[instancer] apply cvar deltas

src/hb-ot-face-table-list.hh

@@ -93,6 +93,7 @@ HB_OT_ACCELERATOR (OT, cff2)
 #ifndef HB_NO_VAR
 HB_OT_CORE_TABLE (OT, fvar)
 HB_OT_CORE_TABLE (OT, avar)
+HB_OT_CORE_TABLE (OT, cvar)
 HB_OT_ACCELERATOR (OT, gvar)
 HB_OT_CORE_TABLE (OT, MVAR)
 #endif

src/hb-ot-var-cvar-table.hh

@@ -48,18 +48,22 @@ struct cvar
 		  tupleVariationData.sanitize (c));
   }
 
-  bool calculate_cvt_deltas (unsigned axis_count,
+  const TupleVariationData* get_tuple_var_data (void) const
+  { return &tupleVariationData; }
+
+  static bool calculate_cvt_deltas (unsigned axis_count,
                                     hb_array_t<int> coords,
                                     unsigned num_cvt_item,
-                             hb_vector_t<float>& cvt_deltas /* OUT */) const
+                                    const TupleVariationData *tuple_var_data,
+                                    const void *base,
+                                    hb_vector_t<float>& cvt_deltas /* OUT */)
   {
     if (!coords) return true;
     hb_vector_t<unsigned> shared_indices;
     TupleVariationData::tuple_iterator_t iterator;
-    unsigned var_data_length = tupleVariationData.get_size (axis_count);
-    hb_bytes_t var_data_bytes = hb_bytes_t (reinterpret_cast<const char*> (&tupleVariationData), var_data_length);
-    if (!TupleVariationData::get_tuple_iterator (var_data_bytes, axis_count,
-                                                 this,
+    unsigned var_data_length = tuple_var_data->get_size (axis_count);
+    hb_bytes_t var_data_bytes = hb_bytes_t (reinterpret_cast<const char*> (tuple_var_data), var_data_length);
+    if (!TupleVariationData::get_tuple_iterator (var_data_bytes, axis_count, base,
                                                  shared_indices, &iterator))
       return true; /* isn't applied at all */
 
@@ -101,7 +105,9 @@ struct cvar
     return true;
   }
 
-  bool add_cvt_and_apply_deltas (hb_subset_plan_t *plan) const
+  static bool add_cvt_and_apply_deltas (hb_subset_plan_t *plan,
+                                        const TupleVariationData *tuple_var_data,
+                                        const void *base)
   {
     const hb_tag_t cvt = HB_TAG('c','v','t',' ');
     hb_blob_t *cvt_blob = hb_face_reference_table (plan->source, cvt);
@@ -122,7 +128,8 @@ struct cvar
     }
     hb_memset (cvt_deltas.arrayZ, 0, cvt_deltas.get_size ());
 
-    if (!calculate_cvt_deltas (plan->normalized_coords.length, plan->normalized_coords.as_array (), num_cvt_item, cvt_deltas))
+    if (!calculate_cvt_deltas (plan->normalized_coords.length, plan->normalized_coords.as_array (),
+                               num_cvt_item, tuple_var_data, base, cvt_deltas))
     {
       hb_blob_destroy (cvt_prime_blob);
       return false;

src/hb-subset-input.cc

@@ -71,7 +71,6 @@ hb_subset_input_t::hb_subset_input_t ()
   hb_tag_t default_no_subset_tables[] = {
     HB_TAG ('a', 'v', 'a', 'r'),
     HB_TAG ('g', 'a', 's', 'p'),
-    HB_TAG ('c', 'v', 't', ' '),
     HB_TAG ('f', 'p', 'g', 'm'),
     HB_TAG ('p', 'r', 'e', 'p'),
     HB_TAG ('V', 'D', 'M', 'X'),

src/hb-subset.cc

@@ -50,6 +50,7 @@
 #include "hb-ot-name-table.hh"
 #include "hb-ot-layout-gsub-table.hh"
 #include "hb-ot-layout-gpos-table.hh"
+#include "hb-ot-var-cvar-table.hh"
 #include "hb-ot-var-fvar-table.hh"
 #include "hb-ot-var-gvar-table.hh"
 #include "hb-ot-var-hvar-table.hh"
@@ -478,6 +479,16 @@ _subset_table (hb_subset_plan_t *plan,
     if (plan->all_axes_pinned) return _subset<const OT::STAT> (plan, buf);
     else return _passthrough (plan, tag);
 
+  case HB_TAG ('c', 'v', 't', ' '):
+#ifndef HB_NO_VAR
+    if (_is_table_present (plan->source, HB_OT_TAG_cvar) &&
+        plan->normalized_coords && !plan->pinned_at_default)
+    {
+      auto &cvar = *plan->source->table.cvar;
+      return OT::cvar::add_cvt_and_apply_deltas (plan, cvar.get_tuple_var_data (), &cvar);
+    }
+#endif
+    return _passthrough (plan, tag);
   default:
     if (plan->flags & HB_SUBSET_FLAGS_PASSTHROUGH_UNRECOGNIZED)
       return _passthrough (plan, tag);

test/subset/data/Makefile.am

@@ -66,6 +66,7 @@ EXTRA_DIST += \
 	expected/mvar_full_instance \
 	expected/instance_comp_glyph_empty_child \
 	expected/post_apply_mvar_delta \
+	expected/apply_cvar_delta \
 	fonts \
 	profiles \
 	$(NULL)

test/subset/data/Makefile.sources

@@ -57,6 +57,7 @@ TESTS = \
 	tests/mvar_full_instance.tests \
 	tests/instance_comp_glyph_empty_child.tests \
 	tests/post_apply_mvar_delta.tests \
+	tests/apply_cvar_delta.tests \
 	$(NULL)
 
 # TODO: re-enable once colrv1 subsetting is stabilized.

test/subset/data/tests/apply_cvar_delta.tests

@@ -0,0 +1,12 @@
+FONTS:
+Comfortaa-Regular-new.ttf
+
+PROFILES:
+default.txt
+
+SUBSETS:
+*
+
+INSTANCES:
+wght=700
+wght=300

test/subset/meson.build

@@ -59,6 +59,7 @@ tests = [
   'mvar_full_instance',
   'instance_comp_glyph_empty_child',
   'post_apply_mvar_delta',
+  'apply_cvar_delta',
 ]
 
 repack_tests = [