[GSUB] Implement ligature substitutions

This commit is contained in:
Behdad Esfahbod 2009-05-05 13:25:13 -04:00
parent 38b011a293
commit bb3899a579
2 changed files with 93 additions and 22 deletions

View File

@ -57,6 +57,8 @@ harfbuzz_dump_LDADD = \
$(libharfbuzz_1_la_LIBADD) \
libharfbuzz-1.la
main_SOURCES = \
main.cc
main_LDADD = \
$(GLIB_LIBS)

View File

@ -44,7 +44,7 @@
hb_ot_layout_t *layout, \
hb_buffer_t *buffer, \
unsigned int context_length, \
unsigned int nesting_level_left, \
unsigned int nesting_level_left HB_GNUC_UNUSED, \
unsigned int lookup_flag
#define SUBTABLE_SUBSTITUTE_ARGS \
layout, \
@ -135,8 +135,6 @@ struct SingleSubst {
inline bool substitute (SUBTABLE_SUBSTITUTE_ARGS_DEF) const {
HB_UNUSED (nesting_level_left);
if (HB_UNLIKELY (context_length < 1))
return false;
@ -205,8 +203,6 @@ struct MultipleSubstFormat1 {
inline bool substitute (SUBTABLE_SUBSTITUTE_ARGS_DEF) const {
HB_UNUSED (nesting_level_left);
if (HB_UNLIKELY (context_length < 1))
return false;
@ -307,8 +303,6 @@ struct AlternateSubstFormat1 {
inline bool substitute (SUBTABLE_SUBSTITUTE_ARGS_DEF) const {
HB_UNUSED (nesting_level_left);
if (HB_UNLIKELY (context_length < 1))
return false;
@ -392,7 +386,77 @@ DEFINE_NULL (AlternateSubst, 2);
struct Ligature {
/* TODO */
friend struct LigatureSet;
private:
DEFINE_ARRAY_TYPE (GlyphID, component, (compCount ? compCount - 1 : 0));
inline bool substitute_ligature (SUBTABLE_SUBSTITUTE_ARGS_DEF, bool is_mark) const {
unsigned int i, j;
unsigned int property;
unsigned int count = compCount;
if (HB_UNLIKELY (buffer->in_pos + count > buffer->in_length ||
context_length < count))
return false; /* Not enough glyphs in input or context */
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 (!(property == HB_OT_LAYOUT_GLYPH_CLASS_MARK ||
property & LookupFlag::MarkAttachmentType))
is_mark = FALSE;
if (HB_LIKELY (IN_GLYPH(j) != (*this)[i - 1]))
return false;
}
if ( _hb_ot_layout_has_new_glyph_classes (layout) )
/* this is just a guess ... */
hb_ot_layout_set_glyph_class (layout, ligGlyph,
is_mark ? HB_OT_LAYOUT_GLYPH_CLASS_MARK
: HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE);
if (j == buffer->in_pos + i) /* No input glyphs skipped */
/* We don't use a new ligature ID if there are no skipped
glyphs and the ligature already has an ID. */
_hb_buffer_add_output_glyph_ids (buffer, i,
1, &ligGlyph,
0xFFFF,
IN_LIGID (buffer->in_pos) ?
0xFFFF : _hb_buffer_allocate_ligid (buffer));
else
{
unsigned int lig_id = _hb_buffer_allocate_ligid (buffer);
_hb_buffer_add_output_glyph (buffer, ligGlyph, 0xFFFF, lig_id);
/* Now we must do a second loop to copy the skipped glyphs to
`out' and assign component values to it. We start with the
glyph after the first component. Glyphs between component
i and i+1 belong to component i. Together with the lig_id
value it is later possible to check whether a specific
component value really belongs to a given ligature. */
for ( i = 0; i < count - 1; i++ )
{
while (!_hb_ot_layout_check_glyph_property (layout, IN_CURITEM(), lookup_flag, &property))
_hb_buffer_add_output_glyph (buffer, IN_CURGLYPH(), i, lig_id);
(buffer->in_pos)++;
}
/* XXX We should possibly reassign lig_id and component for any
* components of a previous ligature that s now being removed as part of
* this ligature. */
}
return true;
}
private:
GlyphID ligGlyph; /* GlyphID of ligature to substitute */
@ -404,7 +468,23 @@ struct Ligature {
DEFINE_NULL_ASSERT_SIZE (Ligature, 4);
struct LigatureSet {
/* TODO */
friend struct LigatureSubstFormat1;
private:
DEFINE_OFFSET_ARRAY_TYPE (Ligature, ligature, ligatureCount);
inline bool substitute_ligature (SUBTABLE_SUBSTITUTE_ARGS_DEF, bool is_mark) const {
unsigned int num_ligs = get_len ();
for (unsigned int i = 0; i < num_ligs; i++) {
const Ligature &lig = (*this)[i];
if (lig.substitute_ligature (SUBTABLE_SUBSTITUTE_ARGS, is_mark))
return true;
}
return false;
}
private:
USHORT ligatureCount; /* Number of Ligature tables */
@ -427,8 +507,6 @@ struct LigatureSubstFormat1 {
inline bool substitute (SUBTABLE_SUBSTITUTE_ARGS_DEF) const {
HB_UNUSED (nesting_level_left);
unsigned int property;
if (!_hb_ot_layout_check_glyph_property (layout, IN_CURITEM (), lookup_flag, &property))
return false;
@ -437,20 +515,11 @@ struct LigatureSubstFormat1 {
unsigned int index = get_glyph_coverage (glyph_id);
const LigatureSet &lig_set = (*this)[index];
bool first_is_mark = (property == HB_OT_LAYOUT_GLYPH_CLASS_MARK ||
property & LookupFlag::MarkAttachmentType);
unsigned int num_sets = get_len ();
for (unsigned int i = 0; i < num_sets; i++) {
const LigatureSet &lig_set = (*this)[i];
}
return false;
const LigatureSet &lig_set = (*this)[index];
return lig_set.substitute_ligature (SUBTABLE_SUBSTITUTE_ARGS, first_is_mark);
}
private: