[GPOS] Divide position_finish() into two phases, for advances and offsets

Right now the position_finish_advances() is empty.  To be used for
spacing attachments proposal later.

src/hb-ot-layout-gpos-table.hh

diff --git a/src/hb-ot-layout-gpos-table.hh b/src/hb-ot-layout-gpos-table.hh
index 8795c8a..bc18c87 100644
--- a/src/hb-ot-layout-gpos-table.hh
+++ b/src/hb-ot-layout-gpos-table.hh
@@ -1512,7 +1512,8 @@
   { return CastR<PosLookup> (GSUBGPOS::get_lookup (i)); }
 
   static inline void position_start (hb_font_t *font, hb_buffer_t *buffer);
-  static inline void position_finish (hb_font_t *font, hb_buffer_t *buffer);
+  static inline void position_finish_advances (hb_font_t *font, hb_buffer_t *buffer);
+  static inline void position_finish_offsets (hb_font_t *font, hb_buffer_t *buffer);
 
   inline bool sanitize (hb_sanitize_context_t *c) const
   {
@@ -1607,7 +1608,13 @@
 }
 
 void
-GPOS::position_finish (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer)
+GPOS::position_finish_advances (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer)
+{
+  //_hb_buffer_assert_gsubgpos_vars (buffer);
+}
+
+void
+GPOS::position_finish_offsets (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer)
 {
   _hb_buffer_assert_gsubgpos_vars (buffer);
 

src/hb-ot-layout-gsub-table.hh

diff --git a/src/hb-ot-layout-gsub-table.hh b/src/hb-ot-layout-gsub-table.hh
index 459a1a3..38c2c64 100644
--- a/src/hb-ot-layout-gsub-table.hh
+++ b/src/hb-ot-layout-gsub-table.hh
@@ -1268,7 +1268,6 @@
   { return CastR<SubstLookup> (GSUBGPOS::get_lookup (i)); }
 
   static inline void substitute_start (hb_font_t *font, hb_buffer_t *buffer);
-  static inline void substitute_finish (hb_font_t *font, hb_buffer_t *buffer);
 
   inline bool sanitize (hb_sanitize_context_t *c) const
   {
@@ -1297,11 +1296,6 @@
   }
 }
 
-void
-GSUB::substitute_finish (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer HB_UNUSED)
-{
-}
-
 
 /* Out-of-class implementation for methods recursing */
 

src/hb-ot-layout-private.hh

diff --git a/src/hb-ot-layout-private.hh b/src/hb-ot-layout-private.hh
index f48184f..da3ba3a 100644
--- a/src/hb-ot-layout-private.hh
+++ b/src/hb-ot-layout-private.hh
@@ -99,21 +99,20 @@
 				const hb_ot_layout_lookup_accelerator_t &accel);
 
 
-/* Should be called after all the substitute_lookup's are done */
-HB_INTERNAL void
-hb_ot_layout_substitute_finish (hb_font_t    *font,
-				hb_buffer_t  *buffer);
-
-
-/* Should be called before all the position_lookup's are done.  Resets positions to zero. */
+/* Should be called before all the position_lookup's are done. */
 HB_INTERNAL void
 hb_ot_layout_position_start (hb_font_t    *font,
 			     hb_buffer_t  *buffer);
 
-/* Should be called after all the position_lookup's are done */
+/* Should be called after all the position_lookup's are done, to finish advances. */
 HB_INTERNAL void
-hb_ot_layout_position_finish (hb_font_t    *font,
-			      hb_buffer_t  *buffer);
+hb_ot_layout_position_finish_advances (hb_font_t    *font,
+				       hb_buffer_t  *buffer);
+
+/* Should be called after hb_ot_layout_position_finish_advances, to finish offsets. */
+HB_INTERNAL void
+hb_ot_layout_position_finish_offsets (hb_font_t    *font,
+				      hb_buffer_t  *buffer);
 
 
 

src/hb-ot-layout.cc

diff --git a/src/hb-ot-layout.cc b/src/hb-ot-layout.cc
index cdffc61..adf232b 100644
--- a/src/hb-ot-layout.cc
+++ b/src/hb-ot-layout.cc
@@ -771,12 +771,6 @@
   OT::GSUB::substitute_start (font, buffer);
 }
 
-void
-hb_ot_layout_substitute_finish (hb_font_t *font, hb_buffer_t *buffer)
-{
-  OT::GSUB::substitute_finish (font, buffer);
-}
-
 /**
  * hb_ot_layout_lookup_substitute_closure:
  *
@@ -811,9 +805,15 @@
 }
 
 void
-hb_ot_layout_position_finish (hb_font_t *font, hb_buffer_t *buffer)
+hb_ot_layout_position_finish_advances (hb_font_t *font, hb_buffer_t *buffer)
 {
-  OT::GPOS::position_finish (font, buffer);
+  OT::GPOS::position_finish_advances (font, buffer);
+}
+
+void
+hb_ot_layout_position_finish_offsets (hb_font_t *font, hb_buffer_t *buffer)
+{
+  OT::GPOS::position_finish_offsets (font, buffer);
 }
 
 /**

src/hb-ot-shape.cc

diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index 10c52cf..0b02328 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -584,8 +584,6 @@
 
   c->plan->substitute (c->font, buffer);
 
-  hb_ot_layout_substitute_finish (c->font, buffer);
-
   return;
 }
 
@@ -733,9 +731,10 @@
       break;
   }
 
+  /* Finishing off GPOS has to follow a certain order. */
+  hb_ot_layout_position_finish_advances (c->font, c->buffer);
   hb_ot_zero_width_default_ignorables (c);
-
-  hb_ot_layout_position_finish (c->font, c->buffer);
+  hb_ot_layout_position_finish_offsets (c->font, c->buffer);
 
   return ret;
 }