Move Chromium subsetter code to sample, update CMakeLists accordingly.

Remove unused const in font.h.

5 files changed, 942 insertions, 1 deletions

diff --git a/cpp/src/sample/chromium/chrome_subsetter.cc b/cpp/src/sample/chromium/chrome_subsetter.cc
index 6f5788e..df15c18 100644
--- a/cpp/src/sample/chromium/chrome_subsetter.cc
+++ b/cpp/src/sample/chromium/chrome_subsetter.cc
@@ -21,7 +21,7 @@
 #include <sstream>
 
 #include "sfntly/port/type.h"
-#include "test/font_subsetter.h"
+#include "font_subsetter.h"
 
 template <typename T>
 class HexTo {
diff --git a/cpp/src/sample/chromium/font_subsetter.cc b/cpp/src/sample/chromium/font_subsetter.cc
new file mode 100644
index 0000000..14f5494
--- /dev/null
+++ b/cpp/src/sample/chromium/font_subsetter.cc
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2011 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "font_subsetter.h"
+
+#include "subsetter_impl.h"
+
+int SfntlyWrapper::SubsetFont(const char* font_name,
+                              const unsigned char* original_font,
+                              size_t font_size,
+                              const unsigned int* glyph_ids,
+                              size_t glyph_count,
+                              unsigned char** output_buffer) {
+  if (output_buffer == NULL ||
+      original_font == NULL || font_size == 0 ||
+      glyph_ids == NULL || glyph_count == 0) {
+    return 0;
+  }
+
+  sfntly::SubsetterImpl subsetter;
+  if (!subsetter.LoadFont(font_name, original_font, font_size)) {
+    return -1;  // Load error or font not found.
+  }
+
+  return subsetter.SubsetFont(glyph_ids, glyph_count, output_buffer);
+}
diff --git a/cpp/src/sample/chromium/font_subsetter.h b/cpp/src/sample/chromium/font_subsetter.h
new file mode 100644
index 0000000..07b1b5b
--- /dev/null
+++ b/cpp/src/sample/chromium/font_subsetter.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2011 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+// File is originally from Chromium third_party/sfntly/src/subsetter.
+// Use as test case in sfntly so that problems can be caught in upstream early.
+#ifndef SFNTLY_CPP_SRC_TEST_FONT_SUBSETTER_H_
+#define SFNTLY_CPP_SRC_TEST_FONT_SUBSETTER_H_
+
+#include <cstddef>
+
+class SfntlyWrapper {
+ public:
+
+  // Font subsetting API
+  //
+  // Input TTF/TTC/OTF fonts, specify the glyph IDs to subset, and the subset
+  // font is returned in |output_buffer| (caller to delete[]).  Return value is
+  // the length of output_buffer allocated.
+  //
+  // If subsetting fails, a negative value is returned.  If none of the glyph
+  // IDs specified is found, the function will return 0.
+  //
+  // |font_name|      Font name, required for TTC files.  If specified NULL,
+  //                  the first available font is selected.
+  // |original_font|  Original font file contents.
+  // |font_size|      Size of |original_font| in bytes.
+  // |glyph_ids|      Glyph IDs to subset.  If the specified glyph ID is not
+  //                  found in the font file, it will be ignored silently.
+  // |glyph_count|    Number of glyph IDs in |glyph_ids|
+  // |output_buffer|  Generated subset font.  Caller to delete[].
+  static int SubsetFont(const char* font_name,
+                        const unsigned char* original_font,
+                        size_t font_size,
+                        const unsigned int* glyph_ids,
+                        size_t glyph_count,
+                        unsigned char** output_buffer);
+};
+
+#endif  // SFNTLY_CPP_SRC_TEST_FONT_SUBSETTER_H_
diff --git a/cpp/src/sample/chromium/subsetter_impl.cc b/cpp/src/sample/chromium/subsetter_impl.cc
new file mode 100644
index 0000000..7e7cf61
--- /dev/null
+++ b/cpp/src/sample/chromium/subsetter_impl.cc
@@ -0,0 +1,777 @@
+/*
+ * Copyright 2011 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "subsetter_impl.h"
+
+#include <string.h>
+
+#include <algorithm>
+#include <iterator>
+#include <map>
+#include <set>
+
+#include "sfntly/table/bitmap/eblc_table.h"
+#include "sfntly/table/bitmap/ebdt_table.h"
+#include "sfntly/table/bitmap/index_sub_table.h"
+#include "sfntly/table/bitmap/index_sub_table_format1.h"
+#include "sfntly/table/bitmap/index_sub_table_format2.h"
+#include "sfntly/table/bitmap/index_sub_table_format3.h"
+#include "sfntly/table/bitmap/index_sub_table_format4.h"
+#include "sfntly/table/bitmap/index_sub_table_format5.h"
+#include "sfntly/table/core/name_table.h"
+#include "sfntly/tag.h"
+#include "sfntly/data/memory_byte_array.h"
+#include "sfntly/port/memory_input_stream.h"
+#include "sfntly/port/memory_output_stream.h"
+
+#if defined U_USING_ICU_NAMESPACE
+  U_NAMESPACE_USE
+#endif
+
+namespace {
+
+using namespace sfntly;
+
+// The bitmap tables must be greater than 16KB to trigger bitmap subsetter.
+static const int BITMAP_SIZE_THRESHOLD = 16384;
+
+void ConstructName(UChar* name_part, UnicodeString* name, int32_t name_id) {
+  switch (name_id) {
+    case NameId::kFullFontName:
+      *name = name_part;
+      break;
+    case NameId::kFontFamilyName:
+    case NameId::kPreferredFamily:
+    case NameId::kWWSFamilyName: {
+      UnicodeString original = *name;
+      *name = name_part;
+      *name += original;
+      break;
+    }
+    case NameId::kFontSubfamilyName:
+    case NameId::kPreferredSubfamily:
+    case NameId::kWWSSubfamilyName:
+      *name += name_part;
+      break;
+    default:
+      // This name part is not used to construct font name (e.g. copyright).
+      // Simply ignore it.
+      break;
+  }
+}
+
+int32_t HashCode(int32_t platform_id, int32_t encoding_id, int32_t language_id,
+                 int32_t name_id) {
+  int32_t result = platform_id << 24 | encoding_id << 16 | language_id << 8;
+  if (name_id == NameId::kFullFontName) {
+    result |= 0xff;
+  } else if (name_id == NameId::kPreferredFamily ||
+             name_id == NameId::kPreferredSubfamily) {
+    result |= 0xf;
+  } else if (name_id == NameId::kWWSFamilyName ||
+             name_id == NameId::kWWSSubfamilyName) {
+    result |= 1;
+  }
+  return result;
+}
+
+bool HasName(const char* font_name, Font* font) {
+  UnicodeString font_string = UnicodeString::fromUTF8(font_name);
+  if (font_string.isEmpty())
+    return false;
+  UnicodeString regular_suffix = UnicodeString::fromUTF8(" Regular");
+  UnicodeString alt_font_string = font_string;
+  alt_font_string += regular_suffix;
+
+  typedef std::map<int32_t, UnicodeString> NameMap;
+  NameMap names;
+  NameTablePtr name_table = down_cast<NameTable*>(font->GetTable(Tag::name));
+  if (name_table == NULL) {
+    return false;
+  }
+
+  for (int32_t i = 0; i < name_table->NameCount(); ++i) {
+    switch (name_table->NameId(i)) {
+      case NameId::kFontFamilyName:
+      case NameId::kFontSubfamilyName:
+      case NameId::kFullFontName:
+      case NameId::kPreferredFamily:
+      case NameId::kPreferredSubfamily:
+      case NameId::kWWSFamilyName:
+      case NameId::kWWSSubfamilyName: {
+        int32_t hash_code = HashCode(name_table->PlatformId(i),
+                                     name_table->EncodingId(i),
+                                     name_table->LanguageId(i),
+                                     name_table->NameId(i));
+        UChar* name_part = name_table->Name(i);
+        ConstructName(name_part, &(names[hash_code]), name_table->NameId(i));
+        delete[] name_part;
+        break;
+      }
+      default:
+        break;
+    }
+  }
+
+  if (!names.empty()) {
+    for (NameMap::iterator i = names.begin(), e = names.end(); i != e; ++i) {
+      if (i->second.caseCompare(font_string, 0) == 0 ||
+          i->second.caseCompare(alt_font_string, 0) == 0) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+Font* FindFont(const char* font_name, const FontArray& font_array) {
+  if (font_array.empty() || font_array[0] == NULL) {
+    return NULL;
+  }
+
+  if (font_name && strlen(font_name)) {
+    for (FontArray::const_iterator i = font_array.begin(), e = font_array.end();
+         i != e; ++i) {
+      if (HasName(font_name, i->p_)) {
+        return i->p_;
+      }
+    }
+  }
+
+  return font_array[0].p_;
+}
+
+bool ResolveCompositeGlyphs(GlyphTable* glyph_table,
+                            LocaTable* loca_table,
+                            const unsigned int* glyph_ids,
+                            size_t glyph_count,
+                            IntegerSet* glyph_id_processed) {
+  if (glyph_table == NULL || loca_table == NULL ||
+      glyph_ids == NULL || glyph_count == 0 || glyph_id_processed == NULL) {
+    return false;
+  }
+
+  // Sort and uniquify glyph ids.
+  IntegerSet glyph_id_remaining;
+  glyph_id_remaining.insert(0);  // Always include glyph id 0.
+  for (size_t i = 0; i < glyph_count; ++i) {
+    glyph_id_remaining.insert(glyph_ids[i]);
+  }
+
+  // Identify if any given glyph id maps to a composite glyph.  If so, include
+  // the glyphs referenced by that composite glyph.
+  while (!glyph_id_remaining.empty()) {
+    IntegerSet comp_glyph_id;
+    for (IntegerSet::iterator i = glyph_id_remaining.begin(),
+                              e = glyph_id_remaining.end(); i != e; ++i) {
+      if (*i < 0 || *i >= loca_table->num_glyphs()) {
+        // Invalid glyph id, ignore.
+        continue;
+      }
+
+      int32_t length = loca_table->GlyphLength(*i);
+      if (length == 0) {
+        // Empty glyph, ignore.
+        continue;
+      }
+      int32_t offset = loca_table->GlyphOffset(*i);
+
+      GlyphPtr glyph;
+      glyph.Attach(glyph_table->GetGlyph(offset, length));
+      if (glyph == NULL) {
+        // Error finding glyph, ignore.
+        continue;
+      }
+
+      if (glyph->GlyphType() == GlyphType::kComposite) {
+        Ptr<GlyphTable::CompositeGlyph> comp_glyph =
+            down_cast<GlyphTable::CompositeGlyph*>(glyph.p_);
+        for (int32_t j = 0; j < comp_glyph->NumGlyphs(); ++j) {
+          int32_t glyph_id = comp_glyph->GlyphIndex(j);
+          if (glyph_id_processed->find(glyph_id) == glyph_id_processed->end() &&
+              glyph_id_remaining.find(glyph_id) == glyph_id_remaining.end()) {
+            comp_glyph_id.insert(comp_glyph->GlyphIndex(j));
+          }
+        }
+      }
+
+      glyph_id_processed->insert(*i);
+    }
+
+    glyph_id_remaining.clear();
+    glyph_id_remaining = comp_glyph_id;
+  }
+
+  return true;
+}
+
+bool SetupGlyfBuilders(Font::Builder* font_builder,
+                       GlyphTable* glyph_table,
+                       LocaTable* loca_table,
+                       const IntegerSet& glyph_ids) {
+  if (!font_builder || !glyph_table || !loca_table) {
+    return false;
+  }
+
+  GlyphTableBuilderPtr glyph_table_builder =
+      down_cast<GlyphTable::Builder*>(font_builder->NewTableBuilder(Tag::glyf));
+  LocaTableBuilderPtr loca_table_builder =
+      down_cast<LocaTable::Builder*>(font_builder->NewTableBuilder(Tag::loca));
+  if (glyph_table_builder == NULL || loca_table_builder == NULL) {
+    // Out of memory.
+    return false;
+  }
+
+  // Extract glyphs and setup loca list.
+  IntegerList loca_list;
+  loca_list.resize(loca_table->num_glyphs());
+  loca_list.push_back(0);
+  int32_t last_glyph_id = 0;
+  int32_t last_offset = 0;
+  GlyphTable::GlyphBuilderList* glyph_builders =
+      glyph_table_builder->GlyphBuilders();
+  for (IntegerSet::const_iterator i = glyph_ids.begin(), e = glyph_ids.end();
+                                  i != e; ++i) {
+    int32_t length = loca_table->GlyphLength(*i);
+    int32_t offset = loca_table->GlyphOffset(*i);
+
+    GlyphPtr glyph;
+    glyph.Attach(glyph_table->GetGlyph(offset, length));
+
+    // Add glyph to new glyf table.
+    ReadableFontDataPtr data = glyph->ReadFontData();
+    WritableFontDataPtr copy_data;
+    copy_data.Attach(WritableFontData::CreateWritableFontData(data->Length()));
+    data->CopyTo(copy_data);
+    GlyphBuilderPtr glyph_builder;
+    glyph_builder.Attach(glyph_table_builder->GlyphBuilder(copy_data));
+    glyph_builders->push_back(glyph_builder);
+
+    // Configure loca list.
+    for (int32_t j = last_glyph_id + 1; j <= *i; ++j) {
+      loca_list[j] = last_offset;
+    }
+    last_offset += length;
+    loca_list[*i + 1] = last_offset;
+    last_glyph_id = *i;
+  }
+  for (int32_t j = last_glyph_id + 1; j <= loca_table->num_glyphs(); ++j) {
+    loca_list[j] = last_offset;
+  }
+  loca_table_builder->SetLocaList(&loca_list);
+
+  return true;
+}
+
+bool HasOverlap(int32_t range_begin, int32_t range_end,
+                const IntegerSet& glyph_ids) {
+  if (range_begin == range_end) {
+    return glyph_ids.find(range_begin) != glyph_ids.end();
+  } else if (range_end > range_begin) {
+    IntegerSet::const_iterator left = glyph_ids.lower_bound(range_begin);
+    IntegerSet::const_iterator right = glyph_ids.lower_bound(range_end);
+    return right != left;
+  }
+  return false;
+}
+
+// Initialize builder, returns false if glyph_id subset is not covered.
+// Not thread-safe, caller to ensure object life-time.
+bool InitializeBitmapBuilder(EbdtTable::Builder* ebdt, EblcTable::Builder* eblc,
+                             const IntegerSet& glyph_ids) {
+  BitmapLocaList loca_list;
+  BitmapSizeTableBuilderList* strikes = eblc->BitmapSizeBuilders();
+
+  // Note: Do not call eblc_builder->GenerateLocaList(&loca_list) and then
+  //       ebdt_builder->SetLoca(loca_list).  For fonts like SimSun, there are
+  //       >28K glyphs inside, where a typical usage will be <1K glyphs.  Doing
+  //       the calls improperly will result in creation of >100K objects that
+  //       will be destroyed immediately, inducing significant slowness.
+  IntegerList removed_strikes;
+  for (size_t i = 0; i < strikes->size(); i++) {
+    if (!HasOverlap((*strikes)[i]->StartGlyphIndex(),
+                    (*strikes)[i]->EndGlyphIndex(), glyph_ids)) {
+      removed_strikes.push_back(i);
+      continue;
+    }
+
+    IndexSubTableBuilderList* index_builders =
+        (*strikes)[i]->IndexSubTableBuilders();
+    IntegerList removed_indexes;
+    BitmapGlyphInfoMap info_map;
+    for (size_t j = 0; j < index_builders->size(); ++j) {
+      int32_t first_glyph_id = (*index_builders)[j]->first_glyph_index();
+      int32_t last_glyph_id = (*index_builders)[j]->last_glyph_index();
+      if (!HasOverlap(first_glyph_id, last_glyph_id, glyph_ids)) {
+        removed_indexes.push_back(j);
+        continue;
+      }
+      for (IntegerSet::const_iterator gid = glyph_ids.begin(),
+                                      gid_end = glyph_ids.end();
+                                      gid != gid_end; gid++) {
+        if (*gid < first_glyph_id) {
+          continue;
+        }
+        if (*gid > last_glyph_id) {
+          break;
+        }
+        BitmapGlyphInfoPtr info;
+        info.Attach((*index_builders)[j]->GlyphInfo(*gid));
+        if (info && info->length()) {  // Do not include gid without bitmap
+          info_map[*gid] = info;
+        }
+      }
+    }
+    if (!info_map.empty()) {
+      loca_list.push_back(info_map);
+    } else {
+      removed_strikes.push_back(i);  // Detected null entries.
+    }
+
+    // Remove unused index sub tables
+    for (IntegerList::reverse_iterator j = removed_indexes.rbegin(),
+                                       e = removed_indexes.rend();
+                                       j != e; j++) {
+      index_builders->erase(index_builders->begin() + *j);
+    }
+  }
+  if (removed_strikes.size() == strikes->size() || loca_list.empty()) {
+    return false;
+  }
+
+  for (IntegerList::reverse_iterator i = removed_strikes.rbegin(),
+                                     e = removed_strikes.rend(); i != e; i++) {
+    strikes->erase(strikes->begin() + *i);
+  }
+
+  if (strikes->empty()) {  // no glyph covered, can safely drop the builders.
+    return false;
+  }
+
+  ebdt->SetLoca(&loca_list);
+  ebdt->GlyphBuilders();  // Initialize the builder.
+  return true;
+}
+
+void CopyBigGlyphMetrics(BigGlyphMetrics::Builder* source,
+                         BigGlyphMetrics::Builder* target) {
+  target->SetHeight(static_cast<byte_t>(source->Height()));
+  target->SetWidth(static_cast<byte_t>(source->Width()));
+  target->SetHoriBearingX(static_cast<byte_t>(source->HoriBearingX()));
+  target->SetHoriBearingY(static_cast<byte_t>(source->HoriBearingY()));
+  target->SetHoriAdvance(static_cast<byte_t>(source->HoriAdvance()));
+  target->SetVertBearingX(static_cast<byte_t>(source->VertBearingX()));
+  target->SetVertBearingY(static_cast<byte_t>(source->VertBearingY()));
+  target->SetVertAdvance(static_cast<byte_t>(source->VertAdvance()));
+}
+
+CALLER_ATTACH IndexSubTable::Builder*
+ConstructIndexFormat4(IndexSubTable::Builder* b, const BitmapGlyphInfoMap& loca,
+                      int32_t* image_data_offset) {
+  IndexSubTableFormat4BuilderPtr builder4;
+  builder4.Attach(IndexSubTableFormat4::Builder::CreateBuilder());
+  CodeOffsetPairBuilderList offset_pairs;
+
+  size_t offset = 0;
+  int32_t lower_bound = b->first_glyph_index();
+  int32_t upper_bound = b->last_glyph_index();
+  int32_t last_gid = -1;
+  BitmapGlyphInfoMap::const_iterator i = loca.lower_bound(lower_bound);
+  BitmapGlyphInfoMap::const_iterator end = loca.end();
+  if (i != end) {
+    last_gid = i->first;
+    builder4->set_first_glyph_index(last_gid);
+    builder4->set_image_format(b->image_format());
+    builder4->set_image_data_offset(*image_data_offset);
+  }
+  for (; i != end; i++) {
+    int32_t gid = i->first;
+    if (gid > upper_bound) {
+      break;
+    }
+    offset_pairs.push_back(
+        IndexSubTableFormat4::CodeOffsetPairBuilder(gid, offset));
+    offset += i->second->length();
+    last_gid = gid;
+  }
+  offset_pairs.push_back(
+      IndexSubTableFormat4::CodeOffsetPairBuilder(-1, offset));
+  builder4->set_last_glyph_index(last_gid);
+  *image_data_offset += offset;
+  builder4->SetOffsetArray(offset_pairs);
+
+  return builder4.Detach();
+}
+
+CALLER_ATTACH IndexSubTable::Builder*
+ConstructIndexFormat5(IndexSubTable::Builder* b, const BitmapGlyphInfoMap& loca,
+                      int32_t* image_data_offset) {
+  IndexSubTableFormat5BuilderPtr new_builder;
+  new_builder.Attach(IndexSubTableFormat5::Builder::CreateBuilder());
+
+  // Copy BigMetrics
+  int32_t image_size = 0;
+  if (b->index_format() == IndexSubTable::Format::FORMAT_2) {
+    IndexSubTableFormat2BuilderPtr builder2 =
+      down_cast<IndexSubTableFormat2::Builder*>(b);
+    CopyBigGlyphMetrics(builder2->BigMetrics(), new_builder->BigMetrics());
+    image_size = builder2->ImageSize();
+  } else {
+    IndexSubTableFormat5BuilderPtr builder5 =
+      down_cast<IndexSubTableFormat5::Builder*>(b);
+    BigGlyphMetricsBuilderPtr metrics_builder;
+    CopyBigGlyphMetrics(builder5->BigMetrics(), new_builder->BigMetrics());
+    image_size = builder5->ImageSize();
+  }
+
+  IntegerList* glyph_array = new_builder->GlyphArray();
+  size_t offset = 0;
+  int32_t lower_bound = b->first_glyph_index();
+  int32_t upper_bound = b->last_glyph_index();
+  int32_t last_gid = -1;
+  BitmapGlyphInfoMap::const_iterator i = loca.lower_bound(lower_bound);
+  BitmapGlyphInfoMap::const_iterator end = loca.end();
+  if (i != end) {
+    last_gid = i->first;
+    new_builder->set_first_glyph_index(last_gid);
+    new_builder->set_image_format(b->image_format());
+    new_builder->set_image_data_offset(*image_data_offset);
+    new_builder->SetImageSize(image_size);
+  }
+  for (; i != end; i++) {
+    int32_t gid = i->first;
+    if (gid > upper_bound) {
+      break;
+    }
+    glyph_array->push_back(gid);
+    offset += i->second->length();
+    last_gid = gid;
+  }
+  new_builder->set_last_glyph_index(last_gid);
+  *image_data_offset += offset;
+  return new_builder.Detach();
+}
+
+CALLER_ATTACH IndexSubTable::Builder*
+SubsetIndexSubTable(IndexSubTable::Builder* builder,
+                    const BitmapGlyphInfoMap& loca,
+                    int32_t* image_data_offset) {
+  switch (builder->index_format()) {
+    case IndexSubTable::Format::FORMAT_1:
+    case IndexSubTable::Format::FORMAT_3:
+    case IndexSubTable::Format::FORMAT_4:
+      return ConstructIndexFormat4(builder, loca, image_data_offset);
+    case IndexSubTable::Format::FORMAT_2:
+    case IndexSubTable::Format::FORMAT_5:
+      return ConstructIndexFormat5(builder, loca, image_data_offset);
+    default:
+      assert(false);
+      break;
+  }
+  return NULL;
+}
+
+}
+
+namespace sfntly {
+
+// Not thread-safe, caller to ensure object life-time.
+void SubsetEBLC(EblcTable::Builder* eblc, const BitmapLocaList& new_loca) {
+  BitmapSizeTableBuilderList* size_builders = eblc->BitmapSizeBuilders();
+  if (size_builders == NULL) {
+    return;
+  }
+
+  int32_t image_data_offset = EbdtTable::Offset::kHeaderLength;
+  for (size_t strike = 0; strike < size_builders->size(); ++strike) {
+    IndexSubTableBuilderList* index_builders =
+        (*size_builders)[strike]->IndexSubTableBuilders();
+    for (size_t index = 0; index < index_builders->size(); ++index) {
+      IndexSubTable::Builder* new_builder_raw =
+          SubsetIndexSubTable((*index_builders)[index], new_loca[strike],
+                              &image_data_offset);
+      if (NULL != new_builder_raw) {
+        (*index_builders)[index].Attach(new_builder_raw);
+      }
+    }
+  }
+}
+
+// EBLC structure (from stuartg)
+//  header
+//  bitmapSizeTable[]
+//    one per strike
+//    holds strike metrics - sbitLineMetrics
+//    holds info about indexSubTableArray
+//  indexSubTableArray[][]
+//    one per strike and then one per indexSubTable for that strike
+//    holds info about the indexSubTable
+//    the indexSubTable entries pointed to can be of different formats
+//  indexSubTable
+//    one per indexSubTableArray entry
+//    tells how to get the glyphs
+//    may hold the glyph metrics if they are uniform for all the glyphs in range
+// Please note that the structure can also be
+//  {indexSubTableArray[], indexSubTables[]}[]
+//  This way is also legal and in fact how Microsoft fonts are laid out.
+//
+// There is nothing that says that the indexSubTableArray entries and/or the
+// indexSubTable items need to be unique. They may be shared between strikes.
+//
+// EBDT structure:
+//  header
+//  glyphs
+//    amorphous blob of data
+//    different glyphs that are only able to be figured out from the EBLC table
+//    may hold metrics - depends on the EBLC entry that pointed to them
+
+// Subsetting EBLC table (from arthurhsu)
+//  Most pages use only a fraction (hundreds or less) glyphs out of a given font
+//  (which can have >20K glyphs for CJK).  It's safe to assume that the subset
+//  font will have sparse bitmap glyphs.  So we reconstruct the EBLC table as
+//  format 4 or 5 here.
+
+enum BuildersToRemove {
+  kRemoveNone,
+  kRemoveBDAT,
+  kRemoveBDATAndEBDT,
+  kRemoveEBDT
+};
+
+int SetupBitmapBuilders(Font* font, Font::Builder* font_builder,
+                        const IntegerSet& glyph_ids) {
+  if (!font || !font_builder) {
+    return false;
+  }
+
+  // Check if bitmap table exists.
+  EbdtTablePtr ebdt_table = down_cast<EbdtTable*>(font->GetTable(Tag::EBDT));
+  EblcTablePtr eblc_table = down_cast<EblcTable*>(font->GetTable(Tag::EBLC));
+  bool use_ebdt = (ebdt_table != NULL && eblc_table != NULL);
+  if (!use_ebdt) {
+    ebdt_table = down_cast<EbdtTable*>(font->GetTable(Tag::bdat));
+    eblc_table = down_cast<EblcTable*>(font->GetTable(Tag::bloc));
+    if (ebdt_table == NULL || eblc_table == NULL) {
+      return kRemoveNone;
+    }
+  }
+
+  // If the bitmap table's size is too small, skip subsetting.
+  if (ebdt_table->DataLength() + eblc_table->DataLength() <
+      BITMAP_SIZE_THRESHOLD) {
+    return use_ebdt ? kRemoveBDAT : kRemoveNone;
+  }
+
+  // Get the builders.
+  EbdtTableBuilderPtr ebdt_table_builder = down_cast<EbdtTable::Builder*>(
+      font_builder->NewTableBuilder(use_ebdt ? Tag::EBDT : Tag::bdat,
+                                    ebdt_table->ReadFontData()));
+  EblcTableBuilderPtr eblc_table_builder = down_cast<EblcTable::Builder*>(
+      font_builder->NewTableBuilder(use_ebdt ? Tag::EBLC : Tag::bloc,
+                                    eblc_table->ReadFontData()));
+  if (ebdt_table_builder == NULL || eblc_table_builder == NULL) {
+    // Out of memory.
+    return use_ebdt ? kRemoveBDAT : kRemoveNone;
+  }
+
+  if (!InitializeBitmapBuilder(ebdt_table_builder, eblc_table_builder,
+                               glyph_ids)) {
+    // Bitmap tables do not cover the glyphs in our subset.
+    font_builder->RemoveTableBuilder(use_ebdt ? Tag::EBLC : Tag::bloc);
+    font_builder->RemoveTableBuilder(use_ebdt ? Tag::EBDT : Tag::bdat);
+    return use_ebdt ? kRemoveBDATAndEBDT : kRemoveEBDT;
+  }
+
+  BitmapLocaList new_loca;
+  ebdt_table_builder->GenerateLocaList(&new_loca);
+  SubsetEBLC(eblc_table_builder, new_loca);
+
+  return use_ebdt ? kRemoveBDAT : kRemoveNone;
+}
+
+SubsetterImpl::SubsetterImpl() {
+}
+
+SubsetterImpl::~SubsetterImpl() {
+}
+
+bool SubsetterImpl::LoadFont(const char* font_name,
+                             const unsigned char* original_font,
+                             size_t font_size) {
+  MemoryInputStream mis;
+  mis.Attach(original_font, font_size);
+  if (factory_ == NULL) {
+    factory_.Attach(FontFactory::GetInstance());
+  }
+
+  FontArray font_array;
+  factory_->LoadFonts(&mis, &font_array);
+  font_ = FindFont(font_name, font_array);
+  if (font_ == NULL) {
+    return false;
+  }
+
+  return true;
+}
+
+int SubsetterImpl::SubsetFont(const unsigned int* glyph_ids,
+                              size_t glyph_count,
+                              unsigned char** output_buffer) {
+  if (factory_ == NULL || font_ == NULL) {
+    return -1;
+  }
+
+  // Find glyf and loca table.
+  GlyphTablePtr glyph_table =
+      down_cast<GlyphTable*>(font_->GetTable(Tag::glyf));
+  LocaTablePtr loca_table = down_cast<LocaTable*>(font_->GetTable(Tag::loca));
+  if (glyph_table == NULL || loca_table == NULL) {
+    // We are not able to subset the font.
+    return 0;
+  }
+
+  IntegerSet glyph_id_processed;
+  if (!ResolveCompositeGlyphs(glyph_table, loca_table,
+                              glyph_ids, glyph_count, &glyph_id_processed) ||
+      glyph_id_processed.empty()) {
+    return 0;
+  }
+
+  FontPtr new_font;
+  new_font.Attach(Subset(glyph_id_processed, glyph_table, loca_table));
+  if (new_font == NULL) {
+    return 0;
+  }
+
+  MemoryOutputStream output_stream;
+  factory_->SerializeFont(new_font, &output_stream);
+  int length = static_cast<int>(output_stream.Size());
+  if (length > 0) {
+    *output_buffer = new unsigned char[length];
+    memcpy(*output_buffer, output_stream.Get(), length);
+  }
+
+  return length;
+}
+
+// Long comments regarding TTF tables and PDF (from stuartg)
+//
+// According to PDF spec 1.4 (section 5.8), the following tables must be
+// present:
+//  head, hhea, loca, maxp, cvt, prep, glyf, hmtx, fpgm
+//  cmap if font is used with a simple font dict and not a CIDFont dict
+//
+// Other tables we need to keep for PDF rendering to support zoom in/out:
+//  bdat, bloc, ebdt, eblc, ebsc, gasp
+//
+// Special table:
+//  CFF - if you have this table then you shouldn't have a glyf table and this
+//        is the table with all the glyphs.  Shall skip subsetting completely
+//        since sfntly is not capable of subsetting it for now.
+//  post - extra info here for printing on PostScript printers but maybe not
+//         enough to outweigh the space taken by the names
+//
+// Tables to break apart:
+//  name - could throw away all but one language and one platform strings/ might
+//         throw away some of the name entries
+//  cmap - could strip out non-needed cmap subtables
+//       - format 4 subtable can be subsetted as well using sfntly
+//
+// Graphite tables:
+//  silf, glat, gloc, feat - should be okay to strip out
+//
+// Tables that can be discarded:
+//  OS/2 - everything here is for layout and description of the font that is
+//         elsewhere (some in the PDF objects)
+//  BASE, GDEF, GSUB, GPOS, JSTF - all used for layout
+//  kern - old style layout
+//  DSIG - this will be invalid after subsetting
+//  hdmx - layout
+//  PCLT - metadata that's not needed
+//  vmtx - layout
+//  vhea - layout
+//  VDMX
+//  VORG - not used by TT/OT - used by CFF
+//  hsty - would be surprised to see one of these - used on the Newton
+//  AAT tables - mort, morx, feat, acnt, bsin, just, lcar, fdsc, fmtx, prop,
+//               Zapf, opbd, trak, fvar, gvar, avar, cvar
+//             - these are all layout tables and once layout happens are not
+//               needed anymore
+//  LTSH - layout
+
+CALLER_ATTACH
+Font* SubsetterImpl::Subset(const IntegerSet& glyph_ids, GlyphTable* glyf,
+                            LocaTable* loca) {
+  // The const is initialized here to workaround VC bug of rendering all Tag::*
+  // as 0.  These tags represents the TTF tables that we will embed in subset
+  // font.
+  const int32_t TABLES_IN_SUBSET[] = {
+    Tag::head, Tag::hhea, Tag::loca, Tag::maxp, Tag::cvt,
+    Tag::prep, Tag::glyf, Tag::hmtx, Tag::fpgm, Tag::EBDT,
+    Tag::EBLC, Tag::EBSC, Tag::bdat, Tag::bloc, Tag::bhed,
+    Tag::cmap,  // Keep here for future tagged PDF development.
+    Tag::name,  // Keep here due to legal concerns: copyright info inside.
+  };
+
+  // Setup font builders we need.
+  FontBuilderPtr font_builder;
+  font_builder.Attach(factory_->NewFontBuilder());
+  IntegerSet remove_tags;
+
+  if (SetupGlyfBuilders(font_builder, glyf, loca, glyph_ids)) {
+    remove_tags.insert(Tag::glyf);
+    remove_tags.insert(Tag::loca);
+  }
+
+  // For old Apple bitmap fonts, they have only bdats and bhed is identical
+  // to head.  As a result, we can't remove bdat tables for those fonts.
+  int setup_result = SetupBitmapBuilders(font_, font_builder, glyph_ids);
+  if (setup_result == kRemoveBDATAndEBDT || setup_result == kRemoveEBDT) {
+    remove_tags.insert(Tag::EBDT);
+    remove_tags.insert(Tag::EBLC);
+    remove_tags.insert(Tag::EBSC);
+  }
+
+  if (setup_result == kRemoveBDAT || setup_result == kRemoveBDATAndEBDT) {
+    remove_tags.insert(Tag::bdat);
+    remove_tags.insert(Tag::bloc);
+    remove_tags.insert(Tag::bhed);
+  }
+
+  IntegerSet allowed_tags;
+  for (size_t i = 0; i < sizeof(TABLES_IN_SUBSET) / sizeof(int32_t); ++i) {
+    allowed_tags.insert(TABLES_IN_SUBSET[i]);
+  }
+
+  IntegerSet result;
+  std::set_difference(allowed_tags.begin(), allowed_tags.end(),
+                      remove_tags.begin(), remove_tags.end(),
+                      std::inserter(result, result.end()));
+  allowed_tags = result;
+
+  // Setup remaining builders.
+  for (IntegerSet::iterator i = allowed_tags.begin(), e = allowed_tags.end();
+                            i != e; ++i) {
+    Table* table = font_->GetTable(*i);
+    if (table) {
+      font_builder->NewTableBuilder(*i, table->ReadFontData());
+    }
+  }
+
+  return font_builder->Build();
+}
+
+}  // namespace sfntly
diff --git a/cpp/src/sample/chromium/subsetter_impl.h b/cpp/src/sample/chromium/subsetter_impl.h
new file mode 100644
index 0000000..ffbf408
--- /dev/null
+++ b/cpp/src/sample/chromium/subsetter_impl.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright 2011 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+// File is originally from Chromium third_party/sfntly/src/subsetter.
+// Use as test case in sfntly so that problems can be caught in upstream early.
+
+#ifndef SFNTLY_CPP_SRC_TEST_SUBSETTER_IMPL_H_
+#define SFNTLY_CPP_SRC_TEST_SUBSETTER_IMPL_H_
+
+#include "sfntly/font.h"
+#include "sfntly/font_factory.h"
+#include "sfntly/table/truetype/glyph_table.h"
+#include "sfntly/table/truetype/loca_table.h"
+#include "sfntly/tag.h"
+
+namespace sfntly {
+
+// Smart pointer usage in sfntly:
+//
+// sfntly carries a smart pointer implementation like COM.  Ref-countable object
+// type inherits from RefCounted<>, which have AddRef and Release just like
+// IUnknown (but no QueryInterface).  Use a Ptr<> based smart pointer to hold
+// the object so that the object ref count is handled correctly.
+//
+// class Foo : public RefCounted<Foo> {
+//  public:
+//   static Foo* CreateInstance() {
+//     Ptr<Foo> obj = new Foo();  // ref count = 1
+//     return obj.detach();
+//   }
+// };
+// typedef Ptr<Foo> FooPtr;  // common short-hand notation
+// FooPtr obj;
+// obj.attach(Foo::CreatedInstance());  // ref count = 1
+// {
+//   FooPtr obj2 = obj;  // ref count = 2
+// }  // ref count = 1, obj2 out of scope
+// obj.release();  // ref count = 0, object destroyed
+
+class SubsetterImpl {
+ public:
+  SubsetterImpl();
+  ~SubsetterImpl();
+
+  bool LoadFont(const char* font_name,
+                const unsigned char* original_font,
+                size_t font_size);
+  int SubsetFont(const unsigned int* glyph_ids,
+                 size_t glyph_count,
+                 unsigned char** output_buffer);
+
+ private:
+  CALLER_ATTACH Font* Subset(const IntegerSet& glyph_ids,
+                             GlyphTable* glyf, LocaTable* loca);
+
+  FontFactoryPtr factory_;
+  FontPtr font_;
+};
+
+}  // namespace sfntly
+
+#endif  // SFNTLY_CPP_SRC_TEST_SUBSETTER_IMPL_H_