[coretext] Attach marks to base clusters
Fixes https://githu.com/behdad/harfbuzz/issues/49
to the extent that it can be fixed.
diff --git a/src/hb-coretext.cc b/src/hb-coretext.cc
index 498b730..5469101 100644
--- a/src/hb-coretext.cc
+++ b/src/hb-coretext.cc
@@ -428,6 +428,22 @@
hb_coretext_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);
hb_coretext_shaper_font_data_t *font_data = HB_SHAPER_DATA_GET (font);
+ /* Attach marks to their bases, to match the 'ot' shaper.
+ * Adapted from hb-ot-shape:hb_form_clusters().
+ * Note that this only makes us be closer to the 'ot' shaper,
+ * but by no means the same. For example, if there's
+ * B1 M1 B2 M2, and B1-B2 form a ligature, M2's cluster will
+ * continue pointing to B2 even though B2 was merged into B1's
+ * cluster... */
+ {
+ hb_unicode_funcs_t *unicode = buffer->unicode;
+ unsigned int count = buffer->len;
+ hb_glyph_info_t *info = buffer->info;
+ for (unsigned int i = 1; i < count; i++)
+ if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (unicode->general_category (info[i].codepoint)))
+ buffer->merge_clusters (i - 1, i + 1);
+ }
+
hb_auto_array_t<feature_record_t> feature_records;
hb_auto_array_t<range_record_t> range_records;
