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750 lines
26 KiB
Rust
750 lines
26 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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use app_units::Au;
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use euclid::point::Point2D;
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#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
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use simd::u32x4;
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use std::cmp::{Ordering, PartialOrd};
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use std::vec::Vec;
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use std::{fmt, mem, u16};
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use util::range::{self, EachIndex, Range, RangeIndex};
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use util::vec::*;
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/// GlyphEntry is a port of Gecko's CompressedGlyph scheme for storing glyph data compactly.
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///
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/// In the common case (reasonable glyph advances, no offsets from the font em-box, and one glyph
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/// per character), we pack glyph advance, glyph id, and some flags into a single u32.
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///
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/// In the uncommon case (multiple glyphs per unicode character, large glyph index/advance, or
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/// glyph offsets), we pack the glyph count into GlyphEntry, and store the other glyph information
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/// in DetailedGlyphStore.
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#[derive(Clone, Debug, Copy, Deserialize, Serialize, PartialEq)]
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struct GlyphEntry {
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value: u32,
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}
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impl GlyphEntry {
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fn new(value: u32) -> GlyphEntry {
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GlyphEntry {
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value: value,
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}
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}
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fn initial() -> GlyphEntry {
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GlyphEntry::new(0)
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}
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// Creates a GlyphEntry for the common case
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fn simple(id: GlyphId, advance: Au) -> GlyphEntry {
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assert!(is_simple_glyph_id(id));
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assert!(is_simple_advance(advance));
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let id_mask = id as u32;
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let Au(advance) = advance;
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let advance_mask = (advance as u32) << GLYPH_ADVANCE_SHIFT;
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GlyphEntry::new(id_mask | advance_mask | FLAG_IS_SIMPLE_GLYPH)
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}
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// Create a GlyphEntry for uncommon case; should be accompanied by
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// initialization of the actual DetailedGlyph data in DetailedGlyphStore
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fn complex(starts_cluster: bool, starts_ligature: bool, glyph_count: usize) -> GlyphEntry {
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assert!(glyph_count <= u16::MAX as usize);
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debug!("creating complex glyph entry: starts_cluster={}, starts_ligature={}, \
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glyph_count={}",
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starts_cluster,
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starts_ligature,
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glyph_count);
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GlyphEntry::new(glyph_count as u32)
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}
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/// Create a GlyphEntry for the case where glyphs couldn't be found for the specified
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/// character.
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fn missing(glyph_count: usize) -> GlyphEntry {
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assert!(glyph_count <= u16::MAX as usize);
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GlyphEntry::new(glyph_count as u32)
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}
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fn is_initial(&self) -> bool {
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*self == GlyphEntry::initial()
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}
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}
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/// The id of a particular glyph within a font
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pub type GlyphId = u32;
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// TODO: make this more type-safe.
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const FLAG_CHAR_IS_SPACE: u32 = 0x40000000;
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const FLAG_IS_SIMPLE_GLYPH: u32 = 0x80000000;
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// glyph advance; in Au's.
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const GLYPH_ADVANCE_MASK: u32 = 0x3FFF0000;
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const GLYPH_ADVANCE_SHIFT: u32 = 16;
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const GLYPH_ID_MASK: u32 = 0x0000FFFF;
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// Non-simple glyphs (more than one glyph per char; missing glyph,
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// newline, tab, large advance, or nonzero x/y offsets) may have one
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// or more detailed glyphs associated with them. They are stored in a
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// side array so that there is a 1:1 mapping of GlyphEntry to
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// unicode char.
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// The number of detailed glyphs for this char.
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const GLYPH_COUNT_MASK: u32 = 0x0000FFFF;
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fn is_simple_glyph_id(id: GlyphId) -> bool {
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((id as u32) & GLYPH_ID_MASK) == id
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}
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fn is_simple_advance(advance: Au) -> bool {
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advance >= Au(0) && {
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let unsigned_au = advance.0 as u32;
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(unsigned_au & (GLYPH_ADVANCE_MASK >> GLYPH_ADVANCE_SHIFT)) == unsigned_au
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}
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}
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type DetailedGlyphCount = u16;
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// Getters and setters for GlyphEntry. Setter methods are functional,
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// because GlyphEntry is immutable and only a u32 in size.
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impl GlyphEntry {
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#[inline(always)]
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fn advance(&self) -> Au {
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Au(((self.value & GLYPH_ADVANCE_MASK) >> GLYPH_ADVANCE_SHIFT) as i32)
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}
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fn id(&self) -> GlyphId {
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self.value & GLYPH_ID_MASK
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}
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/// True if original char was normal (U+0020) space. Other chars may
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/// map to space glyph, but this does not account for them.
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fn char_is_space(&self) -> bool {
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self.has_flag(FLAG_CHAR_IS_SPACE)
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}
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#[inline(always)]
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fn set_char_is_space(&self) -> GlyphEntry {
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GlyphEntry::new(self.value | FLAG_CHAR_IS_SPACE)
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}
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fn glyph_count(&self) -> u16 {
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assert!(!self.is_simple());
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(self.value & GLYPH_COUNT_MASK) as u16
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}
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#[inline(always)]
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fn is_simple(&self) -> bool {
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self.has_flag(FLAG_IS_SIMPLE_GLYPH)
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}
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#[inline(always)]
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fn has_flag(&self, flag: u32) -> bool {
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(self.value & flag) != 0
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}
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#[inline(always)]
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fn adapt_character_flags_of_entry(&self, other: GlyphEntry) -> GlyphEntry {
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GlyphEntry { value: self.value | other.value }
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}
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}
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// Stores data for a detailed glyph, in the case that several glyphs
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// correspond to one character, or the glyph's data couldn't be packed.
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#[derive(Clone, Debug, Copy, Deserialize, Serialize)]
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struct DetailedGlyph {
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id: GlyphId,
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// glyph's advance, in the text's direction (LTR or RTL)
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advance: Au,
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// glyph's offset from the font's em-box (from top-left)
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offset: Point2D<Au>,
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}
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impl DetailedGlyph {
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fn new(id: GlyphId, advance: Au, offset: Point2D<Au>) -> DetailedGlyph {
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DetailedGlyph {
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id: id,
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advance: advance,
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offset: offset,
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}
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}
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}
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#[derive(PartialEq, Clone, Eq, Debug, Copy, Deserialize, Serialize)]
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struct DetailedGlyphRecord {
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// source string offset/GlyphEntry offset in the TextRun
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entry_offset: CharIndex,
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// offset into the detailed glyphs buffer
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detail_offset: usize,
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}
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impl PartialOrd for DetailedGlyphRecord {
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fn partial_cmp(&self, other: &DetailedGlyphRecord) -> Option<Ordering> {
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self.entry_offset.partial_cmp(&other.entry_offset)
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}
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}
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impl Ord for DetailedGlyphRecord {
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fn cmp(&self, other: &DetailedGlyphRecord) -> Ordering {
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self.entry_offset.cmp(&other.entry_offset)
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}
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}
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// Manages the lookup table for detailed glyphs. Sorting is deferred
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// until a lookup is actually performed; this matches the expected
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// usage pattern of setting/appending all the detailed glyphs, and
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// then querying without setting.
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#[derive(Clone, Deserialize, Serialize)]
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struct DetailedGlyphStore {
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// TODO(pcwalton): Allocation of this buffer is expensive. Consider a small-vector
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// optimization.
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detail_buffer: Vec<DetailedGlyph>,
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// TODO(pcwalton): Allocation of this buffer is expensive. Consider a small-vector
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// optimization.
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detail_lookup: Vec<DetailedGlyphRecord>,
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lookup_is_sorted: bool,
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}
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impl<'a> DetailedGlyphStore {
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fn new() -> DetailedGlyphStore {
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DetailedGlyphStore {
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detail_buffer: vec!(), // TODO: default size?
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detail_lookup: vec!(),
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lookup_is_sorted: false,
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}
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}
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fn add_detailed_glyphs_for_entry(&mut self, entry_offset: CharIndex, glyphs: &[DetailedGlyph]) {
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let entry = DetailedGlyphRecord {
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entry_offset: entry_offset,
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detail_offset: self.detail_buffer.len(),
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};
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debug!("Adding entry[off={:?}] for detailed glyphs: {:?}", entry_offset, glyphs);
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/* TODO: don't actually assert this until asserts are compiled
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in/out based on severity, debug/release, etc. This assertion
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would wreck the complexity of the lookup.
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See Rust Issue #3647, #2228, #3627 for related information.
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do self.detail_lookup.borrow |arr| {
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assert !arr.contains(entry)
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}
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*/
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self.detail_lookup.push(entry);
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self.detail_buffer.push_all(glyphs);
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self.lookup_is_sorted = false;
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}
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fn detailed_glyphs_for_entry(&'a self, entry_offset: CharIndex, count: u16)
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-> &'a [DetailedGlyph] {
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debug!("Requesting detailed glyphs[n={}] for entry[off={:?}]", count, entry_offset);
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// FIXME: Is this right? --pcwalton
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// TODO: should fix this somewhere else
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if count == 0 {
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return &self.detail_buffer[0..0];
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}
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assert!((count as usize) <= self.detail_buffer.len());
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assert!(self.lookup_is_sorted);
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let key = DetailedGlyphRecord {
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entry_offset: entry_offset,
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detail_offset: 0, // unused
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};
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let i = self.detail_lookup.binary_search_index(&key)
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.expect("Invalid index not found in detailed glyph lookup table!");
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assert!(i + (count as usize) <= self.detail_buffer.len());
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// return a slice into the buffer
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&self.detail_buffer[i .. i + count as usize]
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}
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fn detailed_glyph_with_index(&'a self,
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entry_offset: CharIndex,
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detail_offset: u16)
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-> &'a DetailedGlyph {
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assert!((detail_offset as usize) <= self.detail_buffer.len());
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assert!(self.lookup_is_sorted);
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let key = DetailedGlyphRecord {
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entry_offset: entry_offset,
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detail_offset: 0, // unused
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};
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let i = self.detail_lookup.binary_search_index(&key)
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.expect("Invalid index not found in detailed glyph lookup table!");
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assert!(i + (detail_offset as usize) < self.detail_buffer.len());
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&self.detail_buffer[i + (detail_offset as usize)]
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}
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fn ensure_sorted(&mut self) {
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if self.lookup_is_sorted {
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return;
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}
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// Sorting a unique vector is surprisingly hard. The following
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// code is a good argument for using DVecs, but they require
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// immutable locations thus don't play well with freezing.
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// Thar be dragons here. You have been warned. (Tips accepted.)
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let mut unsorted_records: Vec<DetailedGlyphRecord> = vec!();
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mem::swap(&mut self.detail_lookup, &mut unsorted_records);
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let mut mut_records: Vec<DetailedGlyphRecord> = unsorted_records;
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mut_records.sort_by(|a, b| {
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if a < b {
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Ordering::Less
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} else {
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Ordering::Greater
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}
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});
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let mut sorted_records = mut_records;
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mem::swap(&mut self.detail_lookup, &mut sorted_records);
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self.lookup_is_sorted = true;
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}
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}
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// This struct is used by GlyphStore clients to provide new glyph data.
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// It should be allocated on the stack and passed by reference to GlyphStore.
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#[derive(Copy, Clone)]
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pub struct GlyphData {
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id: GlyphId,
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advance: Au,
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offset: Point2D<Au>,
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is_missing: bool,
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cluster_start: bool,
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ligature_start: bool,
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}
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impl GlyphData {
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/// Creates a new entry for one glyph.
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pub fn new(id: GlyphId,
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advance: Au,
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offset: Option<Point2D<Au>>,
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is_missing: bool,
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cluster_start: bool,
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ligature_start: bool)
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-> GlyphData {
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GlyphData {
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id: id,
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advance: advance,
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offset: offset.unwrap_or(Point2D::zero()),
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is_missing: is_missing,
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cluster_start: cluster_start,
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ligature_start: ligature_start,
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}
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}
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}
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// This enum is a proxy that's provided to GlyphStore clients when iterating
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// through glyphs (either for a particular TextRun offset, or all glyphs).
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// Rather than eagerly assembling and copying glyph data, it only retrieves
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// values as they are needed from the GlyphStore, using provided offsets.
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#[derive(Copy, Clone)]
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pub enum GlyphInfo<'a> {
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Simple(&'a GlyphStore, CharIndex),
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Detail(&'a GlyphStore, CharIndex, u16),
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}
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impl<'a> GlyphInfo<'a> {
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pub fn id(self) -> GlyphId {
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match self {
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GlyphInfo::Simple(store, entry_i) => store.entry_buffer[entry_i.to_usize()].id(),
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GlyphInfo::Detail(store, entry_i, detail_j) => {
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store.detail_store.detailed_glyph_with_index(entry_i, detail_j).id
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}
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}
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}
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#[inline(always)]
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// FIXME: Resolution conflicts with IteratorUtil trait so adding trailing _
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pub fn advance(self) -> Au {
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match self {
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GlyphInfo::Simple(store, entry_i) => store.entry_buffer[entry_i.to_usize()].advance(),
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GlyphInfo::Detail(store, entry_i, detail_j) => {
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store.detail_store.detailed_glyph_with_index(entry_i, detail_j).advance
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}
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}
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}
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pub fn offset(self) -> Option<Point2D<Au>> {
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match self {
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GlyphInfo::Simple(_, _) => None,
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GlyphInfo::Detail(store, entry_i, detail_j) => {
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Some(store.detail_store.detailed_glyph_with_index(entry_i, detail_j).offset)
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}
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}
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}
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}
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/// Stores the glyph data belonging to a text run.
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///
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/// Simple glyphs are stored inline in the `entry_buffer`, detailed glyphs are
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/// stored as pointers into the `detail_store`.
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///
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/// ~~~ignore
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/// +- GlyphStore --------------------------------+
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/// | +---+---+---+---+---+---+---+ |
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/// | entry_buffer: | | s | | s | | s | s | | d = detailed
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/// | +-|-+---+-|-+---+-|-+---+---+ | s = simple
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/// | | | | |
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/// | | +---+-------+ |
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/// | | | |
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/// | +-V-+-V-+ |
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/// | detail_store: | d | d | |
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/// | +---+---+ |
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/// +---------------------------------------------+
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/// ~~~
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#[derive(Clone, Deserialize, Serialize)]
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pub struct GlyphStore {
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// TODO(pcwalton): Allocation of this buffer is expensive. Consider a small-vector
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// optimization.
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/// A buffer of glyphs within the text run, in the order in which they
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/// appear in the input text.
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/// Any changes will also need to be reflected in
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/// transmute_entry_buffer_to_u32_buffer().
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entry_buffer: Vec<GlyphEntry>,
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/// A store of the detailed glyph data. Detailed glyphs contained in the
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/// `entry_buffer` point to locations in this data structure.
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detail_store: DetailedGlyphStore,
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/// Used to check if fast path should be used in glyph iteration.
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has_detailed_glyphs: bool,
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is_whitespace: bool,
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is_rtl: bool,
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}
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int_range_index! {
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#[derive(Deserialize, Serialize, RustcEncodable)]
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#[doc = "An index that refers to a character in a text run. This could \
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point to the middle of a glyph."]
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#[derive(HeapSizeOf)]
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struct CharIndex(isize)
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}
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impl<'a> GlyphStore {
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/// Initializes the glyph store, but doesn't actually shape anything.
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///
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/// Use the `add_*` methods to store glyph data.
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pub fn new(length: usize, is_whitespace: bool, is_rtl: bool) -> GlyphStore {
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assert!(length > 0);
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GlyphStore {
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entry_buffer: vec![GlyphEntry::initial(); length],
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detail_store: DetailedGlyphStore::new(),
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has_detailed_glyphs: false,
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is_whitespace: is_whitespace,
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is_rtl: is_rtl,
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}
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}
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pub fn char_len(&self) -> CharIndex {
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CharIndex(self.entry_buffer.len() as isize)
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}
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pub fn is_whitespace(&self) -> bool {
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self.is_whitespace
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}
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pub fn finalize_changes(&mut self) {
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self.detail_store.ensure_sorted();
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}
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/// Adds a single glyph. If `character` is present, this represents a single character;
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/// otherwise, this glyph represents multiple characters.
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pub fn add_glyph_for_char_index(&mut self,
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i: CharIndex,
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character: Option<char>,
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data: &GlyphData) {
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fn glyph_is_compressible(data: &GlyphData) -> bool {
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is_simple_glyph_id(data.id)
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&& is_simple_advance(data.advance)
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&& data.offset == Point2D::zero()
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&& data.cluster_start // others are stored in detail buffer
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}
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debug_assert!(data.ligature_start); // can't compress ligature continuation glyphs.
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debug_assert!(i < self.char_len());
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let mut entry = match (data.is_missing, glyph_is_compressible(data)) {
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(true, _) => GlyphEntry::missing(1),
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(false, true) => GlyphEntry::simple(data.id, data.advance),
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(false, false) => {
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let glyph = &[DetailedGlyph::new(data.id, data.advance, data.offset)];
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self.has_detailed_glyphs = true;
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self.detail_store.add_detailed_glyphs_for_entry(i, glyph);
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GlyphEntry::complex(data.cluster_start, data.ligature_start, 1)
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}
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};
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if character == Some(' ') {
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entry = entry.set_char_is_space()
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}
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self.entry_buffer[i.to_usize()] = entry;
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}
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pub fn add_glyphs_for_char_index(&mut self, i: CharIndex, data_for_glyphs: &[GlyphData]) {
|
|
assert!(i < self.char_len());
|
|
assert!(data_for_glyphs.len() > 0);
|
|
|
|
let glyph_count = data_for_glyphs.len();
|
|
|
|
let first_glyph_data = data_for_glyphs[0];
|
|
let entry = match first_glyph_data.is_missing {
|
|
true => GlyphEntry::missing(glyph_count),
|
|
false => {
|
|
let glyphs_vec: Vec<DetailedGlyph> = (0..glyph_count).map(|i| {
|
|
DetailedGlyph::new(data_for_glyphs[i].id,
|
|
data_for_glyphs[i].advance,
|
|
data_for_glyphs[i].offset)
|
|
}).collect();
|
|
|
|
self.has_detailed_glyphs = true;
|
|
self.detail_store.add_detailed_glyphs_for_entry(i, &glyphs_vec);
|
|
GlyphEntry::complex(first_glyph_data.cluster_start,
|
|
first_glyph_data.ligature_start,
|
|
glyph_count)
|
|
}
|
|
}.adapt_character_flags_of_entry(self.entry_buffer[i.to_usize()]);
|
|
|
|
debug!("Adding multiple glyphs[idx={:?}, count={}]: {:?}", i, glyph_count, entry);
|
|
|
|
self.entry_buffer[i.to_usize()] = entry;
|
|
}
|
|
|
|
// used when a character index has no associated glyph---for example, a ligature continuation.
|
|
pub fn add_nonglyph_for_char_index(&mut self,
|
|
i: CharIndex,
|
|
cluster_start: bool,
|
|
ligature_start: bool) {
|
|
assert!(i < self.char_len());
|
|
|
|
let entry = GlyphEntry::complex(cluster_start, ligature_start, 0);
|
|
debug!("adding spacer for character without associated glyph[idx={:?}]", i);
|
|
|
|
self.entry_buffer[i.to_usize()] = entry;
|
|
}
|
|
|
|
#[inline]
|
|
pub fn iter_glyphs_for_char_range(&'a self, rang: &Range<CharIndex>) -> GlyphIterator<'a> {
|
|
if rang.begin() >= self.char_len() {
|
|
panic!("iter_glyphs_for_range: range.begin beyond length!");
|
|
}
|
|
if rang.end() > self.char_len() {
|
|
panic!("iter_glyphs_for_range: range.end beyond length!");
|
|
}
|
|
|
|
GlyphIterator {
|
|
store: self,
|
|
char_index: if self.is_rtl { rang.end() } else { rang.begin() - CharIndex(1) },
|
|
char_range: *rang,
|
|
glyph_range: None,
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
pub fn advance_for_char_range(&self, rang: &Range<CharIndex>) -> Au {
|
|
if !self.has_detailed_glyphs {
|
|
self.advance_for_char_range_simple_glyphs(rang)
|
|
} else {
|
|
self.advance_for_char_range_slow_path(rang)
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
pub fn advance_for_char_range_slow_path(&self, rang: &Range<CharIndex>) -> Au {
|
|
self.iter_glyphs_for_char_range(rang)
|
|
.fold(Au(0), |advance, (_, glyph)| advance + glyph.advance())
|
|
}
|
|
|
|
#[inline]
|
|
#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
|
|
fn advance_for_char_range_simple_glyphs(&self, rang: &Range<CharIndex>) -> Au {
|
|
let mask = u32x4::splat(GLYPH_ADVANCE_MASK);
|
|
let mut simd_advance = u32x4::splat(0);
|
|
let begin = rang.begin().to_usize();
|
|
let len = rang.length().to_usize();
|
|
let num_simd_iterations = len / 4;
|
|
let leftover_entries = rang.end().to_usize() - (len - num_simd_iterations * 4);
|
|
let buf = self.transmute_entry_buffer_to_u32_buffer();
|
|
|
|
for i in 0..num_simd_iterations {
|
|
let mut v = u32x4::load(buf, begin + i * 4);
|
|
v = v & mask;
|
|
v = v >> GLYPH_ADVANCE_SHIFT;
|
|
simd_advance = simd_advance + v;
|
|
}
|
|
|
|
let advance =
|
|
(simd_advance.extract(0) +
|
|
simd_advance.extract(1) +
|
|
simd_advance.extract(2) +
|
|
simd_advance.extract(3)) as i32;
|
|
let mut leftover = Au(0);
|
|
for i in leftover_entries..rang.end().to_usize() {
|
|
leftover = leftover + self.entry_buffer[i].advance();
|
|
}
|
|
Au(advance) + leftover
|
|
}
|
|
|
|
/// When SIMD isn't available (non-x86_x64/aarch64), fallback to the slow path.
|
|
#[inline]
|
|
#[cfg(not(any(target_arch = "x86_64", target_arch = "aarch64")))]
|
|
fn advance_for_char_range_simple_glyphs(&self, rang: &Range<CharIndex>) -> Au {
|
|
self.advance_for_char_range_slow_path(rang)
|
|
}
|
|
|
|
/// Used for SIMD.
|
|
#[inline]
|
|
#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
|
|
fn transmute_entry_buffer_to_u32_buffer(&self) -> &[u32] {
|
|
unsafe { mem::transmute(self.entry_buffer.as_slice()) }
|
|
}
|
|
|
|
pub fn char_is_space(&self, i: CharIndex) -> bool {
|
|
assert!(i < self.char_len());
|
|
self.entry_buffer[i.to_usize()].char_is_space()
|
|
}
|
|
|
|
pub fn space_count_in_range(&self, range: &Range<CharIndex>) -> u32 {
|
|
let mut spaces = 0;
|
|
for index in range.each_index() {
|
|
if self.char_is_space(index) {
|
|
spaces += 1
|
|
}
|
|
}
|
|
spaces
|
|
}
|
|
|
|
pub fn distribute_extra_space_in_range(&mut self, range: &Range<CharIndex>, space: f64) {
|
|
debug_assert!(space >= 0.0);
|
|
if range.is_empty() {
|
|
return
|
|
}
|
|
for index in range.each_index() {
|
|
// TODO(pcwalton): Handle spaces that are detailed glyphs -- these are uncommon but
|
|
// possible.
|
|
let entry = &mut self.entry_buffer[index.to_usize()];
|
|
if entry.is_simple() && entry.char_is_space() {
|
|
// FIXME(pcwalton): This can overflow for very large font-sizes.
|
|
let advance =
|
|
((entry.value & GLYPH_ADVANCE_MASK) >> GLYPH_ADVANCE_SHIFT) +
|
|
Au::from_f64_px(space).0 as u32;
|
|
entry.value = (entry.value & !GLYPH_ADVANCE_MASK) |
|
|
(advance << GLYPH_ADVANCE_SHIFT);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl fmt::Debug for GlyphStore {
|
|
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
|
|
try!(write!(formatter, "GlyphStore:\n"));
|
|
let mut detailed_buffer = self.detail_store.detail_buffer.iter();
|
|
for entry in self.entry_buffer.iter() {
|
|
if entry.is_simple() {
|
|
try!(write!(formatter,
|
|
" simple id={:?} advance={:?}\n",
|
|
entry.id(),
|
|
entry.advance()));
|
|
continue
|
|
}
|
|
if entry.is_initial() {
|
|
continue
|
|
}
|
|
try!(write!(formatter, " complex..."));
|
|
if detailed_buffer.next().is_none() {
|
|
continue
|
|
}
|
|
try!(write!(formatter,
|
|
" detailed id={:?} advance={:?}\n",
|
|
entry.id(),
|
|
entry.advance()));
|
|
}
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
/// An iterator over the glyphs in a character range in a `GlyphStore`.
|
|
pub struct GlyphIterator<'a> {
|
|
store: &'a GlyphStore,
|
|
char_index: CharIndex,
|
|
char_range: Range<CharIndex>,
|
|
glyph_range: Option<EachIndex<isize, CharIndex>>,
|
|
}
|
|
|
|
impl<'a> GlyphIterator<'a> {
|
|
// Slow path when there is a glyph range.
|
|
#[inline(never)]
|
|
fn next_glyph_range(&mut self) -> Option<(CharIndex, GlyphInfo<'a>)> {
|
|
match self.glyph_range.as_mut().unwrap().next() {
|
|
Some(j) => {
|
|
Some((self.char_index,
|
|
GlyphInfo::Detail(self.store, self.char_index, j.get() as u16 /* ??? */)))
|
|
}
|
|
None => {
|
|
// No more glyphs for current character. Try to get another.
|
|
self.glyph_range = None;
|
|
self.next()
|
|
}
|
|
}
|
|
}
|
|
|
|
// Slow path when there is a complex glyph.
|
|
#[inline(never)]
|
|
fn next_complex_glyph(&mut self, entry: &GlyphEntry, i: CharIndex)
|
|
-> Option<(CharIndex, GlyphInfo<'a>)> {
|
|
let glyphs = self.store.detail_store.detailed_glyphs_for_entry(i, entry.glyph_count());
|
|
self.glyph_range = Some(range::each_index(CharIndex(0), CharIndex(glyphs.len() as isize)));
|
|
self.next()
|
|
}
|
|
}
|
|
|
|
impl<'a> Iterator for GlyphIterator<'a> {
|
|
type Item = (CharIndex, GlyphInfo<'a>);
|
|
|
|
// I tried to start with something simpler and apply FlatMap, but the
|
|
// inability to store free variables in the FlatMap struct was problematic.
|
|
//
|
|
// This function consists of the fast path and is designed to be inlined into its caller. The
|
|
// slow paths, which should not be inlined, are `next_glyph_range()` and
|
|
// `next_complex_glyph()`.
|
|
#[inline(always)]
|
|
fn next(&mut self) -> Option<(CharIndex, GlyphInfo<'a>)> {
|
|
// Would use 'match' here but it borrows contents in a way that interferes with mutation.
|
|
if self.glyph_range.is_some() {
|
|
return self.next_glyph_range()
|
|
}
|
|
|
|
// No glyph range. Look at next character.
|
|
self.char_index = self.char_index + if self.store.is_rtl {
|
|
CharIndex(-1)
|
|
} else {
|
|
CharIndex(1)
|
|
};
|
|
let i = self.char_index;
|
|
if !self.char_range.contains(i) {
|
|
return None
|
|
}
|
|
debug_assert!(i < self.store.char_len());
|
|
let entry = self.store.entry_buffer[i.to_usize()];
|
|
if entry.is_simple() {
|
|
Some((i, GlyphInfo::Simple(self.store, i)))
|
|
} else {
|
|
// Fall back to the slow path.
|
|
self.next_complex_glyph(&entry, i)
|
|
}
|
|
}
|
|
}
|