[GSUB] Merge Ligature and context input matching
Looks better now...
diff --git a/src/hb-ot-layout-gsubgpos-private.hh b/src/hb-ot-layout-gsubgpos-private.hh
index 5032d30..3d69736 100644
--- a/src/hb-ot-layout-gsubgpos-private.hh
+++ b/src/hb-ot-layout-gsubgpos-private.hh
@@ -421,13 +421,33 @@
const USHORT input[], /* Array of input values--start with second glyph */
match_func_t match_func,
const void *match_data,
- unsigned int *end_offset = NULL)
+ unsigned int *end_offset = NULL,
+ bool *p_is_mark_ligature = NULL,
+ unsigned int *p_total_component_count = NULL)
{
hb_auto_trace_t<HB_DEBUG_APPLY> trace (&c->debug_depth, "APPLY", NULL, HB_FUNC, "idx %d codepoint %u", c->buffer->idx, c->buffer->cur().codepoint);
hb_apply_context_t::mark_skipping_forward_iterator_t skippy_iter (c, c->buffer->idx, count - 1);
if (skippy_iter.has_no_chance ()) return TRACE_RETURN (false);
+ /*
+ * This is perhaps the trickiest part of OpenType... Remarks:
+ *
+ * - If all components of the ligature were marks, we call this a mark ligature.
+ *
+ * - If there is no GDEF, and the ligature is NOT a mark ligature, we categorize
+ * it as a ligature glyph.
+ *
+ * - Ligatures cannot be formed across glyphs attached to different components
+ * of previous ligatures. Eg. the sequence is LAM,SHADDA,LAM,FATHA,HEH, and
+ * LAM,LAM,HEH form a ligature, leaving SHADDA,FATHA next to eachother.
+ * However, it would be wrong to ligate that SHADDA,FATHA sequence.o
+ * There is an exception to this: If a ligature tries ligating with marks that
+ * belong to it itself, go ahead, assuming that the font designer knows what
+ * they are doing (otherwise it can break Indic stuff when a matra wants to
+ * ligate with a conjunct...)
+ */
+
bool is_mark_ligature = !!(c->property & HB_OT_LAYOUT_GLYPH_CLASS_MARK);
unsigned int total_component_count = 0;
@@ -443,7 +463,6 @@
if (!skippy_iter.next (&property)) return TRACE_RETURN (false);
if (likely (!match_func (c->buffer->info[skippy_iter.idx].codepoint, input[i - 1], match_data))) return false;
-// if (likely (c->buffer->info[skippy_iter.idx].codepoint != component[i])) return TRACE_RETURN (false);
unsigned int this_lig_id = get_lig_id (c->buffer->info[skippy_iter.idx]);
unsigned int this_lig_comp = get_lig_comp (c->buffer->info[skippy_iter.idx]);
@@ -469,6 +488,12 @@
if (end_offset)
*end_offset = skippy_iter.idx - c->buffer->idx + 1;
+ if (p_is_mark_ligature)
+ *p_is_mark_ligature = is_mark_ligature;
+
+ if (p_total_component_count)
+ *p_total_component_count = total_component_count;
+
return true;
}
