[subset] subset MATH table

src/hb-ot-layout-common.hh

@@ -346,6 +346,43 @@ struct
 }
 HB_FUNCOBJ (subset_record_array);
 
+
+template<typename OutputArray>
+struct serialize_math_record_array_t
+{
+  serialize_math_record_array_t (hb_serialize_context_t *serialize_context_,
+                         OutputArray& out_,
+                         const void *base_) : serialize_context (serialize_context_),
+                                              out (out_), base (base_) {}
+
+  template <typename T>
+  bool operator () (T&& record)
+  {
+    if (!serialize_context->copy (record, base)) return false;
+    out.len++;
+    return true;
+  }
+
+  private:
+  hb_serialize_context_t *serialize_context;
+  OutputArray &out;
+  const void *base;
+};
+
+/*
+ * Helper to serialize an array of MATH records.
+ */
+struct
+{
+  template<typename OutputArray>
+  serialize_math_record_array_t<OutputArray>
+  operator () (hb_serialize_context_t *serialize_context, OutputArray& out,
+               const void *base) const
+  { return serialize_math_record_array_t<OutputArray> (serialize_context, out, base); }
+
+}
+HB_FUNCOBJ (serialize_math_record_array);
+
 /*
  *
  * OpenType Layout Common Table Formats

src/hb-ot-math-table.hh

@@ -41,6 +41,16 @@ struct MathValueRecord
   hb_position_t get_y_value (hb_font_t *font, const void *base) const
   { return font->em_scale_y (value) + (base+deviceTable).get_y_delta (font); }
 
+  MathValueRecord* copy (hb_serialize_context_t *c, const void *base) const
+  {
+    TRACE_SERIALIZE (this);
+    auto *out = c->embed (this);
+    if (unlikely (!out)) return_trace (nullptr);
+    out->deviceTable.serialize_copy (c, deviceTable, base, 0, hb_serialize_context_t::Head);
+
+    return_trace (out);
+  }
+
   bool sanitize (hb_sanitize_context_t *c, const void *base) const
   {
     TRACE_SANITIZE (this);
@@ -59,6 +69,29 @@ struct MathValueRecord
 
 struct MathConstants
 {
+  MathConstants* copy (hb_serialize_context_t *c) const
+  {
+    TRACE_SERIALIZE (this);
+    auto *out = c->start_embed (this);
+    if (unlikely (!out)) return_trace (nullptr);
+
+    HBINT16 *p = c->allocate_size<HBINT16> (HBINT16::static_size * 2);
+    if (unlikely (!p)) return_trace (nullptr);
+    memcpy (p, percentScaleDown, HBINT16::static_size * 2);
+
+    HBUINT16 *m = c->allocate_size<HBUINT16> (HBUINT16::static_size * 2);
+    if (unlikely (!m)) return_trace (nullptr);
+    memcpy (m, minHeight, HBUINT16::static_size * 2);
+
+    unsigned count = ARRAY_LENGTH (mathValueRecords);
+    for (unsigned i = 0; i < count; i++)
+      if (!c->copy (mathValueRecords[i], this))
+        return_trace (nullptr);
+
+    if (!c->embed (radicalDegreeBottomRaisePercent)) return_trace (nullptr);
+    return_trace (out);
+  }
+
   bool sanitize_math_value_records (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -165,6 +198,28 @@ struct MathConstants
 
 struct MathItalicsCorrectionInfo
 {
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    const hb_set_t &glyphset = *c->plan->_glyphset_mathed;
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    auto *out = c->serializer->start_embed (*this);
+    if (unlikely (!c->serializer->extend_min (out))) return_trace (false);
+
+    hb_sorted_vector_t<hb_codepoint_t> new_coverage;
+    + hb_zip (this+coverage, italicsCorrection)
+    | hb_filter (glyphset, hb_first)
+    | hb_filter (serialize_math_record_array (c->serializer, out->italicsCorrection, this), hb_second)
+    | hb_map (hb_first)
+    | hb_map (glyph_map)
+    | hb_sink (new_coverage)
+    ;
+
+    out->coverage.serialize_serialize (c->serializer, new_coverage.iter ());
+    return_trace (true);
+  }
+
   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -196,6 +251,28 @@ struct MathItalicsCorrectionInfo
 
 struct MathTopAccentAttachment
 {
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    const hb_set_t &glyphset = *c->plan->_glyphset_mathed;
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    auto *out = c->serializer->start_embed (*this);
+    if (unlikely (!c->serializer->extend_min (out))) return_trace (false);
+
+    hb_sorted_vector_t<hb_codepoint_t> new_coverage;
+    + hb_zip (this+topAccentCoverage, topAccentAttachment)
+    | hb_filter (glyphset, hb_first)
+    | hb_filter (serialize_math_record_array (c->serializer, out->topAccentAttachment, this), hb_second)
+    | hb_map (hb_first)
+    | hb_map (glyph_map)
+    | hb_sink (new_coverage)
+    ;
+
+    out->topAccentCoverage.serialize_serialize (c->serializer, new_coverage.iter ());
+    return_trace (true);
+  }
+
   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -229,6 +306,22 @@ struct MathTopAccentAttachment
 
 struct MathKern
 {
+  MathKern* copy (hb_serialize_context_t *c) const
+  {
+    TRACE_SERIALIZE (this);
+    auto *out = c->start_embed (this);
+    if (unlikely (!out)) return_trace (nullptr);
+
+    if (unlikely (!c->embed (heightCount))) return_trace (nullptr);
+
+    unsigned count = 2 * heightCount + 1;
+    for (unsigned i = 0; i < count; i++)
+      if (!c->copy (mathValueRecordsZ.arrayZ[i], this))
+        return_trace (nullptr);
+
+    return_trace (out);
+  }
+
   bool sanitize_math_value_records (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -295,6 +388,19 @@ struct MathKern
 
 struct MathKernInfoRecord
 {
+  MathKernInfoRecord* copy (hb_serialize_context_t *c, const void *base) const
+  {
+    TRACE_SERIALIZE (this);
+    auto *out = c->embed (this);
+    if (unlikely (!out)) return_trace (nullptr);
+
+    unsigned count = ARRAY_LENGTH (mathKern);
+    for (unsigned i = 0; i < count; i++)
+      out->mathKern[i].serialize_copy (c, mathKern[i], base, 0, hb_serialize_context_t::Head);
+
+    return_trace (out);
+  }
+
   bool sanitize (hb_sanitize_context_t *c, const void *base) const
   {
     TRACE_SANITIZE (this);
@@ -328,6 +434,28 @@ struct MathKernInfoRecord
 
 struct MathKernInfo
 {
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    const hb_set_t &glyphset = *c->plan->_glyphset_mathed;
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    auto *out = c->serializer->start_embed (*this);
+    if (unlikely (!c->serializer->extend_min (out))) return_trace (false);
+
+    hb_sorted_vector_t<hb_codepoint_t> new_coverage;
+    + hb_zip (this+mathKernCoverage, mathKernInfoRecords)
+    | hb_filter (glyphset, hb_first)
+    | hb_filter (serialize_math_record_array (c->serializer, out->mathKernInfoRecords, this), hb_second)
+    | hb_map (hb_first)
+    | hb_map (glyph_map)
+    | hb_sink (new_coverage)
+    ;
+
+    out->mathKernCoverage.serialize_serialize (c->serializer, new_coverage.iter ());
+    return_trace (true);
+  }
+
   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -365,6 +493,30 @@ struct MathKernInfo
 
 struct MathGlyphInfo
 {
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    auto *out = c->serializer->embed (*this);
+    if (unlikely (!out)) return_trace (false);
+
+    out->mathItalicsCorrectionInfo.serialize_subset (c, mathItalicsCorrectionInfo, this);
+    out->mathTopAccentAttachment.serialize_subset (c, mathTopAccentAttachment, this);
+
+    const hb_set_t &glyphset = *c->plan->_glyphset_mathed;
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    auto it =
+    + hb_iter (this+extendedShapeCoverage)
+    | hb_filter (glyphset)
+    | hb_map_retains_sorting (glyph_map)
+    ;
+
+    out->extendedShapeCoverage.serialize_serialize (c->serializer, it);
+
+    out->mathKernInfo.serialize_subset (c, mathKernInfo, this);
+    return_trace (true);
+  }
+
   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -420,6 +572,16 @@ struct MathGlyphVariantRecord
 {
   friend struct MathGlyphConstruction;
 
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    auto *out = c->serializer->embed (this);
+    if (unlikely (!out)) return_trace (false);
+
+    const hb_map_t& glyph_map = *c->plan->glyph_map;
+    return_trace (c->serializer->check_assign (out->variantGlyph, glyph_map.get (variantGlyph), HB_SERIALIZE_ERROR_INT_OVERFLOW));
+  }
+
   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -453,6 +615,16 @@ struct PartFlags : HBUINT16
 
 struct MathGlyphPartRecord
 {
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    auto *out = c->serializer->embed (this);
+    if (unlikely (!out)) return_trace (false);
+
+    const hb_map_t& glyph_map = *c->plan->glyph_map;
+    return_trace (c->serializer->check_assign (out->glyph, glyph_map.get (glyph), HB_SERIALIZE_ERROR_INT_OVERFLOW));
+  }
+
   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -503,6 +675,20 @@ struct MathGlyphPartRecord
 
 struct MathGlyphAssembly
 {
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    auto *out = c->serializer->start_embed (*this);
+    if (unlikely (!out)) return_trace (false);
+
+    if (!c->serializer->copy (italicsCorrection, this)) return_trace (false);
+    if (!c->serializer->copy<HBUINT16> (partRecords.len)) return_trace (false);
+
+    for (const auto& record : partRecords.iter ())
+      if (!record.subset (c)) return_trace (false);
+    return_trace (true);
+  }
+
   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -555,6 +741,22 @@ struct MathGlyphAssembly
 
 struct MathGlyphConstruction
 {
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    auto *out = c->serializer->start_embed (*this);
+    if (unlikely (!c->serializer->extend_min (out))) return_trace (false);
+
+    out->glyphAssembly.serialize_subset (c, glyphAssembly, this);
+
+    if (!c->serializer->check_assign (out->mathGlyphVariantRecord.len, mathGlyphVariantRecord.len, HB_SERIALIZE_ERROR_INT_OVERFLOW))
+      return_trace (false);
+    for (const auto& record : mathGlyphVariantRecord.iter ())
+      if (!record.subset (c)) return_trace (false);
+
+    return_trace (true);
+  }
+
   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -630,6 +832,60 @@ struct MathVariants
       ;
     }
   }
+
+  void collect_coverage_and_indices (hb_sorted_vector_t<hb_codepoint_t>& new_coverage,
+                                     const Offset16To<Coverage>& coverage,
+                                     unsigned i,
+                                     hb_set_t& indices,
+                                     const hb_set_t& glyphset,
+                                     const hb_map_t& glyph_map) const
+  {
+    for (const auto _ : (this+coverage).iter ())
+    {
+      if (glyphset.has (_))
+      {
+        unsigned new_gid = glyph_map.get (_);
+        new_coverage.push (new_gid);
+        indices.add (i);
+      }
+      i++;
+    }
+  }
+
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    const hb_set_t &glyphset = *c->plan->_glyphset_mathed;
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    auto *out = c->serializer->start_embed (*this);
+    if (unlikely (!c->serializer->extend_min (out))) return_trace (false);
+    if (!c->serializer->check_assign (out->minConnectorOverlap, minConnectorOverlap, HB_SERIALIZE_ERROR_INT_OVERFLOW))
+      return_trace (false);
+    
+    hb_sorted_vector_t<hb_codepoint_t> new_vert_coverage;
+    hb_sorted_vector_t<hb_codepoint_t> new_hori_coverage;
+    hb_set_t indices;
+    collect_coverage_and_indices (new_vert_coverage, vertGlyphCoverage, 0, indices, glyphset, glyph_map);
+    collect_coverage_and_indices (new_hori_coverage, horizGlyphCoverage, vertGlyphCount, indices, glyphset, glyph_map);
+    
+    if (!c->serializer->check_assign (out->vertGlyphCount, new_vert_coverage.length, HB_SERIALIZE_ERROR_INT_OVERFLOW))
+      return_trace (false);
+    if (!c->serializer->check_assign (out->horizGlyphCount, new_hori_coverage.length, HB_SERIALIZE_ERROR_INT_OVERFLOW))
+      return_trace (false);
+
+    for (unsigned i : indices.iter ())
+    {
+      auto *o = c->serializer->embed (glyphConstruction[i]);
+      if (!o) return_trace (false);
+      o->serialize_subset (c, glyphConstruction[i], this);
+    }
+
+    out->vertGlyphCoverage.serialize_serialize (c->serializer, new_vert_coverage.iter ());
+    out->horizGlyphCoverage.serialize_serialize (c->serializer, new_hori_coverage.iter ());
+    return_trace (true);
+  }
+
   bool sanitize_offsets (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
@@ -747,6 +1003,18 @@ struct MATH
     }
   }
 
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    auto *out = c->serializer->embed (*this);
+    if (unlikely (!out)) return_trace (false);
+
+    out->mathConstants.serialize_copy (c->serializer, mathConstants, this, 0, hb_serialize_context_t::Head);
+    out->mathGlyphInfo.serialize_subset (c, mathGlyphInfo, this);
+    out->mathVariants.serialize_subset (c, mathVariants, this);
+    return_trace (true);
+  }
+
   bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);

src/hb-subset-plan.cc

@@ -38,6 +38,7 @@
 #include "hb-ot-color-colrv1-closure.hh"
 #include "hb-ot-var-fvar-table.hh"
 #include "hb-ot-stat-table.hh"
+#include "hb-ot-math-table.hh"
 
 
 typedef hb_hashmap_t<unsigned, hb_set_t *, (unsigned)-1, nullptr> script_langsys_map;
@@ -221,6 +222,17 @@ _cmap_closure (hb_face_t	   *face,
   cmap.fini ();
 }
 
+static inline void
+_math_closure (hb_face_t           *face,
+               hb_set_t            *glyphset)
+{
+  hb_blob_ptr_t<OT::MATH> math = hb_sanitize_context_t ().reference_table<OT::MATH> (face);
+  if (math->has_data ())
+    math->closure_glyphs (glyphset);
+  math.destroy ();
+}
+
+
 static inline void
 _remove_invalid_gids (hb_set_t *glyphs,
 		      unsigned int num_glyphs)
@@ -334,8 +346,12 @@ _populate_gids_to_retain (hb_subset_plan_t* plan,
 #endif
   _remove_invalid_gids (plan->_glyphset_gsub, plan->source->get_num_glyphs ());
 
+  hb_set_set (plan->_glyphset_mathed, plan->_glyphset_gsub);
+  _math_closure (plan->source, plan->_glyphset_mathed);
+  _remove_invalid_gids (plan->_glyphset_mathed, plan->source->get_num_glyphs ());
+
   // Collect all glyphs referenced by COLRv0
-  hb_set_t* cur_glyphset = plan->_glyphset_gsub;
+  hb_set_t* cur_glyphset = plan->_glyphset_mathed;
   hb_set_t glyphset_colrv0;
   if (colr.is_valid ())
   {
@@ -468,6 +484,7 @@ hb_subset_plan_create (hb_face_t	 *face,
 
   plan->_glyphset = hb_set_create ();
   plan->_glyphset_gsub = hb_set_create ();
+  plan->_glyphset_mathed = hb_set_create ();
   plan->codepoint_to_glyph = hb_map_create ();
   plan->glyph_map = hb_map_create ();
   plan->reverse_glyph_map = hb_map_create ();
@@ -535,6 +552,7 @@ hb_subset_plan_destroy (hb_subset_plan_t *plan)
   hb_map_destroy (plan->reverse_glyph_map);
   hb_set_destroy (plan->_glyphset);
   hb_set_destroy (plan->_glyphset_gsub);
+  hb_set_destroy (plan->_glyphset_mathed);
   hb_map_destroy (plan->gsub_lookups);
   hb_map_destroy (plan->gpos_lookups);
   hb_map_destroy (plan->gsub_features);

src/hb-subset-plan.hh

@@ -77,6 +77,7 @@ struct hb_subset_plan_t
   unsigned int _num_output_glyphs;
   hb_set_t *_glyphset;
   hb_set_t *_glyphset_gsub;
+  hb_set_t *_glyphset_mathed;
 
   //active lookups we'd like to retain
   hb_map_t *gsub_lookups;

src/hb-subset.cc

@@ -52,6 +52,7 @@
 #include "hb-ot-layout-gpos-table.hh"
 #include "hb-ot-var-gvar-table.hh"
 #include "hb-ot-var-hvar-table.hh"
+#include "hb-ot-math-table.hh"
 #include "hb-repacker.hh"
 
 /**
@@ -305,6 +306,7 @@ _subset_table (hb_subset_plan_t *plan, hb_tag_t tag)
   case HB_OT_TAG_CPAL: return _subset<const OT::CPAL> (plan);
   case HB_OT_TAG_CBLC: return _subset<const OT::CBLC> (plan);
   case HB_OT_TAG_CBDT: return true; /* skip CBDT, handled by CBLC */
+  case HB_OT_TAG_MATH: return _subset<const OT::MATH> (plan);
 
 #ifndef HB_NO_SUBSET_CFF
   case HB_OT_TAG_cff1: return _subset<const OT::cff1> (plan);

test/subset/data/Makefile.am

@@ -44,6 +44,7 @@ EXTRA_DIST += \
 	expected/cbdt \
 	expected/variable \
 	expected/glyph_names \
+	expected/math \
 	fonts \
 	profiles \
 	$(NULL)

test/subset/data/Makefile.sources

@@ -36,6 +36,7 @@ TESTS = \
 	tests/sbix.tests \
 	tests/variable.tests \
 	tests/glyph_names.tests \
+	tests/math.tests \
 	$(NULL)
 
 # TODO: re-enable once colrv1 subsetting is stabilized.

test/subset/data/tests/math.tests

@@ -0,0 +1,12 @@
+FONTS:
+STIXTwoMath-Regular.ttf
+
+PROFILES:
+default.txt
+retain-gids.txt
+glyph-names.txt
+notdef-outline.txt
+
+SUBSETS:
+U+2f,U+7c,U+305
+*

test/subset/meson.build

@@ -32,6 +32,7 @@ tests = [
   'cmap14',
   'sbix',
   'colr',
+  'math',
 # TODO: re-enable once colrv1 subsetting is stabilized.
 # 'colrv1.notoemoji',
 # 'colrv1',