[subset/cff] Reuse a calculate index total data size

src/hb-ot-cff-common.hh

@@ -65,11 +65,12 @@ struct CFFIndex
   template <typename Iterable,
 	    hb_requires (hb_is_iterable (Iterable))>
   bool serialize (hb_serialize_context_t *c,
-		  const Iterable &iterable)
+		  const Iterable &iterable,
+		  unsigned data_size = 0)
   {
     TRACE_SERIALIZE (this);
     auto it = hb_iter (iterable);
-    unsigned size = serialize_header(c, + it | hb_map (hb_iter) | hb_map (hb_len));
+    unsigned size = serialize_header(c, + it | hb_map (hb_iter) | hb_map (hb_len), data_size);
     unsigned char *ret = c->allocate_size<unsigned char> (size, false);
     if (unlikely (!ret)) return_trace (false);
     for (const auto &_ : +it)
@@ -91,11 +92,12 @@ struct CFFIndex
   template <typename Iterator,
 	    hb_requires (hb_is_iterator (Iterator))>
   unsigned serialize_header (hb_serialize_context_t *c,
-			     Iterator it)
+			     Iterator it,
+			     unsigned data_size = 0)
   {
     TRACE_SERIALIZE (this);
 
-    unsigned total = + it | hb_reduce (hb_add, 0);
+    unsigned total = data_size ? data_size : + it | hb_reduce (hb_add, 0);
     unsigned off_size = (hb_bit_storage (total + 1) + 7) / 8;
 
     /* serialize CFFIndex header */
@@ -174,16 +176,22 @@ struct CFFIndex
 
   template <typename Iterable,
 	    hb_requires (hb_is_iterable (Iterable))>
-  static unsigned total_size (const Iterable &iterable)
+  static unsigned total_size (const Iterable &iterable, unsigned *data_size = nullptr)
   {
     auto it = + hb_iter (iterable) | hb_map (hb_iter) | hb_map (hb_len);
-    // The following should return min_size IMO. But that crashes a few
-    // tests. I have not investigated why.
-    if (!it) return 0; //min_size;
+    if (!it)
+    {
+      if (data_size) *data_size = 0;
+      // The following should return min_size IMO. But that crashes a few
+      // tests. I have not investigated why.
+      return 0; //min_size;
+    }
 
     unsigned total = + it | hb_reduce (hb_add, 0);
     unsigned off_size = (hb_bit_storage (total + 1) + 7) / 8;
 
+    if (data_size) *data_size = total;
+
     return min_size + HBUINT8::static_size + (hb_len (it) + 1) * off_size + total;
   }
 

src/hb-subset-cff1.cc

@@ -811,12 +811,13 @@ OT::cff1::accelerator_subset_t::serialize (hb_serialize_context_t *c,
   {
     c->push<CFF1CharStrings> ();
 
-    unsigned total_size = CFF1CharStrings::total_size (plan.subset_charstrings);
+    unsigned data_size = 0;
+    unsigned total_size = CFF1CharStrings::total_size (plan.subset_charstrings, &data_size);
     if (unlikely (!c->start_zerocopy (total_size)))
        return false;
 
     auto *cs = c->start_embed<CFF1CharStrings> ();
-    if (likely (cs->serialize (c, plan.subset_charstrings)))
+    if (likely (cs->serialize (c, plan.subset_charstrings, data_size)))
       plan.info.char_strings_link = c->pop_pack (false);
     else
     {

src/hb-subset-cff2.cc

@@ -560,12 +560,13 @@ OT::cff2::accelerator_subset_t::serialize (hb_serialize_context_t *c,
   {
     c->push ();
 
-    unsigned total_size = CFF2CharStrings::total_size (plan.subset_charstrings);
+    unsigned data_size = 0;
+    unsigned total_size = CFF2CharStrings::total_size (plan.subset_charstrings, &data_size);
     if (unlikely (!c->start_zerocopy (total_size)))
        return false;
 
     auto *cs = c->start_embed<CFF2CharStrings> ();
-    if (likely (cs->serialize (c, plan.subset_charstrings)))
+    if (likely (cs->serialize (c, plan.subset_charstrings, data_size)))
       plan.info.char_strings_link = c->pop_pack (false);
     else
     {