From 3ca5b238238e1128aa7bbfbd5db9e632045d8600 Mon Sep 17 00:00:00 2001
From: Laurenz <laurmaedje@gmail.com>
Date: Mon, 28 Feb 2022 15:50:48 +0100
Subject: Reorganize library

---
 src/library/text/deco.rs    | 250 ++++++++++++++++++
 src/library/text/link.rs    |  64 +++++
 src/library/text/mod.rs     | 409 +++++++++++++++++++++++++++++
 src/library/text/par.rs     | 617 ++++++++++++++++++++++++++++++++++++++++++++
 src/library/text/raw.rs     | 127 +++++++++
 src/library/text/shaping.rs | 552 +++++++++++++++++++++++++++++++++++++++
 6 files changed, 2019 insertions(+)
 create mode 100644 src/library/text/deco.rs
 create mode 100644 src/library/text/link.rs
 create mode 100644 src/library/text/mod.rs
 create mode 100644 src/library/text/par.rs
 create mode 100644 src/library/text/raw.rs
 create mode 100644 src/library/text/shaping.rs

(limited to 'src/library/text')

diff --git a/src/library/text/deco.rs b/src/library/text/deco.rs
new file mode 100644
index 00000000..a288c995
--- /dev/null
+++ b/src/library/text/deco.rs
@@ -0,0 +1,250 @@
+use kurbo::{BezPath, Line, ParamCurve};
+use ttf_parser::{GlyphId, OutlineBuilder};
+
+use super::TextNode;
+use crate::font::FontStore;
+use crate::library::prelude::*;
+
+/// Typeset underline, stricken-through or overlined text.
+#[derive(Debug, Hash)]
+pub struct DecoNode<const L: DecoLine>(pub Template);
+
+/// Typeset underlined text.
+pub type UnderlineNode = DecoNode<UNDERLINE>;
+
+/// Typeset stricken-through text.
+pub type StrikethroughNode = DecoNode<STRIKETHROUGH>;
+
+/// Typeset overlined text.
+pub type OverlineNode = DecoNode<OVERLINE>;
+
+#[class]
+impl<const L: DecoLine> DecoNode<L> {
+    /// Stroke color of the line, defaults to the text color if `None`.
+    #[shorthand]
+    pub const STROKE: Option<Paint> = None;
+    /// Thickness of the line's strokes (dependent on scaled font size), read
+    /// from the font tables if `None`.
+    #[shorthand]
+    pub const THICKNESS: Option<Linear> = None;
+    /// Position of the line relative to the baseline (dependent on scaled font
+    /// size), read from the font tables if `None`.
+    pub const OFFSET: Option<Linear> = None;
+    /// Amount that the line will be longer or shorter than its associated text
+    /// (dependent on scaled font size).
+    pub const EXTENT: Linear = Linear::zero();
+    /// Whether the line skips sections in which it would collide
+    /// with the glyphs. Does not apply to strikethrough.
+    pub const EVADE: bool = true;
+
+    fn construct(_: &mut Context, args: &mut Args) -> TypResult<Template> {
+        Ok(Template::show(Self(args.expect::<Template>("body")?)))
+    }
+}
+
+impl<const L: DecoLine> Show for DecoNode<L> {
+    fn show(&self, ctx: &mut Context, styles: StyleChain) -> TypResult<Template> {
+        Ok(styles
+            .show(self, ctx, [Value::Template(self.0.clone())])?
+            .unwrap_or_else(|| {
+                self.0.clone().styled(TextNode::LINES, vec![Decoration {
+                    line: L,
+                    stroke: styles.get(Self::STROKE),
+                    thickness: styles.get(Self::THICKNESS),
+                    offset: styles.get(Self::OFFSET),
+                    extent: styles.get(Self::EXTENT),
+                    evade: styles.get(Self::EVADE),
+                }])
+            }))
+    }
+}
+
+/// Defines a line that is positioned over, under or on top of text.
+///
+/// For more details, see [`DecoNode`].
+#[derive(Debug, Clone, Eq, PartialEq, Hash)]
+pub struct Decoration {
+    pub line: DecoLine,
+    pub stroke: Option<Paint>,
+    pub thickness: Option<Linear>,
+    pub offset: Option<Linear>,
+    pub extent: Linear,
+    pub evade: bool,
+}
+
+/// A kind of decorative line.
+pub type DecoLine = usize;
+
+/// A line under text.
+pub const UNDERLINE: DecoLine = 0;
+
+/// A line through text.
+pub const STRIKETHROUGH: DecoLine = 1;
+
+/// A line over text.
+pub const OVERLINE: DecoLine = 2;
+
+/// Add line decorations to a single run of shaped text.
+pub fn decorate(
+    frame: &mut Frame,
+    deco: &Decoration,
+    fonts: &FontStore,
+    text: &Text,
+    pos: Point,
+    width: Length,
+) {
+    let face = fonts.get(text.face_id);
+    let metrics = match deco.line {
+        STRIKETHROUGH => face.strikethrough,
+        OVERLINE => face.overline,
+        UNDERLINE | _ => face.underline,
+    };
+
+    let evade = deco.evade && deco.line != STRIKETHROUGH;
+    let extent = deco.extent.resolve(text.size);
+    let offset = deco
+        .offset
+        .map(|s| s.resolve(text.size))
+        .unwrap_or(-metrics.position.resolve(text.size));
+
+    let stroke = Stroke {
+        paint: deco.stroke.unwrap_or(text.fill),
+        thickness: deco
+            .thickness
+            .map(|s| s.resolve(text.size))
+            .unwrap_or(metrics.thickness.resolve(text.size)),
+    };
+
+    let gap_padding = 0.08 * text.size;
+    let min_width = 0.162 * text.size;
+
+    let mut start = pos.x - extent;
+    let end = pos.x + (width + 2.0 * extent);
+
+    let mut push_segment = |from: Length, to: Length| {
+        let origin = Point::new(from, pos.y + offset);
+        let target = Point::new(to - from, Length::zero());
+
+        if target.x >= min_width || !evade {
+            let shape = Shape::stroked(Geometry::Line(target), stroke);
+            frame.push(origin, Element::Shape(shape));
+        }
+    };
+
+    if !evade {
+        push_segment(start, end);
+        return;
+    }
+
+    let line = Line::new(
+        kurbo::Point::new(pos.x.to_raw(), offset.to_raw()),
+        kurbo::Point::new((pos.x + width).to_raw(), offset.to_raw()),
+    );
+
+    let mut x = pos.x;
+    let mut intersections = vec![];
+
+    for glyph in text.glyphs.iter() {
+        let dx = glyph.x_offset.resolve(text.size) + x;
+        let mut builder = BezPathBuilder::new(face.units_per_em, text.size, dx.to_raw());
+
+        let bbox = face.ttf().outline_glyph(GlyphId(glyph.id), &mut builder);
+        let path = builder.finish();
+
+        x += glyph.x_advance.resolve(text.size);
+
+        // Only do the costly segments intersection test if the line
+        // intersects the bounding box.
+        if bbox.map_or(false, |bbox| {
+            let y_min = -face.to_em(bbox.y_max).resolve(text.size);
+            let y_max = -face.to_em(bbox.y_min).resolve(text.size);
+
+            offset >= y_min && offset <= y_max
+        }) {
+            // Find all intersections of segments with the line.
+            intersections.extend(
+                path.segments()
+                    .flat_map(|seg| seg.intersect_line(line))
+                    .map(|is| Length::raw(line.eval(is.line_t).x)),
+            );
+        }
+    }
+
+    // When emitting the decorative line segments, we move from left to
+    // right. The intersections are not necessarily in this order, yet.
+    intersections.sort();
+
+    for gap in intersections.chunks_exact(2) {
+        let l = gap[0] - gap_padding;
+        let r = gap[1] + gap_padding;
+
+        if start >= end {
+            break;
+        }
+
+        if start >= l {
+            start = r;
+            continue;
+        }
+
+        push_segment(start, l);
+        start = r;
+    }
+
+    if start < end {
+        push_segment(start, end);
+    }
+}
+
+/// Builds a kurbo [`BezPath`] for a glyph.
+struct BezPathBuilder {
+    path: BezPath,
+    units_per_em: f64,
+    font_size: Length,
+    x_offset: f64,
+}
+
+impl BezPathBuilder {
+    fn new(units_per_em: f64, font_size: Length, x_offset: f64) -> Self {
+        Self {
+            path: BezPath::new(),
+            units_per_em,
+            font_size,
+            x_offset,
+        }
+    }
+
+    fn finish(self) -> BezPath {
+        self.path
+    }
+
+    fn p(&self, x: f32, y: f32) -> kurbo::Point {
+        kurbo::Point::new(self.s(x) + self.x_offset, -self.s(y))
+    }
+
+    fn s(&self, v: f32) -> f64 {
+        Em::from_units(v, self.units_per_em).resolve(self.font_size).to_raw()
+    }
+}
+
+impl OutlineBuilder for BezPathBuilder {
+    fn move_to(&mut self, x: f32, y: f32) {
+        self.path.move_to(self.p(x, y));
+    }
+
+    fn line_to(&mut self, x: f32, y: f32) {
+        self.path.line_to(self.p(x, y));
+    }
+
+    fn quad_to(&mut self, x1: f32, y1: f32, x: f32, y: f32) {
+        self.path.quad_to(self.p(x1, y1), self.p(x, y));
+    }
+
+    fn curve_to(&mut self, x1: f32, y1: f32, x2: f32, y2: f32, x: f32, y: f32) {
+        self.path.curve_to(self.p(x1, y1), self.p(x2, y2), self.p(x, y));
+    }
+
+    fn close(&mut self) {
+        self.path.close_path();
+    }
+}
diff --git a/src/library/text/link.rs b/src/library/text/link.rs
new file mode 100644
index 00000000..29f41927
--- /dev/null
+++ b/src/library/text/link.rs
@@ -0,0 +1,64 @@
+use super::TextNode;
+use crate::library::prelude::*;
+use crate::util::EcoString;
+
+/// Link text and other elements to an URL.
+#[derive(Debug, Hash)]
+pub struct LinkNode {
+    /// The url the link points to.
+    pub url: EcoString,
+    /// How the link is represented.
+    pub body: Option<Template>,
+}
+
+#[class]
+impl LinkNode {
+    /// The fill color of text in the link. Just the surrounding text color
+    /// if `auto`.
+    pub const FILL: Smart<Paint> = Smart::Auto;
+    /// Whether to underline link.
+    pub const UNDERLINE: bool = true;
+
+    fn construct(_: &mut Context, args: &mut Args) -> TypResult<Template> {
+        Ok(Template::show(Self {
+            url: args.expect::<EcoString>("url")?,
+            body: args.find()?,
+        }))
+    }
+}
+
+impl Show for LinkNode {
+    fn show(&self, ctx: &mut Context, styles: StyleChain) -> TypResult<Template> {
+        let mut body = styles
+            .show(self, ctx, [
+                Value::Str(self.url.clone()),
+                match &self.body {
+                    Some(body) => Value::Template(body.clone()),
+                    None => Value::None,
+                },
+            ])?
+            .or_else(|| self.body.clone())
+            .unwrap_or_else(|| {
+                let url = &self.url;
+                let mut text = url.as_str();
+                for prefix in ["mailto:", "tel:"] {
+                    text = text.trim_start_matches(prefix);
+                }
+                let shorter = text.len() < url.len();
+                Template::Text(if shorter { text.into() } else { url.clone() })
+            });
+
+        let mut map = StyleMap::new();
+        map.set(TextNode::LINK, Some(self.url.clone()));
+
+        if let Smart::Custom(fill) = styles.get(Self::FILL) {
+            map.set(TextNode::FILL, fill);
+        }
+
+        if styles.get(Self::UNDERLINE) {
+            body = body.underlined();
+        }
+
+        Ok(body.styled_with_map(map))
+    }
+}
diff --git a/src/library/text/mod.rs b/src/library/text/mod.rs
new file mode 100644
index 00000000..0df59007
--- /dev/null
+++ b/src/library/text/mod.rs
@@ -0,0 +1,409 @@
+mod deco;
+mod link;
+mod par;
+mod raw;
+mod shaping;
+
+pub use deco::*;
+pub use link::*;
+pub use par::*;
+pub use raw::*;
+pub use shaping::*;
+
+use std::borrow::Cow;
+use std::ops::BitXor;
+
+use ttf_parser::Tag;
+
+use crate::font::{Face, FontStretch, FontStyle, FontWeight, VerticalFontMetric};
+use crate::library::prelude::*;
+use crate::util::EcoString;
+
+/// A single run of text with the same style.
+#[derive(Hash)]
+pub struct TextNode;
+
+#[class]
+impl TextNode {
+    /// A prioritized sequence of font families.
+    #[variadic]
+    pub const FAMILY: Vec<FontFamily> = vec![FontFamily::SansSerif];
+    /// The serif font family/families.
+    pub const SERIF: Vec<NamedFamily> = vec![NamedFamily::new("IBM Plex Serif")];
+    /// The sans-serif font family/families.
+    pub const SANS_SERIF: Vec<NamedFamily> = vec![NamedFamily::new("IBM Plex Sans")];
+    /// The monospace font family/families.
+    pub const MONOSPACE: Vec<NamedFamily> = vec![NamedFamily::new("IBM Plex Mono")];
+    /// Whether to allow font fallback when the primary font list contains no
+    /// match.
+    pub const FALLBACK: bool = true;
+
+    /// How the font is styled.
+    pub const STYLE: FontStyle = FontStyle::Normal;
+    /// The boldness / thickness of the font's glyphs.
+    pub const WEIGHT: FontWeight = FontWeight::REGULAR;
+    /// The width of the glyphs.
+    pub const STRETCH: FontStretch = FontStretch::NORMAL;
+    /// The glyph fill color.
+    #[shorthand]
+    pub const FILL: Paint = Color::BLACK.into();
+
+    /// The size of the glyphs.
+    #[shorthand]
+    #[fold(Linear::compose)]
+    pub const SIZE: Linear = Length::pt(11.0).into();
+    /// The amount of space that should be added between characters.
+    pub const TRACKING: Em = Em::zero();
+    /// The top end of the text bounding box.
+    pub const TOP_EDGE: VerticalFontMetric = VerticalFontMetric::CapHeight;
+    /// The bottom end of the text bounding box.
+    pub const BOTTOM_EDGE: VerticalFontMetric = VerticalFontMetric::Baseline;
+
+    /// Whether to apply kerning ("kern").
+    pub const KERNING: bool = true;
+    /// Whether small capital glyphs should be used. ("smcp")
+    pub const SMALLCAPS: bool = false;
+    /// Whether to apply stylistic alternates. ("salt")
+    pub const ALTERNATES: bool = false;
+    /// Which stylistic set to apply. ("ss01" - "ss20")
+    pub const STYLISTIC_SET: Option<StylisticSet> = None;
+    /// Whether standard ligatures are active. ("liga", "clig")
+    pub const LIGATURES: bool = true;
+    /// Whether ligatures that should be used sparingly are active. ("dlig")
+    pub const DISCRETIONARY_LIGATURES: bool = false;
+    /// Whether historical ligatures are active. ("hlig")
+    pub const HISTORICAL_LIGATURES: bool = false;
+    /// Which kind of numbers / figures to select.
+    pub const NUMBER_TYPE: Smart<NumberType> = Smart::Auto;
+    /// The width of numbers / figures.
+    pub const NUMBER_WIDTH: Smart<NumberWidth> = Smart::Auto;
+    /// How to position numbers.
+    pub const NUMBER_POSITION: NumberPosition = NumberPosition::Normal;
+    /// Whether to have a slash through the zero glyph. ("zero")
+    pub const SLASHED_ZERO: bool = false;
+    /// Whether to convert fractions. ("frac")
+    pub const FRACTIONS: bool = false;
+    /// Raw OpenType features to apply.
+    pub const FEATURES: Vec<(Tag, u32)> = vec![];
+
+    /// Whether the font weight should be increased by 300.
+    #[skip]
+    #[fold(bool::bitxor)]
+    pub const STRONG: bool = false;
+    /// Whether the the font style should be inverted.
+    #[skip]
+    #[fold(bool::bitxor)]
+    pub const EMPH: bool = false;
+    /// Whether a monospace font should be preferred.
+    #[skip]
+    pub const MONOSPACED: bool = false;
+    /// The case transformation that should be applied to the next.
+    #[skip]
+    pub const CASE: Option<Case> = None;
+    /// Decorative lines.
+    #[skip]
+    #[fold(|a, b| a.into_iter().chain(b).collect())]
+    pub const LINES: Vec<Decoration> = vec![];
+    /// An URL the text should link to.
+    #[skip]
+    pub const LINK: Option<EcoString> = None;
+
+    fn construct(_: &mut Context, args: &mut Args) -> TypResult<Template> {
+        // The text constructor is special: It doesn't create a text node.
+        // Instead, it leaves the passed argument structurally unchanged, but
+        // styles all text in it.
+        args.expect("body")
+    }
+}
+
+/// Strong text, rendered in boldface.
+#[derive(Debug, Hash)]
+pub struct StrongNode(pub Template);
+
+#[class]
+impl StrongNode {
+    fn construct(_: &mut Context, args: &mut Args) -> TypResult<Template> {
+        Ok(Template::show(Self(args.expect("body")?)))
+    }
+}
+
+impl Show for StrongNode {
+    fn show(&self, ctx: &mut Context, styles: StyleChain) -> TypResult<Template> {
+        Ok(styles
+            .show(self, ctx, [Value::Template(self.0.clone())])?
+            .unwrap_or_else(|| self.0.clone().styled(TextNode::STRONG, true)))
+    }
+}
+
+/// Emphasized text, rendered with an italic face.
+#[derive(Debug, Hash)]
+pub struct EmphNode(pub Template);
+
+#[class]
+impl EmphNode {
+    fn construct(_: &mut Context, args: &mut Args) -> TypResult<Template> {
+        Ok(Template::show(Self(args.expect("body")?)))
+    }
+}
+
+impl Show for EmphNode {
+    fn show(&self, ctx: &mut Context, styles: StyleChain) -> TypResult<Template> {
+        Ok(styles
+            .show(self, ctx, [Value::Template(self.0.clone())])?
+            .unwrap_or_else(|| self.0.clone().styled(TextNode::EMPH, true)))
+    }
+}
+
+/// A generic or named font family.
+#[derive(Clone, Eq, PartialEq, Hash)]
+pub enum FontFamily {
+    /// A family that has "serifs", small strokes attached to letters.
+    Serif,
+    /// A family in which glyphs do not have "serifs", small attached strokes.
+    SansSerif,
+    /// A family in which (almost) all glyphs are of equal width.
+    Monospace,
+    /// A specific font family like "Arial".
+    Named(NamedFamily),
+}
+
+impl Debug for FontFamily {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        match self {
+            Self::Serif => f.pad("serif"),
+            Self::SansSerif => f.pad("sans-serif"),
+            Self::Monospace => f.pad("monospace"),
+            Self::Named(s) => s.fmt(f),
+        }
+    }
+}
+
+dynamic! {
+    FontFamily: "font family",
+    Value::Str(string) => Self::Named(NamedFamily::new(&string)),
+}
+
+castable! {
+    Vec<FontFamily>,
+    Expected: "string, generic family or array thereof",
+    Value::Str(string) => vec![FontFamily::Named(NamedFamily::new(&string))],
+    Value::Array(values) => {
+        values.into_iter().filter_map(|v| v.cast().ok()).collect()
+    },
+    @family: FontFamily => vec![family.clone()],
+}
+
+/// A specific font family like "Arial".
+#[derive(Clone, Eq, PartialEq, Hash)]
+pub struct NamedFamily(EcoString);
+
+impl NamedFamily {
+    /// Create a named font family variant.
+    pub fn new(string: &str) -> Self {
+        Self(string.to_lowercase().into())
+    }
+
+    /// The lowercased family name.
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+impl Debug for NamedFamily {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+castable! {
+    Vec<NamedFamily>,
+    Expected: "string or array of strings",
+    Value::Str(string) => vec![NamedFamily::new(&string)],
+    Value::Array(values) => values
+        .into_iter()
+        .filter_map(|v| v.cast().ok())
+        .map(|string: EcoString| NamedFamily::new(&string))
+        .collect(),
+}
+
+castable! {
+    FontStyle,
+    Expected: "string",
+    Value::Str(string) => match string.as_str() {
+        "normal" => Self::Normal,
+        "italic" => Self::Italic,
+        "oblique" => Self::Oblique,
+        _ => Err(r#"expected "normal", "italic" or "oblique""#)?,
+    },
+}
+
+castable! {
+    FontWeight,
+    Expected: "integer or string",
+    Value::Int(v) => Value::Int(v)
+        .cast::<usize>()?
+        .try_into()
+        .map_or(Self::BLACK, Self::from_number),
+    Value::Str(string) => match string.as_str() {
+        "thin" => Self::THIN,
+        "extralight" => Self::EXTRALIGHT,
+        "light" => Self::LIGHT,
+        "regular" => Self::REGULAR,
+        "medium" => Self::MEDIUM,
+        "semibold" => Self::SEMIBOLD,
+        "bold" => Self::BOLD,
+        "extrabold" => Self::EXTRABOLD,
+        "black" => Self::BLACK,
+        _ => Err("unknown font weight")?,
+    },
+}
+
+castable! {
+    FontStretch,
+    Expected: "relative",
+    Value::Relative(v) => Self::from_ratio(v.get() as f32),
+}
+
+castable! {
+    Em,
+    Expected: "float",
+    Value::Float(v) => Self::new(v),
+}
+
+castable! {
+    VerticalFontMetric,
+    Expected: "linear or string",
+    Value::Length(v) => Self::Linear(v.into()),
+    Value::Relative(v) => Self::Linear(v.into()),
+    Value::Linear(v) => Self::Linear(v),
+    Value::Str(string) => match string.as_str() {
+        "ascender" => Self::Ascender,
+        "cap-height" => Self::CapHeight,
+        "x-height" => Self::XHeight,
+        "baseline" => Self::Baseline,
+        "descender" => Self::Descender,
+        _ => Err("unknown font metric")?,
+    },
+}
+
+/// A stylistic set in a font face.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub struct StylisticSet(u8);
+
+impl StylisticSet {
+    /// Creates a new set, clamping to 1-20.
+    pub fn new(index: u8) -> Self {
+        Self(index.clamp(1, 20))
+    }
+
+    /// Get the value, guaranteed to be 1-20.
+    pub fn get(self) -> u8 {
+        self.0
+    }
+}
+
+castable! {
+    StylisticSet,
+    Expected: "integer",
+    Value::Int(v) => match v {
+        1 ..= 20 => Self::new(v as u8),
+        _ => Err("must be between 1 and 20")?,
+    },
+}
+
+/// Which kind of numbers / figures to select.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum NumberType {
+    /// Numbers that fit well with capital text. ("lnum")
+    Lining,
+    /// Numbers that fit well into flow of upper- and lowercase text. ("onum")
+    OldStyle,
+}
+
+castable! {
+    NumberType,
+    Expected: "string",
+    Value::Str(string) => match string.as_str() {
+        "lining" => Self::Lining,
+        "old-style" => Self::OldStyle,
+        _ => Err(r#"expected "lining" or "old-style""#)?,
+    },
+}
+
+/// The width of numbers / figures.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum NumberWidth {
+    /// Number widths are glyph specific. ("pnum")
+    Proportional,
+    /// All numbers are of equal width / monospaced. ("tnum")
+    Tabular,
+}
+
+castable! {
+    NumberWidth,
+    Expected: "string",
+    Value::Str(string) => match string.as_str() {
+        "proportional" => Self::Proportional,
+        "tabular" => Self::Tabular,
+        _ => Err(r#"expected "proportional" or "tabular""#)?,
+    },
+}
+
+/// How to position numbers.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum NumberPosition {
+    /// Numbers are positioned on the same baseline as text.
+    Normal,
+    /// Numbers are smaller and placed at the bottom. ("subs")
+    Subscript,
+    /// Numbers are smaller and placed at the top. ("sups")
+    Superscript,
+}
+
+castable! {
+    NumberPosition,
+    Expected: "string",
+    Value::Str(string) => match string.as_str() {
+        "normal" => Self::Normal,
+        "subscript" => Self::Subscript,
+        "superscript" => Self::Superscript,
+        _ => Err(r#"expected "normal", "subscript" or "superscript""#)?,
+    },
+}
+
+castable! {
+    Vec<(Tag, u32)>,
+    Expected: "array of strings or dictionary mapping tags to integers",
+    Value::Array(values) => values
+        .into_iter()
+        .filter_map(|v| v.cast().ok())
+        .map(|string: EcoString| (Tag::from_bytes_lossy(string.as_bytes()), 1))
+        .collect(),
+    Value::Dict(values) => values
+        .into_iter()
+        .filter_map(|(k, v)| {
+            let tag = Tag::from_bytes_lossy(k.as_bytes());
+            let num = v.cast::<i64>().ok()?.try_into().ok()?;
+            Some((tag, num))
+        })
+        .collect(),
+}
+
+/// A case transformation on text.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum Case {
+    /// Everything is uppercased.
+    Upper,
+    /// Everything is lowercased.
+    Lower,
+}
+
+impl Case {
+    /// Apply the case to a string of text.
+    pub fn apply(self, text: &str) -> String {
+        match self {
+            Self::Upper => text.to_uppercase(),
+            Self::Lower => text.to_lowercase(),
+        }
+    }
+}
diff --git a/src/library/text/par.rs b/src/library/text/par.rs
new file mode 100644
index 00000000..812231c2
--- /dev/null
+++ b/src/library/text/par.rs
@@ -0,0 +1,617 @@
+use std::sync::Arc;
+
+use either::Either;
+use unicode_bidi::{BidiInfo, Level};
+use xi_unicode::LineBreakIterator;
+
+use super::{shape, ShapedText, TextNode};
+use crate::font::FontStore;
+use crate::library::layout::SpacingKind;
+use crate::library::prelude::*;
+use crate::util::{ArcExt, EcoString, RangeExt, SliceExt};
+
+/// Arrange text, spacing and inline-level nodes into a paragraph.
+#[derive(Hash)]
+pub struct ParNode(pub StyleVec<ParChild>);
+
+/// A uniformly styled atomic piece of a paragraph.
+#[derive(Hash)]
+pub enum ParChild {
+    /// A chunk of text.
+    Text(EcoString),
+    /// Horizontal spacing between other children.
+    Spacing(SpacingKind),
+    /// An arbitrary inline-level node.
+    Node(LayoutNode),
+}
+
+#[class]
+impl ParNode {
+    /// The direction for text and inline objects.
+    pub const DIR: Dir = Dir::LTR;
+    /// How to align text and inline objects in their line.
+    pub const ALIGN: Align = Align::Left;
+    /// Whether to justify text in its line.
+    pub const JUSTIFY: bool = false;
+    /// The spacing between lines (dependent on scaled font size).
+    pub const LEADING: Linear = Relative::new(0.65).into();
+    /// The extra spacing between paragraphs (dependent on scaled font size).
+    pub const SPACING: Linear = Relative::new(0.55).into();
+    /// The indent the first line of a consecutive paragraph should have.
+    pub const INDENT: Linear = Linear::zero();
+
+    fn construct(_: &mut Context, args: &mut Args) -> TypResult<Template> {
+        // The paragraph constructor is special: It doesn't create a paragraph
+        // since that happens automatically through markup. Instead, it just
+        // lifts the passed body to the block level so that it won't merge with
+        // adjacent stuff and it styles the contained paragraphs.
+        Ok(Template::Block(args.expect("body")?))
+    }
+
+    fn set(args: &mut Args, styles: &mut StyleMap) -> TypResult<()> {
+        let mut dir =
+            args.named("lang")?
+                .map(|iso: EcoString| match iso.to_lowercase().as_str() {
+                    "ar" | "he" | "fa" | "ur" | "ps" | "yi" => Dir::RTL,
+                    "en" | "fr" | "de" => Dir::LTR,
+                    _ => Dir::LTR,
+                });
+
+        if let Some(Spanned { v, span }) = args.named::<Spanned<Dir>>("dir")? {
+            if v.axis() != SpecAxis::Horizontal {
+                bail!(span, "must be horizontal");
+            }
+            dir = Some(v);
+        }
+
+        let align =
+            if let Some(Spanned { v, span }) = args.named::<Spanned<Align>>("align")? {
+                if v.axis() != SpecAxis::Horizontal {
+                    bail!(span, "must be horizontal");
+                }
+                Some(v)
+            } else {
+                dir.map(|dir| dir.start().into())
+            };
+
+        styles.set_opt(Self::DIR, dir);
+        styles.set_opt(Self::ALIGN, align);
+        styles.set_opt(Self::JUSTIFY, args.named("justify")?);
+        styles.set_opt(Self::LEADING, args.named("leading")?);
+        styles.set_opt(Self::SPACING, args.named("spacing")?);
+        styles.set_opt(Self::INDENT, args.named("indent")?);
+
+        Ok(())
+    }
+}
+
+impl ParNode {
+    /// Concatenate all text in the paragraph into one string, replacing spacing
+    /// with a space character and other non-text nodes with the object
+    /// replacement character.
+    fn collect_text(&self) -> String {
+        let mut text = String::new();
+        for string in self.strings() {
+            text.push_str(string);
+        }
+        text
+    }
+
+    /// The range of each item in the collected text.
+    fn ranges(&self) -> impl Iterator<Item = Range> + '_ {
+        let mut cursor = 0;
+        self.strings().map(move |string| {
+            let start = cursor;
+            cursor += string.len();
+            start .. cursor
+        })
+    }
+
+    /// The string representation of each child.
+    fn strings(&self) -> impl Iterator<Item = &str> {
+        self.0.items().map(|child| match child {
+            ParChild::Text(text) => text,
+            ParChild::Spacing(_) => " ",
+            ParChild::Node(_) => "\u{FFFC}",
+        })
+    }
+}
+
+impl Layout for ParNode {
+    fn layout(
+        &self,
+        ctx: &mut Context,
+        regions: &Regions,
+        styles: StyleChain,
+    ) -> TypResult<Vec<Arc<Frame>>> {
+        // Collect all text into one string and perform BiDi analysis.
+        let text = self.collect_text();
+        let bidi = BidiInfo::new(&text, match styles.get(Self::DIR) {
+            Dir::LTR => Some(Level::ltr()),
+            Dir::RTL => Some(Level::rtl()),
+            _ => None,
+        });
+
+        // Prepare paragraph layout by building a representation on which we can
+        // do line breaking without layouting each and every line from scratch.
+        let par = ParLayout::new(ctx, self, bidi, regions, &styles)?;
+
+        // Break the paragraph into lines.
+        let lines = break_into_lines(&mut ctx.fonts, &par, regions.first.x);
+
+        // Stack the lines into one frame per region.
+        Ok(stack_lines(&ctx.fonts, lines, regions, styles))
+    }
+}
+
+impl Debug for ParNode {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.write_str("Par ")?;
+        self.0.fmt(f)
+    }
+}
+
+impl Debug for ParChild {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        match self {
+            Self::Text(text) => write!(f, "Text({:?})", text),
+            Self::Spacing(kind) => write!(f, "{:?}", kind),
+            Self::Node(node) => node.fmt(f),
+        }
+    }
+}
+
+impl Merge for ParChild {
+    fn merge(&mut self, next: &Self) -> bool {
+        if let (Self::Text(left), Self::Text(right)) = (self, next) {
+            left.push_str(right);
+            true
+        } else {
+            false
+        }
+    }
+}
+
+/// A paragraph break.
+pub struct ParbreakNode;
+
+#[class]
+impl ParbreakNode {
+    fn construct(_: &mut Context, _: &mut Args) -> TypResult<Template> {
+        Ok(Template::Parbreak)
+    }
+}
+
+/// A line break.
+pub struct LinebreakNode;
+
+#[class]
+impl LinebreakNode {
+    fn construct(_: &mut Context, _: &mut Args) -> TypResult<Template> {
+        Ok(Template::Linebreak)
+    }
+}
+
+/// A paragraph representation in which children are already layouted and text
+/// is already preshaped.
+struct ParLayout<'a> {
+    /// Bidirectional text embedding levels for the paragraph.
+    bidi: BidiInfo<'a>,
+    /// Spacing, separated text runs and layouted nodes.
+    items: Vec<ParItem<'a>>,
+    /// The ranges of the items in `bidi.text`.
+    ranges: Vec<Range>,
+}
+
+/// Range of a substring of text.
+type Range = std::ops::Range<usize>;
+
+/// A prepared item in a paragraph layout.
+enum ParItem<'a> {
+    /// Absolute spacing between other items.
+    Absolute(Length),
+    /// Fractional spacing between other items.
+    Fractional(Fractional),
+    /// A shaped text run with consistent direction.
+    Text(ShapedText<'a>),
+    /// A layouted child node.
+    Frame(Frame),
+}
+
+impl<'a> ParLayout<'a> {
+    /// Prepare initial shaped text and layouted children.
+    fn new(
+        ctx: &mut Context,
+        par: &'a ParNode,
+        bidi: BidiInfo<'a>,
+        regions: &Regions,
+        styles: &'a StyleChain<'a>,
+    ) -> TypResult<Self> {
+        let mut items = vec![];
+        let mut ranges = vec![];
+
+        // Layout the children and collect them into items.
+        for (range, (child, map)) in par.ranges().zip(par.0.iter()) {
+            let styles = map.chain(styles);
+            match child {
+                ParChild::Text(_) => {
+                    // TODO: Also split by language and script.
+                    let mut cursor = range.start;
+                    for (level, count) in bidi.levels[range].group() {
+                        let start = cursor;
+                        cursor += count;
+                        let subrange = start .. cursor;
+                        let text = &bidi.text[subrange.clone()];
+                        let dir = if level.is_ltr() { Dir::LTR } else { Dir::RTL };
+                        let shaped = shape(&mut ctx.fonts, text, styles, dir);
+                        items.push(ParItem::Text(shaped));
+                        ranges.push(subrange);
+                    }
+                }
+                ParChild::Spacing(kind) => match *kind {
+                    SpacingKind::Linear(v) => {
+                        let resolved = v.resolve(regions.first.x);
+                        items.push(ParItem::Absolute(resolved));
+                        ranges.push(range);
+                    }
+                    SpacingKind::Fractional(v) => {
+                        items.push(ParItem::Fractional(v));
+                        ranges.push(range);
+                    }
+                },
+                ParChild::Node(node) => {
+                    let size = Size::new(regions.first.x, regions.base.y);
+                    let pod = Regions::one(size, regions.base, Spec::splat(false));
+                    let frame = node.layout(ctx, &pod, styles)?.remove(0);
+                    items.push(ParItem::Frame(Arc::take(frame)));
+                    ranges.push(range);
+                }
+            }
+        }
+
+        Ok(Self { bidi, items, ranges })
+    }
+
+    /// Create a line which spans the given range.
+    fn line(
+        &'a self,
+        fonts: &mut FontStore,
+        mut range: Range,
+        mandatory: bool,
+    ) -> LineLayout<'a> {
+        // Find the items which bound the text range.
+        let last_idx = self.find(range.end.saturating_sub(1)).unwrap();
+        let first_idx = if range.is_empty() {
+            last_idx
+        } else {
+            self.find(range.start).unwrap()
+        };
+
+        // Slice out the relevant items and ranges.
+        let mut items = &self.items[first_idx ..= last_idx];
+        let ranges = &self.ranges[first_idx ..= last_idx];
+
+        // Reshape the last item if it's split in half.
+        let mut last = None;
+        if let Some((ParItem::Text(shaped), rest)) = items.split_last() {
+            // Compute the range we want to shape, trimming whitespace at the
+            // end of the line.
+            let base = self.ranges[last_idx].start;
+            let start = range.start.max(base);
+            let end = start + self.bidi.text[start .. range.end].trim_end().len();
+            let shifted = start - base .. end - base;
+
+            // Reshape if necessary.
+            if shifted.len() < shaped.text.len() {
+                // If start == end and the rest is empty, then we have an empty
+                // line. To make that line have the appropriate height, we shape the
+                // empty string.
+                if !shifted.is_empty() || rest.is_empty() {
+                    // Reshape that part.
+                    let reshaped = shaped.reshape(fonts, shifted);
+                    last = Some(ParItem::Text(reshaped));
+                }
+
+                items = rest;
+                range.end = end;
+            }
+        }
+
+        // Reshape the start item if it's split in half.
+        let mut first = None;
+        if let Some((ParItem::Text(shaped), rest)) = items.split_first() {
+            // Compute the range we want to shape.
+            let Range { start: base, end: first_end } = self.ranges[first_idx];
+            let start = range.start;
+            let end = range.end.min(first_end);
+            let shifted = start - base .. end - base;
+
+            // Reshape if necessary.
+            if shifted.len() < shaped.text.len() {
+                if !shifted.is_empty() {
+                    let reshaped = shaped.reshape(fonts, shifted);
+                    first = Some(ParItem::Text(reshaped));
+                }
+
+                items = rest;
+            }
+        }
+
+        let mut width = Length::zero();
+        let mut top = Length::zero();
+        let mut bottom = Length::zero();
+        let mut fr = Fractional::zero();
+
+        // Measure the size of the line.
+        for item in first.iter().chain(items).chain(&last) {
+            match item {
+                ParItem::Absolute(v) => width += *v,
+                ParItem::Fractional(v) => fr += *v,
+                ParItem::Text(shaped) => {
+                    width += shaped.size.x;
+                    top.set_max(shaped.baseline);
+                    bottom.set_max(shaped.size.y - shaped.baseline);
+                }
+                ParItem::Frame(frame) => {
+                    width += frame.size.x;
+                    top.set_max(frame.baseline());
+                    bottom.set_max(frame.size.y - frame.baseline());
+                }
+            }
+        }
+
+        LineLayout {
+            bidi: &self.bidi,
+            range,
+            first,
+            items,
+            last,
+            ranges,
+            size: Size::new(width, top + bottom),
+            baseline: top,
+            fr,
+            mandatory,
+        }
+    }
+
+
+    /// Find the index of the item whose range contains the `text_offset`.
+    fn find(&self, text_offset: usize) -> Option<usize> {
+        self.ranges.binary_search_by(|r| r.locate(text_offset)).ok()
+    }
+}
+
+/// A lightweight representation of a line that spans a specific range in a
+/// paragraph's text. This type enables you to cheaply measure the size of a
+/// line in a range before comitting to building the line's frame.
+struct LineLayout<'a> {
+    /// Bidi information about the paragraph.
+    bidi: &'a BidiInfo<'a>,
+    /// The range the line spans in the paragraph.
+    range: Range,
+    /// A reshaped text item if the line sliced up a text item at the start.
+    first: Option<ParItem<'a>>,
+    /// Middle items which don't need to be reprocessed.
+    items: &'a [ParItem<'a>],
+    /// A reshaped text item if the line sliced up a text item at the end. If
+    /// there is only one text item, this takes precedence over `first`.
+    last: Option<ParItem<'a>>,
+    /// The ranges, indexed as `[first, ..items, last]`. The ranges for `first`
+    /// and `last` aren't trimmed to the line, but it doesn't matter because
+    /// we're just checking which range an index falls into.
+    ranges: &'a [Range],
+    /// The size of the line.
+    size: Size,
+    /// The baseline of the line.
+    baseline: Length,
+    /// The sum of fractional ratios in the line.
+    fr: Fractional,
+    /// Whether the line ends at a mandatory break.
+    mandatory: bool,
+}
+
+impl<'a> LineLayout<'a> {
+    /// Build the line's frame.
+    fn build(
+        &self,
+        fonts: &FontStore,
+        width: Length,
+        align: Align,
+        justify: bool,
+    ) -> Frame {
+        let size = Size::new(width, self.size.y);
+
+        let mut remaining = width - self.size.x;
+        let mut offset = Length::zero();
+        let mut output = Frame::new(size);
+        output.baseline = Some(self.baseline);
+
+        let mut justification = Length::zero();
+        if justify
+            && !self.mandatory
+            && self.range.end < self.bidi.text.len()
+            && self.fr.is_zero()
+        {
+            justification = remaining / self.spaces() as f64;
+            remaining = Length::zero();
+        }
+
+        for item in self.reordered() {
+            let mut position = |frame: Frame| {
+                let x = offset + align.resolve(remaining);
+                let y = self.baseline - frame.baseline();
+                offset += frame.size.x;
+                output.merge_frame(Point::new(x, y), frame);
+            };
+
+            match item {
+                ParItem::Absolute(v) => offset += *v,
+                ParItem::Fractional(v) => offset += v.resolve(self.fr, remaining),
+                ParItem::Text(shaped) => position(shaped.build(fonts, justification)),
+                ParItem::Frame(frame) => position(frame.clone()),
+            }
+        }
+
+        output
+    }
+
+    /// The number of spaces in the line.
+    fn spaces(&self) -> usize {
+        self.shapeds().map(ShapedText::spaces).sum()
+    }
+
+    /// Iterate through the line's items in visual order.
+    fn reordered(&self) -> impl Iterator<Item = &ParItem<'a>> {
+        // The bidi crate doesn't like empty lines.
+        let (levels, runs) = if !self.range.is_empty() {
+            // Find the paragraph that contains the line.
+            let para = self
+                .bidi
+                .paragraphs
+                .iter()
+                .find(|para| para.range.contains(&self.range.start))
+                .unwrap();
+
+            // Compute the reordered ranges in visual order (left to right).
+            self.bidi.visual_runs(para, self.range.clone())
+        } else {
+            (vec![], vec![])
+        };
+
+        runs.into_iter()
+            .flat_map(move |run| {
+                let first_idx = self.find(run.start).unwrap();
+                let last_idx = self.find(run.end - 1).unwrap();
+                let range = first_idx ..= last_idx;
+
+                // Provide the items forwards or backwards depending on the run's
+                // direction.
+                if levels[run.start].is_ltr() {
+                    Either::Left(range)
+                } else {
+                    Either::Right(range.rev())
+                }
+            })
+            .map(move |idx| self.get(idx).unwrap())
+    }
+
+    /// Iterate over the line's items.
+    fn items(&self) -> impl Iterator<Item = &ParItem<'a>> {
+        self.first.iter().chain(self.items).chain(&self.last)
+    }
+
+    /// Iterate through the line's text items.
+    fn shapeds(&self) -> impl Iterator<Item = &ShapedText<'a>> {
+        self.items().filter_map(|item| match item {
+            ParItem::Text(shaped) => Some(shaped),
+            _ => None,
+        })
+    }
+
+    /// Find the index of the item whose range contains the `text_offset`.
+    fn find(&self, text_offset: usize) -> Option<usize> {
+        self.ranges.binary_search_by(|r| r.locate(text_offset)).ok()
+    }
+
+    /// Get the item at the index.
+    fn get(&self, index: usize) -> Option<&ParItem<'a>> {
+        self.items().nth(index)
+    }
+}
+
+/// Perform line breaking.
+fn break_into_lines<'a>(
+    fonts: &mut FontStore,
+    par: &'a ParLayout<'a>,
+    width: Length,
+) -> Vec<LineLayout<'a>> {
+    // The already determined lines and the current line attempt.
+    let mut lines = vec![];
+    let mut start = 0;
+    let mut last = None;
+
+    // Find suitable line breaks.
+    for (end, mandatory) in LineBreakIterator::new(&par.bidi.text) {
+        // Compute the line and its size.
+        let mut line = par.line(fonts, start .. end, mandatory);
+
+        // If the line doesn't fit anymore, we push the last fitting attempt
+        // into the stack and rebuild the line from its end. The resulting
+        // line cannot be broken up further.
+        if !width.fits(line.size.x) {
+            if let Some((last_line, last_end)) = last.take() {
+                lines.push(last_line);
+                start = last_end;
+                line = par.line(fonts, start .. end, mandatory);
+            }
+        }
+
+        // Finish the current line if there is a mandatory line break (i.e.
+        // due to "\n") or if the line doesn't fit horizontally already
+        // since then no shorter line will be possible.
+        if mandatory || !width.fits(line.size.x) {
+            lines.push(line);
+            start = end;
+            last = None;
+        } else {
+            last = Some((line, end));
+        }
+    }
+
+    if let Some((line, _)) = last {
+        lines.push(line);
+    }
+
+    lines
+}
+
+/// Combine the lines into one frame per region.
+fn stack_lines(
+    fonts: &FontStore,
+    lines: Vec<LineLayout>,
+    regions: &Regions,
+    styles: StyleChain,
+) -> Vec<Arc<Frame>> {
+    let em = styles.get(TextNode::SIZE).abs;
+    let leading = styles.get(ParNode::LEADING).resolve(em);
+    let align = styles.get(ParNode::ALIGN);
+    let justify = styles.get(ParNode::JUSTIFY);
+
+    // Determine the paragraph's width: Full width of the region if we
+    // should expand or there's fractional spacing, fit-to-width otherwise.
+    let mut width = regions.first.x;
+    if !regions.expand.x && lines.iter().all(|line| line.fr.is_zero()) {
+        width = lines.iter().map(|line| line.size.x).max().unwrap_or_default();
+    }
+
+    // State for final frame building.
+    let mut regions = regions.clone();
+    let mut finished = vec![];
+    let mut first = true;
+    let mut output = Frame::new(Size::with_x(width));
+
+    // Stack the lines into one frame per region.
+    for line in lines {
+        while !regions.first.y.fits(line.size.y) && !regions.in_last() {
+            finished.push(Arc::new(output));
+            output = Frame::new(Size::with_x(width));
+            regions.next();
+            first = true;
+        }
+
+        if !first {
+            output.size.y += leading;
+        }
+
+        let frame = line.build(fonts, width, align, justify);
+        let pos = Point::with_y(output.size.y);
+        output.size.y += frame.size.y;
+        output.merge_frame(pos, frame);
+
+        regions.first.y -= line.size.y + leading;
+        first = false;
+    }
+
+    finished.push(Arc::new(output));
+    finished
+}
diff --git a/src/library/text/raw.rs b/src/library/text/raw.rs
new file mode 100644
index 00000000..97857f11
--- /dev/null
+++ b/src/library/text/raw.rs
@@ -0,0 +1,127 @@
+use once_cell::sync::Lazy;
+use syntect::easy::HighlightLines;
+use syntect::highlighting::{FontStyle, Highlighter, Style, Theme, ThemeSet};
+use syntect::parsing::SyntaxSet;
+
+use crate::library::prelude::*;
+use crate::library::text::TextNode;
+use crate::source::SourceId;
+use crate::syntax::{self, RedNode};
+
+/// The lazily-loaded theme used for syntax highlighting.
+static THEME: Lazy<Theme> =
+    Lazy::new(|| ThemeSet::load_defaults().themes.remove("InspiredGitHub").unwrap());
+
+/// The lazily-loaded syntect syntax definitions.
+static SYNTAXES: Lazy<SyntaxSet> = Lazy::new(|| SyntaxSet::load_defaults_newlines());
+
+/// Monospaced text with optional syntax highlighting.
+#[derive(Debug, Hash)]
+pub struct RawNode {
+    /// The raw text.
+    pub text: EcoString,
+    /// Whether the node is block-level.
+    pub block: bool,
+}
+
+#[class]
+impl RawNode {
+    /// The language to syntax-highlight in.
+    pub const LANG: Option<EcoString> = None;
+
+    fn construct(_: &mut Context, args: &mut Args) -> TypResult<Template> {
+        Ok(Template::show(Self {
+            text: args.expect("text")?,
+            block: args.named("block")?.unwrap_or(false),
+        }))
+    }
+}
+
+impl Show for RawNode {
+    fn show(&self, ctx: &mut Context, styles: StyleChain) -> TypResult<Template> {
+        let lang = styles.get_ref(Self::LANG).as_ref();
+
+        if let Some(template) = styles.show(self, ctx, [
+            Value::Str(self.text.clone()),
+            match lang {
+                Some(lang) => Value::Str(lang.clone()),
+                None => Value::None,
+            },
+            Value::Bool(self.block),
+        ])? {
+            return Ok(template);
+        }
+
+        let foreground = THEME
+            .settings
+            .foreground
+            .map(Color::from)
+            .unwrap_or(Color::BLACK)
+            .into();
+
+        let mut template = if matches!(
+            lang.map(|s| s.to_lowercase()).as_deref(),
+            Some("typ" | "typst")
+        ) {
+            let mut seq = vec![];
+            let green = crate::parse::parse(&self.text);
+            let red = RedNode::from_root(green, SourceId::from_raw(0));
+            let highlighter = Highlighter::new(&THEME);
+
+            syntax::highlight_syntect(red.as_ref(), &highlighter, &mut |range, style| {
+                seq.push(styled(&self.text[range], foreground, style));
+            });
+
+            Template::sequence(seq)
+        } else if let Some(syntax) =
+            lang.and_then(|token| SYNTAXES.find_syntax_by_token(&token))
+        {
+            let mut seq = vec![];
+            let mut highlighter = HighlightLines::new(syntax, &THEME);
+            for (i, line) in self.text.lines().enumerate() {
+                if i != 0 {
+                    seq.push(Template::Linebreak);
+                }
+
+                for (style, piece) in highlighter.highlight(line, &SYNTAXES) {
+                    seq.push(styled(piece, foreground, style));
+                }
+            }
+
+            Template::sequence(seq)
+        } else {
+            Template::Text(self.text.clone())
+        };
+
+        if self.block {
+            template = Template::Block(template.pack());
+        }
+
+        Ok(template.monospaced())
+    }
+}
+
+/// Style a piece of text with a syntect style.
+fn styled(piece: &str, foreground: Paint, style: Style) -> Template {
+    let mut styles = StyleMap::new();
+    let mut body = Template::Text(piece.into());
+
+    let paint = style.foreground.into();
+    if paint != foreground {
+        styles.set(TextNode::FILL, paint);
+    }
+
+    if style.font_style.contains(FontStyle::BOLD) {
+        styles.set(TextNode::STRONG, true);
+    }
+
+    if style.font_style.contains(FontStyle::ITALIC) {
+        styles.set(TextNode::EMPH, true);
+    }
+
+    if style.font_style.contains(FontStyle::UNDERLINE) {
+        body = body.underlined();
+    }
+
+    body.styled_with_map(styles)
+}
diff --git a/src/library/text/shaping.rs b/src/library/text/shaping.rs
new file mode 100644
index 00000000..26c8daf3
--- /dev/null
+++ b/src/library/text/shaping.rs
@@ -0,0 +1,552 @@
+use std::ops::Range;
+
+use rustybuzz::{Feature, UnicodeBuffer};
+
+use super::*;
+use crate::font::{FaceId, FontStore, FontVariant};
+use crate::library::prelude::*;
+use crate::util::SliceExt;
+
+/// The result of shaping text.
+///
+/// This type contains owned or borrowed shaped text runs, which can be
+/// measured, used to reshape substrings more quickly and converted into a
+/// frame.
+#[derive(Debug, Clone)]
+pub struct ShapedText<'a> {
+    /// The text that was shaped.
+    pub text: Cow<'a, str>,
+    /// The text direction.
+    pub dir: Dir,
+    /// The text's style properties.
+    pub styles: StyleChain<'a>,
+    /// The size of the text's bounding box.
+    pub size: Size,
+    /// The baseline from the top of the frame.
+    pub baseline: Length,
+    /// The shaped glyphs.
+    pub glyphs: Cow<'a, [ShapedGlyph]>,
+}
+
+/// A single glyph resulting from shaping.
+#[derive(Debug, Copy, Clone)]
+pub struct ShapedGlyph {
+    /// The font face the glyph is contained in.
+    pub face_id: FaceId,
+    /// The glyph's index in the face.
+    pub glyph_id: u16,
+    /// The advance width of the glyph.
+    pub x_advance: Em,
+    /// The horizontal offset of the glyph.
+    pub x_offset: Em,
+    /// The start index of the glyph in the source text.
+    pub text_index: usize,
+    /// Whether splitting the shaping result before this glyph would yield the
+    /// same results as shaping the parts to both sides of `text_index`
+    /// separately.
+    pub safe_to_break: bool,
+    /// Whether this glyph represents a space.
+    pub is_space: bool,
+}
+
+/// A side you can go toward.
+enum Side {
+    /// Go toward the west.
+    Left,
+    /// Go toward the east.
+    Right,
+}
+
+impl<'a> ShapedText<'a> {
+    /// Build the shaped text's frame.
+    ///
+    /// The `justification` defines how much extra advance width each
+    /// [space glyph](ShapedGlyph::is_space) will get.
+    pub fn build(&self, fonts: &FontStore, justification: Length) -> Frame {
+        let mut offset = Length::zero();
+        let mut frame = Frame::new(self.size);
+        frame.baseline = Some(self.baseline);
+
+        for (face_id, group) in self.glyphs.as_ref().group_by_key(|g| g.face_id) {
+            let pos = Point::new(offset, self.baseline);
+
+            let size = self.styles.get(TextNode::SIZE).abs;
+            let fill = self.styles.get(TextNode::FILL);
+            let glyphs = group
+                .iter()
+                .map(|glyph| Glyph {
+                    id: glyph.glyph_id,
+                    x_advance: glyph.x_advance
+                        + if glyph.is_space {
+                            frame.size.x += justification;
+                            Em::from_length(justification, size)
+                        } else {
+                            Em::zero()
+                        },
+                    x_offset: glyph.x_offset,
+                })
+                .collect();
+
+            let text = Text { face_id, size, fill, glyphs };
+            let text_layer = frame.layer();
+            let width = text.width();
+
+            // Apply line decorations.
+            for deco in self.styles.get_cloned(TextNode::LINES) {
+                decorate(&mut frame, &deco, fonts, &text, pos, width);
+            }
+
+            frame.insert(text_layer, pos, Element::Text(text));
+            offset += width;
+        }
+
+        // Apply link if it exists.
+        if let Some(url) = self.styles.get_ref(TextNode::LINK) {
+            frame.link(url);
+        }
+
+        frame
+    }
+
+    /// How many spaces the text contains.
+    pub fn spaces(&self) -> usize {
+        self.glyphs.iter().filter(|g| g.is_space).count()
+    }
+
+    /// Reshape a range of the shaped text, reusing information from this
+    /// shaping process if possible.
+    pub fn reshape(
+        &'a self,
+        fonts: &mut FontStore,
+        text_range: Range<usize>,
+    ) -> ShapedText<'a> {
+        if let Some(glyphs) = self.slice_safe_to_break(text_range.clone()) {
+            let (size, baseline) = measure(fonts, glyphs, self.styles);
+            Self {
+                text: Cow::Borrowed(&self.text[text_range]),
+                dir: self.dir,
+                styles: self.styles.clone(),
+                size,
+                baseline,
+                glyphs: Cow::Borrowed(glyphs),
+            }
+        } else {
+            shape(fonts, &self.text[text_range], self.styles.clone(), self.dir)
+        }
+    }
+
+    /// Find the subslice of glyphs that represent the given text range if both
+    /// sides are safe to break.
+    fn slice_safe_to_break(&self, text_range: Range<usize>) -> Option<&[ShapedGlyph]> {
+        let Range { mut start, mut end } = text_range;
+        if !self.dir.is_positive() {
+            std::mem::swap(&mut start, &mut end);
+        }
+
+        let left = self.find_safe_to_break(start, Side::Left)?;
+        let right = self.find_safe_to_break(end, Side::Right)?;
+        Some(&self.glyphs[left .. right])
+    }
+
+    /// Find the glyph offset matching the text index that is most towards the
+    /// given side and safe-to-break.
+    fn find_safe_to_break(&self, text_index: usize, towards: Side) -> Option<usize> {
+        let ltr = self.dir.is_positive();
+
+        // Handle edge cases.
+        let len = self.glyphs.len();
+        if text_index == 0 {
+            return Some(if ltr { 0 } else { len });
+        } else if text_index == self.text.len() {
+            return Some(if ltr { len } else { 0 });
+        }
+
+        // Find any glyph with the text index.
+        let mut idx = self
+            .glyphs
+            .binary_search_by(|g| {
+                let ordering = g.text_index.cmp(&text_index);
+                if ltr { ordering } else { ordering.reverse() }
+            })
+            .ok()?;
+
+        let next = match towards {
+            Side::Left => usize::checked_sub,
+            Side::Right => usize::checked_add,
+        };
+
+        // Search for the outermost glyph with the text index.
+        while let Some(next) = next(idx, 1) {
+            if self.glyphs.get(next).map_or(true, |g| g.text_index != text_index) {
+                break;
+            }
+            idx = next;
+        }
+
+        // RTL needs offset one because the left side of the range should be
+        // exclusive and the right side inclusive, contrary to the normal
+        // behaviour of ranges.
+        if !ltr {
+            idx += 1;
+        }
+
+        self.glyphs[idx].safe_to_break.then(|| idx)
+    }
+}
+
+/// Shape text into [`ShapedText`].
+pub fn shape<'a>(
+    fonts: &mut FontStore,
+    text: &'a str,
+    styles: StyleChain<'a>,
+    dir: Dir,
+) -> ShapedText<'a> {
+    let text = match styles.get(TextNode::CASE) {
+        Some(case) => Cow::Owned(case.apply(text)),
+        None => Cow::Borrowed(text),
+    };
+
+    let mut glyphs = vec![];
+    if !text.is_empty() {
+        shape_segment(
+            fonts,
+            &mut glyphs,
+            0,
+            &text,
+            variant(styles),
+            families(styles),
+            None,
+            dir,
+            &tags(styles),
+        );
+    }
+
+    track(&mut glyphs, styles.get(TextNode::TRACKING));
+    let (size, baseline) = measure(fonts, &glyphs, styles);
+
+    ShapedText {
+        text,
+        dir,
+        styles,
+        size,
+        baseline,
+        glyphs: Cow::Owned(glyphs),
+    }
+}
+
+/// Resolve the font variant with `STRONG` and `EMPH` factored in.
+fn variant(styles: StyleChain) -> FontVariant {
+    let mut variant = FontVariant::new(
+        styles.get(TextNode::STYLE),
+        styles.get(TextNode::WEIGHT),
+        styles.get(TextNode::STRETCH),
+    );
+
+    if styles.get(TextNode::STRONG) {
+        variant.weight = variant.weight.thicken(300);
+    }
+
+    if styles.get(TextNode::EMPH) {
+        variant.style = match variant.style {
+            FontStyle::Normal => FontStyle::Italic,
+            FontStyle::Italic => FontStyle::Normal,
+            FontStyle::Oblique => FontStyle::Normal,
+        }
+    }
+
+    variant
+}
+
+/// Resolve a prioritized iterator over the font families.
+fn families(styles: StyleChain) -> impl Iterator<Item = &str> + Clone {
+    let head = if styles.get(TextNode::MONOSPACED) {
+        styles.get_ref(TextNode::MONOSPACE).as_slice()
+    } else {
+        &[]
+    };
+
+    let core = styles.get_ref(TextNode::FAMILY).iter().flat_map(move |family| {
+        match family {
+            FontFamily::Named(name) => std::slice::from_ref(name),
+            FontFamily::Serif => styles.get_ref(TextNode::SERIF),
+            FontFamily::SansSerif => styles.get_ref(TextNode::SANS_SERIF),
+            FontFamily::Monospace => styles.get_ref(TextNode::MONOSPACE),
+        }
+    });
+
+    let tail: &[&str] = if styles.get(TextNode::FALLBACK) {
+        &["ibm plex sans", "latin modern math", "twitter color emoji"]
+    } else {
+        &[]
+    };
+
+    head.iter()
+        .chain(core)
+        .map(|named| named.as_str())
+        .chain(tail.iter().copied())
+}
+
+/// Collect the tags of the OpenType features to apply.
+fn tags(styles: StyleChain) -> Vec<Feature> {
+    let mut tags = vec![];
+    let mut feat = |tag, value| {
+        tags.push(Feature::new(Tag::from_bytes(tag), value, ..));
+    };
+
+    // Features that are on by default in Harfbuzz are only added if disabled.
+    if !styles.get(TextNode::KERNING) {
+        feat(b"kern", 0);
+    }
+
+    // Features that are off by default in Harfbuzz are only added if enabled.
+    if styles.get(TextNode::SMALLCAPS) {
+        feat(b"smcp", 1);
+    }
+
+    if styles.get(TextNode::ALTERNATES) {
+        feat(b"salt", 1);
+    }
+
+    let storage;
+    if let Some(set) = styles.get(TextNode::STYLISTIC_SET) {
+        storage = [b's', b's', b'0' + set.get() / 10, b'0' + set.get() % 10];
+        feat(&storage, 1);
+    }
+
+    if !styles.get(TextNode::LIGATURES) {
+        feat(b"liga", 0);
+        feat(b"clig", 0);
+    }
+
+    if styles.get(TextNode::DISCRETIONARY_LIGATURES) {
+        feat(b"dlig", 1);
+    }
+
+    if styles.get(TextNode::HISTORICAL_LIGATURES) {
+        feat(b"hilg", 1);
+    }
+
+    match styles.get(TextNode::NUMBER_TYPE) {
+        Smart::Auto => {}
+        Smart::Custom(NumberType::Lining) => feat(b"lnum", 1),
+        Smart::Custom(NumberType::OldStyle) => feat(b"onum", 1),
+    }
+
+    match styles.get(TextNode::NUMBER_WIDTH) {
+        Smart::Auto => {}
+        Smart::Custom(NumberWidth::Proportional) => feat(b"pnum", 1),
+        Smart::Custom(NumberWidth::Tabular) => feat(b"tnum", 1),
+    }
+
+    match styles.get(TextNode::NUMBER_POSITION) {
+        NumberPosition::Normal => {}
+        NumberPosition::Subscript => feat(b"subs", 1),
+        NumberPosition::Superscript => feat(b"sups", 1),
+    }
+
+    if styles.get(TextNode::SLASHED_ZERO) {
+        feat(b"zero", 1);
+    }
+
+    if styles.get(TextNode::FRACTIONS) {
+        feat(b"frac", 1);
+    }
+
+    for &(tag, value) in styles.get_ref(TextNode::FEATURES).iter() {
+        tags.push(Feature::new(tag, value, ..))
+    }
+
+    tags
+}
+
+/// Shape text with font fallback using the `families` iterator.
+fn shape_segment<'a>(
+    fonts: &mut FontStore,
+    glyphs: &mut Vec<ShapedGlyph>,
+    base: usize,
+    text: &str,
+    variant: FontVariant,
+    mut families: impl Iterator<Item = &'a str> + Clone,
+    mut first_face: Option<FaceId>,
+    dir: Dir,
+    tags: &[rustybuzz::Feature],
+) {
+    // No font has newlines.
+    if text.chars().all(|c| c == '\n') {
+        return;
+    }
+
+    // Select the font family.
+    let (face_id, fallback) = loop {
+        // Try to load the next available font family.
+        match families.next() {
+            Some(family) => {
+                if let Some(id) = fonts.select(family, variant) {
+                    break (id, true);
+                }
+            }
+            // We're out of families, so we don't do any more fallback and just
+            // shape the tofus with the first face we originally used.
+            None => match first_face {
+                Some(id) => break (id, false),
+                None => return,
+            },
+        }
+    };
+
+    // Remember the id if this the first available face since we use that one to
+    // shape tofus.
+    first_face.get_or_insert(face_id);
+
+    // Fill the buffer with our text.
+    let mut buffer = UnicodeBuffer::new();
+    buffer.push_str(text);
+    buffer.set_direction(match dir {
+        Dir::LTR => rustybuzz::Direction::LeftToRight,
+        Dir::RTL => rustybuzz::Direction::RightToLeft,
+        _ => unimplemented!(),
+    });
+
+    // Shape!
+    let mut face = fonts.get(face_id);
+    let buffer = rustybuzz::shape(face.ttf(), tags, buffer);
+    let infos = buffer.glyph_infos();
+    let pos = buffer.glyph_positions();
+
+    // Collect the shaped glyphs, doing fallback and shaping parts again with
+    // the next font if necessary.
+    let mut i = 0;
+    while i < infos.len() {
+        let info = &infos[i];
+        let cluster = info.cluster as usize;
+
+        if info.glyph_id != 0 || !fallback {
+            // Add the glyph to the shaped output.
+            // TODO: Don't ignore y_advance and y_offset.
+            glyphs.push(ShapedGlyph {
+                face_id,
+                glyph_id: info.glyph_id as u16,
+                x_advance: face.to_em(pos[i].x_advance),
+                x_offset: face.to_em(pos[i].x_offset),
+                text_index: base + cluster,
+                safe_to_break: !info.unsafe_to_break(),
+                is_space: text[cluster ..].chars().next() == Some(' '),
+            });
+        } else {
+            // Determine the source text range for the tofu sequence.
+            let range = {
+                // First, search for the end of the tofu sequence.
+                let k = i;
+                while infos.get(i + 1).map_or(false, |info| info.glyph_id == 0) {
+                    i += 1;
+                }
+
+                // Then, determine the start and end text index.
+                //
+                // Examples:
+                // Everything is shown in visual order. Tofus are written as "_".
+                // We want to find out that the tofus span the text `2..6`.
+                // Note that the clusters are longer than 1 char.
+                //
+                // Left-to-right:
+                // Text:     h a l i h a l l o
+                // Glyphs:   A   _   _   C   E
+                // Clusters: 0   2   4   6   8
+                //              k=1 i=2
+                //
+                // Right-to-left:
+                // Text:     O L L A H I L A H
+                // Glyphs:   E   C   _   _   A
+                // Clusters: 8   6   4   2   0
+                //                  k=2 i=3
+                let ltr = dir.is_positive();
+                let first = if ltr { k } else { i };
+                let start = infos[first].cluster as usize;
+                let last = if ltr { i.checked_add(1) } else { k.checked_sub(1) };
+                let end = last
+                    .and_then(|last| infos.get(last))
+                    .map_or(text.len(), |info| info.cluster as usize);
+
+                start .. end
+            };
+
+            // Recursively shape the tofu sequence with the next family.
+            shape_segment(
+                fonts,
+                glyphs,
+                base + range.start,
+                &text[range],
+                variant,
+                families.clone(),
+                first_face,
+                dir,
+                tags,
+            );
+
+            face = fonts.get(face_id);
+        }
+
+        i += 1;
+    }
+}
+
+/// Apply tracking to a slice of shaped glyphs.
+fn track(glyphs: &mut [ShapedGlyph], tracking: Em) {
+    if tracking.is_zero() {
+        return;
+    }
+
+    let mut glyphs = glyphs.iter_mut().peekable();
+    while let Some(glyph) = glyphs.next() {
+        if glyphs
+            .peek()
+            .map_or(false, |next| glyph.text_index != next.text_index)
+        {
+            glyph.x_advance += tracking;
+        }
+    }
+}
+
+/// Measure the size and baseline of a run of shaped glyphs with the given
+/// properties.
+fn measure(
+    fonts: &mut FontStore,
+    glyphs: &[ShapedGlyph],
+    styles: StyleChain,
+) -> (Size, Length) {
+    let mut width = Length::zero();
+    let mut top = Length::zero();
+    let mut bottom = Length::zero();
+
+    let size = styles.get(TextNode::SIZE).abs;
+    let top_edge = styles.get(TextNode::TOP_EDGE);
+    let bottom_edge = styles.get(TextNode::BOTTOM_EDGE);
+
+    // Expand top and bottom by reading the face's vertical metrics.
+    let mut expand = |face: &Face| {
+        top.set_max(face.vertical_metric(top_edge, size));
+        bottom.set_max(-face.vertical_metric(bottom_edge, size));
+    };
+
+    if glyphs.is_empty() {
+        // When there are no glyphs, we just use the vertical metrics of the
+        // first available font.
+        for family in families(styles) {
+            if let Some(face_id) = fonts.select(family, variant(styles)) {
+                expand(fonts.get(face_id));
+                break;
+            }
+        }
+    } else {
+        for (face_id, group) in glyphs.group_by_key(|g| g.face_id) {
+            let face = fonts.get(face_id);
+            expand(face);
+
+            for glyph in group {
+                width += glyph.x_advance.resolve(size);
+            }
+        }
+    }
+
+    (Size::new(width, top + bottom), top)
+}
-- 
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