From c5a85a73fa66fee7524f5e39ba5751e25b5b0f49 Mon Sep 17 00:00:00 2001
From: Qunxin Liu <qxliu@google.com>
Date: Fri, 3 May 2024 09:44:14 -0700
Subject: [PATCH] [instancer] support BASE table

---
 src/hb-ot-layout-base-table.hh    | 64 +++++++++++++++++++++++++++----
 src/hb-subset-plan-member-list.hh |  2 +-
 src/hb-subset-plan.cc             | 10 +++--
 3 files changed, 64 insertions(+), 12 deletions(-)

diff --git a/src/hb-ot-layout-base-table.hh b/src/hb-ot-layout-base-table.hh
index 183c1ea73..98ab2c6a3 100644
--- a/src/hb-ot-layout-base-table.hh
+++ b/src/hb-ot-layout-base-table.hh
@@ -125,6 +125,20 @@ struct BaseCoordFormat3
     auto *out = c->serializer->embed (*this);
     if (unlikely (!out)) return_trace (false);
 
+    if (!c->plan->pinned_at_default)
+    {
+      unsigned var_idx = (this+deviceTable).get_variation_index ();
+      if (var_idx != HB_OT_LAYOUT_NO_VARIATIONS_INDEX)
+      {
+        hb_pair_t<unsigned, int> *v;
+        if (!c->plan->base_variation_idx_map.has (var_idx, &v))
+          return_trace (false);
+        
+        if (unlikely (!c->serializer->check_assign (out->coordinate, coordinate + hb_second (*v),
+                                                    HB_SERIALIZE_ERROR_INT_OVERFLOW)))
+          return_trace (false);
+      }
+    }
     return_trace (out->deviceTable.serialize_copy (c->serializer, deviceTable,
                                                    this, 0,
                                                    hb_serialize_context_t::Head,
@@ -706,6 +720,46 @@ struct BASE
     (this+vAxis).collect_variation_indices (plan, varidx_set);
   }
 
+  bool subset_varstore (hb_subset_context_t *c,
+                        BASE *out /* OUT */) const
+  {
+    TRACE_SUBSET (this);
+    if (!c->serializer->allocate_size<Offset32To<ItemVariationStore>> (Offset32To<ItemVariationStore>::static_size))
+        return_trace (false);
+    if (!c->plan->normalized_coords)
+      return_trace (out->varStore.serialize_subset (c, varStore, this, c->plan->base_varstore_inner_maps.as_array ()));
+
+    if (c->plan->all_axes_pinned)
+      return_trace (true);
+
+    item_variations_t item_vars;
+    if (!item_vars.instantiate (this+varStore, c->plan, true, true,
+                                c->plan->base_varstore_inner_maps.as_array ()))
+      return_trace (false);
+
+    if (!out->varStore.serialize_serialize (c->serializer,
+                                            item_vars.has_long_word (),
+                                            c->plan->axis_tags,
+                                            item_vars.get_region_list (),
+                                            item_vars.get_vardata_encodings ()))
+      return_trace (false);
+
+    const hb_map_t &varidx_map = item_vars.get_varidx_map ();
+    /* base_variation_idx_map in the plan is old_varidx->(varidx, delta)
+     * mapping, new varidx is generated for subsetting, we need to remap this
+     * after instancing */
+    for (auto _ : c->plan->base_variation_idx_map.iter_ref ())
+    {
+      uint32_t varidx = _.second.first;
+      uint32_t *new_varidx;
+      if (varidx_map.has (varidx, &new_varidx))
+        _.second.first = *new_varidx;
+      else
+        _.second.first = HB_OT_LAYOUT_NO_VARIATIONS_INDEX;
+    }
+    return_trace (true);
+  }
+
   bool subset (hb_subset_context_t *c) const
   {
     TRACE_SUBSET (this);
@@ -713,19 +767,15 @@ struct BASE
     if (unlikely (!out || !c->serializer->extend_min (out))) return_trace (false);
 
     out->version = version;
+    if (has_var_store () && !subset_varstore (c, out))
+        return_trace (false);
+
     if (hAxis && !out->hAxis.serialize_subset (c, hAxis, this))
       return_trace (false);
 
     if (vAxis && !out->vAxis.serialize_subset (c, vAxis, this))
       return_trace (false);
 
-    if (has_var_store ())
-    {
-      if (!c->serializer->allocate_size<Offset32To<ItemVariationStore>> (Offset32To<ItemVariationStore>::static_size))
-        return_trace (false);
-      return_trace (out->varStore.serialize_subset (c, varStore, this, c->plan->base_varstore_inner_maps.as_array ()));
-    }
-
     return_trace (true);
   }
 
diff --git a/src/hb-subset-plan-member-list.hh b/src/hb-subset-plan-member-list.hh
index 4651f14d8..b02c33e92 100644
--- a/src/hb-subset-plan-member-list.hh
+++ b/src/hb-subset-plan-member-list.hh
@@ -146,7 +146,7 @@ HB_SUBSET_PLAN_MEMBER (mutable hb_hashmap_t E(<hb_codepoint_t, contour_point_vec
 HB_SUBSET_PLAN_MEMBER (hb_set_t, composite_new_gids)
 
 //Old BASE item variation index -> (New varidx, 0) mapping
-HB_SUBSET_PLAN_MEMBER (hb_hashmap_t E(<unsigned, hb_pair_t E(<unsigned, int>)>), base_variation_idx_map)
+HB_SUBSET_PLAN_MEMBER (mutable hb_hashmap_t E(<unsigned, hb_pair_t E(<unsigned, int>)>), base_variation_idx_map)
 
 //BASE table varstore retained varidx mapping
 HB_SUBSET_PLAN_MEMBER (hb_vector_t<hb_inc_bimap_t>, base_varstore_inner_maps)
diff --git a/src/hb-subset-plan.cc b/src/hb-subset-plan.cc
index a84062025..b13e3a917 100644
--- a/src/hb-subset-plan.cc
+++ b/src/hb-subset-plan.cc
@@ -489,13 +489,15 @@ _collect_base_variation_indices (hb_subset_plan_t* plan)
 
   hb_set_t varidx_set;
   base->collect_variation_indices (plan, varidx_set);
-  unsigned subtable_count = base->get_var_store ().get_sub_table_count ();
+  const OT::ItemVariationStore &var_store = base->get_var_store ();
   base.destroy ();
+  unsigned subtable_count = var_store.get_sub_table_count ();
 
-  /* TODO: support instancing for BASE table */
-  _remap_variation_indices (base->get_var_store (), varidx_set,
+  _remap_variation_indices (var_store, varidx_set,
                             plan->normalized_coords,
-                            false, false, plan->base_variation_idx_map);
+                            !plan->pinned_at_default,
+                            plan->all_axes_pinned,
+                            plan->base_variation_idx_map);
   _generate_varstore_inner_maps (varidx_set, subtable_count, plan->base_varstore_inner_maps);
 }