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[GSUB] Support SingleSubst in get_glyph_alternates 

Fixes https://github.com/harfbuzz/harfbuzz/discussions/4146
This commit is contained in:
Behdad Esfahbod 2023-03-07 21:06:01 -07:00
parent 69183217df
commit 7327006d68
2 changed files with 53 additions and 0 deletions
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28
src/OT/Layout/GSUB/SingleSubstFormat1.hh
View File

@ -95,6 +95,34 @@ struct SingleSubstFormat1_3
bool would_apply (hb_would_apply_context_t *c) const
{ return c->len == 1 && (this+coverage).get_coverage (c->glyphs[0]) != NOT_COVERED; }
unsigned
get_glyph_alternates (hb_codepoint_t glyph_id,
unsigned start_offset,
unsigned *alternate_count /* IN/OUT. May be NULL. */,
hb_codepoint_t *alternate_glyphs /* OUT. May be NULL. */) const
{
unsigned int index = (this+coverage).get_coverage (glyph_id);
if (likely (index == NOT_COVERED))
{
if (alternate_count)
*alternate_count = 0;
return 0;
}
if (alternate_count && *alternate_count)
{
hb_codepoint_t d = deltaGlyphID;
hb_codepoint_t mask = get_mask ();
glyph_id = (glyph_id + d) & mask;
*alternate_glyphs = glyph_id;
*alternate_count = 1;
}
return 1;
}
bool apply (hb_ot_apply_context_t *c) const
{
TRACE_APPLY (this);

25
src/OT/Layout/GSUB/SingleSubstFormat2.hh
View File

@ -75,6 +75,31 @@ struct SingleSubstFormat2_4
bool would_apply (hb_would_apply_context_t *c) const
{ return c->len == 1 && (this+coverage).get_coverage (c->glyphs[0]) != NOT_COVERED; }
unsigned
get_glyph_alternates (hb_codepoint_t glyph_id,
unsigned start_offset,
unsigned *alternate_count /* IN/OUT. May be NULL. */,
hb_codepoint_t *alternate_glyphs /* OUT. May be NULL. */) const
{
unsigned int index = (this+coverage).get_coverage (glyph_id);
if (likely (index == NOT_COVERED))
{
if (alternate_count)
*alternate_count = 0;
return 0;
}
if (alternate_count && *alternate_count)
{
glyph_id = substitute[index];
*alternate_glyphs = glyph_id;
*alternate_count = 1;
}
return 1;
}
bool apply (hb_ot_apply_context_t *c) const
{
TRACE_APPLY (this);