src/cobalt/renderer/rasterizer/skia/skia/src/ports/SkFontStyleSet_cobalt.cc - cobalt - Git at Google

 // Copyright 2017 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 "cobalt/renderer/rasterizer/skia/skia/src/ports/SkFontStyleSet_cobalt.h"

 #include <ft2build.h>
 #include FT_FREETYPE_H

 #include <cmath>
 #include <limits>

 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "cobalt/renderer/rasterizer/skia/skia/src/ports/SkTypeface_cobalt.h"
 #include "SkOSFile.h"

 namespace {

 int MatchScore(const SkFontStyle& pattern, const SkFontStyle& candidate) {
   // This logic is taken from Skia and is based upon the algorithm specified
   // within the spec:
   //   https://www.w3.org/TR/css-fonts-3/#font-matching-algorithm

   int score = 0;

   // CSS style (italic/oblique)
   // Being italic trumps all valid weights which are not italic.
   // Note that newer specs differentiate between italic and oblique.
   if (pattern.isItalic() == candidate.isItalic()) {
     score += 1001;
   }

   // The 'closer' to the target weight, the higher the score.
   // 1000 is the 'heaviest' recognized weight
   if (pattern.weight() == candidate.weight()) {
     score += 1000;
   } else if (pattern.weight() <= 500) {
     if (400 <= pattern.weight() && pattern.weight() < 450) {
       if (450 <= candidate.weight() && candidate.weight() <= 500) {
         score += 500;
       }
     }
     if (candidate.weight() <= pattern.weight()) {
       score += 1000 - pattern.weight() + candidate.weight();
     } else {
       score += 1000 - candidate.weight();
     }
   } else if (pattern.weight() > 500) {
     if (candidate.weight() > pattern.weight()) {
       score += 1000 + pattern.weight() - candidate.weight();
     } else {
       score += candidate.weight();
     }
   }

   return score;
 }

 }  // namespace

 // These functions are used by FreeType during FT_Open_Face.
 extern "C" {

 static unsigned long sk_cobalt_ft_stream_io(FT_Stream ftStream,
                                             unsigned long offset,
                                             unsigned char* buffer,
                                             unsigned long count) {
   SkStreamAsset* stream =
       static_cast<SkStreamAsset*>(ftStream->descriptor.pointer);
   stream->seek(offset);
   return stream->read(buffer, count);
 }

 static void sk_cobalt_ft_stream_close(FT_Stream) {}
 }

 SkFontStyleSet_Cobalt::SkFontStyleSet_Cobalt(
     const FontFamilyInfo& family_info, const char* base_path,
     SkFileMemoryChunkStreamManager* const local_typeface_stream_manager,
     SkMutex* const manager_owned_mutex)
     : local_typeface_stream_manager_(local_typeface_stream_manager),
       manager_owned_mutex_(manager_owned_mutex),
       is_fallback_family_(family_info.is_fallback_family),
       language_(family_info.language),
       page_ranges_(family_info.page_ranges),
       is_character_map_generated_(!is_fallback_family_) {
   TRACE_EVENT0("cobalt::renderer",
                "SkFontStyleSet_Cobalt::SkFontStyleSet_Cobalt()");
   DCHECK(manager_owned_mutex_);

   if (family_info.names.count() == 0) {
     return;
   }

   family_name_ = family_info.names[0];

   for (int i = 0; i < family_info.fonts.count(); ++i) {
     const FontFileInfo& font_file = family_info.fonts[i];

     SkString file_path(SkOSPath::Join(base_path, font_file.file_name.c_str()));

     // Validate that the file exists at this location. If it does not, then skip
     // over it; it isn't being added to the set.
     if (!sk_exists(file_path.c_str(), kRead_SkFILE_Flag)) {
       DLOG(INFO) << "Failed to find font file: " << file_path.c_str();
       continue;
     }

     SkFontStyle style(font_file.weight, SkFontStyle::kNormal_Width,
                       font_file.style == FontFileInfo::kItalic_FontStyle
                           ? SkFontStyle::kItalic_Slant
                           : SkFontStyle::kUpright_Slant);

     std::string full_font_name;
     if (!font_file.full_font_name.isEmpty()) {
       full_font_name = std::string(font_file.full_font_name.c_str(),
                                    font_file.full_font_name.size());
     }
     std::string postscript_name;
     if (!font_file.postscript_name.isEmpty()) {
       postscript_name = std::string(font_file.postscript_name.c_str(),
                                     font_file.postscript_name.size());
     }

     styles_.push_back().reset(
         SkNEW_ARGS(SkFontStyleSetEntry_Cobalt,
                    (file_path, font_file.index, style, full_font_name,
                     postscript_name, font_file.disable_synthetic_bolding)));
   }
 }

 int SkFontStyleSet_Cobalt::count() {
   SkAutoMutexAcquire scoped_mutex(*manager_owned_mutex_);
   return styles_.count();
 }

 void SkFontStyleSet_Cobalt::getStyle(int index, SkFontStyle* style,
                                      SkString* name) {
   // SkFontStyleSet_Cobalt does not support publicly interacting with entries
   // via index, as entries can potentially be removed, thereby invalidating the
   // indices.
   NOTREACHED();
 }

 SkTypeface* SkFontStyleSet_Cobalt::createTypeface(int index) {
   // SkFontStyleSet_Cobalt does not support publicly interacting with entries
   // via index, as entries can potentially be removed, thereby invalidating the
   // indices.
   NOTREACHED();
   return NULL;
 }

 SkTypeface* SkFontStyleSet_Cobalt::matchStyle(const SkFontStyle& pattern) {
   SkAutoMutexAcquire scoped_mutex(*manager_owned_mutex_);
   return MatchStyleWithoutLocking(pattern);
 }

 SkTypeface* SkFontStyleSet_Cobalt::MatchStyleWithoutLocking(
     const SkFontStyle& pattern) {
   SkTypeface* typeface = NULL;
   while (typeface == NULL && styles_.count() > 0) {
     typeface = TryRetrieveTypefaceAndRemoveStyleOnFailure(
         GetClosestStyleIndex(pattern));
   }
   return typeface;
 }

 SkTypeface* SkFontStyleSet_Cobalt::MatchFullFontName(const std::string& name) {
   for (int i = 0; i < styles_.count(); ++i) {
     if (styles_[i]->full_font_name == name) {
       return TryRetrieveTypefaceAndRemoveStyleOnFailure(i);
     }
   }
   return NULL;
 }

 SkTypeface* SkFontStyleSet_Cobalt::MatchFontPostScriptName(
     const std::string& name) {
   for (int i = 0; i < styles_.count(); ++i) {
     if (styles_[i]->font_postscript_name == name) {
       return TryRetrieveTypefaceAndRemoveStyleOnFailure(i);
     }
   }
   return NULL;
 }

 SkTypeface* SkFontStyleSet_Cobalt::TryRetrieveTypefaceAndRemoveStyleOnFailure(
     int style_index) {
   DCHECK(style_index >= 0 && style_index < styles_.count());
   SkFontStyleSetEntry_Cobalt* style = styles_[style_index];
   // If the typeface doesn't already exist, then attempt to create it.
   if (style->typeface == NULL) {
     CreateStreamProviderTypeface(style);
     // If the creation attempt failed and the typeface is still NULL, then
     // remove the entry from the set's styles.
     if (style->typeface == NULL) {
       styles_[style_index].swap(&styles_.back());
       styles_.pop_back();
       return NULL;
     }
   }
   return SkRef(style->typeface.get());
 }

 bool SkFontStyleSet_Cobalt::ContainsTypeface(const SkTypeface* typeface) {
   for (int i = 0; i < styles_.count(); ++i) {
     if (styles_[i]->typeface == typeface) {
       return true;
     }
   }
   return false;
 }

 bool SkFontStyleSet_Cobalt::ContainsCharacter(const SkFontStyle& style,
                                               SkUnichar character) {
   // If page ranges exist for this style set, then verify that this character
   // falls within the ranges. Otherwise, the style set is treated as having a
   // page range containing all characters.
   size_t num_ranges = page_ranges_.count();
   if (num_ranges > 0) {
     int16 page = font_character_map::GetPage(character);

     // Verify that the last page range is not less than the page containing the
     // character. If it's less, then this character can't be contained
     // within the pages. Otherwise, this last range acts as a sentinel for the
     // search.
     if (page_ranges_[num_ranges - 1].second < page) {
       return false;
     }

     int range_index = 0;
     while (page_ranges_[range_index].second < page) {
       ++range_index;
     }

     if (page_ranges_[range_index].first > page) {
       return false;
     }
   }

   // If this point is reached, then the character is contained within one of
   // the font style set's page ranges. Now, verify that the specific character
   // is supported by the font style set.

   // The character map is lazily generated. Generate it now if it isn't already
   // generated.
   if (!is_character_map_generated_) {
     TRACE_EVENT0("cobalt::renderer",
                  "SkFontStyleSet_Cobalt::ContainsCharacter() and "
                  "!is_character_map_generated_");
     // Attempt to load the closest font style from the set. If it fails to load,
     // it will be removed from the set and, as long as font styles remain in the
     // set, the logic will be attempted again.
     while (styles_.count() > 0) {
       int style_index = GetClosestStyleIndex(style);
       SkFontStyleSetEntry_Cobalt* closest_style = styles_[style_index];

       SkFileMemoryChunkStreamProvider* stream_provider =
           local_typeface_stream_manager_->GetStreamProvider(
               closest_style->font_file_path.c_str());

       // Create a snapshot prior to loading any additional memory chunks. In the
       // case where the typeface does not end up being created, this enables the
       // stream provider to purge newly created memory chunks, while retaining
       // any pre-existing ones.
       scoped_ptr<const SkFileMemoryChunks> memory_chunks_snapshot(
           stream_provider->CreateMemoryChunksSnapshot());

       SkAutoTUnref<SkFileMemoryChunkStream> stream(
           stream_provider->OpenStream());
       if (GenerateStyleFaceInfo(closest_style, stream)) {
         if (CharacterMapContainsCharacter(character)) {
           CreateStreamProviderTypeface(closest_style, stream_provider);
           return true;
         } else {
           // If a typeface was not created, destroy the stream and purge any
           // newly created memory chunks. The stream must be destroyed first or
           // it will retain references to memory chunks, preventing them from
           // being purged.
           stream.reset(NULL);
           stream_provider->PurgeUnusedMemoryChunks();
           return false;
         }
       }

       styles_[style_index].swap(&styles_.back());
       styles_.pop_back();
     }

     is_character_map_generated_ = true;
   }

   return CharacterMapContainsCharacter(character);
 }

 bool SkFontStyleSet_Cobalt::CharacterMapContainsCharacter(SkUnichar character) {
   font_character_map::CharacterMap::iterator page_iterator =
       character_map_.find(font_character_map::GetPage(character));
   return page_iterator != character_map_.end() &&
          page_iterator->second.test(
              font_character_map::GetPageCharacterIndex(character));
 }

 bool SkFontStyleSet_Cobalt::GenerateStyleFaceInfo(
     SkFontStyleSetEntry_Cobalt* style, SkStreamAsset* stream) {
   if (style->is_face_info_generated) {
     return true;
   }

   TRACE_EVENT0("cobalt::renderer", "GenerateStyleFaceInfo()");

   FT_Library freetype_lib;
   if (FT_Init_FreeType(&freetype_lib) != 0) {
     return false;
   }

   FT_StreamRec streamRec;
   memset(&streamRec, 0, sizeof(streamRec));
   streamRec.size = stream->getLength();
   streamRec.descriptor.pointer = stream;
   streamRec.read = sk_cobalt_ft_stream_io;
   streamRec.close = sk_cobalt_ft_stream_close;

   FT_Open_Args args;
   memset(&args, 0, sizeof(args));
   args.flags = FT_OPEN_STREAM;
   args.stream = &streamRec;

   FT_Face face;
   FT_Error err = FT_Open_Face(freetype_lib, &args, style->face_index, &face);
   if (err) {
     FT_Done_FreeType(freetype_lib);
     return false;
   }

   int face_style = SkTypeface::kNormal;
   if (face->style_flags & FT_STYLE_FLAG_BOLD) {
     face_style |= SkTypeface::kBold;
   }
   if (face->style_flags & FT_STYLE_FLAG_ITALIC) {
     face_style |= SkTypeface::kItalic;
   }

   style->face_name.set(face->family_name);
   style->face_style = static_cast<SkTypeface::Style>(face_style);
   style->face_is_fixed_pitch = FT_IS_FIXED_WIDTH(face);
   style->is_face_info_generated = true;

   // Map out this family's characters if they haven't been generated yet.
   if (!is_character_map_generated_) {
     FT_UInt glyph_index;

     int last_page = -1;
     font_character_map::PageCharacters* page_characters = NULL;

     SkUnichar code_point = FT_Get_First_Char(face, &glyph_index);
     while (glyph_index) {
       int page = font_character_map::GetPage(code_point);
       if (page != last_page) {
         page_characters = &character_map_[page];
         last_page = page;
       }
       page_characters->set(
           font_character_map::GetPageCharacterIndex(code_point));

       code_point = FT_Get_Next_Char(face, code_point, &glyph_index);
     }

     is_character_map_generated_ = true;
   }

   // release this font.
   FT_Done_Face(face);

   // shut down FreeType.
   FT_Done_FreeType(freetype_lib);
   return true;
 }

 int SkFontStyleSet_Cobalt::GetClosestStyleIndex(const SkFontStyle& pattern) {
   int closest_index = 0;
   int max_score = std::numeric_limits<int>::min();
   for (int i = 0; i < styles_.count(); ++i) {
     int score = MatchScore(pattern, styles_[i]->font_style);
     if (score > max_score) {
       closest_index = i;
       max_score = score;
     }
   }
   return closest_index;
 }

 void SkFontStyleSet_Cobalt::CreateStreamProviderTypeface(
     SkFontStyleSetEntry_Cobalt* style_entry,
     SkFileMemoryChunkStreamProvider* stream_provider /*=NULL*/) {
   TRACE_EVENT0("cobalt::renderer",
                "SkFontStyleSet_Cobalt::CreateStreamProviderTypeface()");

   if (!stream_provider) {
     stream_provider = local_typeface_stream_manager_->GetStreamProvider(
         style_entry->font_file_path.c_str());
   }

   SkAutoTUnref<SkFileMemoryChunkStream> stream(stream_provider->OpenStream());
   if (GenerateStyleFaceInfo(style_entry, stream)) {
     LOG(ERROR) << "Scanned font from file: " << style_entry->face_name.c_str()
                << "(" << style_entry->face_style << ")";
     style_entry->typeface.reset(
         SkNEW_ARGS(SkTypeface_CobaltStreamProvider,
                    (stream_provider, style_entry->face_index,
                     style_entry->face_style, style_entry->face_is_fixed_pitch,
                     family_name_, style_entry->disable_synthetic_bolding)));
   } else {
     LOG(ERROR) << "Failed to scan font: "
                << style_entry->font_file_path.c_str();
   }
 }
	// Copyright 2017 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 "cobalt/renderer/rasterizer/skia/skia/src/ports/SkFontStyleSet_cobalt.h"

	#include <ft2build.h>
	#include FT_FREETYPE_H

	#include <cmath>
	#include <limits>

	#include "base/debug/trace_event.h"
	#include "base/logging.h"
	#include "base/memory/ref_counted.h"
	#include "cobalt/renderer/rasterizer/skia/skia/src/ports/SkTypeface_cobalt.h"
	#include "SkOSFile.h"

	namespace {

	int MatchScore(const SkFontStyle& pattern, const SkFontStyle& candidate) {
	// This logic is taken from Skia and is based upon the algorithm specified
	// within the spec:
	// https://www.w3.org/TR/css-fonts-3/#font-matching-algorithm

	int score = 0;

	// CSS style (italic/oblique)
	// Being italic trumps all valid weights which are not italic.
	// Note that newer specs differentiate between italic and oblique.
	if (pattern.isItalic() == candidate.isItalic()) {
	score += 1001;
	}

	// The 'closer' to the target weight, the higher the score.
	// 1000 is the 'heaviest' recognized weight
	if (pattern.weight() == candidate.weight()) {
	score += 1000;
	} else if (pattern.weight() <= 500) {
	if (400 <= pattern.weight() && pattern.weight() < 450) {
	if (450 <= candidate.weight() && candidate.weight() <= 500) {
	score += 500;
	}
	}
	if (candidate.weight() <= pattern.weight()) {
	score += 1000 - pattern.weight() + candidate.weight();
	} else {
	score += 1000 - candidate.weight();
	}
	} else if (pattern.weight() > 500) {
	if (candidate.weight() > pattern.weight()) {
	score += 1000 + pattern.weight() - candidate.weight();
	} else {
	score += candidate.weight();
	}
	}

	return score;
	}

	} // namespace

	// These functions are used by FreeType during FT_Open_Face.
	extern "C" {

	static unsigned long sk_cobalt_ft_stream_io(FT_Stream ftStream,
	unsigned long offset,
	unsigned char* buffer,
	unsigned long count) {
	SkStreamAsset* stream =
	static_cast<SkStreamAsset*>(ftStream->descriptor.pointer);
	stream->seek(offset);
	return stream->read(buffer, count);
	}

	static void sk_cobalt_ft_stream_close(FT_Stream) {}
	}

	SkFontStyleSet_Cobalt::SkFontStyleSet_Cobalt(
	const FontFamilyInfo& family_info, const char* base_path,
	SkFileMemoryChunkStreamManager* const local_typeface_stream_manager,
	SkMutex* const manager_owned_mutex)
	: local_typeface_stream_manager_(local_typeface_stream_manager),
	manager_owned_mutex_(manager_owned_mutex),
	is_fallback_family_(family_info.is_fallback_family),
	language_(family_info.language),
	page_ranges_(family_info.page_ranges),
	is_character_map_generated_(!is_fallback_family_) {
	TRACE_EVENT0("cobalt::renderer",
	"SkFontStyleSet_Cobalt::SkFontStyleSet_Cobalt()");
	DCHECK(manager_owned_mutex_);

	if (family_info.names.count() == 0) {
	return;
	}

	family_name_ = family_info.names[0];

	for (int i = 0; i < family_info.fonts.count(); ++i) {
	const FontFileInfo& font_file = family_info.fonts[i];

	SkString file_path(SkOSPath::Join(base_path, font_file.file_name.c_str()));

	// Validate that the file exists at this location. If it does not, then skip
	// over it; it isn't being added to the set.
	if (!sk_exists(file_path.c_str(), kRead_SkFILE_Flag)) {
	DLOG(INFO) << "Failed to find font file: " << file_path.c_str();
	continue;
	}

	SkFontStyle style(font_file.weight, SkFontStyle::kNormal_Width,
	font_file.style == FontFileInfo::kItalic_FontStyle
	? SkFontStyle::kItalic_Slant
	: SkFontStyle::kUpright_Slant);

	std::string full_font_name;
	if (!font_file.full_font_name.isEmpty()) {
	full_font_name = std::string(font_file.full_font_name.c_str(),
	font_file.full_font_name.size());
	}
	std::string postscript_name;
	if (!font_file.postscript_name.isEmpty()) {
	postscript_name = std::string(font_file.postscript_name.c_str(),
	font_file.postscript_name.size());
	}

	styles_.push_back().reset(
	SkNEW_ARGS(SkFontStyleSetEntry_Cobalt,
	(file_path, font_file.index, style, full_font_name,
	postscript_name, font_file.disable_synthetic_bolding)));
	}
	}

	int SkFontStyleSet_Cobalt::count() {
	SkAutoMutexAcquire scoped_mutex(*manager_owned_mutex_);
	return styles_.count();
	}

	void SkFontStyleSet_Cobalt::getStyle(int index, SkFontStyle* style,
	SkString* name) {
	// SkFontStyleSet_Cobalt does not support publicly interacting with entries
	// via index, as entries can potentially be removed, thereby invalidating the
	// indices.
	NOTREACHED();
	}

	SkTypeface* SkFontStyleSet_Cobalt::createTypeface(int index) {
	// SkFontStyleSet_Cobalt does not support publicly interacting with entries
	// via index, as entries can potentially be removed, thereby invalidating the
	// indices.
	NOTREACHED();
	return NULL;
	}

	SkTypeface* SkFontStyleSet_Cobalt::matchStyle(const SkFontStyle& pattern) {
	SkAutoMutexAcquire scoped_mutex(*manager_owned_mutex_);
	return MatchStyleWithoutLocking(pattern);
	}

	SkTypeface* SkFontStyleSet_Cobalt::MatchStyleWithoutLocking(
	const SkFontStyle& pattern) {
	SkTypeface* typeface = NULL;
	while (typeface == NULL && styles_.count() > 0) {
	typeface = TryRetrieveTypefaceAndRemoveStyleOnFailure(
	GetClosestStyleIndex(pattern));
	}
	return typeface;
	}

	SkTypeface* SkFontStyleSet_Cobalt::MatchFullFontName(const std::string& name) {
	for (int i = 0; i < styles_.count(); ++i) {
	if (styles_[i]->full_font_name == name) {
	return TryRetrieveTypefaceAndRemoveStyleOnFailure(i);
	}
	}
	return NULL;
	}

	SkTypeface* SkFontStyleSet_Cobalt::MatchFontPostScriptName(
	const std::string& name) {
	for (int i = 0; i < styles_.count(); ++i) {
	if (styles_[i]->font_postscript_name == name) {
	return TryRetrieveTypefaceAndRemoveStyleOnFailure(i);
	}
	}
	return NULL;
	}

	SkTypeface* SkFontStyleSet_Cobalt::TryRetrieveTypefaceAndRemoveStyleOnFailure(
	int style_index) {
	DCHECK(style_index >= 0 && style_index < styles_.count());
	SkFontStyleSetEntry_Cobalt* style = styles_[style_index];
	// If the typeface doesn't already exist, then attempt to create it.
	if (style->typeface == NULL) {
	CreateStreamProviderTypeface(style);
	// If the creation attempt failed and the typeface is still NULL, then
	// remove the entry from the set's styles.
	if (style->typeface == NULL) {
	styles_[style_index].swap(&styles_.back());
	styles_.pop_back();
	return NULL;
	}
	}
	return SkRef(style->typeface.get());
	}

	bool SkFontStyleSet_Cobalt::ContainsTypeface(const SkTypeface* typeface) {
	for (int i = 0; i < styles_.count(); ++i) {
	if (styles_[i]->typeface == typeface) {
	return true;
	}
	}
	return false;
	}

	bool SkFontStyleSet_Cobalt::ContainsCharacter(const SkFontStyle& style,
	SkUnichar character) {
	// If page ranges exist for this style set, then verify that this character
	// falls within the ranges. Otherwise, the style set is treated as having a
	// page range containing all characters.
	size_t num_ranges = page_ranges_.count();
	if (num_ranges > 0) {
	int16 page = font_character_map::GetPage(character);

	// Verify that the last page range is not less than the page containing the
	// character. If it's less, then this character can't be contained
	// within the pages. Otherwise, this last range acts as a sentinel for the
	// search.
	if (page_ranges_[num_ranges - 1].second < page) {
	return false;
	}

	int range_index = 0;
	while (page_ranges_[range_index].second < page) {
	++range_index;
	}

	if (page_ranges_[range_index].first > page) {
	return false;
	}
	}

	// If this point is reached, then the character is contained within one of
	// the font style set's page ranges. Now, verify that the specific character
	// is supported by the font style set.

	// The character map is lazily generated. Generate it now if it isn't already
	// generated.
	if (!is_character_map_generated_) {
	TRACE_EVENT0("cobalt::renderer",
	"SkFontStyleSet_Cobalt::ContainsCharacter() and "
	"!is_character_map_generated_");
	// Attempt to load the closest font style from the set. If it fails to load,
	// it will be removed from the set and, as long as font styles remain in the
	// set, the logic will be attempted again.
	while (styles_.count() > 0) {
	int style_index = GetClosestStyleIndex(style);
	SkFontStyleSetEntry_Cobalt* closest_style = styles_[style_index];

	SkFileMemoryChunkStreamProvider* stream_provider =
	local_typeface_stream_manager_->GetStreamProvider(
	closest_style->font_file_path.c_str());

	// Create a snapshot prior to loading any additional memory chunks. In the
	// case where the typeface does not end up being created, this enables the
	// stream provider to purge newly created memory chunks, while retaining
	// any pre-existing ones.
	scoped_ptr<const SkFileMemoryChunks> memory_chunks_snapshot(
	stream_provider->CreateMemoryChunksSnapshot());

	SkAutoTUnref<SkFileMemoryChunkStream> stream(
	stream_provider->OpenStream());
	if (GenerateStyleFaceInfo(closest_style, stream)) {
	if (CharacterMapContainsCharacter(character)) {
	CreateStreamProviderTypeface(closest_style, stream_provider);
	return true;
	} else {
	// If a typeface was not created, destroy the stream and purge any
	// newly created memory chunks. The stream must be destroyed first or
	// it will retain references to memory chunks, preventing them from
	// being purged.
	stream.reset(NULL);
	stream_provider->PurgeUnusedMemoryChunks();
	return false;
	}
	}

	styles_[style_index].swap(&styles_.back());
	styles_.pop_back();
	}

	is_character_map_generated_ = true;
	}

	return CharacterMapContainsCharacter(character);
	}

	bool SkFontStyleSet_Cobalt::CharacterMapContainsCharacter(SkUnichar character) {
	font_character_map::CharacterMap::iterator page_iterator =
	character_map_.find(font_character_map::GetPage(character));
	return page_iterator != character_map_.end() &&
	page_iterator->second.test(
	font_character_map::GetPageCharacterIndex(character));
	}

	bool SkFontStyleSet_Cobalt::GenerateStyleFaceInfo(
	SkFontStyleSetEntry_Cobalt* style, SkStreamAsset* stream) {
	if (style->is_face_info_generated) {
	return true;
	}

	TRACE_EVENT0("cobalt::renderer", "GenerateStyleFaceInfo()");

	FT_Library freetype_lib;
	if (FT_Init_FreeType(&freetype_lib) != 0) {
	return false;
	}

	FT_StreamRec streamRec;
	memset(&streamRec, 0, sizeof(streamRec));
	streamRec.size = stream->getLength();
	streamRec.descriptor.pointer = stream;
	streamRec.read = sk_cobalt_ft_stream_io;
	streamRec.close = sk_cobalt_ft_stream_close;

	FT_Open_Args args;
	memset(&args, 0, sizeof(args));
	args.flags = FT_OPEN_STREAM;
	args.stream = &streamRec;

	FT_Face face;
	FT_Error err = FT_Open_Face(freetype_lib, &args, style->face_index, &face);
	if (err) {
	FT_Done_FreeType(freetype_lib);
	return false;
	}

	int face_style = SkTypeface::kNormal;
	if (face->style_flags & FT_STYLE_FLAG_BOLD) {
	face_style \|= SkTypeface::kBold;
	}
	if (face->style_flags & FT_STYLE_FLAG_ITALIC) {
	face_style \|= SkTypeface::kItalic;
	}

	style->face_name.set(face->family_name);
	style->face_style = static_cast<SkTypeface::Style>(face_style);
	style->face_is_fixed_pitch = FT_IS_FIXED_WIDTH(face);
	style->is_face_info_generated = true;

	// Map out this family's characters if they haven't been generated yet.
	if (!is_character_map_generated_) {
	FT_UInt glyph_index;

	int last_page = -1;
	font_character_map::PageCharacters* page_characters = NULL;

	SkUnichar code_point = FT_Get_First_Char(face, &glyph_index);
	while (glyph_index) {
	int page = font_character_map::GetPage(code_point);
	if (page != last_page) {
	page_characters = &character_map_[page];
	last_page = page;
	}
	page_characters->set(
	font_character_map::GetPageCharacterIndex(code_point));

	code_point = FT_Get_Next_Char(face, code_point, &glyph_index);
	}

	is_character_map_generated_ = true;
	}

	// release this font.
	FT_Done_Face(face);

	// shut down FreeType.
	FT_Done_FreeType(freetype_lib);
	return true;
	}

	int SkFontStyleSet_Cobalt::GetClosestStyleIndex(const SkFontStyle& pattern) {
	int closest_index = 0;
	int max_score = std::numeric_limits<int>::min();
	for (int i = 0; i < styles_.count(); ++i) {
	int score = MatchScore(pattern, styles_[i]->font_style);
	if (score > max_score) {
	closest_index = i;
	max_score = score;
	}
	}
	return closest_index;
	}

	void SkFontStyleSet_Cobalt::CreateStreamProviderTypeface(
	SkFontStyleSetEntry_Cobalt* style_entry,
	SkFileMemoryChunkStreamProvider* stream_provider /=NULL/) {
	TRACE_EVENT0("cobalt::renderer",
	"SkFontStyleSet_Cobalt::CreateStreamProviderTypeface()");

	if (!stream_provider) {
	stream_provider = local_typeface_stream_manager_->GetStreamProvider(
	style_entry->font_file_path.c_str());
	}

	SkAutoTUnref<SkFileMemoryChunkStream> stream(stream_provider->OpenStream());
	if (GenerateStyleFaceInfo(style_entry, stream)) {
	LOG(ERROR) << "Scanned font from file: " << style_entry->face_name.c_str()
	<< "(" << style_entry->face_style << ")";
	style_entry->typeface.reset(
	SkNEW_ARGS(SkTypeface_CobaltStreamProvider,
	(stream_provider, style_entry->face_index,
	style_entry->face_style, style_entry->face_is_fixed_pitch,
	family_name_, style_entry->disable_synthetic_bolding)));
	} else {
	LOG(ERROR) << "Failed to scan font: "
	<< style_entry->font_file_path.c_str();
	}
	}