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[subset] ChainContextFormat3 - don't subset glyph sequences. 

The backtrack, input, and lookahead sequence must be matched in their entirety so these sequences should not be subset. If any of the coverage tables in a sequence subsets to empty then the whole subtable should be dropped since it's not possible for this lookup to be activated.
This commit is contained in:
Garret Rieger 2020-09-28 17:22:01 -07:00
parent e31c2690f8
commit 940e1c6f98
1 changed files with 9 additions and 9 deletions
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18
src/hb-ot-layout-gsubgpos.hh
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@ -3038,20 +3038,21 @@ struct ChainContextFormat3
template<typename Iterator,
hb_requires (hb_is_iterator (Iterator))>
OffsetArrayOf<Coverage>* serialize_coverage_offsets
(hb_subset_context_t *c, Iterator it, const void* base) const
bool serialize_coverage_offsets (hb_subset_context_t *c, Iterator it, const void* base) const
{
TRACE_SERIALIZE (this);
auto *out = c->serializer->start_embed<OffsetArrayOf<Coverage>> ();
if (unlikely (!c->serializer->allocate_size<HBUINT16> (HBUINT16::static_size)))
return_trace (nullptr);
return_trace (false);
+ it
| hb_apply (subset_offset_array (c, *out, base))
;
for (auto& offset : it) {
auto *o = out->serialize_append (c->serializer);
if (unlikely (!o) || !o->serialize_subset (c, offset, base))
return_trace (false);
}
return_trace (out);
return_trace (true);
}
bool subset (hb_subset_context_t *c) const
@ -3066,8 +3067,7 @@ struct ChainContextFormat3
return_trace (false);
const OffsetArrayOf<Coverage> &input = StructAfter<OffsetArrayOf<Coverage>> (backtrack);
OffsetArrayOf<Coverage>* new_coverage = serialize_coverage_offsets (c, input.iter (), this);
if (!new_coverage || !new_coverage->len)
if (!serialize_coverage_offsets (c, input.iter (), this))
return_trace (false);
const OffsetArrayOf<Coverage> &lookahead = StructAfter<OffsetArrayOf<Coverage>> (input);