1 files changed, 41 insertions, 7 deletions

diff --git a/thirdparty/harfbuzz/src/hb-ot-shaper-myanmar.cc b/thirdparty/harfbuzz/src/hb-ot-shaper-myanmar.cc
index 78bd8de524..1b2a085a8d 100644
--- a/thirdparty/harfbuzz/src/hb-ot-shaper-myanmar.cc
+++ b/thirdparty/harfbuzz/src/hb-ot-shaper-myanmar.cc
@@ -98,11 +98,11 @@ is_consonant_myanmar (const hb_glyph_info_t &info)
 }
 
 
-static void
+static bool
 setup_syllables_myanmar (const hb_ot_shape_plan_t *plan,
 			 hb_font_t *font,
 			 hb_buffer_t *buffer);
-static void
+static bool
 reorder_myanmar (const hb_ot_shape_plan_t *plan,
 		 hb_font_t *font,
 		 hb_buffer_t *buffer);
@@ -150,7 +150,7 @@ setup_masks_myanmar (const hb_ot_shape_plan_t *plan HB_UNUSED,
     set_myanmar_properties (info[i]);
 }
 
-static void
+static bool
 setup_syllables_myanmar (const hb_ot_shape_plan_t *plan HB_UNUSED,
 			 hb_font_t *font HB_UNUSED,
 			 hb_buffer_t *buffer)
@@ -159,6 +159,7 @@ setup_syllables_myanmar (const hb_ot_shape_plan_t *plan HB_UNUSED,
   find_syllables_myanmar (buffer);
   foreach_syllable (buffer, start, end)
     buffer->unsafe_to_break (start, end);
+  return false;
 }
 
 static int
@@ -270,6 +271,33 @@ initial_reordering_consonant_syllable (hb_buffer_t *buffer,
 
   /* Sit tight, rock 'n roll! */
   buffer->sort (start, end, compare_myanmar_order);
+
+  /* Flip left-matra sequence. */
+  unsigned first_left_matra = end;
+  unsigned last_left_matra = end;
+  for (unsigned int i = start; i < end; i++)
+  {
+    if (info[i].myanmar_position() == POS_PRE_M)
+    {
+      if (first_left_matra == end)
+	first_left_matra = i;
+      last_left_matra = i;
+    }
+  }
+  /* https://github.com/harfbuzz/harfbuzz/issues/3863 */
+  if (first_left_matra < last_left_matra)
+  {
+    /* No need to merge clusters, done already? */
+    buffer->reverse_range (first_left_matra, last_left_matra + 1);
+    /* Reverse back VS, etc. */
+    unsigned i = first_left_matra;
+    for (unsigned j = i; j <= last_left_matra; j++)
+      if (info[j].myanmar_category() == M_Cat(VPre))
+      {
+	buffer->reverse_range (i, j + 1);
+	i = j + 1;
+      }
+  }
 }
 
 static void
@@ -291,16 +319,18 @@ reorder_syllable_myanmar (const hb_ot_shape_plan_t *plan HB_UNUSED,
   }
 }
 
-static void
+static bool
 reorder_myanmar (const hb_ot_shape_plan_t *plan,
 		 hb_font_t *font,
 		 hb_buffer_t *buffer)
 {
+  bool ret = false;
   if (buffer->message (font, "start reordering myanmar"))
   {
-    hb_syllabic_insert_dotted_circles (font, buffer,
-				       myanmar_broken_cluster,
-				       M_Cat(DOTTEDCIRCLE));
+    if (hb_syllabic_insert_dotted_circles (font, buffer,
+					   myanmar_broken_cluster,
+					   M_Cat(DOTTEDCIRCLE)))
+      ret = true;
 
     foreach_syllable (buffer, start, end)
       reorder_syllable_myanmar (plan, font->face, buffer, start, end);
@@ -309,6 +339,8 @@ reorder_myanmar (const hb_ot_shape_plan_t *plan,
 
   HB_BUFFER_DEALLOCATE_VAR (buffer, myanmar_category);
   HB_BUFFER_DEALLOCATE_VAR (buffer, myanmar_position);
+
+  return ret;
 }
 
 
@@ -331,6 +363,7 @@ const hb_ot_shaper_t _hb_ot_shaper_myanmar =
 };
 
 
+#ifndef HB_NO_OT_SHAPER_MYANMAR_ZAWGYI
 /* Ugly Zawgyi encoding.
  * Disable all auto processing.
  * https://github.com/harfbuzz/harfbuzz/issues/1162 */
@@ -351,6 +384,7 @@ const hb_ot_shaper_t _hb_ot_shaper_myanmar_zawgyi =
   HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
   false, /* fallback_position */
 };
+#endif
 
 
 #endif