Support for raw syntax highlighting in HTML export (#6691)

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/lib.rs

@@ -16,7 +16,7 @@ mod typed;
 pub use self::document::html_document;
 pub use self::dom::*;
 pub use self::encode::html;
-pub use self::rules::register;
+pub use self::rules::{html_span_filled, register};
 
 use ecow::EcoString;
 use typst_library::Category;

crates/typst-html/src/rules.rs

@@ -17,7 +17,7 @@ use typst_library::text::{
     HighlightElem, LinebreakElem, OverlineElem, RawElem, RawLine, SmallcapsElem,
     SpaceElem, StrikeElem, SubElem, SuperElem, UnderlineElem,
 };
-use typst_library::visualize::ImageElem;
+use typst_library::visualize::{Color, ImageElem};
 
 use crate::{FrameElem, HtmlAttrs, HtmlElem, HtmlTag, attr, css, tag};
 
@@ -427,6 +427,20 @@ const RAW_RULE: ShowFn<RawElem> = |elem, _, styles| {
     })
 };
 
+/// This is used by `RawElem::synthesize` through a routine.
+///
+/// It's a temporary workaround until `TextElem::fill` is supported in HTML
+/// export.
+#[doc(hidden)]
+pub fn html_span_filled(content: Content, color: Color) -> Content {
+    let span = content.span();
+    HtmlElem::new(tag::span)
+        .with_styles(css::Properties::new().with("color", css::color(color)))
+        .with_body(Some(content))
+        .pack()
+        .spanned(span)
+}
+
 const RAW_LINE_RULE: ShowFn<RawLine> = |elem, _, _| Ok(elem.body.clone());
 
 const IMAGE_RULE: ShowFn<ImageElem> = |elem, engine, styles| {

crates/typst-library/src/routines.rs

@@ -15,6 +15,7 @@ use crate::foundations::{
 use crate::introspection::{Introspector, Locator, SplitLocator};
 use crate::layout::{Frame, Region};
 use crate::model::DocumentInfo;
+use crate::visualize::Color;
 
 /// Defines the `Routines` struct.
 macro_rules! routines {
@@ -95,6 +96,12 @@ routines! {
 
     /// Constructs the `html` module.
     fn html_module() -> Module
+
+    /// Wraps content in a span with a color.
+    ///
+    /// This is a temporary workaround until `TextElem::fill` is supported in
+    /// HTML export.
+    fn html_span_filled(content: Content, color: Color) -> Content
 }
 
 /// Defines what kind of realization we are performing.

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

@@ -18,11 +18,12 @@ use crate::diag::{
 use crate::engine::Engine;
 use crate::foundations::{
     Bytes, Content, Derived, OneOrMultiple, Packed, PlainText, ShowSet, Smart,
-    StyleChain, Styles, Synthesize, cast, elem, scope,
+    StyleChain, Styles, Synthesize, Target, TargetElem, cast, elem, scope,
 };
 use crate::layout::{Em, HAlignment};
 use crate::loading::{DataSource, Load};
 use crate::model::{Figurable, ParElem};
+use crate::routines::Routines;
 use crate::text::{FontFamily, FontList, LocalName, TextElem, TextSize};
 use crate::visualize::Color;
 
@@ -300,8 +301,12 @@ impl RawElem {
 }
 
 impl Synthesize for Packed<RawElem> {
-    fn synthesize(&mut self, _: &mut Engine, styles: StyleChain) -> SourceResult<()> {
-        let seq = self.highlight(styles);
+    fn synthesize(
+        &mut self,
+        engine: &mut Engine,
+        styles: StyleChain,
+    ) -> SourceResult<()> {
+        let seq = self.highlight(engine.routines, styles);
         self.lines = Some(seq);
         Ok(())
     }
@@ -309,7 +314,7 @@ impl Synthesize for Packed<RawElem> {
 
 impl Packed<RawElem> {
     #[comemo::memoize]
-    fn highlight(&self, styles: StyleChain) -> Vec<Packed<RawLine>> {
+    fn highlight(&self, routines: &Routines, styles: StyleChain) -> Vec<Packed<RawLine>> {
         let elem = self.as_ref();
         let lines = preprocess(&elem.text, styles, self.span());
 
@@ -341,6 +346,7 @@ impl Packed<RawElem> {
         };
 
         let foreground = theme.settings.foreground.unwrap_or(synt::Color::BLACK);
+        let target = styles.get(TargetElem::target);
 
         let mut seq = vec![];
         if matches!(lang.as_deref(), Some("typ" | "typst" | "typc" | "typm")) {
@@ -363,7 +369,15 @@ impl Packed<RawElem> {
                     let span_offset = text[..range.start]
                         .rfind('\n')
                         .map_or(0, |i| range.start - (i + 1));
-                    styled(&text[range], foreground, style, span, span_offset)
+                    styled(
+                        routines,
+                        target,
+                        &text[range],
+                        foreground,
+                        style,
+                        span,
+                        span_offset,
+                    )
                 },
                 &mut |i, range, line| {
                     let span = lines.get(i).map_or_else(Span::detached, |l| l.1);
@@ -400,6 +414,8 @@ impl Packed<RawElem> {
                     .flatten()
                 {
                     line_content.push(styled(
+                        routines,
+                        target,
                         piece,
                         foreground,
                         style,
@@ -769,6 +785,8 @@ fn preprocess(
 
 /// Style a piece of text with a syntect style.
 fn styled(
+    routines: &Routines,
+    target: Target,
     piece: &str,
     foreground: synt::Color,
     style: synt::Style,
@@ -782,7 +800,11 @@ fn styled(
     }
 
     if style.foreground != foreground {
-        body = body.set(TextElem::fill, to_typst(style.foreground).into());
+        let color = to_typst(style.foreground);
+        body = match target {
+            Target::Html => (routines.html_span_filled)(body, color),
+            Target::Paged => body.set(TextElem::fill, color.into()),
+        };
     }
 
     if style.font_style.contains(synt::FontStyle::BOLD) {

crates/typst/src/lib.rs

@@ -358,4 +358,5 @@ pub static ROUTINES: LazyLock<Routines> = LazyLock::new(|| Routines {
     realize: typst_realize::realize,
     layout_frame: typst_layout::layout_frame,
     html_module: typst_html::module,
+    html_span_filled: typst_html::html_span_filled,
 });

tests/ref/html/raw-html.html

@@ -6,6 +6,6 @@
   </head>
   <body>
     <p>This is <code><strong>*</strong><strong>inline</strong><strong>*</strong></code>.</p>
-    <pre><code>#set text(blue)<br><strong>*</strong><strong>Hello</strong><strong>*</strong> <em>_</em><em>world</em><em>_</em>!</code></pre>
+    <pre><code><span style="color: #d73a49">#</span><span style="color: #d73a49">set</span> <span style="color: #4b69c6">text</span>(blue)<br><strong>*</strong><strong>Hello</strong><strong>*</strong> <em>_</em><em>world</em><em>_</em>!</code></pre>
   </body>
 </html>