AuroraMiddleware/harfbuzz
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[aat] Fix unsafe-to-break

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At any position, if state is not zero, mark unsafe-to-break before,
unless we can reason it safe.

At any position, if there's an action entry for end-of-text, mark
unsafe to break.

Also changes buffer diff impl to allow for flag differences as long
as the buffer glyph flags are superset of reference glyph flags.

With this, all MORX tests pass.
This commit is contained in:
Behdad Esfahbod 2018-02-04 14:58:02 -05:00
parent 89b1906d99
commit 54e6efadd6
3 changed files with 49 additions and 19 deletions
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31
src/hb-aat-layout-common-private.hh
View File

@ -614,8 +614,7 @@ struct StateTableDriver
hb_face_t *face_) :
machine (machine_),
buffer (buffer_),
num_glyphs (face_->get_num_glyphs ()),
last_zero (0) {}
num_glyphs (face_->get_num_glyphs ()) {}
template <typename context_t>
inline void drive (context_t *c)
@ -629,9 +628,6 @@ struct StateTableDriver
bool last_was_dont_advance = false;
for (buffer->idx = 0;;)
{
if (!state)
last_zero = buffer->idx;
unsigned int klass = buffer->idx < buffer->len ?
machine.get_class (info[buffer->idx].codepoint, num_glyphs) :
0 /* End of text */;
@ -639,6 +635,30 @@ struct StateTableDriver
if (unlikely (!entry))
break;
/* Unsafe-to-break before this if not in state 0, as things might
* go differently if we start from state 0 here. */
if (state && buffer->idx)
{
/* Special-case easy cases: if starting here at state 0 is not
* actionable, and leads to the same next state, then it's safe.
* Let's hope... Maybe disable the conditional later, if proves
* insufficient. */
const Entry<EntryData> *start_entry = machine.get_entryZ (0, klass);
if (start_entry->newState != entry->newState ||
(start_entry->flags & context_t::DontAdvance) != (entry->flags & context_t::DontAdvance) ||
c->is_actionable (this, entry) ||
c->is_actionable (this, start_entry))
buffer->unsafe_to_break (buffer->idx - 1, buffer->idx + 1);
}
/* Unsafe-to-break if end-of-text would kick in here. */
if (buffer->idx + 2 <= buffer->len)
{
const Entry<EntryData> *end_entry = machine.get_entryZ (state, 0);
if (c->is_actionable (this, end_entry))
buffer->unsafe_to_break (buffer->idx, buffer->idx + 2);
}
if (unlikely (!c->transition (this, entry)))
break;
@ -665,7 +685,6 @@ struct StateTableDriver
const StateTable<EntryData> &machine;
hb_buffer_t *buffer;
unsigned int num_glyphs;
unsigned int last_zero;
};

35
src/hb-aat-layout-morx-table.hh
View File

@ -58,9 +58,13 @@ struct RearrangementSubtable
inline driver_context_t (const RearrangementSubtable *table) :
ret (false),
start (0), end (0),
last_zero_before_start (0) {}
start (0), end (0) {}
inline bool is_actionable (StateTableDriver<void> *driver,
const Entry<void> *entry)
{
return (entry->flags & Verb) && start < end;
}
inline bool transition (StateTableDriver<void> *driver,
const Entry<void> *entry)
{
@ -68,10 +72,7 @@ struct RearrangementSubtable
unsigned int flags = entry->flags;
if (flags & MarkFirst)
{
start = buffer->idx;
last_zero_before_start = driver->last_zero;
}
if (flags & MarkLast)
end = MIN (buffer->idx + 1, buffer->len);
@ -110,7 +111,7 @@ struct RearrangementSubtable
if (end - start >= l + r)
{
buffer->unsafe_to_break (last_zero_before_start, MIN (buffer->idx + 1, buffer->len));
buffer->merge_clusters (start, MIN (buffer->idx + 1, buffer->len));
buffer->merge_clusters (start, end);
hb_glyph_info_t *info = buffer->info;
@ -147,7 +148,6 @@ struct RearrangementSubtable
private:
unsigned int start;
unsigned int end;
unsigned int last_zero_before_start;
};
inline bool apply (hb_aat_apply_context_t *c) const
@ -200,9 +200,18 @@ struct ContextualSubtable
ret (false),
mark_set (false),
mark (0),
last_zero_before_mark (0),
subs (table+table->substitutionTables) {}
inline bool is_actionable (StateTableDriver<EntryData> *driver,
const Entry<EntryData> *entry)
{
hb_buffer_t *buffer = driver->buffer;
if (buffer->idx == buffer->len && !mark_set)
return false;
return entry->data.markIndex != 0xFFFF || entry->data.currentIndex != 0xFFFF;
}
inline bool transition (StateTableDriver<EntryData> *driver,
const Entry<EntryData> *entry)
{
@ -220,7 +229,7 @@ struct ContextualSubtable
const GlyphID *replacement = lookup.get_value (info[mark].codepoint, driver->num_glyphs);
if (replacement)
{
buffer->unsafe_to_break (last_zero_before_mark, MIN (buffer->idx + 1, buffer->len));
buffer->unsafe_to_break (mark, MIN (buffer->idx + 1, buffer->len));
info[mark].codepoint = *replacement;
ret = true;
}
@ -233,7 +242,6 @@ struct ContextualSubtable
const GlyphID *replacement = lookup.get_value (info[idx].codepoint, driver->num_glyphs);
if (replacement)
{
buffer->unsafe_to_break (driver->last_zero, idx + 1);
info[idx].codepoint = *replacement;
ret = true;
}
@ -243,7 +251,6 @@ struct ContextualSubtable
{
mark_set = true;
mark = buffer->idx;
last_zero_before_mark = driver->last_zero;
}
return true;
@ -254,7 +261,6 @@ struct ContextualSubtable
private:
bool mark_set;
unsigned int mark;
unsigned int last_zero_before_mark;
const UnsizedOffsetListOf<Lookup<GlyphID>, HBUINT32> &subs;
};
@ -344,6 +350,11 @@ struct LigatureSubtable
ligature (table+table->ligature),
match_length (0) {}
inline bool is_actionable (StateTableDriver<EntryData> *driver,
const Entry<EntryData> *entry)
{
return !!(entry->flags & PerformAction);
}
inline bool transition (StateTableDriver<EntryData> *driver,
const Entry<EntryData> *entry)
{

2
src/hb-buffer.cc
View File

@ -1933,7 +1933,7 @@ hb_buffer_diff (hb_buffer_t *buffer,
result |= HB_BUFFER_DIFF_FLAG_CODEPOINT_MISMATCH;
if (buf_info->cluster != ref_info->cluster)
result |= HB_BUFFER_DIFF_FLAG_CLUSTER_MISMATCH;
if ((buf_info->mask & HB_GLYPH_FLAG_DEFINED) != (ref_info->mask & HB_GLYPH_FLAG_DEFINED))
if ((buf_info->mask & HB_GLYPH_FLAG_DEFINED) & (ref_info->mask & HB_GLYPH_FLAG_DEFINED) != (ref_info->mask & HB_GLYPH_FLAG_DEFINED))
result |= HB_BUFFER_DIFF_FLAG_GLYPH_FLAGS_MISMATCH;
if (contains && ref_info->codepoint == dottedcircle_glyph)
result |= HB_BUFFER_DIFF_FLAG_DOTTED_CIRCLE_PRESENT;