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826 lines
37 KiB
Rust
826 lines
37 KiB
Rust
//! Shaping: text runs -> positioned glyphs in points (before line breaking).
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use std::ops::Range;
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use std::sync::Arc;
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use unicode_bidi::Level;
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use unicode_script::{Script, UnicodeScript};
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use harfrust::{Direction, Feature, ShapeOptions, Tag, UnicodeBuffer};
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use skrifa::MetadataProvider;
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use skrifa::instance::Size;
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use vectorcraft_doc::text::INLINE_CHAR;
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use vectorcraft_doc::{CharStyle, InlineArt};
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use crate::features::{OtFeatures, ligatures_suppressed_by};
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use crate::fontdb::{FontDb, FontFace};
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/// A shaped glyph with all character-style effects resolved, in points (y down).
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#[derive(Clone, Debug)]
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pub(crate) struct SGlyph {
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pub face: Arc<FontFace>,
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pub gid: u32,
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/// Byte offset of the cluster in the plain text, and its length in bytes.
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pub byte: usize,
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pub len: usize,
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pub run: usize,
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/// Advance in points (tracking, manual kerning and horizontal scale applied).
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pub adv: f64,
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/// Offset from the pen position, y down.
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pub dx: f64,
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pub dy: f64,
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/// Outline scale (font units -> points).
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pub sx: f64,
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pub sy: f64,
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/// Baseline shift in points (positive = up).
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pub bshift: f64,
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/// Character rotation in degrees (counter-clockwise).
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pub rotation: f64,
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pub ascent: f64,
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pub descent: f64,
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pub leading: f64,
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/// Cap height and x height in points.
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pub cap: f64,
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pub xh: f64,
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/// First source character of the cluster.
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pub ch: char,
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/// Vertical type: part of a tate-chu-yoko block (set across the column, upright).
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pub tcy: Option<Tcy>,
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/// Japanese composition: the space taken off before the glyph (an opening bracket after
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/// another, see [`crate::layout`]); the glyph is drawn that much earlier on the line.
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pub lead: f64,
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/// Proportional Metrics changed the glyph's advance (`palt`): it has its proportional width,
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/// and Japanese composition takes no more space off it (#966).
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pub proportional: bool,
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/// Vertical type with Proportional Metrics: what `vpal` does to the glyph when it stands
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/// upright ([`crate::layout`] applies it).
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pub vpal: Option<VAdjust>,
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/// Resolved Unicode bidi embedding level (logical source order).
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pub level: Level,
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/// An inline graphic ([`vectorcraft_doc::TextRun::inline`]) standing in for a glyph.
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pub inline: Option<InlineBox>,
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/// A word of a script written without spaces (Thai, Lao, Khmer, Myanmar) ends after the
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/// glyph's cluster, so a line may break there ([`mark_word_ends`]).
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pub word_end: bool,
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/// No Break (Character panel menu): keep this glyph on the same line as the neighbouring
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/// glyphs that have it.
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pub no_break: bool,
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}
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/// How `vpal` and the vertical kerning with it move an upright glyph in vertical type and change
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/// its length down the column, in points: `advance` down the column, `dx` and `dy` in glyph space
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/// (y down; `dy` is down the column once the glyph stands upright). `proportional`: `vpal` itself
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/// changed the advance.
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#[derive(Clone, Copy, Debug, Default, PartialEq)]
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pub(crate) struct VAdjust {
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pub advance: f64,
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pub dx: f64,
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pub dy: f64,
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pub proportional: bool,
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}
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/// Placement of an inline graphic's art, glyph space being points with the pen at the origin on
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/// the baseline (y down).
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#[derive(Clone, Copy, Debug, PartialEq)]
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pub(crate) struct InlineBox {
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/// The art's bounds in symbol space; `None` when the symbol is missing (the box only takes
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/// up room).
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pub art: Option<kurbo::Rect>,
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/// Art -> glyph space.
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pub xf: kurbo::Affine,
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}
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/// A glyph's place in a tate-chu-yoko block: the block takes one em of the column, its glyphs side
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/// by side across it.
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#[derive(Clone, Copy, Debug, PartialEq)]
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pub(crate) struct Tcy {
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/// Laid-out distance from the block's start to this glyph's pen position.
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pub pen: f64,
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/// Distance from the block's start to the glyph in the block's own (horizontal) setting.
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pub ink: f64,
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/// Width of the block's own setting.
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pub width: f64,
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/// Horizontal scale that fits the block into one em (1 when it fits as it is).
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pub squeeze: f64,
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}
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impl SGlyph {
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pub fn is_space(&self) -> bool {
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self.inline.is_none() && matches!(self.ch, ' ' | '\t' | '\u{3000}' | '\u{2002}'..='\u{200B}')
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}
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/// A line may break after this glyph.
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pub fn break_after(&self) -> bool {
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self.is_space() || self.word_end || matches!(self.ch, '-' | '\u{2010}' | '\u{2013}' | '\u{2014}' | '/' | SOFT_HYPHEN) || is_cjk(self.ch)
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}
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/// A soft (discretionary) hyphen: invisible unless a line breaks after it.
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pub fn is_soft_hyphen(&self) -> bool {
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self.ch == SOFT_HYPHEN
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}
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/// Part of a word that may be hyphenated (letters and apostrophes).
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pub fn is_letter(&self) -> bool {
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self.ch.is_alphabetic() || matches!(self.ch, '\'' | '’')
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}
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/// Vertical type: a tate-chu-yoko glyph after its block's first, sharing that glyph's cell.
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pub fn continues_tcy(&self) -> bool {
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self.tcy.is_some_and(|t| t.pen > 0.0)
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}
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}
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pub(crate) const SOFT_HYPHEN: char = '\u{00AD}';
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/// A visible hyphen in the face and size of `g`, placed at the end of `g`'s cluster (zero source
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/// length) for a line broken inside a word.
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pub(crate) fn hyphen_glyph(g: &SGlyph) -> SGlyph {
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let gid = ['-', '\u{2010}', SOFT_HYPHEN].into_iter().map(|c| g.face.glyph_for(c)).find(|&id| id != 0).unwrap_or(0);
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let mut h = g.clone();
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h.gid = gid;
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h.adv = g.face.advance(gid) * g.sx;
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h.dx = 0.0;
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h.dy = 0.0;
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h.byte = g.byte + g.len;
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h.len = 0;
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h.ch = '-';
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h.inline = None;
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h.proportional = false;
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h.vpal = None;
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h
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}
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/// Kinsoku (Japanese line breaking, the strict set): a character that can't start a line —
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/// closing brackets, the Japanese comma and full stop, middle dots, colons, ! and ?, the long
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/// vowel mark, iteration marks and small kana.
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pub(crate) fn no_line_start(c: char) -> bool {
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matches!(c,
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')' | ']' | '}' | ',' | '.' | ':' | ';' | '!' | '?' | '»' | '’' | '”' | '‐' | '–' | '‼' | '⁇' | '⁈' | '⁉'
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| '、' | '。' | '〉' | '》' | '」' | '』' | '】' | '〕' | '〗' | '〙' | '〛' | '〟' | '〜' | '゠' | '・' | '｠'
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| 'ー' | 'ゝ' | 'ゞ' | 'ヽ' | 'ヾ' | '々' | '〻'
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| 'ぁ' | 'ぃ' | 'ぅ' | 'ぇ' | 'ぉ' | 'っ' | 'ゃ' | 'ゅ' | 'ょ' | 'ゎ' | 'ゕ' | 'ゖ'
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| 'ァ' | 'ィ' | 'ゥ' | 'ェ' | 'ォ' | 'ッ' | 'ャ' | 'ュ' | 'ョ' | 'ヮ' | 'ヵ' | 'ヶ' | 'ㇰ'..='ㇿ'
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| '！' | '）' | '，' | '．' | '：' | '；' | '？' | '］' | '｝' | '～' | '｡' | '｣' | '､' | '･' | 'ｰ' | 'ｧ'..='ｯ')
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}
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/// Soft kinsoku: a character of [`no_line_start`] that may start a line all the same: 々, the
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/// prolonged sound mark ー (JLREQ cl-10) and small kana (cl-11), as JLREQ's level 3 rules allow
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/// (Appendix C.3, https://www.w3.org/TR/jlreq/#addendum_a3).
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pub(crate) fn soft_line_start(c: char) -> bool {
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matches!(
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c,
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'々' | 'ー'
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| '\u{3041}'
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| '\u{3043}'
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| '\u{3045}'
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| '\u{3047}'
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| '\u{3049}'
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| '\u{3063}'
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| '\u{3083}'
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| '\u{3085}'
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| '\u{3087}'
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| '\u{308E}'
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| '\u{3095}'
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| '\u{3096}'
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| '\u{30A1}'
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| '\u{30A3}'
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| '\u{30A5}'
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| '\u{30A7}'
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| '\u{30A9}'
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| '\u{30C3}'
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| '\u{30E3}'
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| '\u{30E5}'
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| '\u{30E7}'
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| '\u{30EE}'
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| '\u{30F5}'
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| '\u{30F6}'
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| '\u{31F0}'..='\u{31FF}'
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)
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}
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/// Kinsoku: a character that can't end a line (opening brackets).
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pub(crate) fn no_line_end(c: char) -> bool {
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matches!(
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c,
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'(' | '['
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| '{'
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| '«'
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| '‘'
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| '“'
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| '〈'
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| '《'
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| '「'
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| '『'
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| '【'
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| '〔'
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| '〖'
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| '〘'
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| '〚'
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| '〝'
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| '（'
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| '［'
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| '｛'
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| '｟'
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| '｢'
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)
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}
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/// Full-width punctuation for Japanese composition (JLREQ cl-01, cl-02, cl-06, cl-07).
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#[derive(Clone, Copy, Debug, PartialEq, Eq)]
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pub(crate) enum Punct {
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/// An opening bracket: its half-em space is before the mark.
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Opening,
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/// A closing bracket, comma or full stop: its half-em space is after the mark.
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Closing,
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}
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pub(crate) fn punct(c: char) -> Option<Punct> {
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match c {
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'（' | '「' | '『' | '【' | '〔' | '〈' | '《' | '［' | '｛' | '〘' | '〖' | '｟' | '〝' => Some(Punct::Opening),
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'）' | '」' | '』' | '】' | '〕' | '〉' | '》' | '］' | '｝' | '〙' | '〗' | '｠' | '〟' | '、' | '。' | '，' | '．' => {
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Some(Punct::Closing)
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}
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_ => None,
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}
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}
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/// Is `c` of a script written without spaces between words, whose line breaks need a model of its
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/// words: Thai, Lao, Khmer or Myanmar (UAX #14's class SA)?
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pub(crate) fn is_unspaced_script(c: char) -> bool {
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matches!(c.script(), Script::Thai | Script::Lao | Script::Khmer | Script::Myanmar)
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}
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/// The byte offsets of `text` where a word of Thai, Lao, Khmer or Myanmar starts or ends: where a
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/// line may break, and where the caret stops word by word, in text without spaces between words.
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/// They come from ICU4X's line segmenter (its dictionaries on the desktop, its far smaller LSTM
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/// models on the web); empty when `text` has none of those scripts. Offsets elsewhere (around
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/// other text) are UAX #14's breaks.
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pub(crate) fn unspaced_word_breaks(text: &str) -> Vec<usize> {
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#[cfg(not(target_arch = "wasm32"))]
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static SEGMENTER: std::sync::LazyLock<icu_segmenter::LineSegmenterBorrowed<'static>> =
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std::sync::LazyLock::new(|| icu_segmenter::LineSegmenter::new_dictionary(Default::default()));
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#[cfg(target_arch = "wasm32")]
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static SEGMENTER: std::sync::LazyLock<icu_segmenter::LineSegmenterBorrowed<'static>> =
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std::sync::LazyLock::new(|| icu_segmenter::LineSegmenter::new_auto(Default::default()));
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if !text.chars().any(is_unspaced_script) {
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return vec![];
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}
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SEGMENTER.segment_str(text).collect()
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}
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/// Mark the glyphs of `sg` (shaped from `text`, which starts at byte `start` of the text the
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/// glyphs index) after which a word of Thai, Lao, Khmer or Myanmar ends ([`unspaced_word_breaks`]);
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/// other text keeps its own breaks.
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pub(crate) fn mark_word_ends(text: &str, start: usize, sg: &mut [SGlyph]) {
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let breaks: Vec<usize> = unspaced_word_breaks(text).into_iter().map(|b| b + start).collect();
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if breaks.is_empty() {
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return;
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}
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for g in sg.iter_mut().filter(|g| g.inline.is_none() && is_unspaced_script(g.ch)) {
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g.word_end = breaks.binary_search(&(g.byte + g.len)).is_ok();
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}
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}
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pub(crate) fn is_cjk(c: char) -> bool {
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matches!(c as u32, 0x2E80..=0x9FFF | 0xAC00..=0xD7AF | 0xF900..=0xFAFF | 0xFF00..=0xFFEF | 0x20000..=0x2FFFF)
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}
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/// Vertical metrics (points) of a style's resolved face: (ascent, descent, leading).
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pub(crate) fn style_metrics(db: &FontDb, st: &CharStyle) -> (f64, f64, f64) {
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let vs = st.v_scale / 100.0;
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let Some(face) = db.style_face(st) else {
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return (st.size * 0.8 * vs, st.size * 0.2 * vs, st.effective_leading());
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};
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let k = st.size / face.upem;
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(face.ascent * k * vs, face.descent * k * vs, st.effective_leading())
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}
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/// Cap height and x height (points) of a style's resolved face.
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pub(crate) fn cap_x_heights(db: &FontDb, st: &CharStyle) -> (f64, f64) {
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let vs = st.v_scale / 100.0;
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let Some(face) = db.style_face(st) else {
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return (st.size * 0.7 * vs, st.size * 0.5 * vs);
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};
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let k = st.size / face.upem * vs;
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(face.cap_height * k, face.x_height * k)
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}
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/// Shape `text[range]`, where `runs` gives each run's byte range in `text` and style, `inlines`
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/// (parallel to `runs`) the inline graphic of each run that is one, and `levels` each byte's bidi
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/// embedding level from `range.start` (empty: all left to right). Glyphs come out in logical
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/// order, right-to-left ones shaped right to left.
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#[allow(clippy::too_many_arguments)]
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pub(crate) fn shape_range(
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db: &FontDb,
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text: &str,
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range: Range<usize>,
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runs: &[(Range<usize>, &CharStyle)],
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inlines: &[Option<&InlineArt>],
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feats: &OtFeatures,
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levels: &[Level],
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out: &mut Vec<SGlyph>,
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) {
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if text.get(range.clone()).is_none() || range.is_empty() {
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return;
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}
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let level_at = |i: usize| levels.get(i - range.start).copied().unwrap_or_else(Level::ltr);
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let output_start = out.len();
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// Text runs also carry attributes the shaper does not read (fill, stroke, baseline shift and
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// others). Adjacent runs that shape alike ([`shapes_alike`]) are shaped together, so that a
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// change of those attributes is not a shaping boundary: kerning pairs, contextual forms and
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// joining go on across it. Each glyph takes those attributes from its own source run, found by
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// its source byte ([`shape_segment`]).
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/// A run of text shaped together: its byte range, style and source runs, or one inline graphic.
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struct ShapeSpan<'a> {
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bytes: Range<usize>,
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st: &'a CharStyle,
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source_runs: Range<usize>,
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art: Option<&'a InlineArt>,
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}
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let mut spans: Vec<ShapeSpan<'_>> = Vec::new();
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for (ri, (rr, st)) in runs.iter().enumerate() {
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let a = rr.start.max(range.start);
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let b = rr.end.min(range.end);
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if a >= b || text.get(a..b).is_none() {
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continue;
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}
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let art = inlines.get(ri).copied().flatten();
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// An inline graphic is a span of its own: never merged with its neighbours.
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if art.is_none()
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&& let Some(previous) = spans.last_mut()
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&& previous.art.is_none()
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&& previous.bytes.end == a
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&& shapes_alike(previous.st, st)
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{
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previous.bytes.end = b;
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previous.source_runs.end = ri + 1;
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continue;
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}
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spans.push(ShapeSpan { bytes: a..b, st, source_runs: ri..ri + 1, art });
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}
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for ShapeSpan { bytes, st, source_runs, art } in spans {
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let a = bytes.start;
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let b = bytes.end;
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if let Some(art) = art {
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if let Some(face) = db.style_face(st).or_else(|| db.face_covering('a')) {
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out.push(inline_glyph(&face, st, art, source_runs.start, a..b, text, level_at(a)));
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}
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continue;
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}
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let Some(primary) = db.style_face(st) else { continue };
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let pmap = primary.skrifa().map(|f| f.charmap());
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// Synthesized Small Caps shape lowercase letters separately (as smaller capitals).
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let small_caps = st.small_caps.is_some() && !st.all_caps;
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// Split into segments by font coverage (and case, for Small Caps).
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let mut seg = Segment { range: a..a, runs, source_runs, st, face: primary.clone(), small: false, level: level_at(a) };
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let mut cache: Vec<(char, Arc<FontFace>)> = Vec::new();
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let mut script = Script::Common;
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for (i, c) in text[a..b].char_indices() {
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let i = a + i;
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// Digits are drawn in the style's numeral system: the font must cover that digit.
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let c = st.digits.map(c);
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let level = level_at(i);
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// Whitespace the primary font doesn't map goes to the fallback face like any other
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// character (#1844): an ideographic space set at zero width would remove an indent.
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// What the layout handles itself (tab, line and paragraph breaks) stays.
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let covered = c.is_control() || pmap.as_ref().is_none_or(|m| m.map(c).is_some());
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let face = if covered {
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primary.clone()
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} else if let Some((_, f)) = cache.iter().find(|(k, _)| *k == c) {
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f.clone()
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} else {
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let f = db.fallback_for_style(c, primary.id(), primary.weight, primary.italic).unwrap_or_else(|| primary.clone());
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cache.push((c, f.clone()));
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f
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};
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let small = small_caps && c.is_lowercase();
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let next_script = shaping_script(c);
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let strong_script = !matches!(next_script, Script::Common | Script::Inherited);
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||
let script_change = strong_script && script != Script::Common && script != next_script;
|
||
// Combining marks, zero width joiners and non-joiners, and variation selectors stay
|
||
// with the character before them.
|
||
if (face.id() != seg.face.id() || small != seg.small || level != seg.level || script_change) && !is_mark(c) {
|
||
if i > seg.range.start {
|
||
seg.range.end = i;
|
||
shape_segment(text, &range, &seg, feats, out);
|
||
}
|
||
seg = Segment { range: i..i, face, small, level, ..seg };
|
||
}
|
||
if strong_script {
|
||
script = next_script;
|
||
}
|
||
}
|
||
if b > seg.range.start {
|
||
seg.range.end = b;
|
||
shape_segment(text, &range, &seg, feats, out);
|
||
}
|
||
}
|
||
// Right-to-left segments come out of the shaper in visual order: back to logical order for
|
||
// line breaking (the lines are put in visual order once broken).
|
||
if levels.iter().any(|l| l.is_rtl())
|
||
&& let Some(o) = out.get_mut(output_start..)
|
||
{
|
||
o.sort_by_key(|g| g.byte);
|
||
}
|
||
}
|
||
|
||
/// Index in the original run list containing `byte`, limited to one coalesced shaping span.
|
||
/// Source runs are ordered and non-overlapping; partitioning keeps attribution bounded when a
|
||
/// document contains many adjacent style runs.
|
||
fn source_run_at(runs: &[(Range<usize>, &CharStyle)], span: &Range<usize>, byte: usize) -> Option<usize> {
|
||
let source = runs.get(span.clone())?;
|
||
let i = source.partition_point(|(range, _)| range.end <= byte);
|
||
source.get(i).filter(|(range, _)| range.contains(&byte)).map(|_| span.start + i)
|
||
}
|
||
|
||
/// Do text runs in styles `a` and `b` shape alike, so that they are shaped as one piece of text?
|
||
/// They do when they differ only in paint and stroke, underline and strikethrough, overprint, the
|
||
/// character style's name, leading, baseline shift, rotation, Character Alignment, Character
|
||
/// Direction (text is shaped apart where its bidi level changes), the kerning (each glyph takes its
|
||
/// run's, see [`shape_segment`]) and the tracking, as long as the tracking keeps or drops standard
|
||
/// ligatures alike ([`crate::features::ligatures_suppressed_by`]).
|
||
fn shapes_alike(a: &CharStyle, b: &CharStyle) -> bool {
|
||
// Every field is named, so that a new attribute has to be sorted into one group or the other.
|
||
let CharStyle {
|
||
font_family,
|
||
font_style,
|
||
font_version,
|
||
font_axes,
|
||
size,
|
||
leading: _,
|
||
tracking,
|
||
kerning: _,
|
||
baseline_shift: _,
|
||
h_scale,
|
||
v_scale,
|
||
rotation: _,
|
||
fill: _,
|
||
stroke: _,
|
||
stroke_width: _,
|
||
underline: _,
|
||
strikethrough: _,
|
||
all_caps,
|
||
features,
|
||
style_name: _,
|
||
overprint_fill: _,
|
||
overprint_stroke: _,
|
||
stroke_cap: _,
|
||
stroke_join: _,
|
||
stroke_miter_limit: _,
|
||
stroke_dash: _,
|
||
stroke_align: _,
|
||
position,
|
||
small_caps,
|
||
char_align: _,
|
||
char_direction: _,
|
||
proportional_metrics,
|
||
tate_chu_yoko,
|
||
digits,
|
||
no_break,
|
||
} = a;
|
||
*font_family == b.font_family
|
||
&& *font_style == b.font_style
|
||
&& *font_version == b.font_version
|
||
&& *font_axes == b.font_axes
|
||
&& *size == b.size
|
||
&& *h_scale == b.h_scale
|
||
&& *v_scale == b.v_scale
|
||
&& *all_caps == b.all_caps
|
||
&& *features == b.features
|
||
&& *position == b.position
|
||
&& *small_caps == b.small_caps
|
||
&& *proportional_metrics == b.proportional_metrics
|
||
&& *tate_chu_yoko == b.tate_chu_yoko
|
||
&& *digits == b.digits
|
||
&& *no_break == b.no_break
|
||
&& ligatures_suppressed_by(*tracking) == ligatures_suppressed_by(b.tracking)
|
||
}
|
||
|
||
/// The script `c` is shaped in: Japanese and Chinese text mixes Han, Hiragana, Katakana and
|
||
/// Bopomofo, shaped together (splitting them would cost a shaper call per change of script).
|
||
fn shaping_script(c: char) -> Script {
|
||
match c.script() {
|
||
Script::Hiragana | Script::Katakana | Script::Bopomofo => Script::Han,
|
||
s => s,
|
||
}
|
||
}
|
||
|
||
/// The synthetic glyph of an inline graphic run (`range` = its one character).
|
||
///
|
||
/// The art is scaled uniformly to `scale` x the font size tall, its left edge on the pen and its
|
||
/// vertical centre on the middle of the cap height raised by the inline's shift (see
|
||
/// [`InlineArt`]). Its advance is the scaled art width plus tracking; the glyph's ascent and
|
||
/// descent grow to the art's extent so a tall graphic opens up its line. A missing symbol takes a
|
||
/// square of the same height and draws nothing.
|
||
fn inline_glyph(face: &Arc<FontFace>, st: &CharStyle, art: &InlineArt, run: usize, range: Range<usize>, text: &str, level: Level) -> SGlyph {
|
||
let size = if st.size.is_finite() { st.size.max(0.0) } else { 0.0 };
|
||
let vs = if st.v_scale.is_finite() { st.v_scale / 100.0 } else { 1.0 };
|
||
let km = size / face.upem;
|
||
let (ascent, descent, cap, xh) = (face.ascent * km * vs, face.descent * km * vs, face.cap_height * km * vs, face.x_height * km * vs);
|
||
let h = art.safe_scale() * size;
|
||
let mid = cap * 0.5 + art.safe_shift();
|
||
let art_bounds = art.bounds.filter(|b| b.height() > 1e-9 && b.width().is_finite() && b.height().is_finite());
|
||
let (xf, width, drawn) = match art_bounds {
|
||
Some(b) if h > 0.0 => {
|
||
let k = h / b.height();
|
||
let xf = kurbo::Affine::translate((0.0, -mid)) * kurbo::Affine::scale(k) * kurbo::Affine::translate((-b.x0, -(b.y0 + b.y1) * 0.5));
|
||
(xf, b.width() * k, Some(b))
|
||
}
|
||
_ => (kurbo::Affine::IDENTITY, h, None),
|
||
};
|
||
let tracking = st.tracking / 1000.0 * size;
|
||
let adv = width + if tracking.is_finite() { tracking } else { 0.0 };
|
||
SGlyph {
|
||
face: face.clone(),
|
||
gid: 0,
|
||
byte: range.start,
|
||
len: range.len().max(1),
|
||
run,
|
||
adv: if adv.is_finite() { adv } else { 0.0 },
|
||
dx: 0.0,
|
||
dy: 0.0,
|
||
// Not used to draw (the art has its own transform), but they make the glyph's em box
|
||
// its run's em: Character Alignment and Top-to-Top leading treat an inline graphic as a
|
||
// character of its run's size, whatever its scale (see `layout::glyph_em`).
|
||
sx: if km.is_finite() { km * vs } else { 0.0 },
|
||
sy: if km.is_finite() { km * vs } else { 0.0 },
|
||
bshift: if st.baseline_shift.is_finite() { st.baseline_shift } else { 0.0 },
|
||
rotation: 0.0,
|
||
ascent: ascent.max(mid + h * 0.5),
|
||
descent: descent.max(h * 0.5 - mid),
|
||
leading: st.effective_leading(),
|
||
cap,
|
||
xh,
|
||
ch: text.get(range.clone()).and_then(|s| s.chars().next()).unwrap_or(INLINE_CHAR),
|
||
tcy: None,
|
||
lead: 0.0,
|
||
proportional: false,
|
||
vpal: None,
|
||
// U+FFFC is a bidi neutral (ON): its level, resolved from its neighbours, places it in
|
||
// RTL text like any other glyph once the line is reordered.
|
||
level,
|
||
inline: Some(InlineBox { art: drawn, xf }),
|
||
word_end: false,
|
||
no_break: st.no_break,
|
||
}
|
||
}
|
||
|
||
/// A piece of text shaped in one go: one face and, for Small Caps, one case, in runs that shape
|
||
/// alike ([`shapes_alike`]).
|
||
#[derive(Clone)]
|
||
struct Segment<'a> {
|
||
range: Range<usize>,
|
||
/// All the runs, and the indices of those the piece's shaping span takes in.
|
||
runs: &'a [(Range<usize>, &'a CharStyle)],
|
||
source_runs: Range<usize>,
|
||
/// The style of the span's first run, which the others shape alike with.
|
||
st: &'a CharStyle,
|
||
face: Arc<FontFace>,
|
||
/// Lowercase letters drawn as synthesized small capitals.
|
||
small: bool,
|
||
level: Level,
|
||
}
|
||
|
||
/// A segment shaped in one style: each glyph's id, cluster, x advance and x and y offset (font
|
||
/// units), whether `palt` gave it another advance, and what `vpal` does to it.
|
||
#[derive(Default)]
|
||
struct Shaped {
|
||
raw: Vec<(u32, u32, i32, i32, i32)>,
|
||
proportional: Vec<bool>,
|
||
vpal: Vec<Option<VAdjust>>,
|
||
}
|
||
|
||
fn is_mark(c: char) -> bool {
|
||
use unicode_general_category::{GeneralCategory, get_general_category};
|
||
matches!(get_general_category(c), GeneralCategory::NonspacingMark | GeneralCategory::SpacingMark | GeneralCategory::EnclosingMark)
|
||
|| matches!(c, '\u{200C}' | '\u{200D}' | '\u{FE00}'..='\u{FE0F}')
|
||
}
|
||
|
||
/// Shape `seg` and append its glyphs to `out`. Each glyph takes the tracking, kerning, baseline
|
||
/// shift, rotation and leading of its own source run. The font's kerning pairs apply after the
|
||
/// characters with automatic kerning: the manual value replaces the font's pair after its
|
||
/// character, and a character before it with automatic kerning keeps the font's pair with it
|
||
/// (except before a character that All Caps or Small Caps sets as several letters, such as ß as
|
||
/// SS). A cluster that would take in characters of runs with different styles (a ligature, a
|
||
/// base with its marks) is not formed: the segment is shaped in pieces at those run boundaries.
|
||
fn shape_segment(text: &str, context: &Range<usize>, seg: &Segment, feats: &OtFeatures, out: &mut Vec<SGlyph>) {
|
||
let Segment { range, runs, source_runs, st, face, small, level } = seg;
|
||
let (range, small) = (range.clone(), *small);
|
||
// The source runs the segment's bytes lie in (a span can hold many segments).
|
||
let span = runs.get(source_runs.clone()).unwrap_or_default();
|
||
let first = span.partition_point(|(r, _)| r.end <= range.start);
|
||
let last = span.partition_point(|(r, _)| r.start < range.end).max(first);
|
||
let source_runs = &(source_runs.start + first..source_runs.start + last);
|
||
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 ascent = face.ascent * km * vs;
|
||
let descent = face.descent * km * vs;
|
||
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(' ');
|
||
// The source run of the character at `byte`: its index and style.
|
||
let run_at = |byte: usize| {
|
||
let i = source_run_at(runs, source_runs, byte).unwrap_or(source_runs.start);
|
||
(i, runs.get(i).map_or(*st, |(_, s)| *s))
|
||
};
|
||
// The starts of the source runs inside the segment.
|
||
let boundaries = || runs.get(source_runs.clone()).unwrap_or_default().iter().map(|(r, _)| r.start).filter(|&b| b > range.start && b < range.end);
|
||
// Shape the pieces of the segment between the bytes `at` (ascending, inside it) on their own.
|
||
let shape_apart = |at: Vec<usize>, out: &mut Vec<SGlyph>| {
|
||
let ends = at.iter().copied().chain([range.end]);
|
||
for (start, end) in std::iter::once(range.start).chain(at.iter().copied()).zip(ends) {
|
||
shape_segment(text, context, &Segment { range: start..end, ..seg.clone() }, feats, out);
|
||
}
|
||
};
|
||
let manual = |byte: usize| run_at(byte).1.kerning.is_some();
|
||
let mixed_kerning = boundaries().any(|b| manual(b) != manual(range.start));
|
||
|
||
// Shape the segment as if all of it were in `st`, with the features `more` on top.
|
||
let shape_in = |st: &CharStyle, more: &[Feature]| {
|
||
let mut shaped = Shaped::default();
|
||
let Shaped { raw, proportional, vpal } = &mut shaped;
|
||
let hb_shaped = face.hb().map(|hb| {
|
||
let shaper = face.shaper.shaper(&hb).instance(face.instance.as_ref()).build();
|
||
// gid, cluster, x and y advance, x and y offset.
|
||
let shape = |feats: &[Feature], direction: Direction| {
|
||
let feats: Vec<Feature> = feats.iter().chain(more).cloned().collect();
|
||
let mut buf = UnicodeBuffer::new();
|
||
for (i, c) in text_seg.char_indices() {
|
||
let cl = (range.start + i) as u32;
|
||
let c = st.digits.map(c);
|
||
if upper {
|
||
for u in c.to_uppercase() {
|
||
buf.add(u, cl);
|
||
}
|
||
} else {
|
||
buf.add(c, cl);
|
||
}
|
||
}
|
||
buf.set_direction(direction);
|
||
buf.guess_segment_properties();
|
||
// Harfrust keeps this Unicode context for joining/positional shaping, but does not emit
|
||
// glyphs for it. This retains context at real style/font segmentation boundaries without
|
||
// shaping across those boundaries or claiming cross-style ligatures/mark attachment.
|
||
if let Some(pre) = text.get(context.start..range.start) {
|
||
buf.set_pre_context(pre);
|
||
}
|
||
if let Some(post) = text.get(range.end..context.end) {
|
||
buf.set_post_context(post);
|
||
}
|
||
let gb = shaper.shape(buf, ShapeOptions::new().features(&feats));
|
||
gb.glyph_infos()
|
||
.iter()
|
||
.zip(gb.glyph_positions())
|
||
.map(|(info, pos)| (info.glyph_id, info.cluster, pos.x_advance, pos.y_advance, pos.x_offset, pos.y_offset))
|
||
.collect::<Vec<_>>()
|
||
};
|
||
let along = if level.is_rtl() { Direction::RightToLeft } else { Direction::LeftToRight };
|
||
*raw = shape(&feats.resolve(st), along).into_iter().map(|(g, c, xa, _, xo, yo)| (g, c, xa, xo, yo)).collect();
|
||
let raw = &*raw;
|
||
let same_glyphs = |v: &[(u32, u32, i32, i32, i32, i32)]| v.len() == raw.len() && v.iter().zip(raw).all(|(a, b)| a.0 == b.0);
|
||
if feats.proportional(st) {
|
||
// `palt` is positioning only: the same glyphs set on their full widths tell which
|
||
// advances it changed (kerning and the rest change both alike).
|
||
let full = shape(&feats.resolve_fixed_width(st), along);
|
||
if same_glyphs(&full) {
|
||
*proportional = full.iter().zip(raw).map(|(a, b)| a.2 != b.2).collect();
|
||
}
|
||
}
|
||
if feats.proportional_vertical(st) {
|
||
// `vpal` adjusts heights, which only top-to-bottom shaping applies: the same glyphs set
|
||
// top to bottom with it (and the vertical kerning that goes with it, `vkrn` and `vapk`)
|
||
// and without either tell how it moves each and changes its advance down the column
|
||
// (y up, advances negative). Which advances `vpal` itself changed comes from setting
|
||
// them with it alone.
|
||
let ttb = |proportional, kerning| shape(&feats.resolve_vertical(st, proportional, kerning), Direction::TopToBottom);
|
||
let (with, without, alone) = (ttb(true, true), ttb(false, false), ttb(true, false));
|
||
if same_glyphs(&with) && same_glyphs(&without) && same_glyphs(&alone) {
|
||
*vpal = with
|
||
.iter()
|
||
.zip(&without)
|
||
.zip(&alone)
|
||
.map(|((a, b), c)| {
|
||
let adj = VAdjust {
|
||
advance: f64::from(b.3 - a.3) * k * vs,
|
||
dx: f64::from(a.4 - b.4) * k * hs,
|
||
dy: -f64::from(a.5 - b.5) * k * vs,
|
||
proportional: c.3 != b.3,
|
||
};
|
||
(adj != VAdjust::default()).then_some(adj)
|
||
})
|
||
.collect();
|
||
}
|
||
}
|
||
});
|
||
if hb_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(), face.location());
|
||
for (i, c) in text_seg.char_indices() {
|
||
let cl = (range.start + i) as u32;
|
||
let c = st.digits.map(c);
|
||
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));
|
||
}
|
||
}
|
||
}
|
||
}
|
||
shaped
|
||
};
|
||
let Shaped { raw, proportional, vpal } = if mixed_kerning {
|
||
// A font's kerning pair applies after a character with automatic kerning and not after one
|
||
// with manual kerning. The segment is shaped apart where manual kerning ends, so each piece
|
||
// is text with automatic kerning followed by text with manual kerning. A piece is shaped
|
||
// with the font's kerning on, and off (`kern`, and the `apkn`, `vkrn` and `vapk` that
|
||
// `OtFeatures` turns off with it) from the second character with manual kerning on: a
|
||
// pair is applied only when both of its glyphs have the feature on.
|
||
let ends: Vec<usize> = boundaries().filter(|&b| manual(b - 1) && !manual(b)).collect();
|
||
if !ends.is_empty() {
|
||
return shape_apart(ends, out);
|
||
}
|
||
let first = boundaries().find(|&b| manual(b)).unwrap_or(range.end);
|
||
// A first character with manual kerning that All Caps or Small Caps sets as several letters
|
||
// (ß as SS) gives them one cluster, which a feature range cannot split, so the font's
|
||
// kerning between them would stay on: it is shaped apart from the text before it.
|
||
if upper && first_char(first).to_uppercase().nth(1).is_some() {
|
||
return shape_apart(vec![first], out);
|
||
}
|
||
let off = text.get(first..range.end).and_then(|s| s.chars().next()).map_or(range.end, |c| first + c.len_utf8());
|
||
let more: Vec<Feature> = [b"kern", b"apkn", b"vkrn", b"vapk"]
|
||
.into_iter()
|
||
.filter(|_| off < range.end)
|
||
.map(|t| Feature::new(Tag::new(t), 0, off..range.end))
|
||
.collect();
|
||
shape_in(&CharStyle { kerning: None, ..(*st).clone() }, &more)
|
||
} else {
|
||
// The span's first run may lie outside the segment (a span split by font, case, script
|
||
// or direction): the kerning mode is that of the segment's own runs.
|
||
shape_in(run_at(range.start).1, &[])
|
||
};
|
||
let mut cluster_starts: Vec<usize> = raw.iter().map(|r| r.1 as usize).collect();
|
||
cluster_starts.sort_unstable();
|
||
cluster_starts.dedup();
|
||
// A glyph is drawn in one style: where a cluster would take in characters of runs in different
|
||
// styles, the runs are shaped apart, as runs that do not shape alike are.
|
||
let inside_clusters: Vec<usize> = boundaries().filter(|&b| cluster_starts.binary_search(&b).is_err() && run_at(b - 1).1 != run_at(b).1).collect();
|
||
if !inside_clusters.is_empty() {
|
||
return shape_apart(inside_clusters, out);
|
||
}
|
||
let n = raw.len();
|
||
for (gi, &(gid, cl, xa, xo, yo)) in raw.iter().enumerate() {
|
||
let cl = cl as usize;
|
||
let (run, gst) = run_at(cl);
|
||
// Cluster end: the next larger cluster value in the segment, else the segment end.
|
||
let end = cluster_starts.get(cluster_starts.partition_point(|&c| c <= cl)).copied().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 {
|
||
let tracking = gst.tracking / 1000.0 * size;
|
||
let manual_kern = gst.kerning.map(|v| v / 1000.0 * size).unwrap_or(0.0);
|
||
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: gst.baseline_shift + pos_shift,
|
||
rotation: gst.rotation,
|
||
ascent,
|
||
descent,
|
||
leading: gst.effective_leading(),
|
||
cap,
|
||
xh,
|
||
ch,
|
||
tcy: None,
|
||
lead: 0.0,
|
||
proportional: proportional.get(gi).copied().unwrap_or(false),
|
||
vpal: vpal.get(gi).copied().flatten(),
|
||
level: *level,
|
||
inline: None,
|
||
word_end: false,
|
||
no_break: gst.no_break,
|
||
});
|
||
}
|
||
}
|