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https://github.com/typst/typst
synced 2025-05-21 04:25:28 +08:00
Simplify shaping 🌱
This commit is contained in:
Laurenz
parent
d1c07260c0
commit
2df8b964d0
@ -116,11 +116,11 @@ impl<'a> TreeLayouter<'a> {
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let boxed = shaping::shape(
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text,
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self.ctx.state.sys.primary,
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self.ctx.state.text.font_size(),
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variant,
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&self.ctx.state.text.fallback,
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self.ctx.state.sys.primary,
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&mut self.ctx.loader.borrow_mut(),
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&self.ctx.state.text.fallback,
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variant,
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)
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.await;
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176
src/shaping.rs
176
src/shaping.rs
@ -7,24 +7,12 @@
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use std::fmt::{self, Debug, Formatter};
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use fontdock::{FaceId, FaceQuery, FallbackTree, FontVariant};
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use ttf_parser::GlyphId;
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use ttf_parser::{Face, GlyphId};
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use crate::font::FontLoader;
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use crate::geom::{Point, Size};
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use crate::layout::{BoxLayout, Dir, LayoutElement};
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/// Shape text into a box containing shaped runs.
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pub async fn shape(
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text: &str,
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dir: Dir,
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size: f64,
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variant: FontVariant,
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fallback: &FallbackTree,
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loader: &mut FontLoader,
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) -> BoxLayout {
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Shaper::new(text, dir, size, variant, fallback, loader).shape().await
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}
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/// A shaped run of text.
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#[derive(Clone, PartialEq)]
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pub struct Shaped {
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@ -70,113 +58,75 @@ impl Debug for Shaped {
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}
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}
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/// Performs super-basic text shaping.
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struct Shaper<'a> {
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text: &'a str,
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/// Shape text into a box containing [`Shaped`] runs.
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///
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/// [`Shaped`]: struct.Shaped.html
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pub async fn shape(
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text: &str,
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size: f64,
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dir: Dir,
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loader: &mut FontLoader,
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fallback: &FallbackTree,
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variant: FontVariant,
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fallback: &'a FallbackTree,
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loader: &'a mut FontLoader,
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shaped: Shaped,
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layout: BoxLayout,
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offset: f64,
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}
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) -> BoxLayout {
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let mut layout = BoxLayout::new(Size::new(0.0, size));
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let mut shaped = Shaped::new(FaceId::MAX, size);
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let mut offset = 0.0;
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impl<'a> Shaper<'a> {
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fn new(
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text: &'a str,
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dir: Dir,
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size: f64,
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variant: FontVariant,
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fallback: &'a FallbackTree,
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loader: &'a mut FontLoader,
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) -> Self {
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Self {
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text,
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dir,
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variant,
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fallback,
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loader,
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shaped: Shaped::new(FaceId::MAX, size),
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layout: BoxLayout::new(Size::new(0.0, size)),
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offset: 0.0,
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}
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}
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// Create an iterator with conditional direction.
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let mut forwards = text.chars();
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let mut backwards = text.chars().rev();
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let chars: &mut dyn Iterator<Item = char> = if dir.is_positive() {
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&mut forwards
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} else {
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&mut backwards
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};
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async fn shape(mut self) -> BoxLayout {
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// If the primary axis is negative, we layout the characters reversed.
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if self.dir.is_positive() {
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for c in self.text.chars() {
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self.shape_char(c).await;
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}
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} else {
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for c in self.text.chars().rev() {
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self.shape_char(c).await;
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}
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}
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// Flush the last buffered parts of the word.
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if !self.shaped.text.is_empty() {
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let pos = Point::new(self.offset, 0.0);
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self.layout.push(pos, LayoutElement::Text(self.shaped));
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}
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self.layout
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}
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async fn shape_char(&mut self, c: char) {
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let (index, glyph, char_width) = match self.select_font(c).await {
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Some(selected) => selected,
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// TODO: Issue warning about missing character.
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None => return,
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};
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// Flush the buffer and issue a font setting action if the font differs
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// from the last character's one.
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if self.shaped.face != index {
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if !self.shaped.text.is_empty() {
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let shaped = std::mem::replace(
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&mut self.shaped,
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Shaped::new(FaceId::MAX, self.layout.size.height),
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);
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let pos = Point::new(self.offset, 0.0);
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self.layout.push(pos, LayoutElement::Text(shaped));
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self.offset = self.layout.size.width;
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}
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self.shaped.face = index;
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}
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self.shaped.text.push(c);
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self.shaped.glyphs.push(glyph);
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self.shaped.offsets.push(self.layout.size.width - self.offset);
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self.layout.size.width += char_width;
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}
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async fn select_font(&mut self, c: char) -> Option<(FaceId, GlyphId, f64)> {
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let query = FaceQuery {
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fallback: self.fallback.iter(),
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variant: self.variant,
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c,
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};
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if let Some((id, owned_face)) = self.loader.query(query).await {
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for c in chars {
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let query = FaceQuery { fallback: fallback.iter(), variant, c };
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if let Some((id, owned_face)) = loader.query(query).await {
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let face = owned_face.get();
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let (glyph, width) = match lookup_glyph(face, c, size) {
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Some(v) => v,
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None => continue,
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};
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let units_per_em = face.units_per_em().unwrap_or(1000) as f64;
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let ratio = 1.0 / units_per_em;
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let font_size = self.layout.size.height;
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let to_raw = |x| ratio * x as f64 * font_size;
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// Flush the buffer if we change the font face.
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if shaped.face != id && !shaped.text.is_empty() {
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let pos = Point::new(layout.size.width, 0.0);
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layout.push(pos, LayoutElement::Text(shaped));
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layout.size.width += offset;
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shaped = Shaped::new(FaceId::MAX, size);
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offset = 0.0;
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}
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// Determine the width of the char.
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let glyph = face.glyph_index(c)?;
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let glyph_width = to_raw(face.glyph_hor_advance(glyph)? as i32);
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Some((id, glyph, glyph_width))
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} else {
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None
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shaped.face = id;
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shaped.text.push(c);
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shaped.glyphs.push(glyph);
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shaped.offsets.push(offset);
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offset += width;
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}
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}
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// Flush the last buffered parts of the word.
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if !shaped.text.is_empty() {
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let pos = Point::new(layout.size.width, 0.0);
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layout.push(pos, LayoutElement::Text(shaped));
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layout.size.width += offset;
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}
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layout
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}
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/// Looks up the glyph for `c` and returns its index alongside its width at the
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/// given `size`.
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fn lookup_glyph(face: &Face, c: char, size: f64) -> Option<(GlyphId, f64)> {
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let glyph = face.glyph_index(c)?;
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// Determine the width of the char.
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let units_per_em = face.units_per_em().unwrap_or(1000) as f64;
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let width_units = face.glyph_hor_advance(glyph)? as f64;
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let width = width_units / units_per_em * size;
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Some((glyph, width))
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}
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