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[GSUB] Implement ContextSubstFormat2

This commit is contained in:
Behdad Esfahbod 2009-05-15 20:25:37 -04:00
parent fc36d9453e
commit 1ff926a568
1 changed files with 97 additions and 8 deletions
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103
src/hb-ot-layout-gsub-private.h
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@ -540,12 +540,8 @@ DEFINE_NULL (LigatureSubst, 2);
struct SubstLookupRecord {
friend struct SubRule;
private:
inline bool substitute (SUBTABLE_SUBSTITUTE_ARGS_DEF) const;
private:
USHORT sequenceIndex; /* Index into current glyph
* sequence--first glyph = 0 */
USHORT lookupListIndex; /* Lookup to apply to that
@ -615,7 +611,6 @@ struct SubRule {
}
}
private:
USHORT glyphCount; /* Total number of glyphs in input
* glyph sequence--includes the first
@ -694,7 +689,66 @@ ASSERT_SIZE (ContextSubstFormat1, 6);
struct SubClassRule {
/* TODO */
friend struct SubClassSet;
private:
DEFINE_ARRAY_TYPE (USHORT, klass, (glyphCount ? glyphCount - 1 : 0));
inline bool substitute_class (SUBTABLE_SUBSTITUTE_ARGS_DEF, const ClassDef &class_def) const {
unsigned int i, j;
unsigned int property;
unsigned int count = glyphCount;
if (HB_UNLIKELY (buffer->in_pos + count > buffer->in_length ||
context_length < count))
return false; /* Not enough glyphs in input or context */
/* XXX context_length should also be checked when skipping glyphs, right?
* What does context_length really mean, anyway? */
for (i = 1, j = buffer->in_pos + 1; i < count; i++, j++) {
while (!_hb_ot_layout_check_glyph_property (layout, IN_ITEM (j), lookup_flag, &property)) {
if (HB_UNLIKELY (j + count - i == buffer->in_length))
return false;
j++;
}
if (HB_LIKELY (class_def.get_class (IN_GLYPH(j)) != (*this)[i - 1]))
return false;
}
/* XXX right? or j - buffer_inpos? */
context_length = count;
unsigned int subst_count = substCount;
const SubstLookupRecord *subst = (const SubstLookupRecord *) ((const char *) klass + sizeof (klass[0]) * glyphCount);
for (i = 0; i < count;)
{
if ( subst_count && i == subst->sequenceIndex )
{
unsigned int old_pos = buffer->in_pos;
/* Do a substitution */
bool done = subst->substitute (SUBTABLE_SUBSTITUTE_ARGS);
subst++;
subst_count--;
i += buffer->in_pos - old_pos;
if (!done)
goto no_subst;
}
else
{
no_subst:
/* No substitution for this index */
_hb_buffer_copy_output_glyph (buffer);
i++;
}
}
}
private:
USHORT glyphCount; /* Total number of classes
@ -710,7 +764,27 @@ struct SubClassRule {
DEFINE_NULL_ASSERT_SIZE (SubClassRule, 4);
struct SubClassSet {
/* TODO */
friend struct ContextSubstFormat2;
private:
DEFINE_OFFSET_ARRAY_TYPE (SubClassRule, subClassRule, subClassRuleCnt);
inline bool substitute_class (SUBTABLE_SUBSTITUTE_ARGS_DEF, const ClassDef &class_def) const {
/* LONGTERMTODO: Old code fetches glyph classes at most once and caches
* them across subrule lookups. Not sure it's worth it.
*/
unsigned int num_rules = get_len ();
for (unsigned int i = 0; i < num_rules; i++) {
const SubClassRule &rule = (*this)[i];
if (rule.substitute_class (SUBTABLE_SUBSTITUTE_ARGS, class_def))
return true;
}
return false;
}
private:
USHORT subClassRuleCnt; /* Number of SubClassRule tables */
@ -725,9 +799,24 @@ struct ContextSubstFormat2 {
friend struct ContextSubst;
private:
/* SubClassSet tables, in Coverage Index order */
DEFINE_OFFSET_ARRAY_TYPE (SubClassSet, subClassSet, subClassSetCnt);
DEFINE_GET_ACCESSOR (Coverage, coverage, coverage);
DEFINE_GET_ACCESSOR (ClassDef, class_def, classDef);
DEFINE_GET_GLYPH_COVERAGE (glyph_coverage);
inline bool substitute (SUBTABLE_SUBSTITUTE_ARGS_DEF) const {
unsigned int property;
if (!_hb_ot_layout_check_glyph_property (layout, IN_CURITEM (), lookup_flag, &property))
return false;
hb_codepoint_t glyph_id = IN_CURGLYPH ();
unsigned int index = get_glyph_coverage (glyph_id);
const SubClassSet &class_set = (*this)[index];
return class_set.substitute_class (SUBTABLE_SUBSTITUTE_ARGS, get_class_def ());
}
private: