Exemplo n.º 1
0
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());
    String familyNameString(getFamilyNameStringFromFontDescriptionAndFamily(fontDescription, family));
    if (!FcPatternAddString(pattern.get(), FC_FAMILY, reinterpret_cast<const FcChar8*>(familyNameString.utf8().data())))
        return 0;

    bool italic = fontDescription.italic();
    if (!FcPatternAddInteger(pattern.get(), FC_SLANT, italic ? FC_SLANT_ITALIC : FC_SLANT_ROMAN))
        return 0;
    if (!FcPatternAddInteger(pattern.get(), FC_WEIGHT, fontWeightToFontconfigWeight(fontDescription.weight())))
        return 0;
    if (!FcPatternAddDouble(pattern.get(), FC_PIXEL_SIZE, fontDescription.computedPixelSize()))
        return 0;

    // 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 0;

    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 0;

    // 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.
    FontPlatformData* platformData = new FontPlatformData(resultPattern.get(), fontDescription);
    if (!platformData->hasCompatibleCharmap()) {
        delete platformData;
        return 0;
    }

    return platformData;
}
Exemplo n.º 2
0
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;
}