"
         ),
+        ValidationError::DuplicateTagId(_id, loc) => {
+            // TODO: display the id and better error message
+            let span = to_span(*loc);
+            error!(span, "{prefix} duplicate tag id")
+        }
+        ValidationError::UnknownHeaderTagId(_id, loc) => {
+            // TODO: display the id and better error message
+            let span = to_span(*loc);
+            error!(span, "{prefix} unknown header tag id")
+        }
     }
 }
 

crates/typst-pdf/src/image.rs

@@ -4,6 +4,7 @@ use std::sync::{Arc, OnceLock};
 use image::{DynamicImage, EncodableLayout, GenericImageView, Rgba};
 use krilla::image::{BitsPerComponent, CustomImage, ImageColorspace};
 use krilla::surface::Surface;
+use krilla::tagging::SpanTag;
 use krilla_svg::{SurfaceExt, SvgSettings};
 use typst_library::diag::{bail, SourceResult};
 use typst_library::foundations::Smart;
@@ -14,6 +15,7 @@ use typst_library::visualize::{
 use typst_syntax::Span;
 
 use crate::convert::{FrameContext, GlobalContext};
+use crate::tags;
 use crate::util::{SizeExt, TransformExt};
 
 #[typst_macros::time(name = "handle image")]
@@ -30,12 +32,11 @@ pub(crate) fn handle_image(
 
     let interpolate = image.scaling() == Smart::Custom(ImageScaling::Smooth);
 
-    if let Some(alt) = image.alt() {
-        surface.start_alt_text(alt);
-    }
-
     gc.image_spans.insert(span);
 
+    let mut handle =
+        tags::start_span(gc, surface, SpanTag::empty().with_alt_text(image.alt()));
+    let surface = handle.surface();
     match image.kind() {
         ImageKind::Raster(raster) => {
             let (exif_transform, new_size) = exif_transform(raster, size);
@@ -62,10 +63,6 @@ pub(crate) fn handle_image(
         }
     }
 
-    if image.alt().is_some() {
-        surface.end_alt_text();
-    }
-
     surface.pop();
     surface.reset_location();
 

crates/typst-pdf/src/lib.rs

@@ -9,6 +9,7 @@ mod outline;
 mod page;
 mod paint;
 mod shape;
+mod tags;
 mod text;
 mod util;
 
@@ -53,6 +54,11 @@ pub struct PdfOptions<'a> {
     pub page_ranges: Option<PageRanges>,
     /// A list of PDF standards that Typst will enforce conformance with.
     pub standards: PdfStandards,
+    /// By default, even when not producing a `PDF/UA-1` document, a tagged PDF
+    /// document is written to provide a baseline of accessibility. In some
+    /// circumstances, for example when trying to reduce the size of a document,
+    /// it can be desirable to disable tagged PDF.
+    pub disable_tags: bool,
 }
 
 /// Encapsulates a list of compatible PDF standards.
@@ -104,6 +110,7 @@ impl PdfStandards {
                 PdfStandard::A_4 => set_validator(Validator::A4)?,
                 PdfStandard::A_4f => set_validator(Validator::A4F)?,
                 PdfStandard::A_4e => set_validator(Validator::A4E)?,
+                PdfStandard::Ua_1 => set_validator(Validator::UA1)?,
             }
         }
 
@@ -187,4 +194,7 @@ pub enum PdfStandard {
     /// PDF/A-4e.
     #[serde(rename = "a-4e")]
     A_4e,
+    /// PDF/UA-1.
+    #[serde(rename = "ua-1")]
+    Ua_1,
 }

crates/typst-pdf/src/link.rs

@@ -1,19 +1,90 @@
+use ecow::EcoString;
 use krilla::action::{Action, LinkAction};
-use krilla::annotation::{LinkAnnotation, Target};
+use krilla::annotation::Target;
+use krilla::configure::Validator;
 use krilla::destination::XyzDestination;
-use krilla::geom::Rect;
-use typst_library::layout::{Abs, Point, Size};
+use krilla::geom as kg;
+use typst_library::layout::{Abs, Point, Position, Size};
 use typst_library::model::Destination;
 
 use crate::convert::{FrameContext, GlobalContext};
+use crate::tags::{self, Placeholder, StackEntryKind, TagNode};
 use crate::util::{AbsExt, PointExt};
 
+pub(crate) struct LinkAnnotation {
+    pub(crate) id: tags::LinkId,
+    pub(crate) placeholder: Placeholder,
+    pub(crate) alt: Option<String>,
+    pub(crate) rect: kg::Rect,
+    pub(crate) quad_points: Vec<kg::Point>,
+    pub(crate) target: Target,
+}
+
 pub(crate) fn handle_link(
     fc: &mut FrameContext,
     gc: &mut GlobalContext,
     dest: &Destination,
     size: Size,
 ) {
+    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 entry = gc.tags.stack.last_mut().expect("a link parent");
+    let StackEntryKind::Link(link_id, ref link) = entry.kind else {
+        unreachable!("expected a link parent")
+    };
+    let alt = link.alt.as_ref().map(EcoString::to_string);
+
+    let rect = to_rect(fc, size);
+    let quadpoints = quadpoints(rect);
+
+    // Unfortunately quadpoints still aren't well supported by most PDF readers,
+    // even by acrobat. Which is understandable since they were only introduced
+    // in PDF 1.6 (2005) /s
+    let should_use_quadpoints = gc.options.standards.config.validator() == Validator::UA1;
+    match fc.get_link_annotation(link_id) {
+        Some(annotation) if should_use_quadpoints => {
+            // Update the bounding box and add the quadpoints to an existing link annotation.
+            annotation.rect = bounding_rect(annotation.rect, rect);
+            annotation.quad_points.extend_from_slice(&quadpoints);
+        }
+        _ => {
+            let placeholder = gc.tags.reserve_placeholder();
+            gc.tags.push(TagNode::Placeholder(placeholder));
+            fc.push_link_annotation(LinkAnnotation {
+                id: link_id,
+                placeholder,
+                rect,
+                quad_points: quadpoints.to_vec(),
+                alt,
+                target,
+            });
+        }
+    }
+}
+
+// Compute the bounding box of the transformed link.
+fn to_rect(fc: &FrameContext, size: Size) -> kg::Rect {
     let mut min_x = Abs::inf();
     let mut min_y = Abs::inf();
     let mut max_x = -Abs::inf();
@@ -21,7 +92,6 @@ pub(crate) fn handle_link(
 
     let pos = Point::zero();
 
-    // Compute the bounding box of the transformed link.
     for point in [
         pos,
         pos + Point::with_x(size.x),
@@ -40,55 +110,32 @@ pub(crate) fn handle_link(
     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 pos = match dest {
-        Destination::Url(u) => {
-            fc.push_annotation(
-                LinkAnnotation::new(
-                    rect,
-                    None,
-                    Target::Action(Action::Link(LinkAction::new(u.to_string()))),
-                )
-                .into(),
-            );
-            return;
-        }
-        Destination::Position(p) => *p,
-        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.
-                fc.push_annotation(
-                    LinkAnnotation::new(
-                        rect,
-                        None,
-                        Target::Destination(krilla::destination::Destination::Named(
-                            nd.clone(),
-                        )),
-                    )
-                    .into(),
-                );
-                return;
-            } else {
-                gc.document.introspector.position(*loc)
-            }
-        }
-    };
-
-    let page_index = pos.page.get() - 1;
-    if let Some(index) = gc.page_index_converter.pdf_page_index(page_index) {
-        fc.push_annotation(
-            LinkAnnotation::new(
-                rect,
-                None,
-                Target::Destination(krilla::destination::Destination::Xyz(
-                    XyzDestination::new(index, pos.point.to_krilla()),
-                )),
-            )
-            .into(),
-        );
-    }
+    kg::Rect::from_ltrb(x1, y1, x2, y2).unwrap()
+}
+
+fn bounding_rect(a: kg::Rect, b: kg::Rect) -> kg::Rect {
+    kg::Rect::from_ltrb(
+        a.left().min(b.left()),
+        a.top().min(b.top()),
+        a.right().max(b.right()),
+        a.bottom().max(b.bottom()),
+    )
+    .unwrap()
+}
+
+fn quadpoints(rect: kg::Rect) -> [kg::Point; 4] {
+    [
+        kg::Point::from_xy(rect.left(), rect.bottom()),
+        kg::Point::from_xy(rect.right(), rect.bottom()),
+        kg::Point::from_xy(rect.right(), rect.top()),
+        kg::Point::from_xy(rect.left(), rect.top()),
+    ]
+}
+
+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)))
 }

crates/typst-pdf/src/shape.rs

@@ -5,8 +5,8 @@ use typst_library::visualize::{Geometry, Shape};
 use typst_syntax::Span;
 
 use crate::convert::{FrameContext, GlobalContext};
-use crate::paint;
 use crate::util::{convert_path, AbsExt, TransformExt};
+use crate::{paint, tags};
 
 #[typst_macros::time(name = "handle shape")]
 pub(crate) fn handle_shape(
@@ -16,6 +16,9 @@ pub(crate) fn handle_shape(
     gc: &mut GlobalContext,
     span: Span,
 ) -> SourceResult<()> {
+    let mut handle = tags::start_marked(gc, surface);
+    let surface = handle.surface();
+
     surface.set_location(span.into_raw().get());
     surface.push_transform(&fc.state().transform().to_krilla());
 

crates/typst-pdf/src/tags.rs

@@ -0,0 +1,533 @@
+use std::cell::OnceCell;
+
+use ecow::EcoString;
+use krilla::page::Page;
+use krilla::surface::Surface;
+use krilla::tagging::{
+    ArtifactType, ContentTag, Identifier, Node, SpanTag, TableCellSpan, TableDataCell,
+    TableHeaderCell, Tag, TagBuilder, TagGroup, TagKind, TagTree,
+};
+use typst_library::foundations::{Content, LinkMarker, Packed, StyleChain, Smart};
+use typst_library::introspection::Location;
+use typst_library::layout::RepeatElem;
+use typst_library::model::{
+    Destination, FigureCaption, FigureElem, HeadingElem, Outlinable, OutlineBody,
+    OutlineEntry, TableCell, TableElem, TableHeaderScope,
+};
+use typst_library::pdf::{ArtifactElem, ArtifactKind, PdfTagElem, PdfTagKind};
+use typst_library::visualize::ImageElem;
+
+use crate::convert::GlobalContext;
+use crate::link::LinkAnnotation;
+
+pub(crate) struct Tags {
+    /// The intermediary stack of nested tag groups.
+    pub(crate) stack: Vec<StackEntry>,
+    /// A list of placeholders corresponding to a [`TagNode::Placeholder`].
+    pub(crate) placeholders: Vec<OnceCell<Node>>,
+    pub(crate) in_artifact: Option<(Location, ArtifactKind)>,
+    pub(crate) link_id: LinkId,
+
+    /// The output.
+    pub(crate) tree: Vec<TagNode>,
+}
+
+pub(crate) struct StackEntry {
+    pub(crate) loc: Location,
+    pub(crate) kind: StackEntryKind,
+    pub(crate) nodes: Vec<TagNode>,
+}
+
+pub(crate) enum StackEntryKind {
+    Standard(Tag),
+    Outline(OutlineCtx),
+    OutlineEntry(Packed<OutlineEntry>),
+    Table(TableCtx),
+    TableCell(Packed<TableCell>),
+    Link(LinkId, Packed<LinkMarker>),
+}
+
+impl StackEntryKind {
+    pub(crate) fn as_standard_mut(&mut self) -> Option<&mut Tag> {
+        if let Self::Standard(v) = self {
+            Some(v)
+        } else {
+            None
+        }
+    }
+}
+
+pub(crate) struct OutlineCtx {
+    stack: Vec<OutlineSection>,
+}
+
+pub(crate) struct OutlineSection {
+    entries: Vec<TagNode>,
+}
+
+impl OutlineSection {
+    const fn new() -> Self {
+        OutlineSection { entries: Vec::new() }
+    }
+
+    fn push(&mut self, entry: TagNode) {
+        self.entries.push(entry);
+    }
+
+    fn into_tag(self) -> TagNode {
+        TagNode::Group(TagKind::TOC.into(), self.entries)
+    }
+}
+
+impl OutlineCtx {
+    fn new() -> Self {
+        Self { stack: Vec::new() }
+    }
+
+    fn insert(
+        &mut self,
+        outline_nodes: &mut Vec<TagNode>,
+        entry: Packed<OutlineEntry>,
+        nodes: Vec<TagNode>,
+    ) {
+        let expected_len = entry.level.get() - 1;
+        if self.stack.len() < expected_len {
+            self.stack.resize_with(expected_len, || OutlineSection::new());
+        } else {
+            while self.stack.len() > expected_len {
+                self.finish_section(outline_nodes);
+            }
+        }
+
+        let section_entry = TagNode::Group(TagKind::TOCI.into(), nodes);
+        self.push(outline_nodes, section_entry);
+    }
+
+    fn finish_section(&mut self, outline_nodes: &mut Vec<TagNode>) {
+        let sub_section = self.stack.pop().unwrap().into_tag();
+        self.push(outline_nodes, sub_section);
+    }
+
+    fn push(&mut self, outline_nodes: &mut Vec<TagNode>, entry: TagNode) {
+        match self.stack.last_mut() {
+            Some(section) => section.push(entry),
+            None => outline_nodes.push(entry),
+        }
+    }
+
+    fn build_outline(mut self, mut outline_nodes: Vec<TagNode>) -> Vec<TagNode> {
+        while self.stack.len() > 0 {
+            self.finish_section(&mut outline_nodes);
+        }
+        outline_nodes
+    }
+}
+
+pub(crate) struct TableCtx {
+    table: Packed<TableElem>,
+    rows: Vec<Vec<Option<(Packed<TableCell>, Tag, Vec<TagNode>)>>>,
+}
+
+impl TableCtx {
+    fn new(table: Packed<TableElem>) -> Self {
+        Self { table: table.clone(), rows: Vec::new() }
+    }
+
+    fn insert(&mut self, cell: Packed<TableCell>, nodes: Vec<TagNode>) {
+        let x = cell.x(StyleChain::default()).unwrap_or_else(|| unreachable!());
+        let y = cell.y(StyleChain::default()).unwrap_or_else(|| unreachable!());
+        let rowspan = cell.rowspan(StyleChain::default()).get();
+        let colspan = cell.colspan(StyleChain::default()).get();
+
+        // TODO: possibly set internal field on TableCell when resolving
+        // the cell grid.
+        let header_scope = cell.header_scope(StyleChain::default());
+        let span = TableCellSpan { rows: rowspan as i32, cols: colspan as i32 };
+        let tag = if let Smart::Custom(scope) = header_scope {
+            let scope = match scope {
+                TableHeaderScope::Both => krilla::tagging::TableHeaderScope::Both,
+                TableHeaderScope::Column => krilla::tagging::TableHeaderScope::Column,
+                TableHeaderScope::Row => krilla::tagging::TableHeaderScope::Row,
+            };
+            TagKind::TH(TableHeaderCell::new(scope).with_span(span))
+        } else {
+            TagKind::TD(TableDataCell::new().with_span(span))
+        };
+
+        let required_height = y + rowspan;
+        if self.rows.len() < required_height {
+            self.rows.resize_with(required_height, Vec::new);
+        }
+
+        let required_width = x + colspan;
+        let row = &mut self.rows[y];
+        if row.len() < required_width {
+            row.resize_with(required_width, || None);
+        }
+
+        row[x] = Some((cell, tag.into(), nodes));
+    }
+
+    fn build_table(self, mut nodes: Vec<TagNode>) -> Vec<TagNode> {
+        // Table layouting ensures that there are no overlapping cells, and that
+        // any gaps left by the user are filled with empty cells.
+        let mut row_chunk = Vec::new();
+        let mut is_header_chunk = false;
+        for row in self.rows.into_iter() {
+            let mut is_header_row = true;
+            let row_nodes = row
+                .into_iter()
+                .flatten()
+                .map(|(cell, tag, nodes)| {
+                    is_header_row &= cell.header_scope(StyleChain::default()).is_custom();
+                    TagNode::Group(tag, nodes)
+                })
+                .collect();
+
+            let row = TagNode::Group(TagKind::TR.into(), row_nodes);
+            if row_chunk.is_empty() {
+                is_header_chunk = is_header_row;
+                row_chunk.push(row);
+            } else if is_header_chunk == is_header_row {
+                row_chunk.push(row);
+            } else {
+                let tag = if is_header_chunk { TagKind::THead } else { TagKind::TBody };
+                nodes.push(TagNode::Group(tag.into(), std::mem::take(&mut row_chunk)));
+
+                is_header_chunk = is_header_row;
+                row_chunk.push(row);
+            }
+        }
+
+        if !row_chunk.is_empty() {
+            let tag = if is_header_chunk { TagKind::THead } else { TagKind::TBody };
+            nodes.push(TagNode::Group(tag.into(), row_chunk));
+        }
+
+        nodes
+    }
+}
+
+pub(crate) enum TagNode {
+    Group(Tag, Vec<TagNode>),
+    Leaf(Identifier),
+    /// Allows inserting a placeholder into the tag tree.
+    /// Currently used for [`krilla::page::Page::add_tagged_annotation`].
+    Placeholder(Placeholder),
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+pub(crate) struct LinkId(u32);
+
+#[derive(Clone, Copy)]
+pub(crate) struct Placeholder(usize);
+
+impl Tags {
+    pub(crate) fn new() -> Self {
+        Self {
+            stack: Vec::new(),
+            placeholders: Vec::new(),
+            in_artifact: None,
+
+            tree: Vec::new(),
+            link_id: LinkId(0),
+        }
+    }
+
+    pub(crate) fn reserve_placeholder(&mut self) -> Placeholder {
+        let idx = self.placeholders.len();
+        self.placeholders.push(OnceCell::new());
+        Placeholder(idx)
+    }
+
+    pub(crate) fn init_placeholder(&mut self, placeholder: Placeholder, node: Node) {
+        self.placeholders[placeholder.0]
+            .set(node)
+            .map_err(|_| ())
+            .expect("placeholder to be uninitialized");
+    }
+
+    pub(crate) fn take_placeholder(&mut self, placeholder: Placeholder) -> Node {
+        self.placeholders[placeholder.0]
+            .take()
+            .expect("initialized placeholder node")
+    }
+
+    /// Returns the current parent's list of children and the structure type ([Tag]).
+    /// In case of the document root the structure type will be `None`.
+    pub(crate) fn parent(&mut self) -> Option<&mut StackEntryKind> {
+        self.stack.last_mut().map(|e| &mut e.kind)
+    }
+
+    pub(crate) fn push(&mut self, node: TagNode) {
+        if let Some(entry) = self.stack.last_mut() {
+            entry.nodes.push(node);
+        } else {
+            self.tree.push(node);
+        }
+    }
+
+    pub(crate) fn build_tree(&mut self) -> TagTree {
+        let children = std::mem::take(&mut self.tree)
+            .into_iter()
+            .map(|node| self.resolve_node(node))
+            .collect::<Vec<_>>();
+        TagTree::from(children)
+    }
+
+    /// Resolves [`Placeholder`] nodes.
+    fn resolve_node(&mut self, node: TagNode) -> Node {
+        match node {
+            TagNode::Group(tag, nodes) => {
+                let children = nodes
+                    .into_iter()
+                    .map(|node| self.resolve_node(node))
+                    .collect::<Vec<_>>();
+                Node::Group(TagGroup::with_children(tag, children))
+            }
+            TagNode::Leaf(identifier) => Node::Leaf(identifier),
+            TagNode::Placeholder(placeholder) => self.take_placeholder(placeholder),
+        }
+    }
+
+    fn context_supports(&self, _tag: &StackEntryKind) -> bool {
+        // TODO: generate using: https://pdfa.org/resource/iso-ts-32005-hierarchical-inclusion-rules/
+        true
+    }
+
+    fn next_link_id(&mut self) -> LinkId {
+        self.link_id.0 += 1;
+        self.link_id
+    }
+}
+
+/// Automatically calls [`Surface::end_tagged`] when dropped.
+pub(crate) struct TagHandle<'a, 'b> {
+    surface: &'b mut Surface<'a>,
+}
+
+impl Drop for TagHandle<'_, '_> {
+    fn drop(&mut self) {
+        self.surface.end_tagged();
+    }
+}
+
+impl<'a> TagHandle<'a, '_> {
+    pub(crate) fn surface<'c>(&'c mut self) -> &'c mut Surface<'a> {
+        &mut self.surface
+    }
+}
+
+/// Returns a [`TagHandle`] that automatically calls [`Surface::end_tagged`]
+/// when dropped.
+pub(crate) fn start_marked<'a, 'b>(
+    gc: &mut GlobalContext,
+    surface: &'b mut Surface<'a>,
+) -> TagHandle<'a, 'b> {
+    start_content(gc, surface, ContentTag::Other)
+}
+
+/// Returns a [`TagHandle`] that automatically calls [`Surface::end_tagged`]
+/// when dropped.
+pub(crate) fn start_span<'a, 'b>(
+    gc: &mut GlobalContext,
+    surface: &'b mut Surface<'a>,
+    span: SpanTag,
+) -> TagHandle<'a, 'b> {
+    start_content(gc, surface, ContentTag::Span(span))
+}
+
+fn start_content<'a, 'b>(
+    gc: &mut GlobalContext,
+    surface: &'b mut Surface<'a>,
+    content: ContentTag,
+) -> TagHandle<'a, 'b> {
+    let content = if let Some((_, kind)) = gc.tags.in_artifact {
+        let ty = artifact_type(kind);
+        ContentTag::Artifact(ty)
+    } else if let Some(StackEntryKind::Table(_)) = gc.tags.stack.last().map(|e| &e.kind) {
+        // Mark any direct child of a table as an aritfact. Any real content
+        // will be wrapped inside a `TableCell`.
+        ContentTag::Artifact(ArtifactType::Other)
+    } else {
+        content
+    };
+    let id = surface.start_tagged(content);
+    gc.tags.push(TagNode::Leaf(id));
+    TagHandle { surface }
+}
+
+/// Add all annotations that were found in the page frame.
+pub(crate) fn add_annotations(
+    gc: &mut GlobalContext,
+    page: &mut Page,
+    annotations: Vec<LinkAnnotation>,
+) {
+    for annotation in annotations.into_iter() {
+        let LinkAnnotation { id: _, placeholder, alt, rect, quad_points, target } =
+            annotation;
+        let annot = krilla::annotation::Annotation::new_link(
+            krilla::annotation::LinkAnnotation::new(rect, Some(quad_points), target),
+            alt,
+        );
+        let annot_id = page.add_tagged_annotation(annot);
+        gc.tags.init_placeholder(placeholder, Node::Leaf(annot_id));
+    }
+}
+
+pub(crate) fn handle_start(gc: &mut GlobalContext, elem: &Content) {
+    if gc.tags.in_artifact.is_some() {
+        // Don't nest artifacts
+        return;
+    }
+
+    let loc = elem.location().unwrap();
+
+    if let Some(artifact) = elem.to_packed::<ArtifactElem>() {
+        let kind = artifact.kind(StyleChain::default());
+        start_artifact(gc, loc, kind);
+        return;
+    } else if let Some(_) = elem.to_packed::<RepeatElem>() {
+        start_artifact(gc, loc, ArtifactKind::Other);
+        return;
+    }
+
+    let tag: Tag = if let Some(pdf_tag) = elem.to_packed::<PdfTagElem>() {
+        let kind = pdf_tag.kind(StyleChain::default());
+        match kind {
+            PdfTagKind::Part => TagKind::Part.into(),
+            _ => todo!(),
+        }
+    } else if let Some(heading) = elem.to_packed::<HeadingElem>() {
+        let level = heading.level();
+        let name = heading.body.plain_text().to_string();
+        match level.get() {
+            1 => TagKind::H1(Some(name)).into(),
+            2 => TagKind::H2(Some(name)).into(),
+            3 => TagKind::H3(Some(name)).into(),
+            4 => TagKind::H4(Some(name)).into(),
+            5 => TagKind::H5(Some(name)).into(),
+            // TODO: when targeting PDF 2.0 headings `> 6` are supported
+            _ => TagKind::H6(Some(name)).into(),
+        }
+    } else if let Some(_) = elem.to_packed::<OutlineBody>() {
+        push_stack(gc, loc, StackEntryKind::Outline(OutlineCtx::new()));
+        return;
+    } else if let Some(entry) = elem.to_packed::<OutlineEntry>() {
+        push_stack(gc, loc, StackEntryKind::OutlineEntry(entry.clone()));
+        return;
+    } else if let Some(_) = elem.to_packed::<FigureElem>() {
+        let alt = None; // TODO
+        TagKind::Figure.with_alt_text(alt)
+    } else if let Some(image) = elem.to_packed::<ImageElem>() {
+        let alt = image.alt(StyleChain::default()).map(|s| s.to_string());
+
+        let figure_tag = (gc.tags.parent())
+            .and_then(StackEntryKind::as_standard_mut)
+            .filter(|tag| tag.kind == TagKind::Figure);
+        if let Some(figure_tag) = figure_tag {
+            // Set alt text of outer figure tag, if not present.
+            if figure_tag.alt_text.is_none() {
+                figure_tag.alt_text = alt;
+            }
+            return;
+        } else {
+            TagKind::Figure.with_alt_text(alt)
+        }
+    } else if let Some(_) = elem.to_packed::<FigureCaption>() {
+        TagKind::Caption.into()
+    } else if let Some(table) = elem.to_packed::<TableElem>() {
+        push_stack(gc, loc, StackEntryKind::Table(TableCtx::new(table.clone())));
+        return;
+    } else if let Some(cell) = elem.to_packed::<TableCell>() {
+        push_stack(gc, loc, StackEntryKind::TableCell(cell.clone()));
+        return;
+    } else if let Some(link) = elem.to_packed::<LinkMarker>() {
+        let link_id = gc.tags.next_link_id();
+        push_stack(gc, loc, StackEntryKind::Link(link_id, link.clone()));
+        return;
+    } else {
+        return;
+    };
+
+    push_stack(gc, loc, StackEntryKind::Standard(tag));
+}
+
+fn push_stack(gc: &mut GlobalContext, loc: Location, kind: StackEntryKind) {
+    if !gc.tags.context_supports(&kind) {
+        // TODO: error or warning?
+    }
+
+    gc.tags.stack.push(StackEntry { loc, kind, nodes: Vec::new() });
+}
+
+pub(crate) fn handle_end(gc: &mut GlobalContext, loc: Location) {
+    if let Some((l, _)) = gc.tags.in_artifact {
+        if l == loc {
+            gc.tags.in_artifact = None;
+        }
+        return;
+    }
+
+    let Some(entry) = gc.tags.stack.pop_if(|e| e.loc == loc) else {
+        return;
+    };
+
+    let node = match entry.kind {
+        StackEntryKind::Standard(tag) => TagNode::Group(tag, entry.nodes),
+        StackEntryKind::Outline(ctx) => {
+            let nodes = ctx.build_outline(entry.nodes);
+            TagNode::Group(TagKind::TOC.into(), nodes)
+        }
+        StackEntryKind::OutlineEntry(outline_entry) => {
+            let parent = gc.tags.stack.last_mut().expect("outline");
+            let StackEntryKind::Outline(outline_ctx) = &mut parent.kind else {
+                unreachable!("expected outline")
+            };
+
+            outline_ctx.insert(&mut parent.nodes, outline_entry, entry.nodes);
+
+            return;
+        }
+        StackEntryKind::Table(ctx) => {
+            let summary = ctx.table.summary(StyleChain::default()).map(EcoString::into);
+            let nodes = ctx.build_table(entry.nodes);
+            TagNode::Group(TagKind::Table(summary).into(), nodes)
+        }
+        StackEntryKind::TableCell(cell) => {
+            let parent = gc.tags.stack.last_mut().expect("table");
+            let StackEntryKind::Table(table_ctx) = &mut parent.kind else {
+                unreachable!("expected table")
+            };
+
+            table_ctx.insert(cell, entry.nodes);
+
+            return;
+        }
+        StackEntryKind::Link(_, link) => {
+            let alt = link.alt.as_ref().map(EcoString::to_string);
+            let tag = TagKind::Link.with_alt_text(alt);
+            let mut node = TagNode::Group(tag, entry.nodes);
+            // Wrap link in reference tag, if it's not a url.
+            if let Destination::Position(_) | Destination::Location(_) = link.dest {
+                node = TagNode::Group(TagKind::Reference.into(), vec![node]);
+            }
+            node
+        }
+    };
+
+    gc.tags.push(node);
+}
+
+fn start_artifact(gc: &mut GlobalContext, loc: Location, kind: ArtifactKind) {
+    gc.tags.in_artifact = Some((loc, kind));
+}
+
+fn artifact_type(kind: ArtifactKind) -> ArtifactType {
+    match kind {
+        ArtifactKind::Header => ArtifactType::Header,
+        ArtifactKind::Footer => ArtifactType::Footer,
+        ArtifactKind::Page => ArtifactType::Page,
+        ArtifactKind::Other => ArtifactType::Other,
+    }
+}

crates/typst-pdf/src/text.rs

@@ -11,8 +11,8 @@ use typst_library::visualize::FillRule;
 use typst_syntax::Span;
 
 use crate::convert::{FrameContext, GlobalContext};
-use crate::paint;
 use crate::util::{display_font, AbsExt, TransformExt};
+use crate::{paint, tags};
 
 #[typst_macros::time(name = "handle text")]
 pub(crate) fn handle_text(
@@ -23,6 +23,9 @@ pub(crate) fn handle_text(
 ) -> SourceResult<()> {
     *gc.languages.entry(t.lang).or_insert(0) += t.glyphs.len();
 
+    let mut handle = tags::start_marked(gc, surface);
+    let surface = handle.surface();
+
     let font = convert_font(gc, t.font.clone())?;
     let fill = paint::convert_fill(
         gc,

crates/typst-render/src/lib.rs

@@ -167,7 +167,7 @@ fn render_frame(canvas: &mut sk::Pixmap, state: State, frame: &Frame) {
             FrameItem::Image(image, size, _) => {
                 image::render_image(canvas, state.pre_translate(*pos), image, *size);
             }
-            FrameItem::Link(_, _) => {}
+            FrameItem::Link(..) => {}
             FrameItem::Tag(_) => {}
         }
     }

crates/typst-svg/src/lib.rs

@@ -207,7 +207,7 @@ impl SVGRenderer {
         for (pos, item) in frame.items() {
             // File size optimization.
             // TODO: SVGs could contain links, couldn't they?
-            if matches!(item, FrameItem::Link(_, _) | FrameItem::Tag(_)) {
+            if matches!(item, FrameItem::Link(..) | FrameItem::Tag(_)) {
                 continue;
             }
 
@@ -228,7 +228,7 @@ impl SVGRenderer {
                     self.render_shape(state.pre_translate(*pos), shape)
                 }
                 FrameItem::Image(image, size, _) => self.render_image(image, size),
-                FrameItem::Link(_, _) => unreachable!(),
+                FrameItem::Link(..) => unreachable!(),
                 FrameItem::Tag(_) => unreachable!(),
             };