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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
use std::cmp::{Ordering, PartialOrd};
use std::vec::Vec;
use std::{fmt, mem, u16};
use app_units::Au;
use euclid::default::Point2D;
pub use gfx_traits::ByteIndex;
use log::debug;
use range::{self, EachIndex, Range, RangeIndex};
use serde::{Deserialize, Serialize};
/// GlyphEntry is a port of Gecko's CompressedGlyph scheme for storing glyph data compactly.
///
/// In the common case (reasonable glyph advances, no offsets from the font em-box, and one glyph
/// per character), we pack glyph advance, glyph id, and some flags into a single u32.
///
/// In the uncommon case (multiple glyphs per unicode character, large glyph index/advance, or
/// glyph offsets), we pack the glyph count into GlyphEntry, and store the other glyph information
/// in DetailedGlyphStore.
#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Serialize)]
pub struct GlyphEntry {
value: u32,
}
impl GlyphEntry {
fn new(value: u32) -> GlyphEntry {
GlyphEntry { value }
}
fn initial() -> GlyphEntry {
GlyphEntry::new(0)
}
// Creates a GlyphEntry for the common case
fn simple(id: GlyphId, advance: Au) -> GlyphEntry {
assert!(is_simple_glyph_id(id));
assert!(is_simple_advance(advance));
let id_mask = id;
let Au(advance) = advance;
let advance_mask = (advance as u32) << GLYPH_ADVANCE_SHIFT;
GlyphEntry::new(id_mask | advance_mask | FLAG_IS_SIMPLE_GLYPH)
}
// Create a GlyphEntry for uncommon case; should be accompanied by
// initialization of the actual DetailedGlyph data in DetailedGlyphStore
fn complex(starts_cluster: bool, starts_ligature: bool, glyph_count: usize) -> GlyphEntry {
assert!(glyph_count <= u16::MAX as usize);
debug!(
"creating complex glyph entry: starts_cluster={}, starts_ligature={}, \
glyph_count={}",
starts_cluster, starts_ligature, glyph_count
);
GlyphEntry::new(glyph_count as u32)
}
fn is_initial(&self) -> bool {
*self == GlyphEntry::initial()
}
}
/// The id of a particular glyph within a font
pub type GlyphId = u32;
// TODO: make this more type-safe.
const FLAG_CHAR_IS_WORD_SEPARATOR: u32 = 0x40000000;
const FLAG_IS_SIMPLE_GLYPH: u32 = 0x80000000;
// glyph advance; in Au's.
const GLYPH_ADVANCE_MASK: u32 = 0x3FFF0000;
const GLYPH_ADVANCE_SHIFT: u32 = 16;
const GLYPH_ID_MASK: u32 = 0x0000FFFF;
// Non-simple glyphs (more than one glyph per char; missing glyph,
// newline, tab, large advance, or nonzero x/y offsets) may have one
// or more detailed glyphs associated with them. They are stored in a
// side array so that there is a 1:1 mapping of GlyphEntry to
// unicode char.
// The number of detailed glyphs for this char.
const GLYPH_COUNT_MASK: u32 = 0x0000FFFF;
fn is_simple_glyph_id(id: GlyphId) -> bool {
(id & GLYPH_ID_MASK) == id
}
fn is_simple_advance(advance: Au) -> bool {
advance >= Au(0) && {
let unsigned_au = advance.0 as u32;
(unsigned_au & (GLYPH_ADVANCE_MASK >> GLYPH_ADVANCE_SHIFT)) == unsigned_au
}
}
// Getters and setters for GlyphEntry. Setter methods are functional,
// because GlyphEntry is immutable and only a u32 in size.
impl GlyphEntry {
#[inline(always)]
fn advance(&self) -> Au {
Au::new(((self.value & GLYPH_ADVANCE_MASK) >> GLYPH_ADVANCE_SHIFT) as i32)
}
#[inline]
fn id(&self) -> GlyphId {
self.value & GLYPH_ID_MASK
}
/// True if the original character was a word separator. These include spaces
/// (U+0020), non-breaking spaces (U+00A0), and a few other characters
/// non-exhaustively listed in the specification. Other characters may map to the same
/// glyphs, but this function does not take mapping into account.
///
/// See <https://drafts.csswg.org/css-text/#word-separator>.
fn char_is_word_separator(&self) -> bool {
self.has_flag(FLAG_CHAR_IS_WORD_SEPARATOR)
}
#[inline(always)]
fn set_char_is_word_separator(&mut self) {
self.value |= FLAG_CHAR_IS_WORD_SEPARATOR;
}
fn glyph_count(&self) -> u16 {
assert!(!self.is_simple());
(self.value & GLYPH_COUNT_MASK) as u16
}
#[inline(always)]
fn is_simple(&self) -> bool {
self.has_flag(FLAG_IS_SIMPLE_GLYPH)
}
#[inline(always)]
fn has_flag(&self, flag: u32) -> bool {
(self.value & flag) != 0
}
}
// Stores data for a detailed glyph, in the case that several glyphs
// correspond to one character, or the glyph's data couldn't be packed.
#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
struct DetailedGlyph {
id: GlyphId,
// glyph's advance, in the text's direction (LTR or RTL)
advance: Au,
// glyph's offset from the font's em-box (from top-left)
offset: Point2D<Au>,
}
impl DetailedGlyph {
fn new(id: GlyphId, advance: Au, offset: Point2D<Au>) -> DetailedGlyph {
DetailedGlyph {
id,
advance,
offset,
}
}
}
#[derive(Clone, Copy, Debug, Deserialize, Eq, PartialEq, Serialize)]
struct DetailedGlyphRecord {
// source string offset/GlyphEntry offset in the TextRun
entry_offset: ByteIndex,
// offset into the detailed glyphs buffer
detail_offset: usize,
}
impl Ord for DetailedGlyphRecord {
fn cmp(&self, other: &DetailedGlyphRecord) -> Ordering {
self.entry_offset.cmp(&other.entry_offset)
}
}
impl PartialOrd for DetailedGlyphRecord {
fn partial_cmp(&self, other: &DetailedGlyphRecord) -> Option<Ordering> {
Some(self.cmp(other))
}
}
// Manages the lookup table for detailed glyphs. Sorting is deferred
// until a lookup is actually performed; this matches the expected
// usage pattern of setting/appending all the detailed glyphs, and
// then querying without setting.
#[derive(Clone, Deserialize, Serialize)]
struct DetailedGlyphStore {
// TODO(pcwalton): Allocation of this buffer is expensive. Consider a small-vector
// optimization.
detail_buffer: Vec<DetailedGlyph>,
// TODO(pcwalton): Allocation of this buffer is expensive. Consider a small-vector
// optimization.
detail_lookup: Vec<DetailedGlyphRecord>,
lookup_is_sorted: bool,
}
impl<'a> DetailedGlyphStore {
fn new() -> DetailedGlyphStore {
DetailedGlyphStore {
detail_buffer: vec![], // TODO: default size?
detail_lookup: vec![],
lookup_is_sorted: false,
}
}
fn add_detailed_glyphs_for_entry(&mut self, entry_offset: ByteIndex, glyphs: &[DetailedGlyph]) {
let entry = DetailedGlyphRecord {
entry_offset,
detail_offset: self.detail_buffer.len(),
};
debug!(
"Adding entry[off={:?}] for detailed glyphs: {:?}",
entry_offset, glyphs
);
debug_assert!(!self.detail_lookup.contains(&entry));
self.detail_lookup.push(entry);
self.detail_buffer.extend_from_slice(glyphs);
self.lookup_is_sorted = false;
}
fn detailed_glyphs_for_entry(
&'a self,
entry_offset: ByteIndex,
count: u16,
) -> &'a [DetailedGlyph] {
debug!(
"Requesting detailed glyphs[n={}] for entry[off={:?}]",
count, entry_offset
);
// FIXME: Is this right? --pcwalton
// TODO: should fix this somewhere else
if count == 0 {
return &self.detail_buffer[0..0];
}
assert!((count as usize) <= self.detail_buffer.len());
assert!(self.lookup_is_sorted);
let key = DetailedGlyphRecord {
entry_offset,
detail_offset: 0, // unused
};
let i = self
.detail_lookup
.binary_search(&key)
.expect("Invalid index not found in detailed glyph lookup table!");
let main_detail_offset = self.detail_lookup[i].detail_offset;
assert!(main_detail_offset + (count as usize) <= self.detail_buffer.len());
// return a slice into the buffer
&self.detail_buffer[main_detail_offset..main_detail_offset + count as usize]
}
fn detailed_glyph_with_index(
&'a self,
entry_offset: ByteIndex,
detail_offset: u16,
) -> &'a DetailedGlyph {
assert!((detail_offset as usize) <= self.detail_buffer.len());
assert!(self.lookup_is_sorted);
let key = DetailedGlyphRecord {
entry_offset,
detail_offset: 0, // unused
};
let i = self
.detail_lookup
.binary_search(&key)
.expect("Invalid index not found in detailed glyph lookup table!");
let main_detail_offset = self.detail_lookup[i].detail_offset;
assert!(main_detail_offset + (detail_offset as usize) < self.detail_buffer.len());
&self.detail_buffer[main_detail_offset + (detail_offset as usize)]
}
fn ensure_sorted(&mut self) {
if self.lookup_is_sorted {
return;
}
// Sorting a unique vector is surprisingly hard. The following
// code is a good argument for using DVecs, but they require
// immutable locations thus don't play well with freezing.
// Thar be dragons here. You have been warned. (Tips accepted.)
let mut unsorted_records: Vec<DetailedGlyphRecord> = vec![];
mem::swap(&mut self.detail_lookup, &mut unsorted_records);
let mut mut_records: Vec<DetailedGlyphRecord> = unsorted_records;
mut_records.sort_by(|a, b| {
if a < b {
Ordering::Less
} else {
Ordering::Greater
}
});
let mut sorted_records = mut_records;
mem::swap(&mut self.detail_lookup, &mut sorted_records);
self.lookup_is_sorted = true;
}
}
// This struct is used by GlyphStore clients to provide new glyph data.
// It should be allocated on the stack and passed by reference to GlyphStore.
#[derive(Clone, Copy)]
pub struct GlyphData {
id: GlyphId,
advance: Au,
offset: Point2D<Au>,
cluster_start: bool,
ligature_start: bool,
}
impl GlyphData {
/// Creates a new entry for one glyph.
pub fn new(
id: GlyphId,
advance: Au,
offset: Option<Point2D<Au>>,
cluster_start: bool,
ligature_start: bool,
) -> GlyphData {
GlyphData {
id,
advance,
offset: offset.unwrap_or(Point2D::zero()),
cluster_start,
ligature_start,
}
}
}
// This enum is a proxy that's provided to GlyphStore clients when iterating
// through glyphs (either for a particular TextRun offset, or all glyphs).
// Rather than eagerly assembling and copying glyph data, it only retrieves
// values as they are needed from the GlyphStore, using provided offsets.
#[derive(Clone, Copy)]
pub enum GlyphInfo<'a> {
Simple(&'a GlyphStore, ByteIndex),
Detail(&'a GlyphStore, ByteIndex, u16),
}
impl<'a> GlyphInfo<'a> {
pub fn id(self) -> GlyphId {
match self {
GlyphInfo::Simple(store, entry_i) => store.entry_buffer[entry_i.to_usize()].id(),
GlyphInfo::Detail(store, entry_i, detail_j) => {
store
.detail_store
.detailed_glyph_with_index(entry_i, detail_j)
.id
},
}
}
#[inline(always)]
// FIXME: Resolution conflicts with IteratorUtil trait so adding trailing _
pub fn advance(self) -> Au {
match self {
GlyphInfo::Simple(store, entry_i) => store.entry_buffer[entry_i.to_usize()].advance(),
GlyphInfo::Detail(store, entry_i, detail_j) => {
store
.detail_store
.detailed_glyph_with_index(entry_i, detail_j)
.advance
},
}
}
#[inline]
pub fn offset(self) -> Option<Point2D<Au>> {
match self {
GlyphInfo::Simple(_, _) => None,
GlyphInfo::Detail(store, entry_i, detail_j) => Some(
store
.detail_store
.detailed_glyph_with_index(entry_i, detail_j)
.offset,
),
}
}
pub fn char_is_word_separator(self) -> bool {
let (store, entry_i) = match self {
GlyphInfo::Simple(store, entry_i) => (store, entry_i),
GlyphInfo::Detail(store, entry_i, _) => (store, entry_i),
};
store.char_is_word_separator(entry_i)
}
}
/// Stores the glyph data belonging to a text run.
///
/// Simple glyphs are stored inline in the `entry_buffer`, detailed glyphs are
/// stored as pointers into the `detail_store`.
///
/// ~~~ascii
/// +- GlyphStore --------------------------------+
/// | +---+---+---+---+---+---+---+ |
/// | entry_buffer: | | s | | s | | s | s | | d = detailed
/// | +-|-+---+-|-+---+-|-+---+---+ | s = simple
/// | | | | |
/// | | +---+-------+ |
/// | | | |
/// | +-V-+-V-+ |
/// | detail_store: | d | d | |
/// | +---+---+ |
/// +---------------------------------------------+
/// ~~~
#[derive(Clone, Deserialize, Serialize)]
pub struct GlyphStore {
// TODO(pcwalton): Allocation of this buffer is expensive. Consider a small-vector
// optimization.
/// A buffer of glyphs within the text run, in the order in which they
/// appear in the input text.
/// Any changes will also need to be reflected in
/// transmute_entry_buffer_to_u32_buffer().
entry_buffer: Vec<GlyphEntry>,
/// A store of the detailed glyph data. Detailed glyphs contained in the
/// `entry_buffer` point to locations in this data structure.
detail_store: DetailedGlyphStore,
/// A cache of the advance of the entire glyph store.
total_advance: Au,
/// A cache of the number of word separators in the entire glyph store.
/// See <https://drafts.csswg.org/css-text/#word-separator>.
total_word_separators: usize,
/// Used to check if fast path should be used in glyph iteration.
has_detailed_glyphs: bool,
is_whitespace: bool,
is_rtl: bool,
}
impl<'a> GlyphStore {
/// Initializes the glyph store, but doesn't actually shape anything.
///
/// Use the `add_*` methods to store glyph data.
pub fn new(length: usize, is_whitespace: bool, is_rtl: bool) -> GlyphStore {
assert!(length > 0);
GlyphStore {
entry_buffer: vec![GlyphEntry::initial(); length],
detail_store: DetailedGlyphStore::new(),
total_advance: Au(0),
total_word_separators: 0,
has_detailed_glyphs: false,
is_whitespace,
is_rtl,
}
}
#[inline]
pub fn total_advance(&self) -> Au {
self.total_advance
}
#[inline]
pub fn len(&self) -> ByteIndex {
ByteIndex(self.entry_buffer.len() as isize)
}
#[inline]
pub fn is_whitespace(&self) -> bool {
self.is_whitespace
}
#[inline]
pub fn total_word_separators(&self) -> usize {
self.total_word_separators
}
pub fn finalize_changes(&mut self) {
self.detail_store.ensure_sorted();
self.cache_total_advance_and_word_separators()
}
#[inline(never)]
fn cache_total_advance_and_word_separators(&mut self) {
let mut total_advance = Au(0);
let mut total_word_separators = 0;
for glyph in self.iter_glyphs_for_byte_range(&Range::new(ByteIndex(0), self.len())) {
total_advance += glyph.advance();
if glyph.char_is_word_separator() {
total_word_separators += 1;
}
}
self.total_advance = total_advance;
self.total_word_separators = total_word_separators;
}
/// Adds a single glyph.
pub fn add_glyph_for_byte_index(&mut self, i: ByteIndex, character: char, data: &GlyphData) {
let glyph_is_compressible = is_simple_glyph_id(data.id) &&
is_simple_advance(data.advance) &&
data.offset == Point2D::zero() &&
data.cluster_start; // others are stored in detail buffer
debug_assert!(data.ligature_start); // can't compress ligature continuation glyphs.
debug_assert!(i < self.len());
let mut entry = if glyph_is_compressible {
GlyphEntry::simple(data.id, data.advance)
} else {
let glyph = &[DetailedGlyph::new(data.id, data.advance, data.offset)];
self.has_detailed_glyphs = true;
self.detail_store.add_detailed_glyphs_for_entry(i, glyph);
GlyphEntry::complex(data.cluster_start, data.ligature_start, 1)
};
// This list is taken from the non-exhaustive list of word separator characters in
// the CSS Text Module Level 3 Spec:
// See https://drafts.csswg.org/css-text/#word-separator
if matches!(
character,
' ' |
'\u{00A0}' | // non-breaking space
'\u{1361}' | // Ethiopic word space
'\u{10100}' | // Aegean word separator
'\u{10101}' | // Aegean word separator
'\u{1039F}' | // Ugartic word divider
'\u{1091F}' // Phoenician word separator
) {
entry.set_char_is_word_separator();
}
self.entry_buffer[i.to_usize()] = entry;
}
pub fn add_glyphs_for_byte_index(&mut self, i: ByteIndex, data_for_glyphs: &[GlyphData]) {
assert!(i < self.len());
assert!(!data_for_glyphs.is_empty());
let glyph_count = data_for_glyphs.len();
let first_glyph_data = data_for_glyphs[0];
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);
let entry = GlyphEntry::complex(
first_glyph_data.cluster_start,
first_glyph_data.ligature_start,
glyph_count,
);
debug!(
"Adding multiple glyphs[idx={:?}, count={}]: {:?}",
i, glyph_count, entry
);
self.entry_buffer[i.to_usize()] = entry;
}
#[inline]
pub fn iter_glyphs_for_byte_range(&'a self, range: &Range<ByteIndex>) -> GlyphIterator<'a> {
if range.begin() >= self.len() {
panic!("iter_glyphs_for_range: range.begin beyond length!");
}
if range.end() > self.len() {
panic!("iter_glyphs_for_range: range.end beyond length!");
}
GlyphIterator {
store: self,
byte_index: if self.is_rtl {
range.end()
} else {
range.begin() - ByteIndex(1)
},
byte_range: *range,
glyph_range: None,
}
}
// Scan the glyphs for a given range until we reach a given advance. Returns the index
// and advance of the glyph in the range at the given advance, if reached. Otherwise, returns the
// the number of glyphs and the advance for the given range.
#[inline]
pub fn range_index_of_advance(
&self,
range: &Range<ByteIndex>,
advance: Au,
extra_word_spacing: Au,
) -> (usize, Au) {
let mut index = 0;
let mut current_advance = Au(0);
for glyph in self.iter_glyphs_for_byte_range(range) {
if glyph.char_is_word_separator() {
current_advance += glyph.advance() + extra_word_spacing
} else {
current_advance += glyph.advance()
}
if current_advance > advance {
break;
}
index += 1;
}
(index, current_advance)
}
#[inline]
pub fn advance_for_byte_range(&self, range: &Range<ByteIndex>, extra_word_spacing: Au) -> Au {
if range.begin() == ByteIndex(0) && range.end() == self.len() {
self.total_advance + extra_word_spacing * (self.total_word_separators as i32)
} else {
self.advance_for_byte_range_simple_glyphs(range, extra_word_spacing)
}
}
#[inline]
pub fn advance_for_byte_range_simple_glyphs(
&self,
range: &Range<ByteIndex>,
extra_word_spacing: Au,
) -> Au {
self.iter_glyphs_for_byte_range(range)
.fold(Au(0), |advance, glyph| {
if glyph.char_is_word_separator() {
advance + glyph.advance() + extra_word_spacing
} else {
advance + glyph.advance()
}
})
}
pub fn char_is_word_separator(&self, i: ByteIndex) -> bool {
assert!(i < self.len());
self.entry_buffer[i.to_usize()].char_is_word_separator()
}
pub fn word_separator_count_in_range(&self, range: &Range<ByteIndex>) -> u32 {
let mut spaces = 0;
for index in range.each_index() {
if self.char_is_word_separator(index) {
spaces += 1
}
}
spaces
}
}
impl fmt::Debug for GlyphStore {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
writeln!(formatter, "GlyphStore:")?;
let mut detailed_buffer = self.detail_store.detail_buffer.iter();
for entry in self.entry_buffer.iter() {
if entry.is_simple() {
writeln!(
formatter,
" simple id={:?} advance={:?}",
entry.id(),
entry.advance()
)?;
continue;
}
if entry.is_initial() {
continue;
}
write!(formatter, " complex...")?;
if detailed_buffer.next().is_none() {
continue;
}
writeln!(
formatter,
" detailed id={:?} advance={:?}",
entry.id(),
entry.advance()
)?;
}
Ok(())
}
}
/// An iterator over the glyphs in a byte range in a `GlyphStore`.
pub struct GlyphIterator<'a> {
store: &'a GlyphStore,
byte_index: ByteIndex,
byte_range: Range<ByteIndex>,
glyph_range: Option<EachIndex<ByteIndex>>,
}
impl<'a> GlyphIterator<'a> {
// Slow path when there is a glyph range.
#[inline(never)]
fn next_glyph_range(&mut self) -> Option<GlyphInfo<'a>> {
match self.glyph_range.as_mut().unwrap().next() {
Some(j) => {
Some(GlyphInfo::Detail(
self.store,
self.byte_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: ByteIndex) -> Option<GlyphInfo<'a>> {
let glyphs = self
.store
.detail_store
.detailed_glyphs_for_entry(i, entry.glyph_count());
self.glyph_range = Some(range::each_index(
ByteIndex(0),
ByteIndex(glyphs.len() as isize),
));
self.next()
}
}
impl<'a> Iterator for GlyphIterator<'a> {
type Item = 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<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 byte.
self.byte_index = self.byte_index +
if self.store.is_rtl {
ByteIndex(-1)
} else {
ByteIndex(1)
};
let i = self.byte_index;
if !self.byte_range.contains(i) {
return None;
}
debug_assert!(i < self.store.len());
let entry = self.store.entry_buffer[i.to_usize()];
if entry.is_simple() {
Some(GlyphInfo::Simple(self.store, i))
} else {
// Fall back to the slow path.
self.next_complex_glyph(&entry, i)
}
}
}