Configurable font edges ⚙

Adds top-edge and bottom-edge parameters to the font function. These define how
the box around a word is computed. The possible values are:
- ascender
- cap-height (default top edge)
- x-height
- baseline (default bottom edge)
- descender

The defaults are chosen so that it's easy to create good-looking designs with
vertical alignment. Since they are much tighter than what most other software
uses by default, the default leading had to be increased to 50% of the font size
and paragraph spacing to 100% of the font size.

The values cap-height and x-height fall back to ascender in case they are zero
because this value may occur in fonts that don't have glyphs with cap- or
x-height (like Twitter Color Emoji). Since cap-height is the default top edge,
doing no fallback would break things badly.

Removes softness in favor of a simple boolean for pages and a more finegread u8
for spacing. This is needed to make paragraph spacing consume line spacing
created by hard line breaks.

50 files changed, 231 insertions, 111 deletions

diff --git a/src/exec/context.rs b/src/exec/context.rs
index 6a1c2416..7fd72fe3 100644
--- a/src/exec/context.rs
+++ b/src/exec/context.rs
@@ -38,7 +38,7 @@ impl<'a> ExecContext<'a> {
             env,
             diags: DiagSet::new(),
             tree: Tree { runs: vec![] },
-            page: Some(PageInfo::new(&state, Softness::Hard)),
+            page: Some(PageInfo::new(&state, true)),
             stack: NodeStack::new(&state),
             par: NodePar::new(&state),
             state,
@@ -77,7 +77,8 @@ impl<'a> ExecContext<'a> {
 
     /// Push a layout node into the active paragraph.
     ///
-    /// Spacing nodes will be handled according to their [`Softness`].
+    /// Spacing nodes will be handled according to their
+    /// [`softness`](NodeSpacing::softness).
     pub fn push(&mut self, node: impl Into<Node>) {
         push(&mut self.par.children, node.into());
     }
@@ -87,7 +88,7 @@ impl<'a> ExecContext<'a> {
         let em = self.state.font.font_size();
         self.push(NodeSpacing {
             amount: self.state.par.word_spacing.resolve(em),
-            softness: Softness::Soft,
+            softness: 1,
         });
     }
 
@@ -109,15 +110,19 @@ impl<'a> ExecContext<'a> {
 
     /// Apply a forced line break.
     pub fn push_linebreak(&mut self) {
-        self.finish_par();
+        let em = self.state.font.font_size();
+        self.push_into_stack(NodeSpacing {
+            amount: self.state.par.leading.resolve(em),
+            softness: 2,
+        });
     }
 
     /// Apply a forced paragraph break.
     pub fn push_parbreak(&mut self) {
         let em = self.state.font.font_size();
         self.push_into_stack(NodeSpacing {
-            amount: self.state.par.par_spacing.resolve(em),
-            softness: Softness::Soft,
+            amount: self.state.par.spacing.resolve(em),
+            softness: 1,
         });
     }
 
@@ -163,11 +168,13 @@ impl<'a> ExecContext<'a> {
 
         NodeText {
             text,
-            aligns: self.state.aligns,
             dir: self.state.dirs.cross,
-            font_size: self.state.font.font_size(),
+            aligns: self.state.aligns,
             families: Rc::clone(&self.state.font.families),
             variant,
+            font_size: self.state.font.font_size(),
+            top_edge: self.state.font.top_edge,
+            bottom_edge: self.state.font.bottom_edge,
         }
     }
 
@@ -192,12 +199,12 @@ impl<'a> ExecContext<'a> {
     }
 
     /// Finish the active page.
-    pub fn finish_page(&mut self, keep: bool, new_softness: Softness, source: Span) {
+    pub fn finish_page(&mut self, keep: bool, hard: bool, source: Span) {
         if let Some(info) = &mut self.page {
-            let info = mem::replace(info, PageInfo::new(&self.state, new_softness));
+            let info = mem::replace(info, PageInfo::new(&self.state, hard));
             let stack = self.finish_stack();
 
-            if !stack.children.is_empty() || (keep && info.softness == Softness::Hard) {
+            if !stack.children.is_empty() || (keep && info.hard) {
                 self.tree.runs.push(NodePages {
                     size: info.size,
                     child: NodePad {
@@ -215,7 +222,7 @@ impl<'a> ExecContext<'a> {
     /// Finish execution and return the created layout tree.
     pub fn finish(mut self) -> Pass<Tree> {
         assert!(self.page.is_some());
-        self.finish_page(true, Softness::Soft, Span::default());
+        self.finish_page(true, false, Span::default());
         Pass::new(self.tree, self.diags)
     }
 }
@@ -223,16 +230,18 @@ impl<'a> ExecContext<'a> {
 /// Push a node into a list, taking care of spacing softness.
 fn push(nodes: &mut Vec<Node>, node: Node) {
     if let Node::Spacing(spacing) = node {
-        if spacing.softness == Softness::Soft && nodes.is_empty() {
+        if nodes.is_empty() && spacing.softness > 0 {
             return;
         }
 
         if let Some(&Node::Spacing(other)) = nodes.last() {
-            if spacing.softness > other.softness {
-                nodes.pop();
-            } else if spacing.softness == Softness::Soft {
+            if spacing.softness > 0 && spacing.softness >= other.softness {
                 return;
             }
+
+            if spacing.softness < other.softness {
+                nodes.pop();
+            }
         }
     }
 
@@ -242,7 +251,7 @@ fn push(nodes: &mut Vec<Node>, node: Node) {
 /// Remove trailing soft spacing from a node list.
 fn trim(nodes: &mut Vec<Node>) {
     if let Some(&Node::Spacing(spacing)) = nodes.last() {
-        if spacing.softness == Softness::Soft {
+        if spacing.softness > 0 {
             nodes.pop();
         }
     }
@@ -252,15 +261,15 @@ fn trim(nodes: &mut Vec<Node>) {
 struct PageInfo {
     size: Size,
     padding: Sides<Linear>,
-    softness: Softness,
+    hard: bool,
 }
 
 impl PageInfo {
-    fn new(state: &State, softness: Softness) -> Self {
+    fn new(state: &State, hard: bool) -> Self {
         Self {
             size: state.page.size,
             padding: state.page.margins(),
-            softness,
+            hard,
         }
     }
 }
@@ -281,7 +290,7 @@ impl NodePar {
         Self {
             dirs: state.dirs,
             aligns: state.aligns,
-            line_spacing: state.par.line_spacing.resolve(em),
+            line_spacing: state.par.leading.resolve(em),
             children: vec![],
         }
     }
diff --git a/src/exec/mod.rs b/src/exec/mod.rs
index 45abca02..35ffa2b6 100644
--- a/src/exec/mod.rs
+++ b/src/exec/mod.rs
@@ -35,15 +35,6 @@ pub fn exec(
     ctx.finish()
 }
 
-/// Defines how an item interacts with surrounding items.
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
-pub enum Softness {
-    /// A soft item can be skipped in some circumstances.
-    Soft,
-    /// A hard item is always retained.
-    Hard,
-}
-
 /// Execute a node.
 ///
 /// This manipulates active styling and document state and produces layout
@@ -106,15 +97,15 @@ impl Exec for NodeRaw {
         ctx.set_monospace();
 
         let em = ctx.state.font.font_size();
-        let line_spacing = ctx.state.par.line_spacing.resolve(em);
+        let leading = ctx.state.par.leading.resolve(em);
 
         let mut children = vec![];
         let mut newline = false;
         for line in &self.lines {
             if newline {
                 children.push(layout::Node::Spacing(NodeSpacing {
-                    amount: line_spacing,
-                    softness: Softness::Soft,
+                    amount: leading,
+                    softness: 2,
                 }));
             }
 
diff --git a/src/exec/state.rs b/src/exec/state.rs
index 65f26439..aa2dde1c 100644
--- a/src/exec/state.rs
+++ b/src/exec/state.rs
@@ -2,10 +2,9 @@ use std::rc::Rc;
 
 use fontdock::{fallback, FallbackTree, FontStretch, FontStyle, FontVariant, FontWeight};
 
-use crate::geom::{
-    Align, Dir, LayoutAligns, LayoutDirs, Length, Linear, Relative, Sides, Size,
-};
+use crate::geom::*;
 use crate::paper::{Paper, PaperClass, PAPER_A4};
+use crate::shaping::VerticalFontMetric;
 
 /// The evaluation state.
 #[derive(Debug, Clone, PartialEq)]
@@ -77,20 +76,20 @@ impl Default for PageState {
 /// Defines paragraph properties.
 #[derive(Debug, Copy, Clone, PartialEq)]
 pub struct ParState {
+    /// The spacing between paragraphs (dependent on scaled font size).
+    pub spacing: Linear,
+    /// The spacing between lines (dependent on scaled font size).
+    pub leading: Linear,
     /// The spacing between words (dependent on scaled font size).
     pub word_spacing: Linear,
-    /// The spacing between lines (dependent on scaled font size).
-    pub line_spacing: Linear,
-    /// The spacing between paragraphs (dependent on scaled font size).
-    pub par_spacing: Linear,
 }
 
 impl Default for ParState {
     fn default() -> Self {
         Self {
+            spacing: Relative::new(1.0).into(),
+            leading: Relative::new(0.5).into(),
             word_spacing: Relative::new(0.25).into(),
-            line_spacing: Linear::ZERO,
-            par_spacing: Relative::new(0.5).into(),
         }
     }
 }
@@ -106,6 +105,10 @@ pub struct FontState {
     pub size: Length,
     /// The linear to apply on the base font size.
     pub scale: Linear,
+    /// The top end of the text bounding box.
+    pub top_edge: VerticalFontMetric,
+    /// The bottom end of the text bounding box.
+    pub bottom_edge: VerticalFontMetric,
     /// Whether the strong toggle is active or inactive. This determines
     /// whether the next `*` adds or removes font weight.
     pub strong: bool,
@@ -141,6 +144,8 @@ impl Default for FontState {
                 stretch: FontStretch::Normal,
             },
             size: Length::pt(11.0),
+            top_edge: VerticalFontMetric::CapHeight,
+            bottom_edge: VerticalFontMetric::Baseline,
             scale: Linear::ONE,
             strong: false,
             emph: false,
diff --git a/src/export/pdf.rs b/src/export/pdf.rs
index f86f977c..43c58403 100644
--- a/src/export/pdf.rs
+++ b/src/export/pdf.rs
@@ -180,6 +180,7 @@ impl<'a> PdfExporter<'a> {
 
                 Element::Text(shaped) => {
                     let mut text = content.text();
+
                     // Check if we need to issue a font switching action.
                     if shaped.face != face || shaped.font_size != size {
                         face = shaped.face;
diff --git a/src/layout/spacing.rs b/src/layout/spacing.rs
index 4b564a2b..2bcb7ac1 100644
--- a/src/layout/spacing.rs
+++ b/src/layout/spacing.rs
@@ -1,7 +1,6 @@
 use std::fmt::{self, Debug, Formatter};
 
 use super::*;
-use crate::exec::Softness;
 
 /// A spacing node.
 #[derive(Copy, Clone, PartialEq)]
@@ -10,13 +9,11 @@ pub struct NodeSpacing {
     pub amount: Length,
     /// Defines how spacing interacts with surrounding spacing.
     ///
-    /// Hard spacing assures that a fixed amount of spacing will always be
-    /// inserted. Soft spacing will be consumed by previous soft spacing or
-    /// neighbouring hard spacing and can be used to insert overridable spacing,
-    /// e.g. between words or paragraphs.
-    ///
-    /// This field is only used in evaluation, not in layouting.
-    pub softness: Softness,
+    /// Hard spacing (`softness = 0`) assures that a fixed amount of spacing
+    /// will always be inserted. Soft spacing (`softness >= 1`) will be consumed
+    /// by other spacing with lower softness and can be used to insert
+    /// overridable spacing, e.g. between words or paragraphs.
+    pub softness: u8,
 }
 
 impl Layout for NodeSpacing {
@@ -27,10 +24,7 @@ impl Layout for NodeSpacing {
 
 impl Debug for NodeSpacing {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        match self.softness {
-            Softness::Soft => write!(f, "Soft({})", self.amount),
-            Softness::Hard => write!(f, "Hard({})", self.amount),
-        }
+        write!(f, "Spacing({}, {})", self.amount, self.softness)
     }
 }
 
diff --git a/src/layout/text.rs b/src/layout/text.rs
index 256a6e6d..7b4eb08e 100644
--- a/src/layout/text.rs
+++ b/src/layout/text.rs
@@ -4,35 +4,41 @@ use std::rc::Rc;
 use fontdock::{FallbackTree, FontVariant};
 
 use super::*;
-use crate::shaping;
+use crate::shaping::{shape, VerticalFontMetric};
 
 /// A text node.
 #[derive(Clone, PartialEq)]
 pub struct NodeText {
+    /// The text.
+    pub text: String,
     /// The text direction.
     pub dir: Dir,
     /// How to align this text node in its parent.
     pub aligns: LayoutAligns,
-    /// The text.
-    pub text: String,
-    /// The font size.
-    pub font_size: Length,
     /// The families used for font fallback.
     pub families: Rc<FallbackTree>,
     /// The font variant,
     pub variant: FontVariant,
+    /// The font size.
+    pub font_size: Length,
+    /// The top end of the text bounding box.
+    pub top_edge: VerticalFontMetric,
+    /// The bottom end of the text bounding box.
+    pub bottom_edge: VerticalFontMetric,
 }
 
 impl Layout for NodeText {
     fn layout(&self, ctx: &mut LayoutContext, _: &Areas) -> Layouted {
         Layouted::Frame(
-            shaping::shape(
+            shape(
                 &self.text,
                 self.dir,
-                self.font_size,
-                &mut ctx.env.fonts,
                 &self.families,
                 self.variant,
+                self.font_size,
+                self.top_edge,
+                self.bottom_edge,
+                &mut ctx.env.fonts,
             ),
             self.aligns,
         )
diff --git a/src/library/font.rs b/src/library/font.rs
index 460cfba1..ecc15d96 100644
--- a/src/library/font.rs
+++ b/src/library/font.rs
@@ -1,6 +1,7 @@
 use fontdock::{FontStretch, FontStyle, FontWeight};
 
 use super::*;
+use crate::shaping::VerticalFontMetric;
 
 /// `font`: Configure the font.
 ///
@@ -13,6 +14,8 @@ use super::*;
 /// - Font Style: `style`, of type `font-style`.
 /// - Font Weight: `weight`, of type `font-weight`.
 /// - Font Stretch: `stretch`, of type `relative`, between 0.5 and 2.0.
+/// - Top edge of the font: `top-edge`, of type `vertical-font-metric`.
+/// - Bottom edge of the font: `bottom-edge`, of type `vertical-font-metric`.
 /// - Serif family definition: `serif`, of type `font-familiy-list`.
 /// - Sans-serif family definition: `sans-serif`, of type `font-familiy-list`.
 /// - Monospace family definition: `monospace`, of type `font-familiy-list`.
@@ -22,15 +25,15 @@ use super::*;
 /// if present.
 ///
 /// # Relevant types and constants
-/// - Type `font-family-list`
-///   - coerces from `string`
-///   - coerces from `array`
-///   - coerces from `font-family`
 /// - Type `font-family`
 ///   - `serif`
 ///   - `sans-serif`
 ///   - `monospace`
 ///   - coerces from `string`
+/// - Type `font-family-list`
+///   - coerces from `string`
+///   - coerces from `array`
+///   - coerces from `font-family`
 /// - Type `font-style`
 ///   - `normal`
 ///   - `italic`
@@ -46,12 +49,20 @@ use super::*;
 ///   - `extrabold` (800)
 ///   - `black` (900)
 ///   - coerces from `integer`
+/// - Type `vertical-font-metric`
+///   - `ascender`
+///   - `cap-height`
+///   - `x-height`
+///   - `baseline`
+///   - `descender`
 pub fn font(ctx: &mut EvalContext, args: &mut ValueArgs) -> Value {
     let size = args.find::<Linear>(ctx);
     let list: Vec<_> = args.filter::<FontFamily>(ctx).map(|f| f.to_string()).collect();
     let style = args.get(ctx, "style");
     let weight = args.get(ctx, "weight");
     let stretch = args.get(ctx, "stretch");
+    let top_edge = args.get(ctx, "top-edge");
+    let bottom_edge = args.get(ctx, "bottom-edge");
     let serif = args.get(ctx, "serif");
     let sans_serif = args.get(ctx, "sans-serif");
     let monospace = args.get(ctx, "monospace");
@@ -87,6 +98,14 @@ pub fn font(ctx: &mut EvalContext, args: &mut ValueArgs) -> Value {
             ctx.state.font.variant.stretch = stretch;
         }
 
+        if let Some(top_edge) = top_edge {
+            ctx.state.font.top_edge = top_edge;
+        }
+
+        if let Some(bottom_edge) = bottom_edge {
+            ctx.state.font.bottom_edge = bottom_edge;
+        }
+
         for (variant, arg) in &[
             (FontFamily::Serif, &serif),
             (FontFamily::SansSerif, &sans_serif),
@@ -185,3 +204,7 @@ typify! {
         };
     },
 }
+
+typify! {
+    VerticalFontMetric: "vertical font metric",
+}
diff --git a/src/library/mod.rs b/src/library/mod.rs
index 09fda20f..453eab26 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -26,9 +26,9 @@ use std::fmt::{self, Display, Formatter};
 use fontdock::{FontStyle, FontWeight};
 
 use crate::eval::{Scope, ValueAny, ValueFunc};
-use crate::exec::Softness;
 use crate::layout::*;
 use crate::prelude::*;
+use crate::shaping::VerticalFontMetric;
 
 /// Construct a scope containing all standard library definitions.
 pub fn new() -> Scope {
@@ -81,6 +81,11 @@ pub fn new() -> Scope {
     set!(any: "bold", FontWeight::BOLD);
     set!(any: "extrabold", FontWeight::EXTRABOLD);
     set!(any: "black", FontWeight::BLACK);
+    set!(any: "ascender", VerticalFontMetric::Ascender);
+    set!(any: "cap-height", VerticalFontMetric::CapHeight);
+    set!(any: "x-height", VerticalFontMetric::XHeight);
+    set!(any: "baseline", VerticalFontMetric::Baseline);
+    set!(any: "descender", VerticalFontMetric::Descender);
 
     std
 }
diff --git a/src/library/page.rs b/src/library/page.rs
index 17021607..f7d76eaf 100644
--- a/src/library/page.rs
+++ b/src/library/page.rs
@@ -95,13 +95,13 @@ pub fn page(ctx: &mut EvalContext, args: &mut ValueArgs) -> Value {
         }
 
         ctx.set_dirs(Gen::new(main, cross));
-        ctx.finish_page(false, Softness::Hard, span);
+        ctx.finish_page(false, true, span);
 
         if let Some(body) = &body {
             // TODO: Restrict body to a single page?
             body.exec(ctx);
             ctx.state = snapshot;
-            ctx.finish_page(true, Softness::Soft, span);
+            ctx.finish_page(true, false, span);
         }
     })
 }
@@ -113,6 +113,6 @@ pub fn page(ctx: &mut EvalContext, args: &mut ValueArgs) -> Value {
 pub fn pagebreak(_: &mut EvalContext, args: &mut ValueArgs) -> Value {
     let span = args.span;
     Value::template("pagebreak", move |ctx| {
-        ctx.finish_page(true, Softness::Hard, span);
+        ctx.finish_page(true, true, span);
     })
 }
diff --git a/src/library/spacing.rs b/src/library/spacing.rs
index d8f18f41..4965a220 100644
--- a/src/library/spacing.rs
+++ b/src/library/spacing.rs
@@ -28,7 +28,7 @@ fn spacing(ctx: &mut EvalContext, args: &mut ValueArgs, axis: SpecAxis) -> Value
     Value::template("spacing", move |ctx| {
         if let Some(linear) = spacing {
             let amount = linear.resolve(ctx.state.font.font_size());
-            let spacing = NodeSpacing { amount, softness: Softness::Hard };
+            let spacing = NodeSpacing { amount, softness: 0 };
             if axis == ctx.state.dirs.main.axis() {
                 ctx.push_into_stack(spacing);
             } else {
diff --git a/src/shaping.rs b/src/shaping.rs
index a8d2b2bf..41119639 100644
--- a/src/shaping.rs
+++ b/src/shaping.rs
@@ -4,7 +4,7 @@
 //! font for each individual character. When the direction is right-to-left, the
 //! word is spelled backwards. Vertical shaping is not supported.
 
-use std::fmt::{self, Debug, Formatter};
+use std::fmt::{self, Debug, Display, Formatter};
 
 use fontdock::{FaceId, FaceQuery, FallbackTree, FontVariant};
 use ttf_parser::{Face, GlyphId};
@@ -58,20 +58,55 @@ impl Debug for Shaped {
     }
 }
 
+/// Identifies a vertical metric of a font.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
+pub enum VerticalFontMetric {
+    /// The distance from the baseline to the typographic ascender.
+    ///
+    /// Corresponds to the typographic ascender from the `OS/2` table if present
+    /// and falls back to the ascender from the `hhea` table otherwise.
+    Ascender,
+    /// The approximate height of uppercase letters.
+    CapHeight,
+    /// The approximate height of non-ascending lowercase letters.
+    XHeight,
+    /// The baseline on which the letters rest.
+    Baseline,
+    /// The distance from the baseline to the typographic descender.
+    ///
+    /// Corresponds to the typographic descender from the `OS/2` table if
+    /// present and falls back to the descender from the `hhea` table otherwise.
+    Descender,
+}
+
+impl Display for VerticalFontMetric {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.pad(match self {
+            Self::Ascender => "ascender",
+            Self::CapHeight => "cap-height",
+            Self::XHeight => "x-height",
+            Self::Baseline => "baseline",
+            Self::Descender => "descender",
+        })
+    }
+}
+
 /// Shape text into a frame containing [`Shaped`] runs.
 pub fn shape(
     text: &str,
     dir: Dir,
-    font_size: Length,
-    loader: &mut FontLoader,
     fallback: &FallbackTree,
     variant: FontVariant,
+    font_size: Length,
+    top_edge: VerticalFontMetric,
+    bottom_edge: VerticalFontMetric,
+    loader: &mut FontLoader,
 ) -> Frame {
-    let mut frame = Frame::new(Size::new(Length::ZERO, font_size));
+    let mut frame = Frame::new(Size::new(Length::ZERO, Length::ZERO));
     let mut shaped = Shaped::new(FaceId::MAX, font_size);
-    let mut offset = Length::ZERO;
-    let mut ascender = Length::ZERO;
-    let mut descender = Length::ZERO;
+    let mut width = Length::ZERO;
+    let mut top = Length::ZERO;
+    let mut bottom = Length::ZERO;
 
     // Create an iterator with conditional direction.
     let mut forwards = text.chars();
@@ -86,7 +121,7 @@ pub fn shape(
         let query = FaceQuery { fallback: fallback.iter(), variant, c };
         if let Some(id) = loader.query(query) {
             let face = loader.face(id).get();
-            let (glyph, width) = match lookup_glyph(face, c) {
+            let (glyph, glyph_width) = match lookup_glyph(face, c) {
                 Some(v) => v,
                 None => continue,
             };
@@ -96,27 +131,35 @@ pub fn shape(
 
             // Flush the buffer and reset the metrics if we use a new font face.
             if shaped.face != id {
-                place(&mut frame, shaped, offset, ascender, descender);
+                place(&mut frame, shaped, width, top, bottom);
 
                 shaped = Shaped::new(id, font_size);
-                offset = Length::ZERO;
-                ascender = convert(f64::from(face.ascender()));
-                descender = convert(f64::from(face.descender()));
+                width = Length::ZERO;
+                top = convert(f64::from(lookup_metric(face, top_edge)));
+                bottom = convert(f64::from(lookup_metric(face, bottom_edge)));
             }
 
             shaped.text.push(c);
             shaped.glyphs.push(glyph);
-            shaped.offsets.push(offset);
-            offset += convert(f64::from(width));
+            shaped.offsets.push(width);
+            width += convert(f64::from(glyph_width));
         }
     }
 
-    // Flush the last buffered parts of the word.
-    place(&mut frame, shaped, offset, ascender, descender);
+    place(&mut frame, shaped, width, top, bottom);
 
     frame
 }
 
+/// Place shaped text into a frame.
+fn place(frame: &mut Frame, shaped: Shaped, width: Length, top: Length, bottom: Length) {
+    if !shaped.text.is_empty() {
+        frame.push(Point::new(frame.size.width, top), Element::Text(shaped));
+        frame.size.width += width;
+        frame.size.height = frame.size.height.max(top - bottom);
+    }
+}
+
 /// Look up the glyph for `c` and returns its index alongside its advance width.
 fn lookup_glyph(face: &Face, c: char) -> Option<(GlyphId, u16)> {
     let glyph = face.glyph_index(c)?;
@@ -124,18 +167,32 @@ fn lookup_glyph(face: &Face, c: char) -> Option<(GlyphId, u16)> {
     Some((glyph, width))
 }
 
-/// Place shaped text into a frame.
-fn place(
-    frame: &mut Frame,
-    shaped: Shaped,
-    offset: Length,
-    ascender: Length,
-    descender: Length,
-) {
-    if !shaped.text.is_empty() {
-        let pos = Point::new(frame.size.width, ascender);
-        frame.push(pos, Element::Text(shaped));
-        frame.size.width += offset;
-        frame.size.height = frame.size.height.max(ascender - descender);
+/// Look up a vertical metric.
+fn lookup_metric(face: &Face, metric: VerticalFontMetric) -> i16 {
+    match metric {
+        VerticalFontMetric::Ascender => lookup_ascender(face),
+        VerticalFontMetric::CapHeight => face
+            .capital_height()
+            .filter(|&h| h > 0)
+            .unwrap_or_else(|| lookup_ascender(face)),
+        VerticalFontMetric::XHeight => face
+            .x_height()
+            .filter(|&h| h > 0)
+            .unwrap_or_else(|| lookup_ascender(face)),
+        VerticalFontMetric::Baseline => 0,
+        VerticalFontMetric::Descender => lookup_descender(face),
     }
 }
+
+/// The ascender of the face.
+fn lookup_ascender(face: &Face) -> i16 {
+    // We prefer the typographic ascender over the Windows ascender because
+    // it can be overly large if the font has large glyphs.
+    face.typographic_ascender().unwrap_or_else(|| face.ascender())
+}
+
+/// The descender of the face.
+fn lookup_descender(face: &Face) -> i16 {
+    // See `lookup_ascender` for reason.
+    face.typographic_descender().unwrap_or_else(|| face.descender())
+}
diff --git a/tests/ref/comment.png b/tests/ref/comment.png
index 1fad97fe..6d5723ef 100644
--- a/tests/ref/comment.png
+++ b/tests/ref/comment.png
diff --git a/tests/ref/control/for.png b/tests/ref/control/for.png
index d04ea62c..f3830b34 100644
--- a/tests/ref/control/for.png
+++ b/tests/ref/control/for.png
diff --git a/tests/ref/control/if.png b/tests/ref/control/if.png
index 99bde49e..0527754e 100644
--- a/tests/ref/control/if.png
+++ b/tests/ref/control/if.png
diff --git a/tests/ref/control/invalid.png b/tests/ref/control/invalid.png
index ff4c6987..e9c64b8a 100644
--- a/tests/ref/control/invalid.png
+++ b/tests/ref/control/invalid.png
diff --git a/tests/ref/control/let.png b/tests/ref/control/let.png
index 5fb1c992..20aad953 100644
--- a/tests/ref/control/let.png
+++ b/tests/ref/control/let.png
diff --git a/tests/ref/control/while.png b/tests/ref/control/while.png
index 890131f1..2ea1bcb0 100644
--- a/tests/ref/control/while.png
+++ b/tests/ref/control/while.png
diff --git a/tests/ref/expand.png b/tests/ref/expand.png
index fc1f5de9..f18e929b 100644
--- a/tests/ref/expand.png
+++ b/tests/ref/expand.png
diff --git a/tests/ref/expr/array.png b/tests/ref/expr/array.png
index 784553b3..b1e20348 100644
--- a/tests/ref/expr/array.png
+++ b/tests/ref/expr/array.png
diff --git a/tests/ref/expr/block-invalid.png b/tests/ref/expr/block-invalid.png
index b380defc..d1e85402 100644
--- a/tests/ref/expr/block-invalid.png
+++ b/tests/ref/expr/block-invalid.png
diff --git a/tests/ref/expr/block.png b/tests/ref/expr/block.png
index d5ad52ae..d8ea84fb 100644
--- a/tests/ref/expr/block.png
+++ b/tests/ref/expr/block.png
diff --git a/tests/ref/expr/call-invalid.png b/tests/ref/expr/call-invalid.png
index 88f13780..eb192357 100644
--- a/tests/ref/expr/call-invalid.png
+++ b/tests/ref/expr/call-invalid.png
diff --git a/tests/ref/expr/call.png b/tests/ref/expr/call.png
index 7197bb90..26f1cb03 100644
--- a/tests/ref/expr/call.png
+++ b/tests/ref/expr/call.png
diff --git a/tests/ref/expr/dict.png b/tests/ref/expr/dict.png
index 28a7cb3b..1caef1e0 100644
--- a/tests/ref/expr/dict.png
+++ b/tests/ref/expr/dict.png
diff --git a/tests/ref/expr/ops.png b/tests/ref/expr/ops.png
index 95a24c0e..2f3a28ea 100644
--- a/tests/ref/expr/ops.png
+++ b/tests/ref/expr/ops.png
diff --git a/tests/ref/full/coma.png b/tests/ref/full/coma.png
index f5db682d..5fd6d801 100644
--- a/tests/ref/full/coma.png
+++ b/tests/ref/full/coma.png
diff --git a/tests/ref/library/font.png b/tests/ref/library/font.png
index 8e611b16..199a15f2 100644
--- a/tests/ref/library/font.png
+++ b/tests/ref/library/font.png
diff --git a/tests/ref/library/image.png b/tests/ref/library/image.png
index af497c8d..0a45e11b 100644
--- a/tests/ref/library/image.png
+++ b/tests/ref/library/image.png
diff --git a/tests/ref/library/pad.png b/tests/ref/library/pad.png
index a655061b..3536db5d 100644
--- a/tests/ref/library/pad.png
+++ b/tests/ref/library/pad.png
diff --git a/tests/ref/library/page.png b/tests/ref/library/page.png
index 1537fad4..7d1ff96f 100644
--- a/tests/ref/library/page.png
+++ b/tests/ref/library/page.png
diff --git a/tests/ref/library/pagebreak.png b/tests/ref/library/pagebreak.png
index b1ee0eef..f0052f9e 100644
--- a/tests/ref/library/pagebreak.png
+++ b/tests/ref/library/pagebreak.png
diff --git a/tests/ref/library/shapes.png b/tests/ref/library/shapes.png
index 8ace6fd6..a244feb1 100644
--- a/tests/ref/library/shapes.png
+++ b/tests/ref/library/shapes.png
diff --git a/tests/ref/library/spacing.png b/tests/ref/library/spacing.png
index 0842d409..6a234a8a 100644
--- a/tests/ref/library/spacing.png
+++ b/tests/ref/library/spacing.png
diff --git a/tests/ref/markup/emph.png b/tests/ref/markup/emph.png
index f002610e..75231a62 100644
--- a/tests/ref/markup/emph.png
+++ b/tests/ref/markup/emph.png
diff --git a/tests/ref/markup/escape.png b/tests/ref/markup/escape.png
index 3fa44c6d..8e946279 100644
--- a/tests/ref/markup/escape.png
+++ b/tests/ref/markup/escape.png
diff --git a/tests/ref/markup/heading.png b/tests/ref/markup/heading.png
index 9f2ce6ec..3473f798 100644
--- a/tests/ref/markup/heading.png
+++ b/tests/ref/markup/heading.png
diff --git a/tests/ref/markup/linebreak.png b/tests/ref/markup/linebreak.png
index fec65248..4e4702f9 100644
--- a/tests/ref/markup/linebreak.png
+++ b/tests/ref/markup/linebreak.png
diff --git a/tests/ref/markup/nbsp.png b/tests/ref/markup/nbsp.png
index 3e1f0ee7..89f75f14 100644
--- a/tests/ref/markup/nbsp.png
+++ b/tests/ref/markup/nbsp.png
diff --git a/tests/ref/markup/raw.png b/tests/ref/markup/raw.png
index ce833428..59a4e3dd 100644
--- a/tests/ref/markup/raw.png
+++ b/tests/ref/markup/raw.png
diff --git a/tests/ref/markup/strong.png b/tests/ref/markup/strong.png
index ac38c436..7e62f0f3 100644
--- a/tests/ref/markup/strong.png
+++ b/tests/ref/markup/strong.png
diff --git a/tests/ref/repr.png b/tests/ref/repr.png
index 2f5697fd..ad10705c 100644
--- a/tests/ref/repr.png
+++ b/tests/ref/repr.png
diff --git a/tests/ref/spacing.png b/tests/ref/spacing.png
index 8bdc9885..454b154f 100644
--- a/tests/ref/spacing.png
+++ b/tests/ref/spacing.png
diff --git a/tests/ref/text.png b/tests/ref/text.png
index 38ae364d..1dd70c1c 100644
--- a/tests/ref/text.png
+++ b/tests/ref/text.png
diff --git a/tests/typ/control/let.typ b/tests/typ/control/let.typ
index dd971ee5..4f84aa67 100644
--- a/tests/typ/control/let.typ
+++ b/tests/typ/control/let.typ
@@ -17,8 +17,8 @@
 
 ---
 // Syntax sugar for function definitions.
-#let background = #239dad
-#let rect(body) = rect(width: 2cm, height: 1cm, fill: background, body)
+#let background = #9feb52
+#let rect(body) = rect(width: 2cm, fill: background, pad(5pt, body))
 #rect[Hi!]
 
 // Error: 13 expected body
diff --git a/tests/typ/full/coma.typ b/tests/typ/full/coma.typ
index 243c667f..619843d7 100644
--- a/tests/typ/full/coma.typ
+++ b/tests/typ/full/coma.typ
@@ -30,8 +30,8 @@
 // the parentheses.
 #align(center)[
     // Markdown-like syntax for headings.
-    ==== 3. Übungsblatt Computerorientierte Mathematik II #v(2mm)
-    *Abgabe: 03.05.2019* (bis 10:10 Uhr in MA 001) #v(2mm)
+    ==== 3. Übungsblatt Computerorientierte Mathematik II #v(4mm)
+    *Abgabe: 03.05.2019* (bis 10:10 Uhr in MA 001) #v(4mm)
     *Alle Antworten sind zu beweisen.*
 ]
 
diff --git a/tests/typ/library/font.typ b/tests/typ/library/font.typ
index c00bff5a..ecea303f 100644
--- a/tests/typ/library/font.typ
+++ b/tests/typ/library/font.typ
@@ -32,6 +32,20 @@ Emoji: 🐪, 🌋, 🏞
 ]
 
 ---
+// Test top and bottom edge.
+
+#page(width: 170pt)
+#let try(top, bottom) = rect(fill: #9feb52)[
+    #font(top-edge: top, bottom-edge: bottom)
+    `From `#top` to `#bottom
+]
+
+#try(ascender, descender)
+#try(ascender, baseline)
+#try(cap-height, baseline)
+#try(x-height, baseline)
+
+---
 // Ref: false
 
 // Error: 7-12 unexpected argument
diff --git a/tests/typ/library/spacing.typ b/tests/typ/library/spacing.typ
index a34840c6..6d50f0dc 100644
--- a/tests/typ/library/spacing.typ
+++ b/tests/typ/library/spacing.typ
@@ -2,7 +2,7 @@
 
 ---
 // Ends paragraphs.
-Tightly #v(-5pt) packed
+Tightly #v(0pt) packed
 
 // Eating up soft spacing.
 Inv #h(0pt) isible
diff --git a/tests/typ/markup/escape.typ b/tests/typ/markup/escape.typ
index eeac4997..b0a809f9 100644
--- a/tests/typ/markup/escape.typ
+++ b/tests/typ/markup/escape.typ
@@ -28,3 +28,7 @@
 // Unterminated.
 // Error: 6 expected closing brace
 \u{41*Bold*
+
+---
+// Some code stuff in text.
+let f() , ; : | + - /= == 12 "string"
diff --git a/tests/typ/markup/raw.typ b/tests/typ/markup/raw.typ
index f5074c8e..005d413e 100644
--- a/tests/typ/markup/raw.typ
+++ b/tests/typ/markup/raw.typ
@@ -7,7 +7,7 @@
 ---
 // Typst syntax inside.
 `#let x = 1` \
-`#[f 1]`
+`#f(1)`
 
 ---
 // Multiline block splits paragraphs.
diff --git a/tests/typ/text.typ b/tests/typ/text.typ
index d86f4895..b424cee8 100644
--- a/tests/typ/text.typ
+++ b/tests/typ/text.typ
@@ -1,8 +1,19 @@
 // Test simple text.
 
----
-Hello 🌏!
+#page(width: 250pt)
 
----
-// Some code stuff in text.
-let f() , ; : | + - /= == 12 "string"
+But, soft! what light through yonder window breaks? It is the east, and Juliet
+is the sun. Arise, fair sun, and kill the envious moon, Who is already sick and
+pale with grief, That thou her maid art far more fair than she: Be not her maid,
+since she is envious; Her vestal livery is but sick and green And none but fools
+do wear it; cast it off. It is my lady, O, it is my love! O, that she knew she
+were! She speaks yet she says nothing: what of that? Her eye discourses; I will
+answer it.
+
+I am too bold, 'tis not to me she speaks: Two of the fairest stars in all the
+heaven, Having some business, do entreat her eyes To twinkle in their spheres
+till they return. What if her eyes were there, they in her head? The brightness
+of her cheek would shame those stars, As daylight doth a lamp; her eyes in
+heaven Would through the airy region stream so bright That birds would sing and
+think it were not night. See, how she leans her cheek upon her hand! O, that I
+were a glove upon that hand, That I might touch that cheek!