Update to 10-12-11 snapshot

Created new chrome_subsetter program to test font subsetter used in Chromium
Fix several porting bugs in previous CL

git-svn-id: http://sfntly.googlecode.com/svn/trunk/cpp/src@101 672e30a5-4c29-85ac-ac6d-611c735e0a51

3 files changed, 568 insertions, 108 deletions

diff --git a/test/bitmap_table_test.cc b/test/bitmap_table_test.cc
index c8f239c..d5d718d 100644
--- a/test/bitmap_table_test.cc
+++ b/test/bitmap_table_test.cc
@@ -18,6 +18,7 @@
 #include "sfntly/font.h"
 #include "sfntly/table/bitmap/ebdt_table.h"
 #include "sfntly/table/bitmap/eblc_table.h"
+#include "sfntly/table/bitmap/index_sub_table_format3.h"
 #include "test/test_data.h"
 #include "test/test_font_utils.h"
 
@@ -35,12 +36,14 @@ const int32_t STRIKE1_PPEM_Y = 10;
 const int32_t STRIKE1_BIT_DEPTH = 1;
 const int32_t STRIKE1_FLAGS = 0x01;
 
+const int32_t STRIKE4_SUB1_INDEX_FORMAT = 3;
 const int32_t STRIKE4_SUB1_IMAGE_FORMAT = 1;
 const int32_t STRIKE4_SUB1_IMAGE_DATA_OFFSET = 0x00005893;
 const int32_t STRIKE4_SUB1_GLYPH_OFFSET[] = {
     0x00005893, 0x00005898, 0x0000589d, 0x000058a2, 0x000058a7,
     0x000058b2, 0x000058c2, 0x000058d0, 0x000058de, 0x000058e6 };
-const int32_t NUM_STRIKE4_SUB1_GLYPH_OFFSET = 10;  // must be 1 less
+const int32_t NUM_STRIKE4_SUB1_GLYPH_OFFSET = 10;
+const int32_t STRIKE4_SUB1_GLYPH2_LENGTH = 0x58a2 - 0x589d;
 
 bool TestReadingBitmapTable() {
   FontFactoryPtr factory;
@@ -79,15 +82,29 @@ bool TestReadingBitmapTable() {
   EXPECT_EQ(strike4->EndGlyphIndex(), STRIKE1_END_GLYPH_INDEX);
   IndexSubTablePtr sub1 = strike4->GetIndexSubTable(0);
   EXPECT_FALSE(sub1 == NULL);
+  EXPECT_EQ(sub1->index_format(), STRIKE4_SUB1_INDEX_FORMAT);
+  EXPECT_EQ(sub1->image_format(), STRIKE4_SUB1_IMAGE_FORMAT);
   EXPECT_EQ(sub1->first_glyph_index(), STRIKE1_START_GLYPH_INDEX);
   EXPECT_EQ(sub1->last_glyph_index(), STRIKE1_END_GLYPH_INDEX);
-  EXPECT_EQ(sub1->image_format(), STRIKE4_SUB1_IMAGE_FORMAT);
   EXPECT_EQ(sub1->image_data_offset(), STRIKE4_SUB1_IMAGE_DATA_OFFSET);
 
   for (int32_t i = 0; i < NUM_STRIKE4_SUB1_GLYPH_OFFSET; ++i) {
       EXPECT_EQ(sub1->GlyphOffset(i), STRIKE4_SUB1_GLYPH_OFFSET[i]);
   }
 
+  // Strike 4 Index Sub Table 1 is a Format 3
+  IndexSubTableFormat3Ptr sub3 =
+      down_cast<IndexSubTableFormat3*>(strike4->GetIndexSubTable(0));
+  EXPECT_FALSE(sub3 == NULL);
+  BitmapGlyphInfoPtr info;
+  info.Attach(sub3->GlyphInfo(2));
+  EXPECT_EQ(info->glyph_id(), 2);
+  EXPECT_EQ(info->block_offset(), STRIKE4_SUB1_IMAGE_DATA_OFFSET);
+  EXPECT_EQ(info->start_offset(),
+            STRIKE4_SUB1_GLYPH_OFFSET[2] - STRIKE4_SUB1_GLYPH_OFFSET[0]);
+  EXPECT_EQ(info->format(), STRIKE4_SUB1_IMAGE_FORMAT);
+  EXPECT_EQ(info->length(), STRIKE4_SUB1_GLYPH2_LENGTH);
+
   return true;
 }
 
diff --git a/test/subsetter_impl.cc b/test/subsetter_impl.cc
index f82a674..7934085 100644
--- a/test/subsetter_impl.cc
+++ b/test/subsetter_impl.cc
@@ -23,6 +23,14 @@
 #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/table/truetype/glyph_table.h"
 #include "sfntly/table/truetype/loca_table.h"
@@ -34,7 +42,7 @@
 namespace sfntly {
 
 void ConstructName(UChar* name_part, UnicodeString* name, int32_t name_id) {
-  switch(name_id) {
+  switch (name_id) {
     case NameId::kFullFontName:
       *name = name_part;
       break;
@@ -73,80 +81,7 @@ int32_t HashCode(int32_t platform_id, int32_t encoding_id, int32_t language_id,
   return result;
 }
 
-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;
-  }
-
-  IntegerSet glyph_id_processed;
-  if (!ResolveCompositeGlyphs(glyph_ids, glyph_count, &glyph_id_processed) ||
-      glyph_id_processed.empty()) {
-    return 0;
-  }
-
-  FontPtr new_font;
-  new_font.Attach(Subset(glyph_id_processed));
-  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;
-}
-
-Font* SubsetterImpl::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 b = font_array.begin(), e = font_array.end();
-         b != e; ++b) {
-      if (HasName(font_name, (*b).p_)) {
-        return (*b).p_;
-      }
-    }
-  }
-
-  return font_array[0].p_;
-}
-
-bool SubsetterImpl::HasName(const char* font_name, Font* font) {
+bool HasName(const char* font_name, Font* font) {
   UnicodeString font_string = UnicodeString::fromUTF8(font_name);
   if (font_string.isEmpty())
     return false;
@@ -162,7 +97,7 @@ bool SubsetterImpl::HasName(const char* font_name, Font* font) {
   }
 
   for (int32_t i = 0; i < name_table->NameCount(); ++i) {
-    switch(name_table->NameId(i)) {
+    switch (name_table->NameId(i)) {
       case NameId::kFontFamilyName:
       case NameId::kFontSubfamilyName:
       case NameId::kFullFontName:
@@ -195,22 +130,37 @@ bool SubsetterImpl::HasName(const char* font_name, Font* font) {
   return false;
 }
 
-bool SubsetterImpl::ResolveCompositeGlyphs(const unsigned int* glyph_ids,
-                                           size_t glyph_count,
-                                           IntegerSet* glyph_id_processed) {
-  if (glyph_ids == NULL || glyph_count == 0 || glyph_id_processed == NULL) {
-    return false;
+Font* FindFont(const char* font_name, const FontArray& font_array) {
+  if (font_array.empty() || font_array[0] == NULL) {
+    return NULL;
   }
 
-  // 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) {
-    // The font is invalid.
+  if (font_name && strlen(font_name)) {
+    for (FontArray::const_iterator b = font_array.begin(), e = font_array.end();
+         b != e; ++b) {
+      if (HasName(font_name, (*b).p_)) {
+        return (*b).p_;
+      }
+    }
+  }
+
+  return font_array[0].p_;
+}
+
+bool ResolveCompositeGlyphs(GlyphTable* glyf,
+                            LocaTable* loca,
+                            const unsigned int* glyph_ids,
+                            size_t glyph_count,
+                            IntegerSet* glyph_id_processed) {
+  if (glyf == NULL || loca == NULL || glyph_ids == NULL || glyph_count == 0 ||
+      glyph_id_processed == NULL) {
     return false;
   }
 
+  // Find glyf and loca table.
+  GlyphTablePtr glyph_table = glyf;
+  LocaTablePtr loca_table = loca;
+
   // Sort and uniquify glyph ids.
   IntegerSet glyph_id_remaining;
   glyph_id_remaining.insert(0);  // Always include glyph id 0.
@@ -265,23 +215,26 @@ bool SubsetterImpl::ResolveCompositeGlyphs(const unsigned int* glyph_ids,
   return true;
 }
 
-CALLER_ATTACH Font* SubsetterImpl::Subset(const IntegerSet& glyph_ids) {
-  // The tables are already checked in ResolveCompositeGlyphs().
-  GlyphTablePtr glyph_table =
-      down_cast<GlyphTable*>(font_->GetTable(Tag::glyf));
-  LocaTablePtr loca_table = down_cast<LocaTable*>(font_->GetTable(Tag::loca));
+bool SetupGlyfBuilders(Font::Builder* builder,
+                       GlyphTable* glyf,
+                       LocaTable* loca,
+                       const IntegerSet& glyph_ids) {
+  if (!builder || !glyf || !loca) {
+    return false;
+  }
 
-  // Setup font builders we need.
-  FontBuilderPtr font_builder;
-  font_builder.Attach(factory_->NewFontBuilder());
+  // The tables are already checked in ResolveCompositeGlyphs().
+  GlyphTablePtr glyph_table = glyf;
+  LocaTablePtr loca_table = loca;
 
+  FontBuilderPtr font_builder = builder;
   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 NULL;
+    return false;
   }
 
   // Extract glyphs and setup loca list.
@@ -322,12 +275,499 @@ CALLER_ATTACH Font* SubsetterImpl::Subset(const IntegerSet& glyph_ids) {
   }
   loca_table_builder->SetLocaList(&loca_list);
 
+  return true;
+}
+
+bool HasOverlap(int32_t range1_begin, int32_t range1_end,
+                int32_t range2_begin, int32_t range2_end) {
+  return (range2_begin < range1_end && range2_begin > range1_begin) ||
+         (range1_begin < range2_end && range1_begin > range2_begin);
+}
+
+// Initialize builder, returns false if glyph_id subset is not covered.
+bool ShallSubset(EbdtTable::Builder* ebdt, EblcTable::Builder* eblc,
+                 const IntegerSet& glyph_ids) {
+  EblcTableBuilderPtr eblc_builder = eblc;
+  EbdtTableBuilderPtr ebdt_builder = ebdt;
+
+  BitmapLocaList loca_list;
+  BitmapSizeTableBuilderList* strikes = eblc_builder->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 inproperly will result in creation of >100K objects that
+  //       will be destroyed immediately and result in significant slowness.
+  IntegerList removed_strikes;
+  for (size_t i = 0; i < strikes->size(); i++) {
+    if (!HasOverlap((*strikes)[i]->StartGlyphIndex(),
+                    (*strikes)[i]->EndGlyphIndex(),
+                    *(glyph_ids.begin()), *(glyph_ids.rbegin()))) {
+      removed_strikes.push_back(i);
+      continue;
+    }
+
+    IndexSubTableBuilderList* index_builders =
+        (*strikes)[i]->IndexSubTableBuilders();
+    IntegerList removed_indexes;
+    for (size_t j = 0; j < index_builders->size(); ++j) {
+      BitmapGlyphInfoMap info_map;
+      for (IntegerSet::const_iterator gid = glyph_ids.begin(),
+                                      gid_end = glyph_ids.end();
+                                      gid != gid_end; gid++) {
+        if ((*index_builders)[j]->first_glyph_index() <= *gid &&
+            (*index_builders)[j]->last_glyph_index() >= *gid &&
+            (*index_builders)[j]->GlyphStartOffset(*gid) != -1) {
+          BitmapGlyphInfoPtr info =
+              new BitmapGlyphInfo(*gid,
+                                  (*index_builders)[j]->image_data_offset() +
+                                  (*index_builders)[j]->GlyphStartOffset(*gid),
+                                  (*index_builders)[j]->GlyphLength(*gid),
+                                  (*index_builders)[j]->image_format());
+          info_map[*gid] = info;
+        }
+      }
+      if (!info_map.empty()) {
+        loca_list.push_back(info_map);
+      } else {
+        removed_indexes.push_back(j);
+      }
+    }
+
+    // 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;  // All strikes shall be gone.
+  }
+
+  // Remove unused strikes
+  for (IntegerList::reverse_iterator j = removed_strikes.rbegin(),
+                                     e = removed_strikes.rend(); j != e; j++) {
+      strikes->erase(strikes->begin() + *j);
+  }
+
+  ebdt_builder->SetLoca(&loca_list);
+  ebdt_builder->GlyphBuilders();  // Initialize the builder.
+  return true;
+}
+
+void GenerateOffsetArray(int32_t first_gid, int32_t last_gid,
+                         const BitmapGlyphInfoMap& loca,
+                         IntegerList* new_offsets) {
+  int32_t offset = 0;
+  int32_t length = 0;
+  for (int32_t i = first_gid; i <= last_gid; ++i) {
+    BitmapGlyphInfoMap::const_iterator it = loca.find(i);
+    if (it != loca.end()) {
+      offset = it->second->offset();
+      length = it->second->length();
+      new_offsets->push_back(offset);
+      if (i == last_gid) {
+        new_offsets->push_back(offset + length);
+      }
+    } else {  // Glyph id is not in subset.
+      offset += length;
+      new_offsets->push_back(offset);
+      length = 0;
+    }
+  }
+}
+
+/******************************************************************************
+ * EXPERIMENTAL CODE STARTS
+ *
+ * The following code is used for experiment.  Will obsolete once we have
+ * support to create format 4 and 5 index sub tables from scratch.
+ *****************************************************************************/
+void SubsetIndexSubTableFormat1(IndexSubTable::Builder* b,
+                                const BitmapGlyphInfoMap& loca) {
+  IndexSubTableFormat1BuilderPtr builder =
+      down_cast<IndexSubTableFormat1::Builder*>(b);
+  if (builder->first_glyph_index() < loca.begin()->first) {
+    builder->set_first_glyph_index(loca.begin()->first);
+  }
+  if (builder->last_glyph_index() > loca.rbegin()->first) {
+    builder->set_last_glyph_index(loca.rbegin()->first);
+  }
+  builder->set_image_data_offset(loca.begin()->second->block_offset());
+
+  IntegerList new_offsets;
+  GenerateOffsetArray(builder->first_glyph_index(), builder->last_glyph_index(),
+                      loca, &new_offsets);
+  builder->SetOffsetArray(new_offsets);
+}
+
+void SubsetIndexSubTableFormat2(IndexSubTable::Builder* b,
+                                const BitmapGlyphInfoMap& loca) {
+  UNREFERENCED_PARAMETER(b);
+  UNREFERENCED_PARAMETER(loca);
+}
+
+void SubsetIndexSubTableFormat3(IndexSubTable::Builder* b,
+                                const BitmapGlyphInfoMap& loca) {
+  IndexSubTableFormat3BuilderPtr builder =
+      down_cast<IndexSubTableFormat3::Builder*>(b);
+  if (builder->first_glyph_index() < loca.begin()->first) {
+    builder->set_first_glyph_index(loca.begin()->first);
+  }
+  if (builder->last_glyph_index() > loca.rbegin()->first) {
+    builder->set_last_glyph_index(loca.rbegin()->first);
+  }
+  builder->set_image_data_offset(loca.begin()->second->block_offset());
+
+  IntegerList new_offsets;
+  GenerateOffsetArray(builder->first_glyph_index(), builder->last_glyph_index(),
+                      loca, &new_offsets);
+  builder->SetOffsetArray(new_offsets);
+}
+
+void SubsetIndexSubTableFormat4(IndexSubTable::Builder* b,
+                                const BitmapGlyphInfoMap& loca) {
+  IndexSubTableFormat4BuilderPtr builder =
+      down_cast<IndexSubTableFormat4::Builder*>(b);
+  CodeOffsetPairBuilderList pairs;
+  pairs.resize(loca.size());
+  size_t index = 0;
+  for (BitmapGlyphInfoMap::const_iterator i = loca.begin(), e = loca.end();
+                                          i != e; i++) {
+    pairs[index].set_glyph_code(i->first);
+    pairs[index].set_offset(i->second->offset());
+    index++;
+  }
+  builder->SetOffsetArray(pairs);
+}
+
+void SubsetIndexSubTableFormat5(IndexSubTable::Builder* b,
+                                const BitmapGlyphInfoMap& loca) {
+  IndexSubTableFormat5BuilderPtr builder =
+      down_cast<IndexSubTableFormat5::Builder*>(b);
+  IntegerList* glyph_array = builder->GlyphArray();
+  for (IntegerList::iterator i = glyph_array->begin(); i != glyph_array->end();
+                             i++) {
+    if (loca.find(*i) == loca.end()) {
+      glyph_array->erase(i);
+    }
+  }
+  if (!glyph_array->empty()) {
+    builder->set_first_glyph_index(*(glyph_array->begin()));
+    builder->set_last_glyph_index(*(glyph_array->rbegin()));
+  } else {
+    builder->set_first_glyph_index(0);
+    builder->set_last_glyph_index(0);
+  }
+}
+
+void SubsetIndexSubTable(IndexSubTable::Builder* builder,
+                         const BitmapGlyphInfoMap& loca) {
+  switch (builder->index_format()) {
+    case 1:
+      SubsetIndexSubTableFormat1(builder, loca);
+      break;
+    case 2:
+      SubsetIndexSubTableFormat2(builder, loca);
+      break;
+    case 3:
+      SubsetIndexSubTableFormat3(builder, loca);
+      break;
+    case 4:
+      SubsetIndexSubTableFormat4(builder, loca);
+      break;
+    case 5:
+      SubsetIndexSubTableFormat5(builder, loca);
+      break;
+    default:
+      assert(false);  // Shall not be here.
+      break;
+  }
+}
+
+void SubsetEBLC(EblcTable::Builder* eblc, const BitmapLocaList& new_loca) {
+  EblcTableBuilderPtr eblc_builder = eblc;
+  BitmapSizeTableBuilderList* size_builders = eblc->BitmapSizeBuilders();
+  if (size_builders == NULL) {
+    return;  // No valid EBLC.
+  }
+
+  for (size_t strike = 0; strike < size_builders->size(); ++strike) {
+    IndexSubTableBuilderList* index_builders =
+        (*size_builders)[strike]->IndexSubTableBuilders();
+    bool format4_processed = false;
+    for (size_t index = 0; index < index_builders->size(); ++index) {
+      // Only one format 4 table per strike.
+      if ((*index_builders)[index]->index_format() == 4 && format4_processed) {
+        continue;
+      }
+      SubsetIndexSubTable((*index_builders)[index], new_loca[strike]);
+      if ((*index_builders)[index]->index_format() == 4) {
+        format4_processed = true;
+      }
+    }
+  }
+}
+/******************************************************************************
+ * EXPERIMENTAL CODE ENDS
+ *****************************************************************************/
+
+/******************************************************************************
+  Long background comments
+
+EBLC structure:
+  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
+
+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:
+  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.  As a result, the EBLC table shall be
+  reconstructed to either format 4 or 5.
+*******************************************************************************/
+bool SetupBitmapBuilders(Font* font, Font::Builder* builder,
+                         const IntegerSet& glyph_ids) {
+  if (!font || !builder) {
+    return false;
+  }
+
+  // Check if bitmap table exists.
+  bool use_ebdt = true;
+  EbdtTablePtr ebdt_table = down_cast<EbdtTable*>(font->GetTable(Tag::EBDT));
+  EblcTablePtr eblc_table = down_cast<EblcTable*>(font->GetTable(Tag::EBLC));
+  if (ebdt_table == NULL && eblc_table == NULL) {
+    use_ebdt = false;
+    // Check BDAT variants.
+    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) {
+    // There's no bitmap tables.
+    return true;
+  }
+
+  // If the bitmap table's size is too small, skip subsetting.
+  // TODO(arthurhsu): temporarily comment out to use smaller font for testing.
+  /*
+  if (ebdt_table->DataLength() + eblc_table->DataLength() <
+      BITMAP_SIZE_THRESHOLD) {
+    return true;
+  }
+  */
+
+  // Get the builders.
+  FontBuilderPtr font_builder = builder;
+  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 false;
+  }
+
+  if (!ShallSubset(ebdt_table_builder, eblc_table_builder, glyph_ids)) {
+    // Bitmap tables do not cover the glyphs in our subset.
+    ebdt_table_builder.Release();
+    eblc_table_builder.Release();
+    font_builder->RemoveTableBuilder(use_ebdt ? Tag::EBDT : Tag::bdat);
+    font_builder->RemoveTableBuilder(use_ebdt ? Tag::EBLC : Tag::bloc);
+    return true;
+  }
+
+  BitmapLocaList new_loca;
+  ebdt_table_builder->GenerateLocaList(&new_loca);
+  SubsetEBLC(eblc_table_builder, new_loca);
+
+  return true;
+}
+
+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));
+  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
+
+According to PDF spec (section 9.9), the following tables must present:
+  head, hhea, loca, maxp, cvt, prep, glyf, hmtx, fpgm
+  cmap if font is used as a TTF 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 - shall 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 if you saw 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) {
+  // 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 VALID_TABLE_TAG[] = {
+    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;
+
+  GlyphTablePtr glyph_table =
+      down_cast<GlyphTable*>(font_->GetTable(Tag::glyf));
+  LocaTablePtr loca_table = down_cast<LocaTable*>(font_->GetTable(Tag::loca));
+
+  if (SetupGlyfBuilders(font_builder, glyph_table, loca_table, glyph_ids)) {
+    remove_tags.insert(Tag::glyf);
+    remove_tags.insert(Tag::loca);
+  }
+  if (SetupBitmapBuilders(font_, font_builder, glyph_ids)) {
+    remove_tags.insert(Tag::bdat);
+    remove_tags.insert(Tag::bloc);
+    remove_tags.insert(Tag::bhed);
+    remove_tags.insert(Tag::EBDT);
+    remove_tags.insert(Tag::EBLC);
+    remove_tags.insert(Tag::EBSC);
+  }
+
+  IntegerSet allowed_tags;
+  for (size_t i = 0; i < sizeof(VALID_TABLE_TAG) / sizeof(int32_t); ++i) {
+    allowed_tags.insert(VALID_TABLE_TAG[i]);
+  }
+  for (IntegerSet::iterator i = remove_tags.begin(), e = remove_tags.end();
+                            i != e; i++) {
+    IntegerSet::iterator it = allowed_tags.find(*i);
+    if (it != allowed_tags.end()) {
+      allowed_tags.erase(it);
+    }
+  }
+
   // Setup remaining builders.
-  for (TableMap::const_iterator i = font_->GetTableMap()->begin(),
-                                e = font_->GetTableMap()->end(); i != e; ++i) {
-    // We already build the builder for glyph and loca.
-    if (i->first != Tag::glyf && i->first != Tag::loca) {
-      font_builder->NewTableBuilder(i->first, i->second->ReadFontData());
+  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());
     }
   }
 
diff --git a/test/subsetter_impl.h b/test/subsetter_impl.h
index f3a8bf3..abcc420 100644
--- a/test/subsetter_impl.h
+++ b/test/subsetter_impl.h
@@ -21,6 +21,7 @@
 
 #include "sfntly/font.h"
 #include "sfntly/font_factory.h"
+#include "sfntly/tag.h"
 
 namespace sfntly {
 
@@ -46,6 +47,13 @@ namespace sfntly {
 // }  // ref count = 1, obj2 out of scope
 // obj.release();  // ref count = 0, object destroyed
 
+namespace {
+
+// The bitmap tables must be greater than 256KB to trigger bitmap subsetter.
+static const int BITMAP_SIZE_THRESHOLD = 262144;
+
+}
+
 class SubsetterImpl {
  public:
   SubsetterImpl();
@@ -59,11 +67,6 @@ class SubsetterImpl {
                  unsigned char** output_buffer);
 
  private:
-  Font* FindFont(const char* font_name, const FontArray& font_array);
-  bool HasName(const char* font_name, Font* font);
-  bool ResolveCompositeGlyphs(const unsigned int* glyph_ids,
-                              size_t glyph_count,
-                              IntegerSet* glyph_id_processed);
   CALLER_ATTACH Font* Subset(const IntegerSet& glyph_ids);
 
   FontFactoryPtr factory_;