blob: d94a4fce1d77c4390fc33cdea4facc07b32096d3 [file] [log] [blame]
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/gfx/font_fallback_win.h"
#include <algorithm>
#include <map>
#include "base/macros.h"
#include "base/memory/singleton.h"
#include "base/metrics/histogram_macros.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/task/current_thread.h"
#include "base/trace_event/trace_event.h"
#include "base/win/registry.h"
#include "ui/gfx/font.h"
#include "ui/gfx/font_fallback.h"
#include "ui/gfx/font_fallback_skia_impl.h"
#include "ui/gfx/platform_font.h"
namespace gfx {
namespace {
// Queries the registry to get a mapping from font filenames to font names.
void QueryFontsFromRegistry(std::map<std::string, std::string>* map) {
const wchar_t* kFonts =
L"Software\\Microsoft\\Windows NT\\CurrentVersion\\Fonts";
base::win::RegistryValueIterator it(HKEY_LOCAL_MACHINE, kFonts);
for (; it.Valid(); ++it) {
const std::string filename =
(*map)[filename] = base::WideToUTF8(it.Name());
// Fills |font_names| with a list of font families found in the font file at
// |filename|. Takes in a |font_map| from font filename to font families, which
// is filled-in by querying the registry, if empty.
void GetFontNamesFromFilename(const std::string& filename,
std::map<std::string, std::string>* font_map,
std::vector<std::string>* font_names) {
if (font_map->empty())
std::map<std::string, std::string>::const_iterator it =
if (it == font_map->end())
internal::ParseFontFamilyString(it->second, font_names);
// Returns true if |text| contains only ASCII digits.
bool ContainsOnlyDigits(const std::string& text) {
return text.find_first_not_of("0123456789") == base::string16::npos;
// Appends a Font with the given |name| and |size| to |fonts| unless the last
// entry is already a font with that name.
void AppendFont(const std::string& name, int size, std::vector<Font>* fonts) {
if (fonts->empty() || fonts->back().GetFontName() != name)
fonts->push_back(Font(name, size));
// Queries the registry to get a list of linked fonts for |font|.
void QueryLinkedFontsFromRegistry(const Font& font,
std::map<std::string, std::string>* font_map,
std::vector<Font>* linked_fonts) {
const wchar_t* kSystemLink =
L"Software\\Microsoft\\Windows NT\\CurrentVersion\\FontLink\\SystemLink";
base::win::RegKey key;
if (FAILED(key.Open(HKEY_LOCAL_MACHINE, kSystemLink, KEY_READ)))
const std::wstring original_font_name = base::UTF8ToWide(font.GetFontName());
std::vector<std::wstring> values;
if (FAILED(key.ReadValues(original_font_name.c_str(), &values))) {
std::string filename;
std::string font_name;
for (size_t i = 0; i < values.size(); ++i) {
base::WideToUTF8(values[i]), &filename, &font_name);
// If the font name is present, add that directly, otherwise add the
// font names corresponding to the filename.
if (!font_name.empty()) {
AppendFont(font_name, font.GetFontSize(), linked_fonts);
} else if (!filename.empty()) {
std::vector<std::string> filename_fonts;
GetFontNamesFromFilename(filename, font_map, &filename_fonts);
for (const std::string& filename_font : filename_fonts)
AppendFont(filename_font, font.GetFontSize(), linked_fonts);
// CachedFontLinkSettings is a singleton cache of the Windows font settings
// from the registry. It maintains a cached view of the registry's list of
// system fonts and their font link chains.
class CachedFontLinkSettings {
static CachedFontLinkSettings* GetInstance();
// Returns the linked fonts list correspond to |font|. Returned value will
// never be null.
const std::vector<Font>* GetLinkedFonts(const Font& font);
friend struct base::DefaultSingletonTraits<CachedFontLinkSettings>;
virtual ~CachedFontLinkSettings();
// Map of system fonts, from file names to font families.
std::map<std::string, std::string> cached_system_fonts_;
// Map from font names to vectors of linked fonts.
std::map<std::string, std::vector<Font> > cached_linked_fonts_;
// static
CachedFontLinkSettings* CachedFontLinkSettings::GetInstance() {
return base::Singleton<
const std::vector<Font>* CachedFontLinkSettings::GetLinkedFonts(
const Font& font) {
const std::string& font_name = font.GetFontName();
std::map<std::string, std::vector<Font> >::const_iterator it =
if (it != cached_linked_fonts_.end())
return &it->second;
std::vector<Font>* linked_fonts = &cached_linked_fonts_[font_name];
QueryLinkedFontsFromRegistry(font, &cached_system_fonts_, linked_fonts);
return linked_fonts;
CachedFontLinkSettings::CachedFontLinkSettings() {
CachedFontLinkSettings::~CachedFontLinkSettings() {
} // namespace
namespace internal {
void ParseFontLinkEntry(const std::string& entry,
std::string* filename,
std::string* font_name) {
std::vector<std::string> parts = base::SplitString(
entry, ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
if (parts.size() > 0)
*filename = parts[0];
// The second entry may be the font name or the first scaling factor, if the
// entry does not contain a font name. If it contains only digits, assume it
// is a scaling factor.
if (parts.size() > 1 && !ContainsOnlyDigits(parts[1]))
*font_name = parts[1];
void ParseFontFamilyString(const std::string& family,
std::vector<std::string>* font_names) {
// The entry is comma separated, having the font filename as the first value
// followed optionally by the font family name and a pair of integer scaling
// factors.
// TODO(asvitkine): Should we support these scaling factors?
*font_names = base::SplitString(family, "&", base::TRIM_WHITESPACE,
if (!font_names->empty()) {
const size_t index = font_names->back().find('(');
if (index != std::string::npos) {
base::TrimWhitespaceASCII(font_names->back(), base::TRIM_TRAILING,
} // namespace internal
std::vector<Font> GetFallbackFonts(const Font& font) {
TRACE_EVENT0("fonts", "gfx::GetFallbackFonts");
std::string font_family = font.GetFontName();
CachedFontLinkSettings* font_link = CachedFontLinkSettings::GetInstance();
// GetLinkedFonts doesn't care about the font size, so we always pass 10.
return *font_link->GetLinkedFonts(Font(font_family, 10));
bool GetFallbackFont(const Font& font,
const std::string& locale,
base::StringPiece16 text,
Font* result) {
TRACE_EVENT0("fonts", "gfx::GetFallbackFont");
// Creating a DirectWrite font fallback can be expensive. It's ok in the
// browser process because we can use the shared system fallback, but in the
// renderer this can cause hangs. Code that needs font fallback in the
// renderer should instead use the font proxy.
// The text passed must be at least length 1.
if (text.empty())
return false;
// Check that we have at least as much text as was claimed. If we have less
// text than expected then DirectWrite will become confused and crash. This
// shouldn't happen, but shows that it happens sometimes.
constexpr base::char16 kNulCharacter = '\0';
if (text.find(kNulCharacter) != base::StringPiece16::npos)
return false;
sk_sp<SkTypeface> fallback_typeface =
GetSkiaFallbackTypeface(font, locale, text);
if (!fallback_typeface)
return false;
// Fallback needs to keep the exact SkTypeface, as re-matching the font using
// family name and styling information loses access to the underlying platform
// font handles and is not guaranteed to result in the correct typeface, see
*result = Font(PlatformFont::CreateFromSkTypeface(
std::move(fallback_typeface), font.GetFontSize(), base::nullopt));
return true;
} // namespace gfx