From e94fe2adf379b1a802e1ecdd393858474a02970b Mon Sep 17 00:00:00 2001
From: Qunxin Liu <qxliu@google.com>
Date: Tue, 20 Sep 2022 13:14:26 -0700
Subject: [PATCH] [instance] minor optimizations to glyf instancing

---
 src/OT/glyf/Glyph.hh       | 13 +++++++++----
 src/OT/glyf/SimpleGlyph.hh | 26 ++++++++++++--------------
 src/OT/glyf/glyf.hh        | 22 +++++++++++++++++-----
 3 files changed, 38 insertions(+), 23 deletions(-)

diff --git a/src/OT/glyf/Glyph.hh b/src/OT/glyf/Glyph.hh
index abb4fd0ac..73fefc5d8 100644
--- a/src/OT/glyf/Glyph.hh
+++ b/src/OT/glyf/Glyph.hh
@@ -150,7 +150,8 @@ struct Glyph
                                   hb_bytes_t &dest_end /* OUT */)
   {
     contour_point_vector_t all_points, deltas;
-    get_points (font, glyf, all_points, &deltas, false, false);
+    if (!get_points (font, glyf, all_points, &deltas, false, false))
+      return false;
 
     // .notdef, set type to empty so we only update metrics and don't compile bytes for
     // it
@@ -179,7 +180,12 @@ struct Glyph
       break;
     }
 
-    return compile_header_bytes (plan, all_points, dest_start);
+    if (!compile_header_bytes (plan, all_points, dest_start))
+    {
+      dest_end.fini ();
+      return false;
+    }
+    return true;
   }
 
 
@@ -247,8 +253,7 @@ struct Glyph
     if (deltas != nullptr && depth == 0 && type == COMPOSITE)
     {
       if (unlikely (!deltas->resize (points.length))) return false;
-      for (unsigned i = 0 ; i < points.length; i++)
-        deltas->arrayZ[i] = points.arrayZ[i];
+      deltas->copy_vector (points);
     }
 
 #ifndef HB_NO_VAR
diff --git a/src/OT/glyf/SimpleGlyph.hh b/src/OT/glyf/SimpleGlyph.hh
index b99665d6a..d45f4eb35 100644
--- a/src/OT/glyf/SimpleGlyph.hh
+++ b/src/OT/glyf/SimpleGlyph.hh
@@ -271,31 +271,29 @@ struct SimpleGlyph
     }
     //convert absolute values to relative values
     unsigned num_points = all_points.length - 4;
-    hb_vector_t<hb_pair_t<int, int>> deltas;
-    deltas.resize (num_points);
-
-    for (unsigned i = 0; i < num_points; i++)
-    {
-      deltas[i].first = i == 0 ? roundf (all_points[i].x) : roundf (all_points[i].x) - roundf (all_points[i-1].x);
-      deltas[i].second = i == 0 ? roundf (all_points[i].y) : roundf (all_points[i].y) - roundf (all_points[i-1].y);
-    }
 
     hb_vector_t<uint8_t> flags, x_coords, y_coords;
-    flags.alloc (num_points);
-    x_coords.alloc (2*num_points);
-    y_coords.alloc (2*num_points);
+    if (unlikely (!flags.alloc (num_points))) return false;
+    if (unlikely (!x_coords.alloc (2*num_points))) return false;
+    if (unlikely (!y_coords.alloc (2*num_points))) return false;
 
     uint8_t lastflag = 0, repeat = 0;
-
+    int prev_x = 0.f, prev_y = 0.f;
+    
     for (unsigned i = 0; i < num_points; i++)
     {
       uint8_t flag = all_points[i].flag;
       flag &= FLAG_ON_CURVE + FLAG_OVERLAP_SIMPLE;
 
-      encode_coord (deltas[i].first, flag, FLAG_X_SHORT, FLAG_X_SAME, x_coords);
-      encode_coord (deltas[i].second, flag, FLAG_Y_SHORT, FLAG_Y_SAME, y_coords);
+      float cur_x = roundf (all_points[i].x);
+      float cur_y = roundf (all_points[i].y);
+      encode_coord (cur_x - prev_x, flag, FLAG_X_SHORT, FLAG_X_SAME, x_coords);
+      encode_coord (cur_y - prev_y, flag, FLAG_Y_SHORT, FLAG_Y_SAME, y_coords);
       if (i == 0) lastflag = flag + 1; //make lastflag != flag for the first point
       encode_flag (flag, repeat, lastflag, flags);
+
+      prev_x = cur_x;
+      prev_y = cur_y;
     }
 
     unsigned len_before_instrs = 2 * header.numberOfContours + 2;
diff --git a/src/OT/glyf/glyf.hh b/src/OT/glyf/glyf.hh
index 5355e5b2a..45316dffd 100644
--- a/src/OT/glyf/glyf.hh
+++ b/src/OT/glyf/glyf.hh
@@ -75,7 +75,10 @@ struct glyf
     _populate_subset_glyphs (c->plan, &glyphs);
 
     if (!c->plan->pinned_at_default)
-      _compile_subset_glyphs_with_deltas (c->plan, &glyphs);
+    {
+      if (!_compile_subset_glyphs_with_deltas (c->plan, &glyphs))
+        return_trace (false);
+    }
 
     auto padded_offsets =
     + hb_iter (glyphs)
@@ -107,7 +110,7 @@ struct glyf
   _populate_subset_glyphs (const hb_subset_plan_t   *plan,
 			   hb_vector_t<glyf_impl::SubsetGlyph> *glyphs /* OUT */) const;
   
-  void
+  bool
   _compile_subset_glyphs_with_deltas (const hb_subset_plan_t *plan,
                                       hb_vector_t<glyf_impl::SubsetGlyph> *glyphs /* OUT */) const;
 
@@ -404,15 +407,17 @@ glyf::_populate_subset_glyphs (const hb_subset_plan_t   *plan,
   ;
 }
 
-inline void
+inline bool
 glyf::_compile_subset_glyphs_with_deltas (const hb_subset_plan_t *plan,
                                           hb_vector_t<glyf_impl::SubsetGlyph> *glyphs /* OUT */) const
 {
   OT::glyf_accelerator_t glyf (plan->source);
   hb_font_t *font = hb_font_create (plan->source);
+  if (unlikely (!font)) return false;
 
   hb_vector_t<hb_variation_t> vars;
-  vars.alloc (plan->user_axes_location->get_population ());
+  if (unlikely (!vars.alloc (plan->user_axes_location->get_population ())))
+    return false;
 
   for (auto _ : *plan->user_axes_location)
   {
@@ -424,9 +429,16 @@ glyf::_compile_subset_glyphs_with_deltas (const hb_subset_plan_t *plan,
 
   hb_font_set_variations (font, vars.arrayZ, plan->user_axes_location->get_population ());
   for (auto& subset_glyph : *glyphs)
-    const_cast<glyf_impl::SubsetGlyph &> (subset_glyph).compile_bytes_with_deltas (plan, font, glyf);
+  {
+    if (!const_cast<glyf_impl::SubsetGlyph &> (subset_glyph).compile_bytes_with_deltas (plan, font, glyf))
+    {
+      hb_font_destroy (font);
+      return false;
+    }
+  }
 
   hb_font_destroy (font);
+  return true;
 }