feat: highlight, super- and sub-script text attributes

crates/typst-pdf/src/tags/context.rs

@@ -3,31 +3,27 @@ use std::collections::HashMap;
 use std::slice::SliceIndex;
 
 use krilla::geom as kg;
-use krilla::tagging::{
-    BBox, Identifier, LineHeight, NaiveRgbColor, Node, Tag, TagKind, TagTree,
-    TextDecorationType,
-};
-use typst_library::diag::{SourceResult, bail};
-use typst_library::foundations::{Content, LinkMarker, Packed};
+use krilla::tagging::{BBox, Identifier, Node, TagKind, TagTree};
+use typst_library::foundations::{LinkMarker, Packed};
 use typst_library::introspection::Location;
-use typst_library::layout::{Abs, Length, Point, Rect};
+use typst_library::layout::{Abs, Point, Rect};
 use typst_library::model::{OutlineEntry, TableCell};
 use typst_library::pdf::ArtifactKind;
 use typst_library::text::Lang;
 use typst_syntax::Span;
 
-use crate::PdfOptions;
 use crate::convert::FrameContext;
 use crate::tags::list::ListCtx;
 use crate::tags::outline::OutlineCtx;
 use crate::tags::table::TableCtx;
+use crate::tags::text::{ResolvedTextAttrs, TextAttrs};
 use crate::tags::{Placeholder, TagNode};
 use crate::util::AbsExt;
 
 pub struct Tags {
     /// The language of the first text item that has been encountered.
     pub doc_lang: Option<Lang>,
-    /// The current set of text attributes.
+    /// The set of text attributes.
     pub text_attrs: TextAttrs,
     /// The intermediary stack of nested tag groups.
     pub stack: TagStack,
@@ -75,6 +71,11 @@ impl Tags {
     }
 
     pub fn push_text(&mut self, new_attrs: ResolvedTextAttrs, id: Identifier) {
+        if new_attrs.is_empty() {
+            self.push(TagNode::Leaf(id));
+            return;
+        }
+
         // FIXME: Artifacts will force a split in the spans, and decoartions
         // generate artifacts
         let last_node = if let Some(entry) = self.stack.last_mut() {
@@ -102,11 +103,11 @@ impl Tags {
     pub fn build_tree(&mut self) -> TagTree {
         assert!(self.stack.items.is_empty(), "tags weren't properly closed");
 
-        let mut nodes = Vec::new();
-        for child in std::mem::take(&mut self.tree) {
-            self.resolve_node(&mut nodes, child);
-        }
-        TagTree::from(nodes)
+        let children = std::mem::take(&mut self.tree)
+            .into_iter()
+            .map(|node| self.resolve_node(node))
+            .collect::<Vec<_>>();
+        TagTree::from(children)
     }
 
     /// Try to set the language of a parent tag, or the entire document.
@@ -128,45 +129,28 @@ impl Tags {
     }
 
     /// Resolves nodes into an accumulator.
-    fn resolve_node(&mut self, accum: &mut Vec<Node>, node: TagNode) {
+    fn resolve_node(&mut self, node: TagNode) -> Node {
         match node {
             TagNode::Group(group) => {
-                let mut nodes = Vec::new();
-                for child in group.nodes {
-                    self.resolve_node(&mut nodes, child);
-                }
+                let nodes = (group.nodes.into_iter())
+                    .map(|node| self.resolve_node(node))
+                    .collect();
                 let group = krilla::tagging::TagGroup::with_children(group.tag, nodes);
-                accum.push(Node::Group(group));
-            }
-            TagNode::Leaf(identifier) => {
-                accum.push(Node::Leaf(identifier));
-            }
-            TagNode::Placeholder(placeholder) => {
-                accum.push(self.placeholders.take(placeholder));
+                Node::Group(group)
             }
+            TagNode::Leaf(identifier) => Node::Leaf(identifier),
+            TagNode::Placeholder(placeholder) => self.placeholders.take(placeholder),
             TagNode::FootnoteEntry(loc) => {
                 let node = (self.footnotes.remove(&loc))
                     .and_then(|ctx| ctx.entry)
                     .expect("footnote");
-                self.resolve_node(accum, node)
+                self.resolve_node(node)
             }
             TagNode::Text(attrs, ids) => {
-                let children = ids.into_iter().map(|id| Node::Leaf(id));
-                if attrs.is_empty() {
-                    accum.extend(children);
-                } else {
-                    let tag = Tag::Span
-                        .with_line_height(attrs.lineheight)
-                        .with_baseline_shift(attrs.baseline_shift)
-                        .with_text_decoration_type(attrs.deco.map(|d| d.kind.to_krilla()))
-                        .with_text_decoration_color(attrs.deco.and_then(|d| d.color))
-                        .with_text_decoration_thickness(
-                            attrs.deco.and_then(|d| d.thickness),
-                        );
-                    let group =
-                        krilla::tagging::TagGroup::with_children(tag, children.collect());
-                    accum.push(Node::Group(group));
-                }
+                let tag = attrs.to_tag();
+                let children = ids.into_iter().map(|id| Node::Leaf(id)).collect();
+                let group = krilla::tagging::TagGroup::with_children(tag, children);
+                Node::Group(group)
             }
         }
     }
@@ -194,123 +178,6 @@ pub enum Disable {
     Tiling,
 }
 
-#[derive(Clone, Debug)]
-pub struct TextAttrs {
-    lineheight: Option<LineHeight>,
-    baseline_shift: Option<f32>,
-    /// PDF can only represent one of the following attributes at a time.
-    /// Keep track of all of them, and depending if PDF/UA-1 is enforced, either
-    /// throw an error, or just use one of them.
-    decos: Vec<(Location, TextDeco)>,
-}
-
-impl TextAttrs {
-    pub fn new() -> Self {
-        Self {
-            lineheight: None,
-            baseline_shift: None,
-            decos: Vec::new(),
-        }
-    }
-
-    pub fn push_deco(
-        &mut self,
-        options: &PdfOptions,
-        elem: &Content,
-        kind: TextDecoKind,
-        stroke: TextDecoStroke,
-    ) -> SourceResult<()> {
-        let deco = TextDeco { kind, stroke };
-
-        // TODO: can overlapping tags break this?
-        if options.is_pdf_ua() && self.decos.iter().any(|(_, d)| d.kind != deco.kind) {
-            let validator = options.standards.config.validator();
-            let validator = validator.as_str();
-            bail!(
-                elem.span(),
-                "{validator} error: cannot combine underline, overline, and or strike"
-            );
-        }
-
-        let loc = elem.location().unwrap();
-        self.decos.push((loc, deco));
-        Ok(())
-    }
-
-    /// Returns true if a decoration was removed.
-    pub fn pop_deco(&mut self, loc: Location) -> bool {
-        // TODO: Ideally we would just check the top of the stack, can
-        // overlapping tags even happen for decorations?
-        if let Some(i) = self.decos.iter().rposition(|(l, _)| *l == loc) {
-            self.decos.remove(i);
-            return true;
-        }
-        false
-    }
-
-    pub fn resolve(&self, em: Abs) -> ResolvedTextAttrs {
-        let deco = self.decos.last().map(|&(_, TextDeco { kind, stroke })| {
-            let thickness = stroke.thickness.map(|t| t.at(em).to_f32());
-            ResolvedTextDeco { kind, color: stroke.color, thickness }
-        });
-
-        ResolvedTextAttrs {
-            lineheight: self.lineheight,
-            baseline_shift: self.baseline_shift,
-            deco,
-        }
-    }
-}
-
-#[derive(Clone, Copy, Debug)]
-pub struct TextDeco {
-    kind: TextDecoKind,
-    stroke: TextDecoStroke,
-}
-
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub enum TextDecoKind {
-    Underline,
-    Overline,
-    Strike,
-}
-
-impl TextDecoKind {
-    fn to_krilla(self) -> TextDecorationType {
-        match self {
-            TextDecoKind::Underline => TextDecorationType::Underline,
-            TextDecoKind::Overline => TextDecorationType::Overline,
-            TextDecoKind::Strike => TextDecorationType::LineThrough,
-        }
-    }
-}
-
-#[derive(Clone, Copy, Debug, Default)]
-pub struct TextDecoStroke {
-    pub color: Option<NaiveRgbColor>,
-    pub thickness: Option<Length>,
-}
-
-#[derive(Clone, Copy, Debug, PartialEq)]
-pub struct ResolvedTextAttrs {
-    lineheight: Option<LineHeight>,
-    baseline_shift: Option<f32>,
-    deco: Option<ResolvedTextDeco>,
-}
-
-impl ResolvedTextAttrs {
-    pub fn is_empty(&self) -> bool {
-        self.lineheight.is_none() && self.baseline_shift.is_none() && self.deco.is_none()
-    }
-}
-
-#[derive(Clone, Copy, Debug, PartialEq)]
-pub struct ResolvedTextDeco {
-    kind: TextDecoKind,
-    color: Option<NaiveRgbColor>,
-    thickness: Option<f32>,
-}
-
 #[derive(Debug)]
 pub struct TagStack {
     items: Vec<StackEntry>,

crates/typst-pdf/src/tags/mod.rs

@@ -5,11 +5,10 @@ use krilla::configure::Validator;
 use krilla::page::Page;
 use krilla::surface::Surface;
 use krilla::tagging::{
-    ArtifactType, ContentTag, Identifier, ListNumbering, NaiveRgbColor, Node, SpanTag,
-    Tag, TagKind,
+    ArtifactType, ContentTag, Identifier, ListNumbering, Node, SpanTag, Tag, TagKind,
 };
 use typst_library::diag::{SourceResult, bail};
-use typst_library::foundations::{Content, LinkMarker, Smart};
+use typst_library::foundations::{Content, LinkMarker};
 use typst_library::introspection::Location;
 use typst_library::layout::{HideElem, Point, Rect, RepeatElem, Size};
 use typst_library::math::EquationElem;
@@ -20,9 +19,10 @@ use typst_library::model::{
 };
 use typst_library::pdf::{ArtifactElem, ArtifactKind, PdfMarkerTag, PdfMarkerTagKind};
 use typst_library::text::{
-    Lang, OverlineElem, RawElem, StrikeElem, TextItem, UnderlineElem,
+    HighlightElem, Lang, OverlineElem, RawElem, ScriptKind, StrikeElem, SubElem,
+    SuperElem, TextItem, UnderlineElem,
 };
-use typst_library::visualize::{Image, ImageElem, Paint, Shape, Stroke};
+use typst_library::visualize::{Image, ImageElem, Shape};
 use typst_syntax::Span;
 
 use crate::convert::{FrameContext, GlobalContext};
@@ -30,6 +30,7 @@ use crate::link::LinkAnnotation;
 use crate::tags::list::ListCtx;
 use crate::tags::outline::OutlineCtx;
 use crate::tags::table::TableCtx;
+use crate::tags::text::{ResolvedTextAttrs, TextDecoKind};
 use crate::tags::util::{PropertyOptRef, PropertyValCloned, PropertyValCopied};
 
 pub use context::*;
@@ -38,6 +39,7 @@ mod context;
 mod list;
 mod outline;
 mod table;
+mod text;
 mod util;
 
 #[derive(Debug, Clone, PartialEq)]
@@ -248,19 +250,35 @@ pub fn handle_start(
         });
         push_stack(gc, elem, StackEntryKind::Code(desc))?;
         return Ok(());
+    } else if let Some(sub) = elem.to_packed::<SubElem>() {
+        let baseline_shift = sub.baseline.val();
+        let lineheight = sub.size.val();
+        let kind = ScriptKind::Sub;
+        gc.tags.text_attrs.push_script(elem, kind, baseline_shift, lineheight);
+        return Ok(());
+    } else if let Some(sub) = elem.to_packed::<SuperElem>() {
+        let baseline_shift = sub.baseline.val();
+        let lineheight = sub.size.val();
+        let kind = ScriptKind::Super;
+        gc.tags.text_attrs.push_script(elem, kind, baseline_shift, lineheight);
+        return Ok(());
+    } else if let Some(highlight) = elem.to_packed::<HighlightElem>() {
+        let paint = highlight.fill.opt_ref();
+        gc.tags.text_attrs.push_highlight(elem, paint);
+        return Ok(());
     } else if let Some(underline) = elem.to_packed::<UnderlineElem>() {
         let kind = TextDecoKind::Underline;
-        let stroke = deco_stroke(underline.stroke.val_cloned());
+        let stroke = underline.stroke.val_cloned();
         gc.tags.text_attrs.push_deco(gc.options, elem, kind, stroke)?;
         return Ok(());
     } else if let Some(overline) = elem.to_packed::<OverlineElem>() {
         let kind = TextDecoKind::Overline;
-        let stroke = deco_stroke(overline.stroke.val_cloned());
+        let stroke = overline.stroke.val_cloned();
         gc.tags.text_attrs.push_deco(gc.options, elem, kind, stroke)?;
         return Ok(());
     } else if let Some(strike) = elem.to_packed::<StrikeElem>() {
         let kind = TextDecoKind::Strike;
-        let stroke = deco_stroke(strike.stroke.val_cloned());
+        let stroke = strike.stroke.val_cloned();
         gc.tags.text_attrs.push_deco(gc.options, elem, kind, stroke)?;
         return Ok(());
     } else {
@@ -272,26 +290,6 @@ pub fn handle_start(
     Ok(())
 }
 
-fn deco_stroke(stroke: Smart<Stroke>) -> TextDecoStroke {
-    let Smart::Custom(stroke) = stroke else {
-        return TextDecoStroke::default();
-    };
-    let color = stroke.paint.custom().and_then(|paint| match paint {
-        Paint::Solid(color) => {
-            let c = color.to_rgb();
-            Some(NaiveRgbColor::new(c.red, c.green, c.blue))
-        }
-        // TODO: Don't fail silently, maybe make a best effort to convert a
-        // gradient to a single solid color?
-        Paint::Gradient(_) => None,
-        // TODO: Don't fail silently, maybe just error in PDF/UA mode?
-        Paint::Tiling(_) => None,
-    });
-
-    let thickness = stroke.thickness.custom();
-    TextDecoStroke { color, thickness }
-}
-
 fn push_stack(
     gc: &mut GlobalContext,
     elem: &Content,
@@ -350,7 +348,7 @@ pub fn handle_end(
         return Ok(());
     }
 
-    if gc.tags.text_attrs.pop_deco(loc) {
+    if gc.tags.text_attrs.pop(loc) {
         return Ok(());
     }
 
@@ -640,7 +638,7 @@ pub fn text<'a, 'b>(
         return TagHandle { surface, started: false };
     }
 
-    let attrs = gc.tags.text_attrs.resolve(text.size);
+    let attrs = gc.tags.text_attrs.resolve(text);
 
     // Marked content
     let lang = gc.tags.try_set_lang(text.lang);

crates/typst-pdf/src/tags/text.rs

@@ -0,0 +1,292 @@
+use krilla::tagging::{LineHeight, NaiveRgbColor, Tag, TextDecorationType, kind};
+use typst_library::diag::{SourceResult, bail};
+use typst_library::foundations::{Content, Smart};
+use typst_library::introspection::Location;
+use typst_library::layout::{Abs, Length};
+use typst_library::text::{Font, ScriptKind, TextItem, TextSize};
+use typst_library::visualize::{Paint, Stroke};
+
+use crate::PdfOptions;
+use crate::util::AbsExt;
+
+#[derive(Clone, Debug)]
+pub struct TextAttrs {
+    /// Store the last resolved set of text attribute. The resolution isn't that
+    /// expensive, but for large bodies of text it is resolved quite often.
+    last_resolved: Option<(TextParams, ResolvedTextAttrs)>,
+    items: Vec<(Location, TextAttr)>,
+}
+
+impl TextAttrs {
+    pub const fn new() -> Self {
+        Self { last_resolved: None, items: Vec::new() }
+    }
+
+    pub fn push_script(
+        &mut self,
+        elem: &Content,
+        kind: ScriptKind,
+        baseline_shift: Smart<Length>,
+        lineheight: Smart<TextSize>,
+    ) {
+        let val = Script { kind, baseline_shift, lineheight };
+        let loc = elem.location().unwrap();
+        self.push(loc, TextAttr::Script(val));
+    }
+
+    pub fn push_highlight(&mut self, elem: &Content, paint: Option<&Paint>) {
+        let color = match paint {
+            // TODO: don't fail silently
+            Some(paint) => color_from_paint(paint),
+            None => None,
+        };
+        let loc = elem.location().unwrap();
+        self.push(loc, TextAttr::Highlight(color));
+    }
+
+    pub fn push_deco(
+        &mut self,
+        options: &PdfOptions,
+        elem: &Content,
+        kind: TextDecoKind,
+        stroke: Smart<Stroke>,
+    ) -> SourceResult<()> {
+        let stroke = TextDecoStroke::from(stroke);
+        let deco = TextDeco { kind, stroke };
+
+        // TODO: can overlapping tags break this?
+        // PDF can only represent one text decoration style at a time.
+        // If PDF/UA-1 is enforced throw an error.
+        if options.is_pdf_ua()
+            && self
+                .items
+                .iter()
+                .filter_map(|(_, a)| a.as_deco())
+                .any(|d| d.kind != deco.kind)
+        {
+            let validator = options.standards.config.validator();
+            let validator = validator.as_str();
+            bail!(
+                elem.span(),
+                "{validator} error: cannot combine underline, overline, and or strike"
+            );
+        }
+
+        let loc = elem.location().unwrap();
+        self.push(loc, TextAttr::Deco(deco));
+        Ok(())
+    }
+
+    fn push(&mut self, loc: Location, attr: TextAttr) {
+        self.last_resolved = None;
+        self.items.push((loc, attr));
+    }
+
+    /// Returns true if a decoration was removed.
+    pub fn pop(&mut self, loc: Location) -> bool {
+        self.last_resolved = None;
+
+        // TODO: Ideally we would just check the top of the stack, can
+        // overlapping tags even happen for decorations?
+        if let Some(i) = self.items.iter().rposition(|(l, _)| *l == loc) {
+            self.items.remove(i);
+            return true;
+        }
+        false
+    }
+
+    pub fn resolve(&mut self, text: &TextItem) -> ResolvedTextAttrs {
+        let params = TextParams::new(text);
+        if let Some((prev_params, attrs)) = &self.last_resolved
+            && prev_params == &params
+        {
+            return *attrs;
+        }
+
+        let attrs = resolve_attrs(&self.items, &text.font, text.size);
+        self.last_resolved = Some((params, attrs));
+        attrs
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+enum TextAttr {
+    Script(Script),
+    Highlight(Option<NaiveRgbColor>),
+    Deco(TextDeco),
+}
+
+impl TextAttr {
+    fn as_deco(&self) -> Option<&TextDeco> {
+        if let Self::Deco(v) = self { Some(v) } else { None }
+    }
+}
+
+/// Sub- or super-script.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+struct Script {
+    kind: ScriptKind,
+    baseline_shift: Smart<Length>,
+    lineheight: Smart<TextSize>,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+struct TextDeco {
+    kind: TextDecoKind,
+    stroke: TextDecoStroke,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum TextDecoKind {
+    Underline,
+    Overline,
+    Strike,
+}
+
+impl TextDecoKind {
+    fn to_krilla(self) -> TextDecorationType {
+        match self {
+            TextDecoKind::Underline => TextDecorationType::Underline,
+            TextDecoKind::Overline => TextDecorationType::Overline,
+            TextDecoKind::Strike => TextDecorationType::LineThrough,
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+struct TextDecoStroke {
+    color: Option<NaiveRgbColor>,
+    thickness: Option<Length>,
+}
+
+impl TextDecoStroke {
+    fn from(stroke: Smart<Stroke>) -> Self {
+        let Smart::Custom(stroke) = stroke else {
+            return TextDecoStroke::default();
+        };
+        let color = match stroke.paint.custom() {
+            // TODO: don't fail silently
+            Some(paint) => color_from_paint(&paint),
+            None => None,
+        };
+        let thickness = stroke.thickness.custom();
+        TextDecoStroke { color, thickness }
+    }
+}
+
+fn color_from_paint(paint: &Paint) -> Option<NaiveRgbColor> {
+    match paint {
+        Paint::Solid(color) => {
+            let c = color.to_rgb();
+            Some(NaiveRgbColor::new(c.red, c.green, c.blue))
+        }
+        // TODO: Don't fail silently, maybe make a best effort to convert a
+        // gradient to a single solid color?
+        Paint::Gradient(_) => None,
+        // TODO: Don't fail silently, maybe just error in PDF/UA mode?
+        Paint::Tiling(_) => None,
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct ResolvedTextAttrs {
+    script: Option<ResolvedScript>,
+    background: Option<Option<NaiveRgbColor>>,
+    deco: Option<ResolvedTextDeco>,
+}
+
+impl ResolvedTextAttrs {
+    pub const EMPTY: Self = Self { script: None, background: None, deco: None };
+
+    pub fn is_empty(&self) -> bool {
+        self == &Self::EMPTY
+    }
+
+    pub fn all_resolved(&self) -> bool {
+        self.script.is_some() && self.background.is_some() && self.deco.is_some()
+    }
+
+    pub fn to_tag(self) -> Tag<kind::Span> {
+        Tag::Span
+            .with_line_height(self.script.map(|s| s.lineheight))
+            .with_baseline_shift(self.script.map(|s| s.baseline_shift))
+            .with_background_color(self.background.flatten())
+            .with_text_decoration_type(self.deco.map(|d| d.kind.to_krilla()))
+            .with_text_decoration_color(self.deco.and_then(|d| d.color))
+            .with_text_decoration_thickness(self.deco.and_then(|d| d.thickness))
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct ResolvedScript {
+    baseline_shift: f32,
+    lineheight: LineHeight,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct ResolvedTextDeco {
+    kind: TextDecoKind,
+    color: Option<NaiveRgbColor>,
+    thickness: Option<f32>,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+struct TextParams {
+    font_index: u32,
+    size: Abs,
+}
+
+impl TextParams {
+    fn new(text: &TextItem) -> TextParams {
+        TextParams {
+            // Comparing font indices is enough.
+            font_index: text.font.index(),
+            size: text.size,
+        }
+    }
+}
+
+fn resolve_attrs(
+    items: &[(Location, TextAttr)],
+    font: &Font,
+    size: Abs,
+) -> ResolvedTextAttrs {
+    let mut attrs = ResolvedTextAttrs::EMPTY;
+    for (_, attr) in items.iter().rev() {
+        match *attr {
+            TextAttr::Script(script) => {
+                // TODO: The `typographic` setting is ignored for now.
+                // Is it better to be acurate regarding the layouting, and
+                // thus don't write any baseline shift and lineheight when
+                // a typographic sub/super script glyph is used? Or should
+                // we always write the shift so the sub/super script can be
+                // picked up by AT?
+                let script_metrics = script.kind.read_metrics(font.metrics());
+                // NOTE: The user provided baseline_shift needs to be inverted.
+                let baseline_shift = (script.baseline_shift.map(|s| -s.at(size)))
+                    .unwrap_or_else(|| script_metrics.vertical_offset.at(size));
+                let lineheight = (script.lineheight.map(|s| s.0.at(size)))
+                    .unwrap_or_else(|| script_metrics.height.at(size));
+
+                attrs.script.get_or_insert_with(|| ResolvedScript {
+                    baseline_shift: baseline_shift.to_f32(),
+                    lineheight: LineHeight::Custom(lineheight.to_f32()),
+                });
+            }
+            TextAttr::Highlight(color) => {
+                attrs.background.get_or_insert(color);
+            }
+            TextAttr::Deco(TextDeco { kind, stroke }) => {
+                attrs.deco.get_or_insert_with(|| {
+                    let thickness = stroke.thickness.map(|t| t.at(size).to_f32());
+                    ResolvedTextDeco { kind, color: stroke.color, thickness }
+                });
+            }
+        }
+
+        if attrs.all_resolved() {
+            break;
+        }
+    }
+    attrs
+}

tests/ref/pdftags/deco-tags-highlight-basic.yml

@@ -0,0 +1,9 @@
+- Tag: P
+  /K:
+    - Content: page=0 mcid=0
+    - Tag: Span
+      /BackgroundColor: #fffd11
+      /K:
+        - Content: page=0 mcid=1
+    - Content: page=0 mcid=2
+    - Content: page=0 mcid=3

tests/ref/pdftags/deco-tags-script-custom-baseline.yml

@@ -0,0 +1,13 @@
+- Tag: P
+  /K:
+    - Tag: Span
+      /BaselineShift:  -2.500
+      /LineHeight:   6.000
+      /K:
+        - Content: page=0 mcid=0
+    - Content: page=0 mcid=1
+    - Tag: Span
+      /BaselineShift:   9.500
+      /LineHeight:   6.000
+      /K:
+        - Content: page=0 mcid=2

tests/ref/pdftags/deco-tags-subscript-basic.yml

@@ -0,0 +1,14 @@
+- Tag: P
+  /K:
+    - Content: page=0 mcid=0
+    - Tag: Span
+      /BaselineShift:  -0.750
+      /LineHeight:   6.000
+      /K:
+        - Content: page=0 mcid=1
+    - Content: page=0 mcid=2
+    - Tag: Span
+      /BaselineShift:  -0.750
+      /LineHeight:   6.000
+      /K:
+        - Content: page=0 mcid=3

tests/ref/pdftags/deco-tags-superscript-basic.yml

@@ -0,0 +1,10 @@
+- Tag: P
+  /K:
+    - Content: page=0 mcid=0
+    - Tag: Span
+      /BaselineShift:   3.500
+      /LineHeight:   6.000
+      /K:
+        - Content: page=0 mcid=1
+    - Content: page=0 mcid=2
+    - Content: page=0 mcid=3

tests/suite/pdftags/deco.typ

@@ -16,9 +16,9 @@ blue underlined text
 
 --- deco-tags-different-stroke-thickness pdftags ---
 #show: underline.with(stroke: 2pt)
-red underlined text
+thick underlined
 #show: underline.with(stroke: 1pt)
-blue underlined text
+thin underlined
 
 --- deco-tags-different-type pdftags ---
 #underline[underlined]\
@@ -30,3 +30,20 @@ blue underlined text
 // Error: 2-16 PDF/UA1 error: cannot combine underline, overline, and or strike
 #show: overline
 text with a bunch of lines
+
+--- deco-tags-highlight-basic pdftags ---
+A #highlight[highlighted] alksjdflk asdjlkfj alskdj word.
+
+--- deco-tags-subscript-basic pdftags ---
+CO#sub[2] emissions.
+A2#sub[hex]
+
+--- deco-tags-superscript-basic pdftags ---
+CI#super[-] has a negative charge.
+
+--- deco-tags-script-custom-baseline pdftags ---
+// NOTE: the baseline shift values attribute is inverted.
+#set sub(baseline: 2.5pt)
+#set super(baseline: -9.5pt)
+#sub[sub]
+#super[super]