318 lines
12 KiB
Rust
318 lines
12 KiB
Rust
//! Shaping: text runs -> positioned glyphs in points (before line breaking).
|
||
|
||
use std::ops::Range;
|
||
use std::sync::Arc;
|
||
|
||
use harfrust::{Direction, Feature, ShapeOptions, UnicodeBuffer};
|
||
use skrifa::MetadataProvider;
|
||
use skrifa::instance::{LocationRef, Size};
|
||
use vectorcraft_doc::CharStyle;
|
||
|
||
use crate::features::OtFeatures;
|
||
use crate::fontdb::{FontDb, FontFace};
|
||
|
||
/// A shaped glyph with all character-style effects resolved, in points (y down).
|
||
#[derive(Clone, Debug)]
|
||
pub(crate) struct SGlyph {
|
||
pub face: Arc<FontFace>,
|
||
pub gid: u32,
|
||
/// Byte offset of the cluster in the plain text, and its length in bytes.
|
||
pub byte: usize,
|
||
pub len: usize,
|
||
pub run: usize,
|
||
/// Advance in points (tracking, manual kerning and horizontal scale applied).
|
||
pub adv: f64,
|
||
/// Offset from the pen position, y down.
|
||
pub dx: f64,
|
||
pub dy: f64,
|
||
/// Outline scale (font units -> points).
|
||
pub sx: f64,
|
||
pub sy: f64,
|
||
/// Baseline shift in points (positive = up).
|
||
pub bshift: f64,
|
||
/// Character rotation in degrees (counter-clockwise).
|
||
pub rotation: f64,
|
||
pub ascent: f64,
|
||
pub descent: f64,
|
||
pub leading: f64,
|
||
/// Cap height and x height in points.
|
||
pub cap: f64,
|
||
pub xh: f64,
|
||
/// First source character of the cluster.
|
||
pub ch: char,
|
||
/// Vertical type: part of a tate-chu-yoko block (set across the column, upright).
|
||
pub tcy: Option<Tcy>,
|
||
}
|
||
|
||
/// A glyph's place in a tate-chu-yoko block: the block takes one em of the column, its glyphs side
|
||
/// by side across it.
|
||
#[derive(Clone, Copy, Debug, PartialEq)]
|
||
pub(crate) struct Tcy {
|
||
/// Laid-out distance from the block's start to this glyph's pen position.
|
||
pub pen: f64,
|
||
/// Distance from the block's start to the glyph in the block's own (horizontal) setting.
|
||
pub ink: f64,
|
||
/// Width of the block's own setting.
|
||
pub width: f64,
|
||
/// Horizontal scale that fits the block into one em (1 when it fits as it is).
|
||
pub squeeze: f64,
|
||
}
|
||
|
||
impl SGlyph {
|
||
pub fn is_space(&self) -> bool {
|
||
matches!(self.ch, ' ' | '\t' | '\u{3000}' | '\u{2002}'..='\u{200B}')
|
||
}
|
||
/// A line may break after this glyph.
|
||
pub fn break_after(&self) -> bool {
|
||
self.is_space() || matches!(self.ch, '-' | '\u{2010}' | '\u{2013}' | '\u{2014}' | '/' | SOFT_HYPHEN) || is_cjk(self.ch)
|
||
}
|
||
/// A soft (discretionary) hyphen: invisible unless a line breaks after it.
|
||
pub fn is_soft_hyphen(&self) -> bool {
|
||
self.ch == SOFT_HYPHEN
|
||
}
|
||
/// Part of a word that may be hyphenated (letters and apostrophes).
|
||
pub fn is_letter(&self) -> bool {
|
||
self.ch.is_alphabetic() || matches!(self.ch, '\'' | '’')
|
||
}
|
||
}
|
||
|
||
pub(crate) const SOFT_HYPHEN: char = '\u{00AD}';
|
||
|
||
/// A visible hyphen in the face and size of `g`, placed at the end of `g`'s cluster (zero source
|
||
/// length) for a line broken inside a word.
|
||
pub(crate) fn hyphen_glyph(g: &SGlyph) -> SGlyph {
|
||
let gid = ['-', '\u{2010}', SOFT_HYPHEN].into_iter().map(|c| g.face.glyph_for(c)).find(|&id| id != 0).unwrap_or(0);
|
||
let mut h = g.clone();
|
||
h.gid = gid;
|
||
h.adv = g.face.advance(gid) * g.sx;
|
||
h.dx = 0.0;
|
||
h.dy = 0.0;
|
||
h.byte = g.byte + g.len;
|
||
h.len = 0;
|
||
h.ch = '-';
|
||
h
|
||
}
|
||
|
||
/// Kinsoku (Japanese line breaking, the strict set): a character that can't start a line —
|
||
/// closing brackets, the Japanese comma and full stop, middle dots, colons, ! and ?, the long
|
||
/// vowel mark, iteration marks and small kana.
|
||
pub(crate) fn no_line_start(c: char) -> bool {
|
||
matches!(c,
|
||
')' | ']' | '}' | ',' | '.' | ':' | ';' | '!' | '?' | '»' | '’' | '”' | '‐' | '–' | '‼' | '⁇' | '⁈' | '⁉'
|
||
| '、' | '。' | '〉' | '》' | '」' | '』' | '】' | '〕' | '〗' | '〙' | '〛' | '〟' | '〜' | '゠' | '・' | '｠'
|
||
| 'ー' | 'ゝ' | 'ゞ' | 'ヽ' | 'ヾ' | '々' | '〻'
|
||
| 'ぁ' | 'ぃ' | 'ぅ' | 'ぇ' | 'ぉ' | 'っ' | 'ゃ' | 'ゅ' | 'ょ' | 'ゎ' | 'ゕ' | 'ゖ'
|
||
| 'ァ' | 'ィ' | 'ゥ' | 'ェ' | 'ォ' | 'ッ' | 'ャ' | 'ュ' | 'ョ' | 'ヮ' | 'ヵ' | 'ヶ' | 'ㇰ'..='ㇿ'
|
||
| '！' | '）' | '，' | '．' | '：' | '；' | '？' | '］' | '｝' | '～' | '｡' | '｣' | '､' | '･' | 'ｰ' | 'ｧ'..='ｯ')
|
||
}
|
||
|
||
/// Kinsoku: a character that can't end a line (opening brackets).
|
||
pub(crate) fn no_line_end(c: char) -> bool {
|
||
matches!(
|
||
c,
|
||
'(' | '['
|
||
| '{'
|
||
| '«'
|
||
| '‘'
|
||
| '“'
|
||
| '〈'
|
||
| '《'
|
||
| '「'
|
||
| '『'
|
||
| '【'
|
||
| '〔'
|
||
| '〖'
|
||
| '〘'
|
||
| '〚'
|
||
| '〝'
|
||
| '（'
|
||
| '［'
|
||
| '｛'
|
||
| '｟'
|
||
| '｢'
|
||
)
|
||
}
|
||
|
||
fn is_cjk(c: char) -> bool {
|
||
matches!(c as u32, 0x2E80..=0x9FFF | 0xAC00..=0xD7AF | 0xF900..=0xFAFF | 0xFF00..=0xFFEF | 0x20000..=0x2FFFF)
|
||
}
|
||
|
||
/// Vertical metrics (points) of a style's resolved face: (ascent, descent, leading).
|
||
pub(crate) fn style_metrics(db: &FontDb, st: &CharStyle) -> (f64, f64, f64) {
|
||
let vs = st.v_scale / 100.0;
|
||
let Some(face) = db.face(&st.font_family, &st.font_style) else { return (st.size * 0.8 * vs, st.size * 0.2 * vs, st.effective_leading()) };
|
||
let k = st.size / face.upem;
|
||
(face.ascent * k * vs, face.descent * k * vs, st.effective_leading())
|
||
}
|
||
|
||
/// Cap height and x height (points) of a style's resolved face.
|
||
pub(crate) fn cap_x_heights(db: &FontDb, st: &CharStyle) -> (f64, f64) {
|
||
let vs = st.v_scale / 100.0;
|
||
let Some(face) = db.face(&st.font_family, &st.font_style) else { return (st.size * 0.7 * vs, st.size * 0.5 * vs) };
|
||
let k = st.size / face.upem * vs;
|
||
(face.cap_height * k, face.x_height * k)
|
||
}
|
||
|
||
/// Shape `text[range]`, where `runs` gives each run's byte range in `text` and style.
|
||
pub(crate) fn shape_range(
|
||
db: &FontDb,
|
||
text: &str,
|
||
range: Range<usize>,
|
||
runs: &[(Range<usize>, &CharStyle)],
|
||
feats: &OtFeatures,
|
||
out: &mut Vec<SGlyph>,
|
||
) {
|
||
for (ri, (rr, st)) in runs.iter().enumerate() {
|
||
let a = rr.start.max(range.start);
|
||
let b = rr.end.min(range.end);
|
||
if a >= b {
|
||
continue;
|
||
}
|
||
let Some(primary) = db.face(&st.font_family, &st.font_style) else { continue };
|
||
let pmap = primary.skrifa().map(|f| f.charmap());
|
||
// Synthesized Small Caps shape lowercase letters separately (as smaller capitals).
|
||
let small_caps = st.small_caps.is_some() && !st.all_caps;
|
||
// Split into segments by font coverage (and case, for Small Caps).
|
||
let mut seg = Segment { range: a..a, run: ri, st, face: primary.clone(), small: false };
|
||
let mut cache: Vec<(char, Arc<FontFace>)> = Vec::new();
|
||
for (i, c) in text[a..b].char_indices() {
|
||
let i = a + i;
|
||
let covered = c.is_whitespace() || c.is_control() || pmap.as_ref().is_none_or(|m| m.map(c).is_some());
|
||
let face = if covered {
|
||
primary.clone()
|
||
} else if let Some((_, f)) = cache.iter().find(|(k, _)| *k == c) {
|
||
f.clone()
|
||
} else {
|
||
let f = db.fallback_for(c, primary.id()).unwrap_or_else(|| primary.clone());
|
||
cache.push((c, f.clone()));
|
||
f
|
||
};
|
||
let small = small_caps && c.is_lowercase();
|
||
// Combining marks stay with their base.
|
||
if (face.id() != seg.face.id() || small != seg.small) && !is_mark(c) {
|
||
if i > seg.range.start {
|
||
seg.range.end = i;
|
||
shape_segment(text, &seg, feats, out);
|
||
}
|
||
seg = Segment { range: i..i, face, small, ..seg };
|
||
}
|
||
}
|
||
if b > seg.range.start {
|
||
seg.range.end = b;
|
||
shape_segment(text, &seg, feats, out);
|
||
}
|
||
}
|
||
}
|
||
|
||
/// A piece of one run shaped in one go: one face and, for Small Caps, one case.
|
||
struct Segment<'a> {
|
||
range: Range<usize>,
|
||
run: usize,
|
||
st: &'a CharStyle,
|
||
face: Arc<FontFace>,
|
||
/// Lowercase letters drawn as synthesized small capitals.
|
||
small: bool,
|
||
}
|
||
|
||
fn is_mark(c: char) -> bool {
|
||
matches!(c as u32, 0x0300..=0x036F | 0x1AB0..=0x1AFF | 0x1DC0..=0x1DFF | 0x20D0..=0x20FF | 0xFE20..=0xFE2F | 0x200D | 0xFE00..=0xFE0F)
|
||
}
|
||
|
||
fn shape_segment(text: &str, seg: &Segment, feats: &OtFeatures, out: &mut Vec<SGlyph>) {
|
||
let Segment { range, run, st, face, small } = seg;
|
||
let (range, run, small) = (range.clone(), *run, *small);
|
||
let text_seg = &text[range.clone()];
|
||
let full = st.size.max(0.0);
|
||
// Superscript/subscript and small capitals shrink the glyphs; line metrics keep the full size.
|
||
let (pos_scale, pos_shift) = st.position.scale_shift(full);
|
||
let small_scale = if small { st.small_caps.unwrap_or(100.0) / 100.0 } else { 1.0 };
|
||
let size = full * pos_scale * small_scale;
|
||
let k = size / face.upem;
|
||
let km = full / face.upem;
|
||
let hs = st.h_scale / 100.0;
|
||
let vs = st.v_scale / 100.0;
|
||
let tracking = st.tracking / 1000.0 * size;
|
||
let manual_kern = st.kerning.map(|v| v / 1000.0 * size).unwrap_or(0.0);
|
||
let ascent = face.ascent * km * vs;
|
||
let descent = face.descent * km * vs;
|
||
let leading = st.effective_leading();
|
||
let cap = face.cap_height * km * vs;
|
||
let xh = face.x_height * km * vs;
|
||
let upper = st.all_caps || small;
|
||
let first_char = |byte: usize| text[byte..].chars().next().unwrap_or(' ');
|
||
|
||
let mut raw: Vec<(u32, u32, i32, i32, i32)> = Vec::with_capacity(text_seg.len()); // gid, cluster, xadv, xoff, yoff
|
||
let shaped = face.hb().map(|hb| {
|
||
let shaper = face.shaper.shaper(&hb).build();
|
||
let mut buf = UnicodeBuffer::new();
|
||
for (i, c) in text_seg.char_indices() {
|
||
let cl = (range.start + i) as u32;
|
||
if upper {
|
||
for u in c.to_uppercase() {
|
||
buf.add(u, cl);
|
||
}
|
||
} else {
|
||
buf.add(c, cl);
|
||
}
|
||
}
|
||
buf.set_direction(Direction::LeftToRight);
|
||
buf.guess_segment_properties();
|
||
let feats: Vec<Feature> = feats.resolve(st);
|
||
let gb = shaper.shape(buf, ShapeOptions::new().features(&feats));
|
||
for (info, pos) in gb.glyph_infos().iter().zip(gb.glyph_positions()) {
|
||
raw.push((info.glyph_id, info.cluster, pos.x_advance, pos.x_offset, pos.y_offset));
|
||
}
|
||
});
|
||
if shaped.is_none() {
|
||
// Fallback: nominal glyphs and hmtx advances, no shaping.
|
||
if let Some(f) = face.skrifa() {
|
||
let cmap = f.charmap();
|
||
let gm = f.glyph_metrics(Size::unscaled(), LocationRef::default());
|
||
for (i, c) in text_seg.char_indices() {
|
||
let cl = (range.start + i) as u32;
|
||
let chars: Vec<char> = if upper { c.to_uppercase().collect() } else { vec![c] };
|
||
for u in chars {
|
||
let g = cmap.map(u).unwrap_or_default();
|
||
let adv = gm.advance_width(g).unwrap_or(face.upem as f32 * 0.5);
|
||
raw.push((g.to_u32(), cl, adv.round() as i32, 0, 0));
|
||
}
|
||
}
|
||
}
|
||
}
|
||
let n = raw.len();
|
||
for (gi, &(gid, cl, xa, xo, yo)) in raw.iter().enumerate() {
|
||
let cl = cl as usize;
|
||
// Cluster end: the next larger cluster value in the segment, else the segment end.
|
||
let end = raw[gi + 1..].iter().map(|r| r.1 as usize).find(|&c| c > cl).unwrap_or(range.end);
|
||
let last_in_cluster = gi + 1 == n || raw[gi + 1].1 as usize != cl;
|
||
let ch = first_char(cl);
|
||
let mut adv = xa as f64 * k * hs;
|
||
if ch == SOFT_HYPHEN {
|
||
adv = 0.0;
|
||
} else if last_in_cluster {
|
||
adv += tracking + manual_kern;
|
||
}
|
||
out.push(SGlyph {
|
||
face: face.clone(),
|
||
gid,
|
||
byte: cl,
|
||
len: end.saturating_sub(cl).max(1),
|
||
run,
|
||
adv,
|
||
dx: xo as f64 * k * hs,
|
||
dy: -(yo as f64) * k * vs,
|
||
sx: k * hs,
|
||
sy: k * vs,
|
||
bshift: st.baseline_shift + pos_shift,
|
||
rotation: st.rotation,
|
||
ascent,
|
||
descent,
|
||
leading,
|
||
cap,
|
||
xh,
|
||
ch,
|
||
tcy: None,
|
||
});
|
||
}
|
||
}
|