From be8e8e8c80cc69d9d3a02f357a3ef252738d96e6 Mon Sep 17 00:00:00 2001
From: Qunxin Liu <qxliu@google.com>
Date: Thu, 30 Jun 2022 14:24:36 -0700
Subject: [PATCH] [instance] prune name tables after axes pinned at fixed
 locations

Restricting axes to ranges is not supported yet.
---
 src/hb-ot-stat-table.hh     | 19 +++++++++++++-
 src/hb-ot-var-fvar-table.hh | 51 +++++++++++++++++++++++++++----------
 src/hb-subset-plan.cc       | 11 +++++---
 3 files changed, 63 insertions(+), 18 deletions(-)

diff --git a/src/hb-ot-stat-table.hh b/src/hb-ot-stat-table.hh
index e3a2e89a0..95d2a4bd5 100644
--- a/src/hb-ot-stat-table.hh
+++ b/src/hb-ot-stat-table.hh
@@ -401,6 +401,18 @@ struct AxisValue
     }
   }
 
+  bool keep_axis_value (const hb_array_t<const StatAxisRecord> axis_records,
+                        hb_hashmap_t<hb_tag_t, float> *user_axes_location) const
+  {
+    switch (u.format)
+    {
+    case 1: return u.format1.keep_axis_value (axis_records, user_axes_location);
+    case 2: return u.format2.keep_axis_value (axis_records, user_axes_location);
+    case 3: return u.format3.keep_axis_value (axis_records, user_axes_location);
+    case 4: return u.format4.keep_axis_value (axis_records, user_axes_location);
+    default:return false;
+    }
+  }
 
   bool sanitize (hb_sanitize_context_t *c) const
   {
@@ -505,7 +517,8 @@ struct STAT
     return axis_value.get_value_name_id ();
   }
 
-  void collect_name_ids (hb_set_t *nameids_to_retain) const
+  void collect_name_ids (hb_hashmap_t<hb_tag_t, float> *user_axes_location,
+                         hb_set_t *nameids_to_retain /* OUT */) const
   {
     if (!has_data ()) return;
 
@@ -514,8 +527,12 @@ struct STAT
     | hb_sink (nameids_to_retain)
     ;
 
+    auto designAxes = get_design_axes ();
+
     + get_axis_value_offsets ()
     | hb_map (hb_add (&(this + offsetToAxisValueOffsets)))
+    | hb_filter ([&] (const AxisValue& _)
+                 { return _.keep_axis_value (designAxes, user_axes_location); })
     | hb_map (&AxisValue::get_value_name_id)
     | hb_sink (nameids_to_retain)
     ;
diff --git a/src/hb-ot-var-fvar-table.hh b/src/hb-ot-var-fvar-table.hh
index 6300a42b8..77bb551e2 100644
--- a/src/hb-ot-var-fvar-table.hh
+++ b/src/hb-ot-var-fvar-table.hh
@@ -272,24 +272,49 @@ struct fvar
     return axisCount;
   }
 
-  void collect_name_ids (hb_set_t *nameids) const
+  void collect_name_ids (hb_hashmap_t<hb_tag_t, float> *user_axes_location,
+			 hb_set_t *nameids  /* IN/OUT */) const
   {
     if (!has_data ()) return;
+    hb_map_t pinned_axes;
 
-    + get_axes ()
-    | hb_map (&AxisRecord::get_name_id)
-    | hb_sink (nameids)
-    ;
+    auto axis_records = get_axes ();
+    for (unsigned i = 0 ; i < (unsigned)axisCount; i++)
+    {
+      hb_tag_t axis_tag = axis_records[i].get_axis_tag ();
+      if (user_axes_location->has (axis_tag))
+      {
+        pinned_axes.set (i, axis_tag);
+        continue;
+      }
 
-    + hb_range ((unsigned) instanceCount)
-    | hb_map ([this] (const unsigned _) { return get_instance_subfamily_name_id (_); })
-    | hb_sink (nameids)
-    ;
+      nameids->add (axis_records[i].get_name_id ());
+    }
 
-    + hb_range ((unsigned) instanceCount)
-    | hb_map ([this] (const unsigned _) { return get_instance_postscript_name_id (_); })
-    | hb_sink (nameids)
-    ;
+    for (unsigned i = 0 ; i < (unsigned)instanceCount; i++)
+    {
+      const InstanceRecord *instance = get_instance (i);
+
+      if (hb_any (+ hb_zip (instance->get_coordinates (axisCount), hb_range ((unsigned)axisCount))
+                  | hb_filter (pinned_axes, hb_second)
+                  | hb_map ([&] (const hb_pair_t<const HBFixed&, unsigned>& _)
+                            {
+                              hb_tag_t axis_tag = pinned_axes.get (_.second);
+                              float location = user_axes_location->get (axis_tag);
+                              if (fabs ((double)location - (double)_.first.to_float ()) > 0.001) return true;
+                              return false;
+                            })
+                  ))
+        continue;
+
+      nameids->add (instance->subfamilyNameID);
+
+      if (instanceSize >= axisCount * 4 + 6)
+      {
+        unsigned post_script_name_id = StructAfter<NameID> (instance->get_coordinates (axisCount));
+        if (post_script_name_id != HB_OT_NAME_ID_INVALID) nameids->add (post_script_name_id);
+      }
+    }
   }
 
   public:
diff --git a/src/hb-subset-plan.cc b/src/hb-subset-plan.cc
index 6dd0a2880..29b89c774 100644
--- a/src/hb-subset-plan.cc
+++ b/src/hb-subset-plan.cc
@@ -576,13 +576,16 @@ _create_old_gid_to_new_gid_map (const hb_face_t *face,
 
 static void
 _nameid_closure (hb_face_t *face,
-		 hb_set_t  *nameids)
+		 hb_set_t  *nameids,
+		 bool all_axes_pinned,
+		 hb_hashmap_t<hb_tag_t, float> *user_axes_location)
 {
 #ifndef HB_NO_STYLE
-  face->table.STAT->collect_name_ids (nameids);
+  face->table.STAT->collect_name_ids (user_axes_location, nameids);
 #endif
 #ifndef HB_NO_VAR
-  face->table.fvar->collect_name_ids (nameids);
+  if (!all_axes_pinned)
+    face->table.fvar->collect_name_ids (user_axes_location, nameids);
 #endif
 }
 
@@ -658,7 +661,6 @@ hb_subset_plan_create_or_fail (hb_face_t	 *face,
   plan->unicode_to_new_gid_list.init ();
 
   plan->name_ids = hb_set_copy (input->sets.name_ids);
-  _nameid_closure (face, plan->name_ids);
   plan->name_languages = hb_set_copy (input->sets.name_languages);
   plan->layout_features = hb_set_copy (input->sets.layout_features);
   plan->layout_scripts = hb_set_copy (input->sets.layout_scripts);
@@ -733,6 +735,7 @@ hb_subset_plan_create_or_fail (hb_face_t	 *face,
                             plan->axes_location,
                             plan->all_axes_pinned);
 
+  _nameid_closure (face, plan->name_ids, plan->all_axes_pinned, plan->user_axes_location);
   if (unlikely (plan->in_error ())) {
     hb_subset_plan_destroy (plan);
     return nullptr;