From 4867e0b192b1efcc28e12bfd8f997ca9377d65ce Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 6 Jan 2023 11:39:13 -0700
Subject: [PATCH] [subset-cff2] Faster instancing

Instantiate blends during parsing. Dedups code as well.
---
 src/hb-cff2-interp-cs.hh | 12 +++++++-----
 src/hb-subset-cff2.cc    | 37 +------------------------------------
 2 files changed, 8 insertions(+), 41 deletions(-)

diff --git a/src/hb-cff2-interp-cs.hh b/src/hb-cff2-interp-cs.hh
index 6686ad41f..857250951 100644
--- a/src/hb-cff2-interp-cs.hh
+++ b/src/hb-cff2-interp-cs.hh
@@ -163,15 +163,14 @@ struct cff2_cs_interp_env_t : cs_interp_env_t<ELEM, CFF2Subrs>
     return v;
   }
 
-  protected:
+  public:
   const int     *coords;
   unsigned int  num_coords;
+  protected:
   const	 CFF2VariationStore *varStore;
   unsigned int  region_count;
   unsigned int  ivs;
-  public:
   hb_vector_t<float>  scalars;
-  protected:
   bool	  do_blend;
   bool	  seen_vsindex_;
   bool	  seen_blend;
@@ -224,7 +223,10 @@ struct cff2_cs_opset_t : cs_opset_t<ELEM, OPSET, cff2_cs_interp_env_t<ELEM>, PAR
 				 const hb_array_t<const ELEM> blends,
 				 unsigned n, unsigned i)
   {
-    arg.set_blends (n, i, blends);
+    if (env.num_coords)
+      arg.set_int (round (arg.to_real () + env.blend_deltas (blends)));
+    else
+      arg.set_blends (n, i, blends);
   }
   template <typename T = ELEM,
 	    hb_enable_if (!hb_is_same (T, blend_arg_t))>
@@ -233,7 +235,7 @@ struct cff2_cs_opset_t : cs_opset_t<ELEM, OPSET, cff2_cs_interp_env_t<ELEM>, PAR
 				 const hb_array_t<const ELEM> blends,
 				 unsigned n, unsigned i)
   {
-    arg.set_real (arg.to_real () + env.blend_deltas (blends));
+    arg.set_int (round (arg.to_real () + env.blend_deltas (blends)));
   }
 
   static void process_blend (cff2_cs_interp_env_t<ELEM> &env, PARAM& param)
diff --git a/src/hb-subset-cff2.cc b/src/hb-subset-cff2.cc
index 89fed3358..01eb3fe89 100644
--- a/src/hb-subset-cff2.cc
+++ b/src/hb-subset-cff2.cc
@@ -122,43 +122,8 @@ struct cff2_cs_opset_flatten_t : cff2_cs_opset_t<cff2_cs_opset_flatten_t, flatte
     SUPER::flush_args (env, param);
   }
 
-  static double instantiate_blend (const blend_arg_t &arg, cff2_cs_interp_env_t<blend_arg_t> &env, flatten_param_t& param)
-  {
-    double v = arg.to_real ();
-
-    auto &scalars = env.scalars;
-    auto &deltas = arg.deltas;
-
-    if (scalars.length != deltas.length)
-      return v;
-
-    unsigned count = scalars.length;
-    for (unsigned i = 0; i < count; i++)
-      v += (double) scalars.arrayZ[i] * deltas.arrayZ[i].to_real ();
-
-    return v;
-  }
-
   static void flatten_blends (const blend_arg_t &arg, unsigned int i, cff2_cs_interp_env_t<blend_arg_t> &env, flatten_param_t& param)
   {
-    if (param.plan->normalized_coords)
-    {
-      str_encoder_t  encoder (param.flatStr);
-      for (unsigned int j = 0; j < arg.numValues; j++)
-      {
-	blend_arg_t arg1 = env.argStack[i + j];
-	if (unlikely (!((arg1.blending () && (arg.numValues == arg1.numValues) && (arg1.valueIndex == j) &&
-		(arg1.deltas.length == env.get_region_count ())))))
-	{
-	  env.set_error ();
-	  return;
-	}
-	arg1.set_int (round (instantiate_blend (arg1, env, param)));
-	encoder.encode_num (arg1);
-      }
-      return;
-    }
-
     /* flatten the default values */
     str_encoder_t  encoder (param.flatStr);
     for (unsigned int j = 0; j < arg.numValues; j++)
@@ -276,7 +241,7 @@ struct cff2_subset_plan {
 
     drop_hints = plan->flags & HB_SUBSET_FLAGS_NO_HINTING;
     desubroutinize = plan->flags & HB_SUBSET_FLAGS_DESUBROUTINIZE ||
-		     plan->normalized_coords;
+		     plan->normalized_coords; // For instancing we need this path
 
     if (desubroutinize)
     {