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// Copyright 2015 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.h"
#include <CoreText/CoreText.h>
#import <Foundation/Foundation.h>
#include "base/mac/foundation_util.h"
#import "base/mac/mac_util.h"
#include "base/mac/scoped_cftyperef.h"
#import "base/strings/sys_string_conversions.h"
#include "ui/gfx/font.h"
namespace gfx {
namespace {
// CTFontCreateForString() sometimes re-wraps its result in a new CTFontRef with
// identical attributes. This wastes time shaping the text run and confounds
// Skia's internal typeface cache.
bool FontsEqual(CTFontRef lhs, CTFontRef rhs) {
if (lhs == rhs)
return true;
// Compare ATSFontRef typeface IDs. These are typedef uint32_t. Typically if
// RenderText decided to hunt for a fallback in the first place, this check
// fails and FontsEqual returns here.
if (CTFontGetPlatformFont(lhs, nil) != CTFontGetPlatformFont(rhs, nil))
return false;
// Comparing addresses of descriptors seems to be sufficient for other cases.
base::ScopedCFTypeRef<CTFontDescriptorRef> lhs_descriptor(
base::ScopedCFTypeRef<CTFontDescriptorRef> rhs_descriptor(
return lhs_descriptor.get() == rhs_descriptor.get();
} // namespace
std::vector<Font> GetFallbackFonts(const Font& font) {
// On Mac "There is a system default cascade list (which is polymorphic, based
// on the user's language setting and current font)" - CoreText Programming
// Guide.
NSArray* languages = [[NSUserDefaults standardUserDefaults]
CFArrayRef languages_cf = base::mac::NSToCFCast(languages);
base::ScopedCFTypeRef<CFArrayRef> cascade_list(
static_cast<CTFontRef>(font.GetNativeFont()), languages_cf));
std::vector<Font> fallback_fonts;
if (!cascade_list)
return fallback_fonts; // This should only happen for an invalid |font|.
const CFIndex fallback_count = CFArrayGetCount(cascade_list);
for (CFIndex i = 0; i < fallback_count; ++i) {
CTFontDescriptorRef descriptor =
CFArrayGetValueAtIndex(cascade_list, i));
base::ScopedCFTypeRef<CTFontRef> font(
CTFontCreateWithFontDescriptor(descriptor, 0.0, nullptr));
if (font.get())
if (fallback_fonts.empty())
return std::vector<Font>(1, font);
return fallback_fonts;
bool GetFallbackFont(const Font& font,
const base::char16* text,
int text_length,
Font* result) {
base::ScopedCFTypeRef<CFStringRef> cf_string(
CFStringCreateWithCharactersNoCopy(kCFAllocatorDefault, text, text_length,
CTFontRef ct_font = base::mac::NSToCFCast(font.GetNativeFont());
base::ScopedCFTypeRef<CTFontRef> ct_result(
CTFontCreateForString(ct_font, cf_string, {0, text_length}));
if (FontsEqual(ct_font, ct_result))
return false;
*result = Font(base::mac::CFToNSCast(ct_result.get()));
return true;
} // namespace gfx