Support for outline in HTML

crates/typst-html/src/css.rs

@@ -26,7 +26,6 @@ impl Properties {
     }
 
     /// Adds a new property in builder-style.
-    #[expect(unused)]
     pub fn with(mut self, property: &str, value: impl Display) -> Self {
         self.push(property, value);
         self

crates/typst-html/src/rules.rs

@@ -1,17 +1,18 @@
 use std::num::NonZeroUsize;
 
+use comemo::Track;
 use ecow::{eco_format, EcoVec};
 use typst_library::diag::{warning, At};
 use typst_library::foundations::{
-    Content, NativeElement, NativeRuleMap, ShowFn, Smart, StyleChain, Target,
+    Content, Context, NativeElement, NativeRuleMap, ShowFn, Smart, StyleChain, Target,
 };
 use typst_library::introspection::{Counter, Locator};
 use typst_library::layout::resolve::{table_to_cellgrid, Cell, CellGrid, Entry};
 use typst_library::layout::{OuterVAlignment, Sizing};
 use typst_library::model::{
     Attribution, CiteElem, CiteGroup, Destination, EmphElem, EnumElem, FigureCaption,
-    FigureElem, HeadingElem, LinkElem, LinkTarget, ListElem, ParbreakElem, QuoteElem,
-    RefElem, StrongElem, TableCell, TableElem, TermsElem,
+    FigureElem, HeadingElem, LinkElem, LinkTarget, ListElem, OutlineElem, OutlineEntry,
+    ParbreakElem, QuoteElem, RefElem, StrongElem, TableCell, TableElem, TermsElem,
 };
 use typst_library::text::{
     HighlightElem, LinebreakElem, OverlineElem, RawElem, RawLine, SpaceElem, StrikeElem,
@@ -36,6 +37,8 @@ pub fn register(rules: &mut NativeRuleMap) {
     rules.register(Html, FIGURE_RULE);
     rules.register(Html, FIGURE_CAPTION_RULE);
     rules.register(Html, QUOTE_RULE);
+    rules.register(Html, OUTLINE_RULE);
+    rules.register(Html, OUTLINE_ENTRY_RULE);
     rules.register(Html, REF_RULE);
     rules.register(Html, CITE_GROUP_RULE);
     rules.register(Html, TABLE_RULE);
@@ -274,6 +277,56 @@ const QUOTE_RULE: ShowFn<QuoteElem> = |elem, _, styles| {
     Ok(realized)
 };
 
+const OUTLINE_RULE: ShowFn<OutlineElem> = |elem, engine, styles| {
+    let (title, entries) = elem.realize(engine, styles)?;
+    let list = HtmlElem::new(tag::ol)
+        .with_attr(attr::class, "outline")
+        .with_styles(css::Properties::new().with("list-style", "none"))
+        .with_body(Some(Content::sequence(entries)))
+        .pack()
+        .spanned(elem.span());
+    Ok(title.unwrap_or_default() + list)
+};
+
+const OUTLINE_ENTRY_RULE: ShowFn<OutlineEntry> = |elem, engine, styles| {
+    let span = elem.span();
+    let context = Context::new(None, Some(styles));
+    let context = context.track();
+
+    let prefix = elem.prefix(engine, context, span)?;
+    let body = elem.body().at(elem.span())?;
+
+    let inner = if let Some(prefix) = prefix {
+        let separator = if let Some(elem) = elem.element.to_packed::<FigureElem>() {
+            match elem.caption.get_ref(styles) {
+                Some(caption) => caption.get_separator(styles),
+                None => FigureCaption::local_separator_in(styles),
+            }
+        } else {
+            SpaceElem::shared().clone()
+        };
+        Content::sequence([
+            HtmlElem::new(tag::span)
+                .with_attr(attr::class, "prefix")
+                .with_body(Some(prefix))
+                .pack()
+                .spanned(elem.span()),
+            separator,
+            body,
+        ])
+    } else {
+        body
+    };
+
+    let loc = elem.element_location().at(span)?;
+    let dest = Destination::Location(loc);
+
+    Ok(HtmlElem::new(tag::li)
+        .with_body(Some(LinkElem::new(dest.into(), inner).pack()))
+        .pack()
+        .spanned(elem.span()))
+};
+
 const REF_RULE: ShowFn<RefElem> = |elem, engine, styles| elem.realize(engine, styles);
 
 const CITE_GROUP_RULE: ShowFn<CiteGroup> = |elem, engine, _| elem.realize(engine);

crates/typst-layout/src/rules.rs

@@ -20,8 +20,8 @@ use typst_library::math::EquationElem;
 use typst_library::model::{
     Attribution, BibliographyElem, CiteElem, CiteGroup, CslSource, Destination, EmphElem,
     EnumElem, FigureCaption, FigureElem, FootnoteElem, FootnoteEntry, HeadingElem,
-    LinkElem, ListElem, Outlinable, OutlineElem, OutlineEntry, ParElem, ParbreakElem,
-    QuoteElem, RefElem, StrongElem, TableCell, TableElem, TermsElem, Works,
+    LinkElem, ListElem, OutlineElem, OutlineEntry, ParElem, ParbreakElem, QuoteElem,
+    RefElem, StrongElem, TableCell, TableElem, TermsElem, Works,
 };
 use typst_library::pdf::EmbedElem;
 use typst_library::text::{
@@ -412,38 +412,8 @@ const FOOTNOTE_ENTRY_RULE: ShowFn<FootnoteEntry> = |elem, engine, styles| {
 };
 
 const OUTLINE_RULE: ShowFn<OutlineElem> = |elem, engine, styles| {
-    let span = elem.span();
-
-    // Build the outline title.
-    let mut seq = vec![];
-    if let Some(title) = elem.title.get_cloned(styles).unwrap_or_else(|| {
-        Some(TextElem::packed(Packed::<OutlineElem>::local_name_in(styles)).spanned(span))
-    }) {
-        seq.push(
-            HeadingElem::new(title)
-                .with_depth(NonZeroUsize::ONE)
-                .pack()
-                .spanned(span),
-        );
-    }
-
-    let elems = engine.introspector.query(&elem.target.get_ref(styles).0);
-    let depth = elem.depth.get(styles).unwrap_or(NonZeroUsize::MAX);
-
-    // Build the outline entries.
-    for elem in elems {
-        let Some(outlinable) = elem.with::<dyn Outlinable>() else {
-            bail!(span, "cannot outline {}", elem.func().name());
-        };
-
-        let level = outlinable.level();
-        if outlinable.outlined() && level <= depth {
-            let entry = OutlineEntry::new(level, elem);
-            seq.push(entry.pack().spanned(span));
-        }
-    }
-
-    Ok(Content::sequence(seq))
+    let (title, entries) = elem.realize(engine, styles)?;
+    Ok(Content::sequence(title.into_iter().chain(entries)))
 };
 
 const OUTLINE_ENTRY_RULE: ShowFn<OutlineEntry> = |elem, engine, styles| {
@@ -454,6 +424,7 @@ const OUTLINE_ENTRY_RULE: ShowFn<OutlineEntry> = |elem, engine, styles| {
     let prefix = elem.prefix(engine, context, span)?;
     let inner = elem.inner(engine, context, span)?;
     let block = if elem.element.is::<EquationElem>() {
+        // Equation has no body and no levels, so indenting makes no sense.
         let body = prefix.unwrap_or_default() + inner;
         BlockElem::new()
             .with_body(Some(BlockBody::Content(body)))

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

@@ -19,7 +19,7 @@ use crate::layout::{
     VAlignment,
 };
 use crate::model::{Numbering, NumberingPattern, Outlinable, Refable, Supplement};
-use crate::text::{Lang, Region, TextElem};
+use crate::text::{Lang, TextElem};
 use crate::visualize::ImageElem;
 
 /// A figure with an optional caption.
@@ -526,23 +526,23 @@ impl FigureCaption {
         Ok(realized)
     }
 
-    /// Gets the default separator in the given language and (optionally)
-    /// region.
-    fn local_separator(lang: Lang, _: Option<Region>) -> &'static str {
-        match lang {
-            Lang::CHINESE => "\u{2003}",
-            Lang::FRENCH => ".\u{a0}– ",
-            Lang::RUSSIAN => ". ",
-            Lang::ENGLISH | _ => ": ",
-        }
+    /// Retrieves the locale separator.
+    pub fn get_separator(&self, styles: StyleChain) -> Content {
+        self.separator
+            .get_cloned(styles)
+            .unwrap_or_else(|| Self::local_separator_in(styles))
     }
 
-    fn get_separator(&self, styles: StyleChain) -> Content {
-        self.separator.get_cloned(styles).unwrap_or_else(|| {
-            TextElem::packed(Self::local_separator(
-                styles.get(TextElem::lang),
-                styles.get(TextElem::region),
-            ))
+    /// Gets the default separator in the given language and (optionally)
+    /// region.
+    pub fn local_separator_in(styles: StyleChain) -> Content {
+        styles.get_cloned(Self::separator).unwrap_or_else(|| {
+            TextElem::packed(match styles.get(TextElem::lang) {
+                Lang::CHINESE => "\u{2003}",
+                Lang::FRENCH => ".\u{a0}– ",
+                Lang::RUSSIAN => ". ",
+                Lang::ENGLISH | _ => ": ",
+            })
         })
     }
 }

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

@@ -248,6 +248,53 @@ impl OutlineElem {
     type OutlineEntry;
 }
 
+impl Packed<OutlineElem> {
+    /// Realizes the title and entries.
+    pub fn realize(
+        &self,
+        engine: &mut Engine,
+        styles: StyleChain,
+    ) -> SourceResult<(Option<Content>, Vec<Content>)> {
+        let span = self.span();
+
+        // Build the outline title.
+        let title = self
+            .title
+            .get_cloned(styles)
+            .unwrap_or_else(|| {
+                Some(
+                    TextElem::packed(Packed::<OutlineElem>::local_name_in(styles))
+                        .spanned(span),
+                )
+            })
+            .map(|title| {
+                HeadingElem::new(title)
+                    .with_depth(NonZeroUsize::ONE)
+                    .pack()
+                    .spanned(span)
+            });
+
+        let elems = engine.introspector.query(&self.target.get_ref(styles).0);
+        let depth = self.depth.get(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());
+            };
+
+            let level = outlinable.level();
+            if outlinable.outlined() && level <= depth {
+                let entry = OutlineEntry::new(level, elem);
+                entries.push(entry.pack().spanned(span));
+            }
+        }
+
+        Ok((title, entries))
+    }
+}
+
 impl ShowSet for Packed<OutlineElem> {
     fn show_set(&self, styles: StyleChain) -> Styles {
         let mut out = Styles::new();

tests/ref/html/outline-figure-html.html

@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+  </head>
+  <body>
+    <h2>Contents</h2>
+    <ol class="outline" style="list-style: none">
+      <li><a href="#loc-1"><span class="prefix">Figure 1</span>: A</a></li>
+      <li><a href="#loc-2"><span class="prefix">Figure 2</span>: B</a></li>
+    </ol>
+    <figure id="loc-1">
+      <p>An A</p>
+      <figcaption>Figure 1: A</figcaption>
+    </figure>
+    <figure id="loc-2">
+      <p>An B</p>
+      <figcaption>Figure 2: B</figcaption>
+    </figure>
+  </body>
+</html>

tests/ref/html/outline-html.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+  </head>
+  <body>
+    <h2>Contents</h2>
+    <ol class="outline" style="list-style: none">
+      <li><a href="#a"><span class="prefix">1</span> A</a></li>
+      <li><a href="#b"><span class="prefix">2</span> B</a></li>
+      <li><a href="#c"><span class="prefix">3</span> C</a></li>
+      <li><a href="#d"><span class="prefix">4</span> D</a></li>
+      <li><a href="#e"><span class="prefix">4.1</span> E</a></li>
+      <li><a href="#f"><span class="prefix">4.2</span> F</a></li>
+    </ol>
+    <h2 id="a">1 A</h2>
+    <h2 id="b">2 B</h2>
+    <h2 id="c">3 C</h2>
+    <h2 id="d">4 D</h2>
+    <h3 id="e">4.1 E</h3>
+    <h3 id="f">4.2 F</h3>
+  </body>
+</html>

tests/suite/model/outline.typ

@@ -252,6 +252,23 @@ A
 = B
 = C
 
+--- outline-html html ---
+#set heading(numbering: "1.1")
+
+#outline()
+
+= A <a>
+= B <b>
+= C <c>
+= D <d>
+== E <e>
+== F <f>
+
+--- outline-figure-html html ---
+#outline(target: figure)
+#figure([An A], caption: [A])
+#figure([An B], caption: [B])
+
 --- issue-2048-outline-multiline ---
 // Without the word joiner between the dots and the page number,
 // the page number would be alone in its line.