From 0c3b061ac244fa8a8657366e1b95523503fdf7be Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 7 Nov 2018 13:58:41 -0500
Subject: [PATCH] [kern] Apply erlier, where GPOS/kerx are applied

---
 src/hb-aat-layout-kerx-table.hh |  3 +--
 src/hb-ot-shape-fallback.cc     |  9 +++++++++
 src/hb-ot-shape.cc              | 12 +++++-------
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/hb-aat-layout-kerx-table.hh b/src/hb-aat-layout-kerx-table.hh
index 6bbeda764..8b87e176f 100644
--- a/src/hb-aat-layout-kerx-table.hh
+++ b/src/hb-aat-layout-kerx-table.hh
@@ -889,8 +889,7 @@ struct KerxTable
       if (HB_DIRECTION_IS_HORIZONTAL (c->buffer->props.direction) != st->u.header.is_horizontal ())
 	goto skip;
 
-      reverse = T::Types::extended /* TODO remove after kern application is moved earlier. */ &&
-		bool (st->u.header.coverage & st->u.header.Backwards) !=
+      reverse = bool (st->u.header.coverage & st->u.header.Backwards) !=
 		HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction);
 
       if (!c->buffer->message (c->font, "start %c%c%c%c subtable %d", HB_UNTAG (thiz()->tableTag), c->lookup_index))
diff --git a/src/hb-ot-shape-fallback.cc b/src/hb-ot-shape-fallback.cc
index cfd06e7fd..bbc410ad6 100644
--- a/src/hb-ot-shape-fallback.cc
+++ b/src/hb-ot-shape-fallback.cc
@@ -464,9 +464,18 @@ _hb_ot_shape_fallback_kern (const hb_ot_shape_plan_t *plan,
       !font->has_glyph_h_kerning_func () :
       !font->has_glyph_v_kerning_func ())
     return;
+
+  bool reverse = HB_DIRECTION_IS_BACKWARD (buffer->props.direction);
+
+  if (reverse)
+    buffer->reverse ();
+
   hb_ot_shape_fallback_kern_driver_t driver (font, buffer);
   OT::hb_kern_machine_t<hb_ot_shape_fallback_kern_driver_t> machine (driver);
   machine.kern (font, buffer, plan->kern_mask, false);
+
+  if (reverse)
+    buffer->reverse ();
 }
 
 
diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index 98c29a483..d2f771320 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -866,10 +866,15 @@ hb_ot_position_complex (const hb_ot_shape_context_t *c)
 	break;
     }
 
+  /* XXX Clean up relationship between these. */
   if (c->plan->apply_gpos)
     c->plan->position (c->font, c->buffer);
   else if (c->plan->apply_kerx)
     hb_aat_layout_position (c->plan, c->font, c->buffer);
+  else if (c->plan->apply_kern)
+    hb_ot_layout_kern (c->plan, c->font, c->buffer);
+  else if (c->plan->fallback_kerning)
+    _hb_ot_shape_fallback_kern (c->plan, c->font, c->buffer);
 
   if (c->plan->apply_trak)
     hb_aat_layout_track (c->plan, c->font, c->buffer);
@@ -915,13 +920,6 @@ hb_ot_position (const hb_ot_shape_context_t *c)
   if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
     hb_buffer_reverse (c->buffer);
 
-  /* Visual fallback goes here. */
-
-  if (c->plan->apply_kern)
-    hb_ot_layout_kern (c->plan, c->font, c->buffer);
-  else if (c->plan->fallback_kerning)
-    _hb_ot_shape_fallback_kern (c->plan, c->font, c->buffer);
-
   _hb_buffer_deallocate_gsubgpos_vars (c->buffer);
 }