mirror of
https://github.com/typst/typst
synced 2025-05-17 02:25:27 +08:00
424 lines
11 KiB
Rust
424 lines
11 KiB
Rust
use kurbo::{BezPath, Line, ParamCurve};
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use ttf_parser::{GlyphId, OutlineBuilder};
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use super::TextElem;
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use crate::prelude::*;
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/// Underline text.
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///
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/// ## Example { #example }
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/// ```example
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/// This is #underline[important].
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/// ```
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///
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/// Display: Underline
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/// Category: text
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#[element(Show)]
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pub struct UnderlineElem {
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/// How to stroke the line.
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///
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/// See the [line's documentation]($func/line.stroke) for more details. If
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/// set to `{auto}`, takes on the text's color and a thickness defined in
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/// the current font.
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///
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/// ```example
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/// Take #underline(
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/// stroke: 1.5pt + red,
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/// offset: 2pt,
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/// [care],
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/// )
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/// ```
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#[resolve]
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#[fold]
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pub stroke: Smart<PartialStroke>,
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/// Position of the line relative to the baseline, read from the font tables
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/// if `{auto}`.
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///
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/// ```example
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/// #underline(offset: 5pt)[
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/// The Tale Of A Faraway Line I
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/// ]
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/// ```
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#[resolve]
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pub offset: Smart<Length>,
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/// Amount that the line will be longer or shorter than its associated text.
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///
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/// ```example
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/// #align(center,
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/// underline(extent: 2pt)[Chapter 1]
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/// )
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/// ```
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#[resolve]
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pub extent: Length,
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/// Whether the line skips sections in which it would collide with the
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/// glyphs.
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///
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/// ```example
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/// This #underline(evade: true)[is great].
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/// This #underline(evade: false)[is less great].
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/// ```
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#[default(true)]
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pub evade: bool,
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/// The content to underline.
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#[required]
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pub body: Content,
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}
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impl Show for UnderlineElem {
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#[tracing::instrument(name = "UnderlineElem::show", skip_all)]
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fn show(&self, _: &mut Vt, styles: StyleChain) -> SourceResult<Content> {
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Ok(self.body().styled(TextElem::set_deco(Decoration {
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line: DecoLine::Underline,
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stroke: self.stroke(styles).unwrap_or_default(),
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offset: self.offset(styles),
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extent: self.extent(styles),
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evade: self.evade(styles),
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})))
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}
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}
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/// Add a line over text.
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///
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/// ## Example { #example }
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/// ```example
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/// #overline[A line over text.]
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/// ```
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///
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/// Display: Overline
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/// Category: text
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#[element(Show)]
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pub struct OverlineElem {
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/// How to stroke the line.
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///
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/// See the [line's documentation]($func/line.stroke) for more details. If
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/// set to `{auto}`, takes on the text's color and a thickness defined in
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/// the current font.
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///
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/// ```example
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/// #set text(fill: olive)
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/// #overline(
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/// stroke: green.darken(20%),
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/// offset: -12pt,
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/// [The Forest Theme],
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/// )
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/// ```
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#[resolve]
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#[fold]
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pub stroke: Smart<PartialStroke>,
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/// Position of the line relative to the baseline, read from the font tables
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/// if `{auto}`.
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///
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/// ```example
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/// #overline(offset: -1.2em)[
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/// The Tale Of A Faraway Line II
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/// ]
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/// ```
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#[resolve]
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pub offset: Smart<Length>,
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/// Amount that the line will be longer or shorter than its associated text.
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///
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/// ```example
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/// #set overline(extent: 4pt)
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/// #set underline(extent: 4pt)
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/// #overline(underline[Typography Today])
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/// ```
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#[resolve]
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pub extent: Length,
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/// Whether the line skips sections in which it would collide with the
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/// glyphs.
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///
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/// ```example
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/// #overline(
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/// evade: false,
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/// offset: -7.5pt,
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/// stroke: 1pt,
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/// extent: 3pt,
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/// [Temple],
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/// )
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/// ```
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#[default(true)]
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pub evade: bool,
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/// The content to add a line over.
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#[required]
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pub body: Content,
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}
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impl Show for OverlineElem {
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#[tracing::instrument(name = "OverlineElem::show", skip_all)]
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fn show(&self, _: &mut Vt, styles: StyleChain) -> SourceResult<Content> {
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Ok(self.body().styled(TextElem::set_deco(Decoration {
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line: DecoLine::Overline,
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stroke: self.stroke(styles).unwrap_or_default(),
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offset: self.offset(styles),
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extent: self.extent(styles),
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evade: self.evade(styles),
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})))
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}
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}
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/// Strike through text.
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///
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/// ## Example { #example }
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/// ```example
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/// This is #strike[not] relevant.
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/// ```
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///
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/// Display: Strikethrough
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/// Category: text
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#[element(Show)]
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pub struct StrikeElem {
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/// How to stroke the line.
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///
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/// See the [line's documentation]($func/line.stroke) for more details. If
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/// set to `{auto}`, takes on the text's color and a thickness defined in
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/// the current font.
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///
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/// _Note:_ Please don't use this for real redaction as you can still
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/// copy paste the text.
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///
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/// ```example
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/// This is #strike(stroke: 1.5pt + red)[very stricken through]. \
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/// This is #strike(stroke: 10pt)[redacted].
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/// ```
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#[resolve]
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#[fold]
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pub stroke: Smart<PartialStroke>,
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/// Position of the line relative to the baseline, read from the font tables
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/// if `{auto}`.
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///
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/// This is useful if you are unhappy with the offset your font provides.
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///
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/// ```example
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/// #set text(font: "Inria Serif")
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/// This is #strike(offset: auto)[low-ish]. \
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/// This is #strike(offset: -3.5pt)[on-top].
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/// ```
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#[resolve]
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pub offset: Smart<Length>,
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/// Amount that the line will be longer or shorter than its associated text.
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///
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/// ```example
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/// This #strike(extent: -2pt)[skips] parts of the word.
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/// This #strike(extent: 2pt)[extends] beyond the word.
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/// ```
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#[resolve]
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pub extent: Length,
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/// The content to strike through.
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#[required]
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pub body: Content,
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}
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impl Show for StrikeElem {
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#[tracing::instrument(name = "StrikeElem::show", skip_all)]
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fn show(&self, _: &mut Vt, styles: StyleChain) -> SourceResult<Content> {
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Ok(self.body().styled(TextElem::set_deco(Decoration {
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line: DecoLine::Strikethrough,
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stroke: self.stroke(styles).unwrap_or_default(),
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offset: self.offset(styles),
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extent: self.extent(styles),
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evade: false,
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})))
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}
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}
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/// Defines a line that is positioned over, under or on top of text.
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#[derive(Debug, Clone, Eq, PartialEq, Hash)]
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pub struct Decoration {
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pub line: DecoLine,
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pub stroke: PartialStroke<Abs>,
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pub offset: Smart<Abs>,
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pub extent: Abs,
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pub evade: bool,
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}
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impl Fold for Decoration {
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type Output = Vec<Self>;
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fn fold(self, mut outer: Self::Output) -> Self::Output {
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outer.insert(0, self);
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outer
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}
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}
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cast! {
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type Decoration: "decoration",
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}
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/// A kind of decorative line.
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#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
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pub enum DecoLine {
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Underline,
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Strikethrough,
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Overline,
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}
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/// Add line decorations to a single run of shaped text.
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pub(super) fn decorate(
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frame: &mut Frame,
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deco: &Decoration,
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text: &TextItem,
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shift: Abs,
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pos: Point,
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width: Abs,
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) {
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let font_metrics = text.font.metrics();
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let metrics = match deco.line {
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DecoLine::Strikethrough => font_metrics.strikethrough,
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DecoLine::Overline => font_metrics.overline,
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DecoLine::Underline => font_metrics.underline,
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};
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let offset = deco.offset.unwrap_or(-metrics.position.at(text.size)) - shift;
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let stroke = deco.stroke.clone().unwrap_or(Stroke {
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paint: text.fill.clone(),
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thickness: metrics.thickness.at(text.size),
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..Stroke::default()
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});
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let gap_padding = 0.08 * text.size;
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let min_width = 0.162 * text.size;
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let mut start = pos.x - deco.extent;
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let end = pos.x + (width + 2.0 * deco.extent);
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let mut push_segment = |from: Abs, to: Abs| {
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let origin = Point::new(from, pos.y + offset);
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let target = Point::new(to - from, Abs::zero());
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if target.x >= min_width || !deco.evade {
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let shape = Geometry::Line(target).stroked(stroke.clone());
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frame.push(origin, FrameItem::Shape(shape, Span::detached()));
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}
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};
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if !deco.evade {
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push_segment(start, end);
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return;
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}
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let line = Line::new(
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kurbo::Point::new(pos.x.to_raw(), offset.to_raw()),
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kurbo::Point::new((pos.x + width).to_raw(), offset.to_raw()),
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);
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let mut x = pos.x;
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let mut intersections = vec![];
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for glyph in text.glyphs.iter() {
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let dx = glyph.x_offset.at(text.size) + x;
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let mut builder =
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BezPathBuilder::new(font_metrics.units_per_em, text.size, dx.to_raw());
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let bbox = text.font.ttf().outline_glyph(GlyphId(glyph.id), &mut builder);
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let path = builder.finish();
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x += glyph.x_advance.at(text.size);
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// Only do the costly segments intersection test if the line
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// intersects the bounding box.
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let intersect = bbox.map_or(false, |bbox| {
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let y_min = -text.font.to_em(bbox.y_max).at(text.size);
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let y_max = -text.font.to_em(bbox.y_min).at(text.size);
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offset >= y_min && offset <= y_max
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});
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if intersect {
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// Find all intersections of segments with the line.
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intersections.extend(
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path.segments()
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.flat_map(|seg| seg.intersect_line(line))
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.map(|is| Abs::raw(line.eval(is.line_t).x)),
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);
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}
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}
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// When emitting the decorative line segments, we move from left to
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// right. The intersections are not necessarily in this order, yet.
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intersections.sort();
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for gap in intersections.chunks_exact(2) {
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let l = gap[0] - gap_padding;
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let r = gap[1] + gap_padding;
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if start >= end {
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break;
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}
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if start >= l {
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start = r;
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continue;
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}
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push_segment(start, l);
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start = r;
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}
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if start < end {
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push_segment(start, end);
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}
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}
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/// Builds a kurbo [`BezPath`] for a glyph.
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struct BezPathBuilder {
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path: BezPath,
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units_per_em: f64,
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font_size: Abs,
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x_offset: f64,
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}
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impl BezPathBuilder {
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fn new(units_per_em: f64, font_size: Abs, x_offset: f64) -> Self {
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Self {
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path: BezPath::new(),
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units_per_em,
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font_size,
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x_offset,
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}
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}
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fn finish(self) -> BezPath {
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self.path
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}
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fn p(&self, x: f32, y: f32) -> kurbo::Point {
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kurbo::Point::new(self.s(x) + self.x_offset, -self.s(y))
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}
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fn s(&self, v: f32) -> f64 {
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Em::from_units(v, self.units_per_em).at(self.font_size).to_raw()
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}
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}
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impl OutlineBuilder for BezPathBuilder {
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fn move_to(&mut self, x: f32, y: f32) {
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self.path.move_to(self.p(x, y));
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}
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fn line_to(&mut self, x: f32, y: f32) {
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self.path.line_to(self.p(x, y));
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}
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fn quad_to(&mut self, x1: f32, y1: f32, x: f32, y: f32) {
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self.path.quad_to(self.p(x1, y1), self.p(x, y));
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}
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fn curve_to(&mut self, x1: f32, y1: f32, x2: f32, y2: f32, x: f32, y: f32) {
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self.path.curve_to(self.p(x1, y1), self.p(x2, y2), self.p(x, y));
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}
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fn close(&mut self) {
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self.path.close_path();
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}
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}
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