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[GPOS] Fix cursive connection with mix of RTL and non-RTL lookups 

See thread "Issue with cursive attachment" started by Khaled.
Turned out fixing this wasn't as bad as I had assumed.  I like the
new code better; we now have a theoretical model of cursive
connections that is easier to reason about.
This commit is contained in:
Behdad Esfahbod 2015-08-25 20:24:59 +01:00
parent 7368da6724
commit 6578575cc8
1 changed files with 34 additions and 0 deletions
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34
src/hb-ot-layout-gpos-table.hh
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@ -883,6 +883,9 @@ struct EntryExitRecord
DEFINE_SIZE_STATIC (4);
};
static void
reverse_cursive_minor_offset (hb_glyph_position_t *pos, unsigned int i, hb_direction_t direction, unsigned int new_parent);
struct CursivePosFormat1
{
inline void collect_glyphs (hb_collect_glyphs_context_t *c) const
@ -980,6 +983,13 @@ struct CursivePosFormat1
y_offset = -y_offset;
}
/* If child was already connected to someone else, walk through its old
* chain and reverse the link direction, such that the whole tree of its
* previous connection now attaches to new parent. Watch out for case
* where new parent is on the path from old chain...
*/
reverse_cursive_minor_offset (pos, child, c->direction, parent);
pos[child].cursive_chain() = parent - child;
if (likely (HB_DIRECTION_IS_HORIZONTAL (c->direction)))
pos[child].y_offset = y_offset;
@ -1494,6 +1504,30 @@ struct GPOS : GSUBGPOS
};
static void
reverse_cursive_minor_offset (hb_glyph_position_t *pos, unsigned int i, hb_direction_t direction, unsigned int new_parent)
{
unsigned int j = pos[i].cursive_chain();
if (likely (!j))
return;
j += i;
pos[i].cursive_chain() = 0;
/* Stop if we see new parent in the chain. */
if (j == new_parent)
return;
reverse_cursive_minor_offset (pos, j, direction, new_parent);
if (HB_DIRECTION_IS_HORIZONTAL (direction))
pos[j].y_offset = -pos[i].y_offset;
else
pos[j].x_offset = -pos[i].x_offset;
pos[j].cursive_chain() = i - j;
}
static void
fix_cursive_minor_offset (hb_glyph_position_t *pos, unsigned int i, hb_direction_t direction)
{