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NetterSilverandClaude Haiku 5.5
61d5f3a1ef
Found while testing crates/engine/src/math.rs:393 Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com> Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
776 lines
28 KiB
Rust
776 lines
28 KiB
Rust
//! Math expressions: a LaTeX subset typeset into boxes and written as SVG (text in the bundled
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//! serif, rules and radicals as paths). Covers fractions, super/subscripts, square and n-th roots,
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//! big operators with limits, Greek letters, common symbols, `\text{}`, `\mathrm{}`, spacing
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//! commands and `\left( … \right)`.
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use std::fmt::Write as _;
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use designcraft_fonts::{FontDb, FontFace};
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/// A positioned piece of the formula (baseline-relative: y grows downwards).
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#[derive(Clone, Debug, PartialEq)]
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enum Elem {
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Text {
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x: f64,
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y: f64,
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s: String,
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size: f64,
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italic: bool,
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},
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Rule {
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x: f64,
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y: f64,
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w: f64,
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h: f64,
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},
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/// A polyline (radical sign), stroke width `w`.
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Line {
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pts: Vec<(f64, f64)>,
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w: f64,
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},
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}
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/// A laid-out box: width, height above and depth below the baseline.
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#[derive(Clone, Debug, Default)]
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struct MBox {
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w: f64,
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asc: f64,
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desc: f64,
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els: Vec<Elem>,
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}
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impl MBox {
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fn shifted(mut self, dx: f64, dy: f64) -> Vec<Elem> {
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for e in &mut self.els {
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match e {
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Elem::Text { x, y, .. } | Elem::Rule { x, y, .. } => {
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*x += dx;
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*y += dy;
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}
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Elem::Line { pts, .. } => {
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for p in pts {
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p.0 += dx;
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p.1 += dy;
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}
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}
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}
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}
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self.els
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}
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}
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#[derive(Clone, Debug, PartialEq)]
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enum Node {
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/// A character run: identifiers italic, numbers and symbols upright.
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Sym(String, Class),
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Group(Vec<Node>),
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Frac(Box<Node>, Box<Node>),
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Sqrt(Option<Box<Node>>, Box<Node>),
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Scripts {
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base: Box<Node>,
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sup: Option<Box<Node>>,
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sub: Option<Box<Node>>,
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},
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Text(String),
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Space(f64),
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/// A big operator (∑ ∏ ∫): drawn larger, limits as scripts.
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Big(String),
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/// `\left( … \right)`: delimiters sized to the content.
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Fenced(String, Box<Node>, String),
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}
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#[derive(Clone, Copy, Debug, PartialEq)]
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enum Class {
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Ident,
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Number,
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/// Binary operator (+ − × ·): medium space both sides.
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Bin,
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/// Relation (= < ≤ →): thick space both sides.
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Rel,
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Punct,
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Plain,
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}
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fn symbol(name: &str) -> Option<(&'static str, Class)> {
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use Class::*;
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Some(match name {
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"alpha" => ("α", Ident),
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"beta" => ("β", Ident),
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"gamma" => ("γ", Ident),
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"delta" => ("δ", Ident),
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"epsilon" | "varepsilon" => ("ε", Ident),
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"zeta" => ("ζ", Ident),
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"eta" => ("η", Ident),
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"theta" => ("θ", Ident),
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"iota" => ("ι", Ident),
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"kappa" => ("κ", Ident),
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"lambda" => ("λ", Ident),
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"mu" => ("μ", Ident),
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"nu" => ("ν", Ident),
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"xi" => ("ξ", Ident),
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"pi" => ("π", Ident),
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"rho" => ("ρ", Ident),
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"sigma" => ("σ", Ident),
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"tau" => ("τ", Ident),
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"phi" | "varphi" => ("φ", Ident),
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"chi" => ("χ", Ident),
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"psi" => ("ψ", Ident),
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"omega" => ("ω", Ident),
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"Gamma" => ("Γ", Plain),
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"Delta" => ("Δ", Plain),
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"Theta" => ("Θ", Plain),
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"Lambda" => ("Λ", Plain),
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"Pi" => ("Π", Plain),
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"Sigma" => ("Σ", Plain),
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"Phi" => ("Φ", Plain),
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"Psi" => ("Ψ", Plain),
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"Omega" => ("Ω", Plain),
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"times" => ("×", Bin),
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"cdot" => ("·", Bin),
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"pm" => ("±", Bin),
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"mp" => ("∓", Bin),
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"div" => ("÷", Bin),
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"le" | "leq" => ("≤", Rel),
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"ge" | "geq" => ("≥", Rel),
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"neq" | "ne" => ("≠", Rel),
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"approx" => ("≈", Rel),
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"equiv" => ("≡", Rel),
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"to" | "rightarrow" => ("→", Rel),
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"leftarrow" => ("←", Rel),
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"Rightarrow" => ("⇒", Rel),
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"in" => ("∈", Rel),
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"infty" => ("∞", Plain),
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"partial" => ("∂", Plain),
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"nabla" => ("∇", Plain),
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"ldots" | "dots" => ("…", Plain),
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"cdots" => ("⋯", Plain),
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"prime" => ("′", Plain),
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"degree" => ("°", Plain),
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_ => return None,
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})
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}
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fn big_op(name: &str) -> Option<&'static str> {
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Some(match name {
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"sum" => "∑",
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"prod" => "∏",
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"int" => "∫",
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"oint" => "∮",
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_ => return None,
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})
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}
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/// Deepest expression nesting parsed. Recursive descent must not overflow the stack on hostile
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/// input (`\frac\frac…`, `{{{{…`, `\left(\left(…`); past the cap groups stop descending.
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const MAX_NESTING: usize = 256;
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struct Parser<'a> {
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s: &'a [char],
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i: usize,
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/// Enclosing group depth, at most [`MAX_NESTING`].
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depth: usize,
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}
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impl Parser<'_> {
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fn peek(&self) -> Option<char> {
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self.s.get(self.i).copied()
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}
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fn skip_ws(&mut self) {
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while self.peek().is_some_and(char::is_whitespace) {
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self.i += 1;
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}
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}
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fn command(&mut self) -> String {
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let mut name = String::new();
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if let Some(c) = self.peek()
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&& !c.is_ascii_alphabetic()
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{
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self.i += 1;
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return c.to_string();
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}
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while let Some(c) = self.peek().filter(char::is_ascii_alphabetic) {
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name.push(c);
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self.i += 1;
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}
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name
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}
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/// Raw text of a `{…}` argument.
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fn raw_group(&mut self) -> String {
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self.skip_ws();
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if self.peek() != Some('{') {
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return self
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.peek()
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.map(|c| {
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self.i += 1;
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c.to_string()
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})
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.unwrap_or_default();
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}
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self.i += 1;
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let mut depth = 1;
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let mut out = String::new();
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while let Some(c) = self.peek() {
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self.i += 1;
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match c {
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'{' => depth += 1,
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'}' => {
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depth -= 1;
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if depth == 0 {
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break;
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}
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}
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_ => {}
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}
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out.push(c);
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}
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out
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}
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fn arg(&mut self) -> Node {
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if self.depth >= MAX_NESTING {
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return Node::Group(Vec::new());
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}
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self.depth += 1;
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self.skip_ws();
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let n = if self.peek() == Some('{') {
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self.i += 1;
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Node::Group(self.list(Some('}')))
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} else {
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self.atom().unwrap_or(Node::Group(vec![]))
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};
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self.depth -= 1;
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n
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}
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fn delimiter(&mut self) -> String {
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self.skip_ws();
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match self.peek() {
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Some('\\') => {
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self.i += 1;
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match self.command().as_str() {
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"{" => "{".into(),
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"}" => "}".into(),
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"|" => "‖".into(),
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"langle" => "⟨".into(),
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"rangle" => "⟩".into(),
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_ => String::new(),
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}
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}
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Some('.') => {
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self.i += 1;
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String::new()
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}
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Some(c) => {
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self.i += 1;
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c.to_string()
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}
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None => String::new(),
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}
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}
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fn atom(&mut self) -> Option<Node> {
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self.skip_ws();
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let c = self.peek()?;
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self.i += 1;
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Some(match c {
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'{' => Node::Group(self.list(Some('}'))),
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'\\' => {
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let name = self.command();
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match name.as_str() {
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"frac" | "dfrac" | "tfrac" => {
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let a = self.arg();
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let b = self.arg();
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Node::Frac(Box::new(a), Box::new(b))
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}
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"sqrt" => {
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self.skip_ws();
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let idx = (self.peek() == Some('[')).then(|| {
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self.i += 1;
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let mut s = String::new();
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while let Some(c) = self.peek() {
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self.i += 1;
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if c == ']' {
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break;
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}
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s.push(c);
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}
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Box::new(parse_at(&s, self.depth + 1))
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});
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let a = self.arg();
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Node::Sqrt(idx, Box::new(a))
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}
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"text" | "mathrm" | "textrm" | "operatorname" => Node::Text(self.raw_group()),
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"sin" | "cos" | "tan" | "log" | "ln" | "exp" | "lim" | "max" | "min" => Node::Text(name),
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"," => Node::Space(3.0 / 18.0),
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":" | ">" => Node::Space(4.0 / 18.0),
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";" => Node::Space(5.0 / 18.0),
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"quad" => Node::Space(1.0),
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"qquad" => Node::Space(2.0),
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"!" => Node::Space(-3.0 / 18.0),
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" " => Node::Space(0.25),
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"left" => {
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let open = self.delimiter();
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let body = self.list_until_right();
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let close = self.delimiter();
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Node::Fenced(open, Box::new(Node::Group(body)), close)
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}
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"{" => Node::Sym("{".into(), Class::Punct),
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"}" => Node::Sym("}".into(), Class::Punct),
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"%" | "$" | "#" | "&" | "_" => Node::Sym(name, Class::Plain),
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n => match (big_op(n), symbol(n)) {
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(Some(op), _) => Node::Big(op.into()),
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(None, Some((s, cl))) => Node::Sym(s.into(), cl),
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_ => Node::Text(format!("\\{n}")),
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},
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}
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}
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c if c.is_ascii_digit() || c == '.' => {
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let mut s = c.to_string();
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while let Some(d) = self.peek().filter(|d| d.is_ascii_digit() || *d == '.') {
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s.push(d);
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self.i += 1;
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}
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Node::Sym(s, Class::Number)
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}
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c if c.is_alphabetic() => Node::Sym(c.to_string(), Class::Ident),
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'+' => Node::Sym("+".into(), Class::Bin),
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'-' => Node::Sym("−".into(), Class::Bin),
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'*' => Node::Sym("∗".into(), Class::Bin),
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'=' | '<' | '>' => Node::Sym(c.to_string(), Class::Rel),
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',' | ';' => Node::Sym(c.to_string(), Class::Punct),
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'\'' => Node::Sym("′".into(), Class::Plain),
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c => Node::Sym(c.to_string(), Class::Plain),
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})
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}
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fn list(&mut self, end: Option<char>) -> Vec<Node> {
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if self.depth >= MAX_NESTING {
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return Vec::new();
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}
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self.depth += 1;
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let mut out: Vec<Node> = Vec::new();
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loop {
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self.skip_ws();
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match self.peek() {
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None => break,
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Some(c) if Some(c) == end => {
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self.i += 1;
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break;
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}
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Some('^') | Some('_') => {
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let up = self.peek() == Some('^');
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self.i += 1;
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let a = self.arg();
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let base = out.pop().unwrap_or(Node::Group(vec![]));
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let node = match base {
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Node::Scripts { base, sup, sub } => {
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if up {
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Node::Scripts { base, sup: Some(Box::new(a)), sub }
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} else {
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Node::Scripts { base, sup, sub: Some(Box::new(a)) }
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}
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}
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b => Node::Scripts { base: Box::new(b), sup: up.then(|| Box::new(a.clone())), sub: (!up).then(|| Box::new(a)) },
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};
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out.push(node);
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}
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Some(_) => {
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if let Some(a) = self.atom() {
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out.push(a);
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}
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}
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}
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}
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self.depth -= 1;
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out
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}
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fn list_until_right(&mut self) -> Vec<Node> {
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if self.depth >= MAX_NESTING {
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return Vec::new();
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}
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let mut out = Vec::new();
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loop {
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self.skip_ws();
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if self.peek().is_none() {
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break;
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}
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if self.s[self.i..].starts_with(&['\\', 'r', 'i', 'g', 'h', 't']) && !self.s.get(self.i + 6).is_some_and(|c| c.is_ascii_alphabetic()) {
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self.i += 6;
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break;
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}
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let mut p = Parser { s: self.s, i: self.i, depth: self.depth + 1 };
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let one = p.list_one();
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self.i = p.i;
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out.extend(one);
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}
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out
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}
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/// One atom plus any scripts on it.
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fn list_one(&mut self) -> Vec<Node> {
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let mut out = Vec::new();
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if let Some(a) = self.atom() {
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out.push(a);
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}
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loop {
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self.skip_ws();
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match self.peek() {
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Some('^') | Some('_') => {
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let up = self.peek() == Some('^');
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self.i += 1;
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let a = self.arg();
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let base = out.pop().unwrap_or(Node::Group(vec![]));
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out.push(match base {
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Node::Scripts { base, sub, .. } if up => Node::Scripts { base, sup: Some(Box::new(a)), sub },
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Node::Scripts { base, sup, .. } => Node::Scripts { base, sup, sub: Some(Box::new(a)) },
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b => Node::Scripts { base: Box::new(b), sup: up.then(|| Box::new(a.clone())), sub: (!up).then(|| Box::new(a)) },
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});
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}
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_ => break,
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}
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}
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out
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}
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}
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fn parse(src: &str) -> Node {
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parse_at(src, 0)
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}
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fn parse_at(src: &str, depth: usize) -> Node {
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let chars: Vec<char> = src.chars().collect();
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let mut p = Parser { s: &chars, i: 0, depth };
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Node::Group(p.list(None))
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}
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/// Typesetting fonts and metrics.
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struct Fonts {
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upright: std::sync::Arc<FontFace>,
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italic: std::sync::Arc<FontFace>,
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fallback: std::sync::Arc<FontFace>,
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}
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impl Fonts {
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fn face(&self, c: char, italic: bool) -> &FontFace {
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let f = if italic { &self.italic } else { &self.upright };
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if f.glyph_for(c) != 0 { f } else { &self.fallback }
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}
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fn width(&self, s: &str, size: f64, italic: bool) -> f64 {
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s.chars()
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.map(|c| {
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let f = self.face(c, italic);
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f.advance(f.glyph_for(c)) / f.units_per_em().max(1.0) * size
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})
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.sum()
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}
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}
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const FAMILY: &str = designcraft_fonts::DEFAULT_FAMILY;
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const FALLBACK: &str = "Source Sans 3";
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fn text_box(f: &Fonts, s: &str, size: f64, italic: bool) -> MBox {
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let w = f.width(s, size, italic);
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MBox { w, asc: size * 0.72, desc: size * 0.22, els: vec![Elem::Text { x: 0.0, y: 0.0, s: s.to_string(), size, italic }] }
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}
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fn hbox(parts: Vec<(MBox, f64)>) -> MBox {
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// (box, space before) laid out along the baseline.
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let mut out = MBox::default();
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let mut x = 0.0;
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for (b, before) in parts {
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x += before;
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out.asc = out.asc.max(b.asc);
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out.desc = out.desc.max(b.desc);
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let w = b.w;
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out.els.extend(b.shifted(x, 0.0));
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x += w;
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}
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out.w = x.max(0.0);
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out
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}
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fn layout(f: &Fonts, n: &Node, size: f64) -> MBox {
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let axis = size * 0.25;
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match n {
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Node::Sym(s, cl) => text_box(f, s, size, *cl == Class::Ident),
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Node::Text(s) => text_box(f, s, size, false),
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Node::Space(em) => MBox { w: em * size, ..Default::default() },
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Node::Group(list) => {
|
||
let mut parts = Vec::new();
|
||
let mut prev: Option<Class> = None;
|
||
for (k, item) in list.iter().enumerate() {
|
||
let cl = match item {
|
||
Node::Sym(_, c) => Some(*c),
|
||
Node::Scripts { base, .. } => match &**base {
|
||
Node::Sym(_, c) => Some(*c),
|
||
_ => None,
|
||
},
|
||
_ => None,
|
||
};
|
||
// A leading + or − (or after another operator) is a sign, not a binary operator.
|
||
let cl = if cl == Some(Class::Bin) && (k == 0 || matches!(prev, Some(Class::Bin | Class::Rel | Class::Punct))) {
|
||
Some(Class::Plain)
|
||
} else {
|
||
cl
|
||
};
|
||
let gap = |c: Option<Class>| match c {
|
||
Some(Class::Bin) => size * 4.0 / 18.0,
|
||
Some(Class::Rel) => size * 5.0 / 18.0,
|
||
_ => 0.0,
|
||
};
|
||
let mut before = gap(cl).max(gap(prev));
|
||
if k == 0 {
|
||
before = 0.0;
|
||
}
|
||
if prev == Some(Class::Punct) {
|
||
before = before.max(size * 3.0 / 18.0);
|
||
}
|
||
parts.push((layout(f, item, size), before));
|
||
prev = cl;
|
||
}
|
||
hbox(parts)
|
||
}
|
||
Node::Frac(a, b) => {
|
||
let s2 = size * 0.85;
|
||
let (na, nb) = (layout(f, a, s2), layout(f, b, s2));
|
||
let w = na.w.max(nb.w) + size * 0.2;
|
||
let t = (size * 0.06).max(0.4);
|
||
let gap = size * 0.15;
|
||
let num_base = -(axis + t / 2.0 + gap + na.desc);
|
||
let den_base = -axis + t / 2.0 + gap + nb.asc;
|
||
let mut out = MBox { w, asc: -num_base + na.asc, desc: den_base + nb.desc, els: Vec::new() };
|
||
out.els.push(Elem::Rule { x: 0.0, y: -axis - t / 2.0, w, h: t });
|
||
let (wa, wb) = (na.w, nb.w);
|
||
out.els.extend(na.shifted((w - wa) / 2.0, num_base));
|
||
out.els.extend(nb.shifted((w - wb) / 2.0, den_base));
|
||
out
|
||
}
|
||
Node::Sqrt(idx, a) => {
|
||
let inner = layout(f, a, size);
|
||
let t = (size * 0.05).max(0.4);
|
||
let gap = size * 0.12;
|
||
let top = inner.asc + gap + t;
|
||
let bottom = inner.desc;
|
||
let hook = size * 0.55;
|
||
let mut out = MBox { w: hook + inner.w + size * 0.1, asc: top, desc: bottom, els: Vec::new() };
|
||
// The radical: a short rise, the long stroke down, then up to the bar.
|
||
out.els.push(Elem::Line {
|
||
pts: vec![(0.0, -axis * 0.6), (hook * 0.25, -axis), (hook * 0.55, bottom), (hook, -top + t / 2.0), (out.w, -top + t / 2.0)],
|
||
w: t,
|
||
});
|
||
let iw = inner.w;
|
||
let _ = iw;
|
||
out.els.extend(inner.shifted(hook, 0.0));
|
||
if let Some(i) = idx {
|
||
let ib = layout(f, i, size * 0.55);
|
||
let (ia, iw2) = (ib.asc, ib.w);
|
||
out.els.extend(ib.shifted((hook * 0.3 - iw2).max(0.0) - 0.0, -axis - size * 0.1));
|
||
out.asc = out.asc.max(axis + size * 0.1 + ia);
|
||
}
|
||
out
|
||
}
|
||
Node::Big(op) => {
|
||
let mut b = text_box(f, op, size * 1.5, false);
|
||
b.asc = size * 1.05;
|
||
b.desc = size * 0.35;
|
||
for e in &mut b.els {
|
||
if let Elem::Text { y, .. } = e {
|
||
// Centre the glyph on the math axis.
|
||
*y = size * 0.32;
|
||
}
|
||
}
|
||
b
|
||
}
|
||
Node::Scripts { base, sup, sub } => {
|
||
let big = matches!(&**base, Node::Big(_));
|
||
let b = layout(f, base, size);
|
||
let s2 = size * 0.7;
|
||
let (bw, basc, bdesc) = (b.w, b.asc, b.desc);
|
||
let mut out = MBox { w: bw, asc: basc, desc: bdesc, els: b.els };
|
||
if big {
|
||
// Limits above and below.
|
||
let mut w = bw;
|
||
if let Some(sp) = sup {
|
||
let sb = layout(f, sp, s2);
|
||
let y = -basc - size * 0.1 - sb.desc;
|
||
w = w.max(sb.w);
|
||
let (sw, sa) = (sb.w, sb.asc);
|
||
out.els.extend(sb.shifted((bw - sw) / 2.0, y));
|
||
out.asc = out.asc.max(-y + sa);
|
||
}
|
||
if let Some(sbn) = sub {
|
||
let sb = layout(f, sbn, s2);
|
||
let y = bdesc + size * 0.1 + sb.asc;
|
||
w = w.max(sb.w);
|
||
let (sw, sd) = (sb.w, sb.desc);
|
||
out.els.extend(sb.shifted((bw - sw) / 2.0, y));
|
||
out.desc = out.desc.max(y + sd);
|
||
}
|
||
// Centre the operator over the widest limit.
|
||
let dx = (w - bw) / 2.0;
|
||
let els = std::mem::take(&mut out.els);
|
||
out = MBox { w, asc: out.asc, desc: out.desc, els: MBox { els, ..Default::default() }.shifted(dx, 0.0) };
|
||
return out;
|
||
}
|
||
let mut w = bw;
|
||
if let Some(sp) = sup {
|
||
let sb = layout(f, sp, s2);
|
||
let y = -(size * 0.42).max(basc - sb.asc * 0.6);
|
||
w = w.max(bw + sb.w + size * 0.05);
|
||
let sa = sb.asc;
|
||
out.els.extend(sb.shifted(bw + size * 0.05, y));
|
||
out.asc = out.asc.max(-y + sa);
|
||
}
|
||
if let Some(sbn) = sub {
|
||
let sb = layout(f, sbn, s2);
|
||
let y = (size * 0.2).max(bdesc * 0.8);
|
||
w = w.max(bw + sb.w + size * 0.05);
|
||
let sd = sb.desc;
|
||
out.els.extend(sb.shifted(bw + size * 0.05, y));
|
||
out.desc = out.desc.max(y + sd);
|
||
}
|
||
out.w = w;
|
||
out
|
||
}
|
||
Node::Fenced(open, body, close) => {
|
||
let inner = layout(f, body, size);
|
||
let h = (inner.asc + inner.desc).max(size);
|
||
let k = h / size;
|
||
let ds = size * k.max(1.0);
|
||
let mk = |s: &str| -> MBox {
|
||
if s.is_empty() {
|
||
return MBox::default();
|
||
}
|
||
let mut b = text_box(f, s, ds, false);
|
||
// Scaled delimiters centred on the content.
|
||
let mid = (inner.desc - inner.asc) / 2.0;
|
||
for e in &mut b.els {
|
||
if let Elem::Text { y, .. } = e {
|
||
*y = mid + ds * 0.25;
|
||
}
|
||
}
|
||
b.asc = inner.asc.max(size * 0.72);
|
||
b.desc = inner.desc.max(size * 0.22);
|
||
b
|
||
};
|
||
let (l, r) = (mk(open), mk(close));
|
||
hbox(vec![(l, 0.0), (inner, size * 0.05), (r, size * 0.05)])
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Typeset `latex` at `size` points: SVG bytes and the size in points.
|
||
pub fn to_svg(latex: &str, size: f64) -> (Vec<u8>, (f64, f64)) {
|
||
let db = FontDb::global();
|
||
let f = Fonts { upright: db.face(FAMILY, "Regular"), italic: db.face(FAMILY, "Italic"), fallback: db.face(FALLBACK, "Regular") };
|
||
let b = layout(&f, &parse(latex), size);
|
||
let pad = size * 0.1;
|
||
let (w, h) = (b.w + 2.0 * pad, b.asc + b.desc + 2.0 * pad);
|
||
let base = pad + b.asc;
|
||
let mut svg = String::new();
|
||
let _ = write!(svg, "<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"{w:.2}pt\" height=\"{h:.2}pt\" viewBox=\"0 0 {w:.3} {h:.3}\">");
|
||
let esc = |s: &str| s.replace('&', "&").replace('<', "<").replace('>', ">");
|
||
for e in &b.els {
|
||
match e {
|
||
Elem::Text { x, y, s, size, italic } => {
|
||
// Per character, so each uses a face that has it.
|
||
let mut cx = *x;
|
||
for c in s.chars() {
|
||
let face = f.face(c, *italic);
|
||
let fam = if std::ptr::eq(face, &*f.fallback) { FALLBACK } else { FAMILY };
|
||
let it = *italic && !std::ptr::eq(face, &*f.fallback);
|
||
let _ = write!(
|
||
svg,
|
||
"<text x=\"{:.3}\" y=\"{:.3}\" font-family=\"'{fam}'\" font-size=\"{size:.3}\"{}>{}</text>",
|
||
pad + cx,
|
||
base + y,
|
||
if it { " font-style=\"italic\"" } else { "" },
|
||
esc(&c.to_string())
|
||
);
|
||
cx += f.width(&c.to_string(), *size, *italic);
|
||
}
|
||
}
|
||
Elem::Rule { x, y, w: rw, h: rh } => {
|
||
let _ = write!(svg, "<rect x=\"{:.3}\" y=\"{:.3}\" width=\"{rw:.3}\" height=\"{rh:.3}\"/>", pad + x, base + y);
|
||
}
|
||
Elem::Line { pts, w: lw } => {
|
||
let d: Vec<String> = pts.iter().map(|(x, y)| format!("{:.3},{:.3}", pad + x, base + y)).collect();
|
||
let _ = write!(
|
||
svg,
|
||
"<polyline points=\"{}\" fill=\"none\" stroke=\"black\" stroke-width=\"{lw:.3}\" stroke-linejoin=\"round\"/>",
|
||
d.join(" ")
|
||
);
|
||
}
|
||
}
|
||
}
|
||
svg.push_str("</svg>");
|
||
(svg.into_bytes(), (w, h))
|
||
}
|
||
|
||
#[cfg(test)]
|
||
mod tests {
|
||
use super::*;
|
||
|
||
#[test]
|
||
fn parses_the_common_constructs() {
|
||
let n = parse(r"\frac{a^2+b}{\sqrt[3]{x}}");
|
||
let Node::Group(v) = n else { panic!() };
|
||
assert!(matches!(&v[0], Node::Frac(_, _)));
|
||
let n = parse(r"\sum_{i=1}^{n} i^2 \le \alpha");
|
||
let Node::Group(v) = n else { panic!() };
|
||
assert!(matches!(&v[0], Node::Scripts { base, sup: Some(_), sub: Some(_) } if matches!(**base, Node::Big(_))));
|
||
assert!(v.iter().any(|x| *x == Node::Sym("≤".into(), Class::Rel)));
|
||
assert!(v.iter().any(|x| *x == Node::Sym("α".into(), Class::Ident)));
|
||
let n = parse(r"\left( \frac{1}{2} \right) + \text{if } x");
|
||
let Node::Group(v) = n else { panic!() };
|
||
assert!(matches!(&v[0], Node::Fenced(o, _, c) if o == "(" && c == ")"));
|
||
assert!(v.contains(&Node::Text("if ".into())));
|
||
}
|
||
|
||
/// A command that merely starts with "right" (`\rightarrow`) must not close a `\left` fence.
|
||
#[test]
|
||
fn right_prefixed_commands_do_not_close_a_fence() {
|
||
let n = parse(r"\left( x \rightarrow y \right)");
|
||
let Node::Group(v) = n else { panic!() };
|
||
assert_eq!(v.len(), 1, "{v:?}");
|
||
let Node::Fenced(o, body, c) = &v[0] else { panic!("{v:?}") };
|
||
assert!(o == "(" && c == ")", "{v:?}");
|
||
let Node::Group(b) = &**body else { panic!("{v:?}") };
|
||
assert_eq!(*b, vec![Node::Sym("x".into(), Class::Ident), Node::Sym("→".into(), Class::Rel), Node::Sym("y".into(), Class::Ident)]);
|
||
// An unknown `\right…` command stays inside the fence too.
|
||
let Node::Group(v) = parse(r"\left[ \rightfoo \right]") else { panic!() };
|
||
assert_eq!(v.len(), 1, "{v:?}");
|
||
assert!(matches!(&v[0], Node::Fenced(o, _, c) if o == "[" && c == "]"), "{v:?}");
|
||
// Real closers still close it.
|
||
for (src, close) in [(r"\left( x \right)", ")"), (r"\left( x \right.", ""), (r"\left( x \right)y", ")")] {
|
||
let Node::Group(v) = parse(src) else { panic!() };
|
||
assert!(matches!(&v[0], Node::Fenced(_, _, c) if c == close), "{src}: {v:?}");
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn layout_sizes_and_svg() {
|
||
let (svg, (w, h)) = to_svg(r"E = mc^2", 12.0);
|
||
let s = String::from_utf8(svg).unwrap();
|
||
assert!(s.starts_with("<svg") && s.contains("font-style=\"italic\">E<") && s.contains(">2<"));
|
||
assert!(w > 30.0 && h > 10.0, "{w} {h}");
|
||
// A fraction is taller than its numerator alone; a big operator with limits taller still.
|
||
let (_, (_, h1)) = to_svg("x", 12.0);
|
||
let (_, (_, h2)) = to_svg(r"\frac{x}{y}", 12.0);
|
||
let (_, (_, h3)) = to_svg(r"\sum_{i=0}^{n}", 12.0);
|
||
assert!(h2 > h1 * 1.4 && h3 > h2, "{h1} {h2} {h3}");
|
||
// The SVG parses and rasterises.
|
||
let (svg, _) = to_svg(r"\sqrt{a^2+b^2} \ne \pi", 14.0);
|
||
assert!(designcraft_images::svg_tree(&svg).is_some());
|
||
}
|
||
|
||
/// Hostile input must not overflow the stack: nesting past the cap stops descending instead
|
||
/// of recursing once per group (100k levels used to abort the process).
|
||
#[test]
|
||
fn an_over_deep_expression_is_bounded() {
|
||
for latex in [
|
||
format!("{}x{}", "{".repeat(100_000), "}".repeat(100_000)),
|
||
format!("{}x", r"\frac".repeat(100_000)),
|
||
format!("{}x", r"\left(".repeat(100_000)),
|
||
] {
|
||
let (svg, _) = to_svg(&latex, 12.0);
|
||
assert!(!svg.is_empty());
|
||
}
|
||
}
|
||
}
|