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Add contextual lookups #6

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merged 4 commits into from
Jul 26, 2024
Merged

Add contextual lookups #6

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34a7e49
Add contextual lookups
dfrg Jul 26, 2024
c5f3ab8
remove random std::ops::Sub import
dfrg Jul 26, 2024
1e9b19a
remove ttf-parser context lookups
dfrg Jul 26, 2024
23d6f01
use our own SequenceLookupRecord
dfrg Jul 26, 2024
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267 changes: 243 additions & 24 deletions src/hb/fonta/ot/contextual.rs
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Original file line number Diff line number Diff line change
@@ -1,17 +1,190 @@
use super::{coverage_index, covered, glyph_class};
use crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t;
use crate::hb::ot_layout_gsubgpos::{
apply_lookup, match_backtrack, match_func_t, match_glyph, match_input, match_lookahead, Apply,
WouldApply, WouldApplyContext,
};
use skrifa::raw::tables::layout::{
ChainedSequenceContextFormat1, ChainedSequenceContextFormat2, ChainedSequenceContextFormat3,
SequenceContextFormat1, SequenceContextFormat2, SequenceContextFormat3, SequenceLookupRecord,
};
use skrifa::raw::types::BigEndian;
use ttf_parser::{opentype_layout::SequenceLookupRecord, GlyphId};
use ttf_parser::GlyphId;

impl WouldApply for SequenceContextFormat1<'_> {
fn would_apply(&self, ctx: &WouldApplyContext) -> bool {
coverage_index(self.coverage(), ctx.glyphs[0])
.and_then(|index| {
self.seq_rule_sets()
.get(index as usize)
.transpose()
.ok()
.flatten()
})
.map(|set| {
set.seq_rules().iter().any(|rule| {
rule.map(|rule| {
let input = rule.input_sequence();
ctx.glyphs.len() == input.len() + 1
&& input.iter().enumerate().all(|(i, value)| {
match_glyph(ctx.glyphs[i + 1], value.get().to_u16())
})
})
.unwrap_or(false)
})
})
.unwrap_or_default()
}
}

impl Apply for SequenceContextFormat1<'_> {
fn apply(
&self,
ctx: &mut crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t,
) -> Option<()> {
let glyph = skrifa::GlyphId::from(ctx.buffer.cur(0).as_glyph().0);
let index = self.coverage().ok()?.get(glyph)? as usize;
let set = self.seq_rule_sets().get(index)?.ok()?;
for rule in set.seq_rules().iter().filter_map(|rule| rule.ok()) {
let input = rule.input_sequence();
if apply_context(ctx, input, &match_glyph, rule.seq_lookup_records()).is_some() {
return Some(());
}
}
None
}
}

impl WouldApply for SequenceContextFormat2<'_> {
fn would_apply(&self, ctx: &WouldApplyContext) -> bool {
let class_def = self.class_def().ok();
let match_fn = &match_class(&class_def);
let class = glyph_class(self.class_def(), ctx.glyphs[0]);
self.class_seq_rule_sets()
.get(class as usize)
.transpose()
.ok()
.flatten()
.map(|set| {
set.class_seq_rules().iter().any(|rule| {
rule.map(|rule| {
let input = rule.input_sequence();
ctx.glyphs.len() == input.len() + 1
&& input
.iter()
.enumerate()
.all(|(i, value)| match_fn(ctx.glyphs[i + 1], value.get()))
})
.unwrap_or(false)
})
})
.unwrap_or_default()
}
}

impl Apply for SequenceContextFormat2<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let input_classes = self.class_def().ok();
let glyph = ctx.buffer.cur(0).as_skrifa_glyph16();
self.coverage().ok()?.get(glyph)?;
let index = input_classes.as_ref()?.get(glyph) as usize;
let set = self.class_seq_rule_sets().get(index)?.ok()?;
for rule in set.class_seq_rules().iter().filter_map(|rule| rule.ok()) {
let input = rule.input_sequence();
if apply_context(
ctx,
input,
&match_class(&input_classes),
rule.seq_lookup_records(),
)
.is_some()
{
return Some(());
}
}
None
}
}

impl WouldApply for SequenceContextFormat3<'_> {
fn would_apply(&self, ctx: &WouldApplyContext) -> bool {
let coverages = self.coverages();
ctx.glyphs.len() == usize::from(coverages.len()) + 1
&& coverages
.iter()
.enumerate()
.all(|(i, coverage)| covered(coverage, ctx.glyphs[i + 1]))
}
}

impl Apply for SequenceContextFormat3<'_> {
fn apply(
&self,
ctx: &mut crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t,
) -> Option<()> {
let glyph = skrifa::GlyphId::from(ctx.buffer.cur(0).as_glyph().0);
let input_coverages = self.coverages();
input_coverages.get(0).ok()?.get(glyph)?;
let input = |glyph: GlyphId, index: u16| {
input_coverages
.get(index as usize + 1)
.map(|cov| cov.get(skrifa::GlyphId::from(glyph.0)).is_some())
.unwrap_or_default()
};
let mut match_end = 0;
let mut match_positions = smallvec::SmallVec::from_elem(0, 4);
if match_input(
ctx,
input_coverages.len() as u16 - 1,
&input,
&mut match_end,
&mut match_positions,
None,
) {
ctx.buffer
.unsafe_to_break_from_outbuffer(Some(ctx.buffer.idx), Some(match_end));
apply_lookup(
ctx,
input_coverages.len() - 1,
&mut match_positions,
match_end,
self.seq_lookup_records(),
);
Some(())
} else {
ctx.buffer
.unsafe_to_concat(Some(ctx.buffer.idx), Some(match_end));
None
}
}
}

impl WouldApply for ChainedSequenceContextFormat1<'_> {
fn would_apply(&self, _ctx: &WouldApplyContext) -> bool {
false
fn would_apply(&self, ctx: &WouldApplyContext) -> bool {
coverage_index(self.coverage(), ctx.glyphs[0])
.and_then(|index| {
self.chained_seq_rule_sets()
.get(index as usize)
.transpose()
.ok()
.flatten()
})
.map(|set| {
set.chained_seq_rules().iter().any(|rule| {
rule.map(|rule| {
let input = rule.input_sequence();
(!ctx.zero_context
|| (rule.backtrack_glyph_count() == 0
&& rule.lookahead_glyph_count() == 0))
&& ctx.glyphs.len() == input.len() + 1
&& input.iter().enumerate().all(|(i, value)| {
match_glyph(ctx.glyphs[i + 1], value.get().to_u16())
})
})
.unwrap_or(false)
})
})
.unwrap_or_default()
}
}

Expand All @@ -30,12 +203,7 @@ impl Apply for ChainedSequenceContextFormat1<'_> {
input,
lookahead,
[&match_glyph; 3],
rule.seq_lookup_records()
.iter()
.map(|rec| SequenceLookupRecord {
sequence_index: rec.sequence_index(),
lookup_list_index: rec.lookup_list_index(),
}),
rule.seq_lookup_records(),
)
.is_some()
{
Expand All @@ -47,8 +215,32 @@ impl Apply for ChainedSequenceContextFormat1<'_> {
}

impl WouldApply for ChainedSequenceContextFormat2<'_> {
fn would_apply(&self, _ctx: &WouldApplyContext) -> bool {
false
fn would_apply(&self, ctx: &WouldApplyContext) -> bool {
let class_def = self.input_class_def().ok();
let match_fn = &match_class(&class_def);
let class = glyph_class(self.input_class_def(), ctx.glyphs[0]);
self.chained_class_seq_rule_sets()
.get(class as usize)
.transpose()
.ok()
.flatten()
.map(|set| {
set.chained_class_seq_rules().iter().any(|rule| {
rule.map(|rule| {
let input = rule.input_sequence();
(!ctx.zero_context
|| (rule.backtrack_glyph_count() == 0
&& rule.lookahead_glyph_count() == 0))
&& ctx.glyphs.len() == input.len() + 1
&& input
.iter()
.enumerate()
.all(|(i, value)| match_fn(ctx.glyphs[i + 1], value.get()))
})
.unwrap_or(false)
})
})
.unwrap_or_default()
}
}

Expand Down Expand Up @@ -91,12 +283,7 @@ impl Apply for ChainedSequenceContextFormat2<'_> {
&match_class(&input_classes),
&match_class(&lookahead_classes),
],
rule.seq_lookup_records()
.iter()
.map(|rec| SequenceLookupRecord {
sequence_index: rec.sequence_index(),
lookup_list_index: rec.lookup_list_index(),
}),
rule.seq_lookup_records(),
)
.is_some()
{
Expand Down Expand Up @@ -207,12 +394,7 @@ impl Apply for ChainedSequenceContextFormat3<'_> {
input_coverages.len() - 1,
&mut match_positions,
match_end,
self.seq_lookup_records()
.iter()
.map(|rec| SequenceLookupRecord {
sequence_index: rec.sequence_index(),
lookup_list_index: rec.lookup_list_index(),
}),
self.seq_lookup_records(),
);

Some(())
Expand All @@ -235,13 +417,50 @@ impl ToU16 for BigEndian<u16> {
}
}

fn apply_context<T: ToU16>(
ctx: &mut hb_ot_apply_context_t,
input: &[T],
match_func: &match_func_t,
lookups: &[SequenceLookupRecord],
) -> Option<()> {
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🤨

let match_func = |glyph, index| {
let value = input.get(index as usize).unwrap().to_u16();
match_func(glyph, value)
};

let mut match_end = 0;
let mut match_positions = smallvec::SmallVec::from_elem(0, 4);

if match_input(
ctx,
input.len() as _,
&match_func,
&mut match_end,
&mut match_positions,
None,
) {
ctx.buffer
.unsafe_to_break(Some(ctx.buffer.idx), Some(match_end));
apply_lookup(
ctx,
usize::from(input.len()),
&mut match_positions,
match_end,
lookups,
);
return Some(());
}

None
}

fn apply_chain_context<T: ToU16>(
ctx: &mut hb_ot_apply_context_t,
backtrack: &[T],
input: &[T],
lookahead: &[T],
match_funcs: [&match_func_t; 3],
lookups: impl Iterator<Item = SequenceLookupRecord>,
lookups: &[SequenceLookupRecord],
) -> Option<()> {
// NOTE: Whenever something in this method changes, we also need to
// change it in the `apply` implementation for ChainedContextLookup.
Expand Down
14 changes: 5 additions & 9 deletions src/hb/fonta/ot/gpos/mod.rs
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Original file line number Diff line number Diff line change
@@ -1,9 +1,9 @@
//! OpenType GPOS lookups.

use super::{LookupCache, LookupInfo};
use crate::hb::{
ot_layout::TableIndex, ot_layout_gpos_table::ValueRecordExt,
ot_layout_gsubgpos::OT::hb_ot_apply_context_t,
use crate::{
hb::{ot_layout::TableIndex, ot_layout_gsubgpos::OT::hb_ot_apply_context_t},
GlyphPosition,
};
use skrifa::raw::{
tables::{
Expand Down Expand Up @@ -53,7 +53,7 @@ struct Value<'a> {
data: FontData<'a>,
}

impl ValueRecordExt for Value<'_> {
impl Value<'_> {
fn is_empty(&self) -> bool {
self.record.x_placement.is_none()
&& self.record.y_placement.is_none()
Expand All @@ -72,11 +72,7 @@ impl ValueRecordExt for Value<'_> {
worked
}

fn apply_to_pos(
&self,
ctx: &mut hb_ot_apply_context_t,
pos: &mut crate::GlyphPosition,
) -> bool {
fn apply_to_pos(&self, ctx: &mut hb_ot_apply_context_t, pos: &mut GlyphPosition) -> bool {
let horizontal = ctx.buffer.direction.is_horizontal();
let mut worked = false;

Expand Down
1 change: 0 additions & 1 deletion src/hb/fonta/ot/gpos/pair.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,3 @@
use crate::hb::ot_layout_gpos_table::ValueRecordExt;
use crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t;
use crate::hb::ot_layout_gsubgpos::{skipping_iterator_t, Apply};
use skrifa::raw::tables::gpos::{PairPosFormat1, PairPosFormat2, PairValueRecord};
Expand Down
1 change: 0 additions & 1 deletion src/hb/fonta/ot/gpos/single.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,4 @@
use super::Value;
use crate::hb::ot_layout_gpos_table::ValueRecordExt;
use crate::hb::ot_layout_gsubgpos::Apply;
use crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t;
use skrifa::raw::tables::gpos::{SinglePosFormat1, SinglePosFormat2};
Expand Down
23 changes: 0 additions & 23 deletions src/hb/fonta/ot/lookup_cache.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -182,29 +182,6 @@ impl LookupCache {
lookup_type: subtable_kind as u8,
digest: Default::default(),
};
// TODO: update as we add more subtables
let is_supported = match (data.is_subst, subtable_kind) {
// (true, 1) | (true, 2) | (true, 3) | (true, 4) => true,
(true, 1) | (true, 2) | (true, 3) | (true, 4) => true,
(false, 4) | (false, 6) => true,
// single pos
(false, 1) => true,
// pair pos
(false, 2) => true,
// cursive pos
(false, 3) => true,
// mark lig pos
(false, 5) => true,
// chained sequence context
(true, 6) => true,
(false, 8) => true,
// reverse chained context
(true, 8) => true,
_ => false,
};
if !is_supported {
return Err(ReadError::MalformedData("unsupported subtable"));
}
let subtable = subtable_info.materialize(data.table_data.as_bytes())?;
let (coverage, coverage_offset) = subtable.coverage_and_offset()?;
add_coverage_to_digest(&coverage, &mut subtable_info.digest);
Expand Down
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