std::unique_ptr<FontPlatformData> FontCache::createFontPlatformData(const FontDescription& fontDescription, const AtomicString& family)
{
// The CSS font matching algorithm (http://www.w3.org/TR/css3-fonts/#font-matching-algorithm)
// says that we must find an exact match for font family, slant (italic or oblique can be used)
// and font weight (we only match bold/non-bold here).
RefPtr<FcPattern> pattern = adoptRef(FcPatternCreate());
// Never choose unscalable fonts, as they pixelate when displayed at different sizes.
FcPatternAddBool(pattern.get(), FC_SCALABLE, FcTrue);
String familyNameString(getFamilyNameStringFromFamily(family));
if (!FcPatternAddString(pattern.get(), FC_FAMILY, reinterpret_cast<const FcChar8*>(familyNameString.utf8().data())))
return nullptr;
bool italic = fontDescription.italic();
if (!FcPatternAddInteger(pattern.get(), FC_SLANT, italic ? FC_SLANT_ITALIC : FC_SLANT_ROMAN))
return nullptr;
if (!FcPatternAddInteger(pattern.get(), FC_WEIGHT, fontWeightToFontconfigWeight(fontDescription.weight())))
return nullptr;
if (!FcPatternAddDouble(pattern.get(), FC_PIXEL_SIZE, fontDescription.computedPixelSize()))
return nullptr;
// The strategy is originally from Skia (src/ports/SkFontHost_fontconfig.cpp):
// Allow Fontconfig to do pre-match substitution. Unless we are accessing a "fallback"
// family like "sans," this is the only time we allow Fontconfig to substitute one
// family name for another (i.e. if the fonts are aliased to each other).
FcConfigSubstitute(0, pattern.get(), FcMatchPattern);
FcDefaultSubstitute(pattern.get());
FcChar8* fontConfigFamilyNameAfterConfiguration;
FcPatternGetString(pattern.get(), FC_FAMILY, 0, &fontConfigFamilyNameAfterConfiguration);
String familyNameAfterConfiguration = String::fromUTF8(reinterpret_cast<char*>(fontConfigFamilyNameAfterConfiguration));
FcResult fontConfigResult;
RefPtr<FcPattern> resultPattern = adoptRef(FcFontMatch(0, pattern.get(), &fontConfigResult));
if (!resultPattern) // No match.
return nullptr;
FcChar8* fontConfigFamilyNameAfterMatching;
FcPatternGetString(resultPattern.get(), FC_FAMILY, 0, &fontConfigFamilyNameAfterMatching);
String familyNameAfterMatching = String::fromUTF8(reinterpret_cast<char*>(fontConfigFamilyNameAfterMatching));
// If Fontconfig gave use a different font family than the one we requested, we should ignore it
// and allow WebCore to give us the next font on the CSS fallback list. The only exception is if
// this family name is a commonly used generic family.
if (!equalIgnoringCase(familyNameAfterConfiguration, familyNameAfterMatching)
&& !(equalIgnoringCase(familyNameString, "sans") || equalIgnoringCase(familyNameString, "sans-serif")
|| equalIgnoringCase(familyNameString, "serif") || equalIgnoringCase(familyNameString, "monospace")
|| equalIgnoringCase(familyNameString, "fantasy") || equalIgnoringCase(familyNameString, "cursive")))
return nullptr;
// Verify that this font has an encoding compatible with Fontconfig. Fontconfig currently
// supports three encodings in FcFreeTypeCharIndex: Unicode, Symbol and AppleRoman.
// If this font doesn't have one of these three encodings, don't select it.
auto platformData = std::make_unique<FontPlatformData>(resultPattern.get(), fontDescription);
if (!platformData->hasCompatibleCharmap())
return nullptr;
return platformData;
}
std::unique_ptr<FontPlatformData> FontCache::createFontPlatformData(const FontDescription& fontDescription, const AtomicString& family)
{
// The CSS font matching algorithm (http://www.w3.org/TR/css3-fonts/#font-matching-algorithm)
// says that we must find an exact match for font family, slant (italic or oblique can be used)
// and font weight (we only match bold/non-bold here).
RefPtr<FcPattern> pattern = adoptRef(FcPatternCreate());
// Never choose unscalable fonts, as they pixelate when displayed at different sizes.
FcPatternAddBool(pattern.get(), FC_SCALABLE, FcTrue);
String familyNameString(getFamilyNameStringFromFamily(family));
if (!FcPatternAddString(pattern.get(), FC_FAMILY, reinterpret_cast<const FcChar8*>(familyNameString.utf8().data())))
return nullptr;
bool italic = fontDescription.italic();
if (!FcPatternAddInteger(pattern.get(), FC_SLANT, italic ? FC_SLANT_ITALIC : FC_SLANT_ROMAN))
return nullptr;
if (!FcPatternAddInteger(pattern.get(), FC_WEIGHT, fontWeightToFontconfigWeight(fontDescription.weight())))
return nullptr;
if (!FcPatternAddDouble(pattern.get(), FC_PIXEL_SIZE, fontDescription.computedPixelSize()))
return nullptr;
// The strategy is originally from Skia (src/ports/SkFontHost_fontconfig.cpp):
//
// We do not normally allow fontconfig to substitute one font family for another, since this
// would break CSS font family fallback: the website should be in control of fallback. During
// normal font matching, the only font family substitution permitted is for generic families
// (sans, serif, monospace) or for strongly-aliased fonts (which are to be treated as
// effectively identical). This is because the font matching step is designed to always find a
// match for the font, which we don't want.
//
// Fontconfig is used in two stages: (1) configuration and (2) matching. During the
// configuration step, before any matching occurs, we allow arbitrary family substitutions,
// since this is an exact matter of respecting the user's font configuration.
FcConfigSubstitute(nullptr, pattern.get(), FcMatchPattern);
FcDefaultSubstitute(pattern.get());
FcChar8* fontConfigFamilyNameAfterConfiguration;
FcPatternGetString(pattern.get(), FC_FAMILY, 0, &fontConfigFamilyNameAfterConfiguration);
String familyNameAfterConfiguration = String::fromUTF8(reinterpret_cast<char*>(fontConfigFamilyNameAfterConfiguration));
FcResult fontConfigResult;
RefPtr<FcPattern> resultPattern = adoptRef(FcFontMatch(nullptr, pattern.get(), &fontConfigResult));
if (!resultPattern) // No match.
return nullptr;
FcChar8* fontConfigFamilyNameAfterMatching;
FcPatternGetString(resultPattern.get(), FC_FAMILY, 0, &fontConfigFamilyNameAfterMatching);
String familyNameAfterMatching = String::fromUTF8(reinterpret_cast<char*>(fontConfigFamilyNameAfterMatching));
// If Fontconfig gave us a different font family than the one we requested, we should ignore it
// and allow WebCore to give us the next font on the CSS fallback list. The exceptions are if
// this family name is a commonly-used generic family, or if the families are strongly-aliased.
// Checking for a strong alias comes last, since it is slow.
if (!equalIgnoringCase(familyNameAfterConfiguration, familyNameAfterMatching)
&& !(equalIgnoringCase(familyNameString, "sans") || equalIgnoringCase(familyNameString, "sans-serif")
|| equalIgnoringCase(familyNameString, "serif") || equalIgnoringCase(familyNameString, "monospace")
|| equalIgnoringCase(familyNameString, "fantasy") || equalIgnoringCase(familyNameString, "cursive"))
&& !areStronglyAliased(familyNameAfterConfiguration, familyNameAfterMatching))
return nullptr;
// Verify that this font has an encoding compatible with Fontconfig. Fontconfig currently
// supports three encodings in FcFreeTypeCharIndex: Unicode, Symbol and AppleRoman.
// If this font doesn't have one of these three encodings, don't select it.
auto platformData = std::make_unique<FontPlatformData>(resultPattern.get(), fontDescription);
if (!platformData->hasCompatibleCharmap())
return nullptr;
return platformData;
}
