path: root/src/gui/text/unix/qfontconfigdatabase.cpp

// Copyright (C) 2019 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#include "qfontconfigdatabase_p.h"
#include "qfontenginemultifontconfig_p.h"

#include <QtGui/private/qfontengine_ft_p.h>

#include <QtCore/QList>
#include <QtCore/QElapsedTimer>
#include <QtCore/QFile>

#include <qpa/qplatformnativeinterface.h>
#include <qpa/qplatformscreen.h>
#include <qpa/qplatformintegration.h>
#include <qpa/qplatformservices.h>

#include <QtGui/private/qguiapplication_p.h>
#include <QtGui/private/qhighdpiscaling_p.h>

#include <QtGui/qguiapplication.h>

#include <QtCore/private/qduplicatetracker_p.h>

#include <fontconfig/fontconfig.h>
#if FC_VERSION >= 20402
#include <fontconfig/fcfreetype.h>
#endif

QT_BEGIN_NAMESPACE

static inline int mapToQtWeightForRange(int fcweight, int fcLower, int fcUpper, int qtLower, int qtUpper)
{
    return qtLower + ((fcweight - fcLower) * (qtUpper - qtLower)) / (fcUpper - fcLower);
}

static inline int weightFromFcWeight(int fcweight)
{
    // Font Config uses weights from 0 to 215 (the highest enum value) while QFont ranges from
    // 1 to 1000. The spacing between the values for the enums are uneven so a linear mapping from
    // Font Config values to Qt would give surprising results.  So, we do a piecewise linear
    // mapping.  This ensures that where there is a corresponding enum on both sides (for example
    // FC_WEIGHT_DEMIBOLD and QFont::DemiBold) we map one to the other but other values map
    // to intermediate Qt weights.

    if (fcweight <= FC_WEIGHT_THIN)
        return QFont::Thin;
    if (fcweight <= FC_WEIGHT_ULTRALIGHT)
        return mapToQtWeightForRange(fcweight, FC_WEIGHT_THIN, FC_WEIGHT_ULTRALIGHT, QFont::Thin, QFont::ExtraLight);
    if (fcweight <= FC_WEIGHT_LIGHT)
        return mapToQtWeightForRange(fcweight, FC_WEIGHT_ULTRALIGHT, FC_WEIGHT_LIGHT, QFont::ExtraLight, QFont::Light);
    if (fcweight <= FC_WEIGHT_NORMAL)
        return mapToQtWeightForRange(fcweight, FC_WEIGHT_LIGHT, FC_WEIGHT_NORMAL, QFont::Light, QFont::Normal);
    if (fcweight <= FC_WEIGHT_MEDIUM)
        return mapToQtWeightForRange(fcweight, FC_WEIGHT_NORMAL, FC_WEIGHT_MEDIUM, QFont::Normal, QFont::Medium);
    if (fcweight <= FC_WEIGHT_DEMIBOLD)
        return mapToQtWeightForRange(fcweight, FC_WEIGHT_MEDIUM, FC_WEIGHT_DEMIBOLD, QFont::Medium, QFont::DemiBold);
    if (fcweight <= FC_WEIGHT_BOLD)
        return mapToQtWeightForRange(fcweight, FC_WEIGHT_DEMIBOLD, FC_WEIGHT_BOLD, QFont::DemiBold, QFont::Bold);
    if (fcweight <= FC_WEIGHT_ULTRABOLD)
        return mapToQtWeightForRange(fcweight, FC_WEIGHT_BOLD, FC_WEIGHT_ULTRABOLD, QFont::Bold, QFont::ExtraBold);
    if (fcweight <= FC_WEIGHT_BLACK)
        return mapToQtWeightForRange(fcweight, FC_WEIGHT_ULTRABOLD, FC_WEIGHT_BLACK, QFont::ExtraBold, QFont::Black);
    if (fcweight <= FC_WEIGHT_ULTRABLACK)
        return mapToQtWeightForRange(fcweight, FC_WEIGHT_BLACK, FC_WEIGHT_ULTRABLACK, QFont::Black,
                                     QFONT_WEIGHT_MAX);
    return QFONT_WEIGHT_MAX;
}

static inline int stretchFromFcWidth(int fcwidth)
{
    // Font Config enums for width match pretty closely with those used by Qt so just use
    // Font Config values directly while enforcing the same limits imposed by QFont.
    const int maxStretch = 4000;
    int qtstretch;
    if (fcwidth < 1)
        qtstretch = 1;
    else if (fcwidth > maxStretch)
        qtstretch = maxStretch;
    else
        qtstretch = fcwidth;

    return qtstretch;
}

static const char specialLanguages[][6] = {
    "", // Unknown
    "", // Inherited
    "", // Common
    "en", // Latin
    "el", // Greek
    "ru", // Cyrillic
    "hy", // Armenian
    "he", // Hebrew
    "ar", // Arabic
    "syr", // Syriac
    "dv", // Thaana
    "hi", // Devanagari
    "bn", // Bengali
    "pa", // Gurmukhi
    "gu", // Gujarati
    "or", // Oriya
    "ta", // Tamil
    "te", // Telugu
    "kn", // Kannada
    "ml", // Malayalam
    "si", // Sinhala
    "th", // Thai
    "lo", // Lao
    "bo", // Tibetan
    "my", // Myanmar
    "ka", // Georgian
    "ko", // Hangul
    "am", // Ethiopic
    "chr", // Cherokee
    "cr", // CanadianAboriginal
    "sga", // Ogham
    "non", // Runic
    "km", // Khmer
    "mn", // Mongolian
    "ja", // Hiragana
    "ja", // Katakana
    "zh-TW", // Bopomofo
    "", // Han
    "ii", // Yi
    "ett", // OldItalic
    "got", // Gothic
    "en", // Deseret
    "fil", // Tagalog
    "hnn", // Hanunoo
    "bku", // Buhid
    "tbw", // Tagbanwa
    "cop", // Coptic
    "lif", // Limbu
    "tdd", // TaiLe
    "grc", // LinearB
    "uga", // Ugaritic
    "en", // Shavian
    "so", // Osmanya
    "grc", // Cypriot
    "", // Braille
    "bug", // Buginese
    "khb", // NewTaiLue
    "cu", // Glagolitic
    "shi", // Tifinagh
    "syl", // SylotiNagri
    "peo", // OldPersian
    "pra", // Kharoshthi
    "ban", // Balinese
    "akk", // Cuneiform
    "phn", // Phoenician
    "lzh", // PhagsPa
    "man", // Nko
    "su", // Sundanese
    "lep", // Lepcha
    "sat", // OlChiki
    "vai", // Vai
    "saz", // Saurashtra
    "eky", // KayahLi
    "rej", // Rejang
    "xlc", // Lycian
    "xcr", // Carian
    "xld", // Lydian
    "cjm", // Cham
    "nod", // TaiTham
    "blt", // TaiViet
    "ae", // Avestan
    "egy", // EgyptianHieroglyphs
    "smp", // Samaritan
    "lis", // Lisu
    "bax", // Bamum
    "jv", // Javanese
    "mni", // MeeteiMayek
    "arc", // ImperialAramaic
    "xsa", // OldSouthArabian
    "xpr", // InscriptionalParthian
    "pal", // InscriptionalPahlavi
    "otk", // OldTurkic
    "bh", // Kaithi
    "bbc", // Batak
    "pra", // Brahmi
    "myz", // Mandaic
    "ccp", // Chakma
    "xmr", // MeroiticCursive
    "xmr", // MeroiticHieroglyphs
    "hmd", // Miao
    "sa", // Sharada
    "srb", // SoraSompeng
    "doi", // Takri
    "lez", // CaucasianAlbanian
    "bsq", // BassaVah
    "fr", // Duployan
    "sq", // Elbasan
    "sa", // Grantha
    "hnj", // PahawhHmong
    "sd", // Khojki
    "lab", // LinearA
    "hi", // Mahajani
    "xmn", // Manichaean
    "men", // MendeKikakui
    "mr", // Modi
    "mru", // Mro
    "xna", // OldNorthArabian
    "arc", // Nabataean
    "arc", // Palmyrene
    "ctd", // PauCinHau
    "kv", // OldPermic
    "pal", // PsalterPahlavi
    "sa", // Siddham
    "sd", // Khudawadi
    "mai", // Tirhuta
    "hoc", // WarangCiti
    "", // Ahom
    "", // AnatolianHieroglyphs
    "", // Hatran
    "", // Multani
    "", // OldHungarian
    "", // SignWriting
    "", // Adlam
    "", // Bhaiksuki
    "", // Marchen
    "", // Newa
    "", // Osage
    "", // Tangut
    "", // MasaramGondi
    "", // Nushu
    "", // Soyombo
    "", // ZanabazarSquare
    "", // Dogra
    "", // GunjalaGondi
    "", // HanifiRohingya
    "", // Makasar
    "", // Medefaidrin
    "", // OldSogdian
    "", // Sogdian
    "", // Elymaic
    "", // Nandinagari
    "", // NyiakengPuachueHmong
    "", // Wancho
    "", // Chorasmian
    "", // DivesAkuru
    "", // KhitanSmallScript
    "", // Yezidi
    "", // CyproMinoan
    "", // OldUyghur
    "", // Tangsa
    "", // Toto
    "", // Vithkuqi
};
static_assert(sizeof specialLanguages / sizeof *specialLanguages == QChar::ScriptCount);

// this could become a list of all languages used for each writing
// system, instead of using the single most common language.
static const char languageForWritingSystem[][6] = {
    "",     // Any
    "en",  // Latin
    "el",  // Greek
    "ru",  // Cyrillic
    "hy",  // Armenian
    "he",  // Hebrew
    "ar",  // Arabic
    "syr", // Syriac
    "div", // Thaana
    "hi",  // Devanagari
    "bn",  // Bengali
    "pa",  // Gurmukhi
    "gu",  // Gujarati
    "or",  // Oriya
    "ta",  // Tamil
    "te",  // Telugu
    "kn",  // Kannada
    "ml",  // Malayalam
    "si",  // Sinhala
    "th",  // Thai
    "lo",  // Lao
    "bo",  // Tibetan
    "my",  // Myanmar
    "ka",  // Georgian
    "km",  // Khmer
    "zh-cn", // SimplifiedChinese
    "zh-tw", // TraditionalChinese
    "ja",  // Japanese
    "ko",  // Korean
    "vi",  // Vietnamese
    "", // Symbol
    "sga", // Ogham
    "non", // Runic
    "man" // N'Ko
};
static_assert(sizeof languageForWritingSystem / sizeof *languageForWritingSystem == QFontDatabase::WritingSystemsCount);

#if FC_VERSION >= 20297
// Newer FontConfig let's us sort out fonts that report certain scripts support,
// but no open type tables for handling them correctly.
// Check the reported script presence in the FC_CAPABILITY's "otlayout:" section.
static const char capabilityForWritingSystem[][5] = {
    "",     // Any
    "",  // Latin
    "",  // Greek
    "",  // Cyrillic
    "",  // Armenian
    "",  // Hebrew
    "",  // Arabic
    "syrc",  // Syriac
    "thaa",  // Thaana
    "deva",  // Devanagari
    "beng",  // Bengali
    "guru",  // Gurmukhi
    "gujr",  // Gujarati
    "orya",  // Oriya
    "taml",  // Tamil
    "telu",  // Telugu
    "knda",  // Kannada
    "mlym",  // Malayalam
    "sinh",  // Sinhala
    "",  // Thai
    "",  // Lao
    "tibt",  // Tibetan
    "mymr",  // Myanmar
    "",  // Georgian
    "khmr",  // Khmer
    "", // SimplifiedChinese
    "", // TraditionalChinese
    "",  // Japanese
    "",  // Korean
    "",  // Vietnamese
    "", // Symbol
    "", // Ogham
    "", // Runic
    "nko " // N'Ko
};
static_assert(sizeof(capabilityForWritingSystem) / sizeof(*capabilityForWritingSystem) == QFontDatabase::WritingSystemsCount);
#endif

static const char *getFcFamilyForStyleHint(const QFont::StyleHint style)
{
    const char *stylehint = nullptr;
    switch (style) {
    case QFont::SansSerif:
        stylehint = "sans-serif";
        break;
    case QFont::Serif:
        stylehint = "serif";
        break;
    case QFont::TypeWriter:
    case QFont::Monospace:
        stylehint = "monospace";
        break;
    case QFont::Cursive:
        stylehint = "cursive";
        break;
    case QFont::Fantasy:
        stylehint = "fantasy";
        break;
    default:
        break;
    }
    return stylehint;
}

static inline bool requiresOpenType(int writingSystem)
{
    return ((writingSystem >= QFontDatabase::Syriac && writingSystem <= QFontDatabase::Sinhala)
            || writingSystem == QFontDatabase::Khmer || writingSystem == QFontDatabase::Nko);
}

static void populateFromPattern(FcPattern *pattern, QFontDatabasePrivate::ApplicationFont *applicationFont = nullptr)
{
    QString familyName;
    QString familyNameLang;
    FcChar8 *value = nullptr;
    int weight_value;
    int slant_value;
    int spacing_value;
    int width_value;
    FcChar8 *file_value;
    int indexValue;
    FcChar8 *foundry_value;
    FcChar8 *style_value;
    FcBool scalable;
    FcBool antialias;

    if (FcPatternGetString(pattern, FC_FAMILY, 0, &value) != FcResultMatch)
        return;

    familyName = QString::fromUtf8((const char *)value);

    if (FcPatternGetString(pattern, FC_FAMILYLANG, 0, &value) == FcResultMatch)
        familyNameLang = QString::fromUtf8((const char *)value);

    slant_value = FC_SLANT_ROMAN;
    weight_value = FC_WEIGHT_REGULAR;
    spacing_value = FC_PROPORTIONAL;
    file_value = nullptr;
    indexValue = 0;
    scalable = FcTrue;


    if (FcPatternGetInteger(pattern, FC_SLANT, 0, &slant_value) != FcResultMatch)
        slant_value = FC_SLANT_ROMAN;
    if (FcPatternGetInteger(pattern, FC_WEIGHT, 0, &weight_value) != FcResultMatch)
        weight_value = FC_WEIGHT_REGULAR;
    if (FcPatternGetInteger(pattern, FC_WIDTH, 0, &width_value) != FcResultMatch)
        width_value = FC_WIDTH_NORMAL;
    if (FcPatternGetInteger(pattern, FC_SPACING, 0, &spacing_value) != FcResultMatch)
        spacing_value = FC_PROPORTIONAL;
    if (FcPatternGetString(pattern, FC_FILE, 0, &file_value) != FcResultMatch)
        file_value = nullptr;
    if (FcPatternGetInteger(pattern, FC_INDEX, 0, &indexValue) != FcResultMatch)
        indexValue = 0;
    if (FcPatternGetBool(pattern, FC_SCALABLE, 0, &scalable) != FcResultMatch)
        scalable = FcTrue;
    if (FcPatternGetString(pattern, FC_FOUNDRY, 0, &foundry_value) != FcResultMatch)
        foundry_value = nullptr;
    if (FcPatternGetString(pattern, FC_STYLE, 0, &style_value) != FcResultMatch)
        style_value = nullptr;
    if (FcPatternGetBool(pattern,FC_ANTIALIAS,0,&antialias) != FcResultMatch)
        antialias = true;

    QSupportedWritingSystems writingSystems;
    FcLangSet *langset = nullptr;
    FcResult res = FcPatternGetLangSet(pattern, FC_LANG, 0, &langset);
    if (res == FcResultMatch) {
        bool hasLang = false;
#if FC_VERSION >= 20297
        FcChar8 *cap = nullptr;
        FcResult capRes = FcResultNoMatch;
#endif
        for (int j = 1; j < QFontDatabase::WritingSystemsCount; ++j) {
            const FcChar8 *lang = (const FcChar8*) languageForWritingSystem[j];
            if (lang) {
                FcLangResult langRes = FcLangSetHasLang(langset, lang);
                if (langRes != FcLangDifferentLang) {
#if FC_VERSION >= 20297
                    if (*capabilityForWritingSystem[j] && requiresOpenType(j)) {
                        if (cap == nullptr)
                            capRes = FcPatternGetString(pattern, FC_CAPABILITY, 0, &cap);
                        if (capRes == FcResultMatch && strstr(reinterpret_cast<const char *>(cap), capabilityForWritingSystem[j]) == nullptr)
                            continue;
                    }
#endif
                    writingSystems.setSupported(QFontDatabase::WritingSystem(j));
                    hasLang = true;
                }
            }
        }
        if (!hasLang)
            // none of our known languages, add it to the other set
            writingSystems.setSupported(QFontDatabase::Other);
    } else {
        // we set Other to supported for symbol fonts. It makes no
        // sense to merge these with other ones, as they are
        // special in a way.
        writingSystems.setSupported(QFontDatabase::Other);
    }

    FontFile *fontFile = new FontFile;
    fontFile->fileName = QString::fromLocal8Bit((const char *)file_value);
    fontFile->indexValue = indexValue;

    QFont::Style style = (slant_value == FC_SLANT_ITALIC)
                     ? QFont::StyleItalic
                     : ((slant_value == FC_SLANT_OBLIQUE)
                        ? QFont::StyleOblique
                        : QFont::StyleNormal);
    // Note: weight should really be an int but registerFont incorrectly uses an enum
    QFont::Weight weight = QFont::Weight(weightFromFcWeight(weight_value));

    double pixel_size = 0;
    if (!scalable)
        FcPatternGetDouble (pattern, FC_PIXEL_SIZE, 0, &pixel_size);

    bool fixedPitch = spacing_value >= FC_MONO;
    // Note: stretch should really be an int but registerFont incorrectly uses an enum
    QFont::Stretch stretch = QFont::Stretch(stretchFromFcWidth(width_value));
    QString styleName = style_value ? QString::fromUtf8((const char *) style_value) : QString();

    if (applicationFont != nullptr) {
        QFontDatabasePrivate::ApplicationFont::Properties properties;
        properties.familyName = familyName;
        properties.styleName = styleName;
        properties.weight = weight;
        properties.style = style;
        properties.stretch = stretch;

        applicationFont->properties.append(properties);
    }

    QPlatformFontDatabase::registerFont(familyName,styleName,QLatin1StringView((const char *)foundry_value),weight,style,stretch,antialias,scalable,pixel_size,fixedPitch,writingSystems,fontFile);
//        qDebug() << familyName << (const char *)foundry_value << weight << style << &writingSystems << scalable << true << pixel_size;

    for (int k = 1; FcPatternGetString(pattern, FC_FAMILY, k, &value) == FcResultMatch; ++k) {
        const QString altFamilyName = QString::fromUtf8((const char *)value);
        // Extra family names can be aliases or subfamilies.
        // If it is a subfamily, register it as a separate font, so only members of the subfamily are
        // matched when the subfamily is requested.
        QString altStyleName;
        if (FcPatternGetString(pattern, FC_STYLE, k, &value) == FcResultMatch)
            altStyleName = QString::fromUtf8((const char *)value);
        else
            altStyleName = styleName;

        QString altFamilyNameLang;
        if (FcPatternGetString(pattern, FC_FAMILYLANG, k, &value) == FcResultMatch)
            altFamilyNameLang = QString::fromUtf8((const char *)value);
        else
            altFamilyNameLang = familyNameLang;

        if (familyNameLang == altFamilyNameLang && altStyleName != styleName) {
            if (applicationFont != nullptr) {
                QFontDatabasePrivate::ApplicationFont::Properties properties;
                properties.familyName = altFamilyName;
                properties.styleName = altStyleName;
                properties.weight = weight;
                properties.style = style;
                properties.stretch = stretch;

                applicationFont->properties.append(properties);
            }
            FontFile *altFontFile = new FontFile(*fontFile);
            QPlatformFontDatabase::registerFont(altFamilyName, altStyleName, QLatin1StringView((const char *)foundry_value),weight,style,stretch,antialias,scalable,pixel_size,fixedPitch,writingSystems,altFontFile);
        } else {
            QPlatformFontDatabase::registerAliasToFontFamily(familyName, altFamilyName);
        }
    }

}

QFontconfigDatabase::~QFontconfigDatabase()
{
    FcConfigDestroy(FcConfigGetCurrent());
}

void QFontconfigDatabase::populateFontDatabase()
{
    FcInit();
    FcFontSet  *fonts;

    {
        FcObjectSet *os = FcObjectSetCreate();
        FcPattern *pattern = FcPatternCreate();
        const char *properties [] = {
            FC_FAMILY, FC_STYLE, FC_WEIGHT, FC_SLANT,
            FC_SPACING, FC_FILE, FC_INDEX,
            FC_LANG, FC_CHARSET, FC_FOUNDRY, FC_SCALABLE, FC_PIXEL_SIZE,
            FC_WIDTH, FC_FAMILYLANG,
#if FC_VERSION >= 20297
            FC_CAPABILITY,
#endif
            (const char *)nullptr
        };
        const char **p = properties;
        while (*p) {
            FcObjectSetAdd(os, *p);
            ++p;
        }
        fonts = FcFontList(nullptr, pattern, os);
        FcObjectSetDestroy(os);
        FcPatternDestroy(pattern);
        if (!fonts)
            return;
    }

    for (int i = 0; i < fonts->nfont; i++)
        populateFromPattern(fonts->fonts[i]);

    FcFontSetDestroy (fonts);

    struct FcDefaultFont {
        const char *qtname;
        const char *rawname;
        bool fixed;
    };
    const FcDefaultFont defaults[] = {
        { "Serif", "serif", false },
        { "Sans Serif", "sans-serif", false },
        { "Monospace", "monospace", true },
        { nullptr, nullptr, false }
    };
    const FcDefaultFont *f = defaults;
    // aliases only make sense for 'common', not for any of the specials
    QSupportedWritingSystems ws;
    ws.setSupported(QFontDatabase::Latin);

    while (f->qtname) {
        QString familyQtName = QString::fromLatin1(f->qtname);
        registerFont(familyQtName,QString(),QString(),QFont::Normal,QFont::StyleNormal,QFont::Unstretched,true,true,0,f->fixed,ws,nullptr);
        registerFont(familyQtName,QString(),QString(),QFont::Normal,QFont::StyleItalic,QFont::Unstretched,true,true,0,f->fixed,ws,nullptr);
        registerFont(familyQtName,QString(),QString(),QFont::Normal,QFont::StyleOblique,QFont::Unstretched,true,true,0,f->fixed,ws,nullptr);
        ++f;
    }

    //QPA has very lazy population of the font db. We want it to be initialized when
    //QApplication is constructed, so that the population procedure can do something like this to
    //set the default font
//    const FcDefaultFont *s = defaults;
//    QFont font("Sans Serif");
//    font.setPointSize(9);
//    QApplication::setFont(font);
}

void QFontconfigDatabase::invalidate()
{
    // Clear app fonts.
    FcConfigAppFontClear(nullptr);
}

QFontEngineMulti *QFontconfigDatabase::fontEngineMulti(QFontEngine *fontEngine, QChar::Script script)
{
    return new QFontEngineMultiFontConfig(fontEngine, script);
}

namespace {
QFontEngine::HintStyle defaultHintStyleFromMatch(QFont::HintingPreference hintingPreference, FcPattern *match, bool useXftConf)
{
    switch (hintingPreference) {
    case QFont::PreferNoHinting:
        return QFontEngine::HintNone;
    case QFont::PreferVerticalHinting:
        return QFontEngine::HintLight;
    case QFont::PreferFullHinting:
        return QFontEngine::HintFull;
    case QFont::PreferDefaultHinting:
        break;
    }

    if (QHighDpiScaling::isActive())
        return QFontEngine::HintNone;

    int hint_style = 0;
    if (FcPatternGetInteger (match, FC_HINT_STYLE, 0, &hint_style) == FcResultMatch) {
        switch (hint_style) {
        case FC_HINT_NONE:
            return QFontEngine::HintNone;
        case FC_HINT_SLIGHT:
            return QFontEngine::HintLight;
        case FC_HINT_MEDIUM:
            return QFontEngine::HintMedium;
        case FC_HINT_FULL:
            return QFontEngine::HintFull;
        default:
            Q_UNREACHABLE();
            break;
        }
    }

    if (useXftConf) {
        void *hintStyleResource =
                QGuiApplication::platformNativeInterface()->nativeResourceForScreen("hintstyle",
                                                                                    QGuiApplication::primaryScreen());
        int hintStyle = int(reinterpret_cast<qintptr>(hintStyleResource));
        if (hintStyle > 0)
            return QFontEngine::HintStyle(hintStyle - 1);
    }

    return QFontEngine::HintFull;
}

QFontEngine::SubpixelAntialiasingType subpixelTypeFromMatch(FcPattern *match, bool useXftConf)
{
    int subpixel = FC_RGBA_UNKNOWN;
    if (FcPatternGetInteger(match, FC_RGBA, 0, &subpixel) == FcResultMatch) {
        switch (subpixel) {
        case FC_RGBA_UNKNOWN:
        case FC_RGBA_NONE:
            return QFontEngine::Subpixel_None;
        case FC_RGBA_RGB:
            return QFontEngine::Subpixel_RGB;
        case FC_RGBA_BGR:
            return QFontEngine::Subpixel_BGR;
        case FC_RGBA_VRGB:
            return QFontEngine::Subpixel_VRGB;
        case FC_RGBA_VBGR:
            return QFontEngine::Subpixel_VBGR;
        default:
            Q_UNREACHABLE();
            break;
        }
    }

    if (useXftConf) {
        void *subpixelTypeResource =
                QGuiApplication::platformNativeInterface()->nativeResourceForScreen("subpixeltype",
                                                                                    QGuiApplication::primaryScreen());
        int subpixelType = int(reinterpret_cast<qintptr>(subpixelTypeResource));
        if (subpixelType > 0)
            return QFontEngine::SubpixelAntialiasingType(subpixelType - 1);
    }

    return QFontEngine::Subpixel_None;
}
} // namespace

QFontEngine *QFontconfigDatabase::fontEngine(const QFontDef &f, void *usrPtr)
{
    if (!usrPtr)
        return nullptr;

    FontFile *fontfile = static_cast<FontFile *> (usrPtr);
    QFontEngine::FaceId fid;
    fid.filename = QFile::encodeName(fontfile->fileName);
    fid.index = fontfile->indexValue;

    // FIXME: Unify with logic in QFontEngineFT::create()
    QFontEngineFT *engine = new QFontEngineFT(f);
    engine->face_id = fid;

    setupFontEngine(engine, f);

    if (!engine->init(fid, engine->antialias, engine->defaultFormat) || engine->invalid()) {
        delete engine;
        engine = nullptr;
    }

    return engine;
}

QFontEngine *QFontconfigDatabase::fontEngine(const QByteArray &fontData, qreal pixelSize, QFont::HintingPreference hintingPreference)
{
    QFontEngineFT *engine = static_cast<QFontEngineFT*>(QFreeTypeFontDatabase::fontEngine(fontData, pixelSize, hintingPreference));
    if (engine == nullptr)
        return nullptr;

    setupFontEngine(engine, engine->fontDef);

    return engine;
}

QStringList QFontconfigDatabase::fallbacksForFamily(const QString &family, QFont::Style style, QFont::StyleHint styleHint, QChar::Script script) const
{
    QStringList fallbackFamilies;
    FcPattern *pattern = FcPatternCreate();
    if (!pattern)
        return fallbackFamilies;

    FcValue value;
    value.type = FcTypeString;
    const QByteArray cs = family.toUtf8();
    value.u.s = (const FcChar8 *)cs.data();
    FcPatternAdd(pattern,FC_FAMILY,value,true);

    int slant_value = FC_SLANT_ROMAN;
    if (style == QFont::StyleItalic)
        slant_value = FC_SLANT_ITALIC;
    else if (style == QFont::StyleOblique)
        slant_value = FC_SLANT_OBLIQUE;
    FcPatternAddInteger(pattern, FC_SLANT, slant_value);

    Q_ASSERT(uint(script) < QChar::ScriptCount);
    if (*specialLanguages[script] != '\0') {
        FcLangSet *ls = FcLangSetCreate();
        FcLangSetAdd(ls, (const FcChar8*)specialLanguages[script]);
        FcPatternAddLangSet(pattern, FC_LANG, ls);
        FcLangSetDestroy(ls);
    } else if (!family.isEmpty()) {
        // If script is Common or Han, then it may include languages like CJK,
        // we should attach system default language set to the pattern
        // to obtain correct font fallback list (i.e. if LANG=zh_CN
        // then we normally want to use a Chinese font for CJK text;
        // while a Japanese font should be used for that if LANG=ja)
        FcPattern *dummy = FcPatternCreate();
        FcDefaultSubstitute(dummy);
        FcChar8 *lang = nullptr;
        FcResult res = FcPatternGetString(dummy, FC_LANG, 0, &lang);
        if (res == FcResultMatch)
            FcPatternAddString(pattern, FC_LANG, lang);
        FcPatternDestroy(dummy);
    }

    const char *stylehint = getFcFamilyForStyleHint(styleHint);
    if (stylehint) {
        value.u.s = (const FcChar8 *)stylehint;
        FcPatternAddWeak(pattern, FC_FAMILY, value, FcTrue);
    }

    FcConfigSubstitute(nullptr, pattern, FcMatchPattern);
    FcDefaultSubstitute(pattern);

    FcResult result = FcResultMatch;
    FcFontSet *fontSet = FcFontSort(nullptr,pattern,FcFalse,nullptr,&result);
    FcPatternDestroy(pattern);

    if (fontSet) {
        QDuplicateTracker<QString> duplicates(fontSet->nfont + 1);
        (void)duplicates.hasSeen(family.toCaseFolded());
        for (int i = 0; i < fontSet->nfont; i++) {
            FcChar8 *value = nullptr;
            if (FcPatternGetString(fontSet->fonts[i], FC_FAMILY, 0, &value) != FcResultMatch)
                continue;
            //         capitalize(value);
            const QString familyName = QString::fromUtf8((const char *)value);
            const QString familyNameCF = familyName.toCaseFolded();
            if (!duplicates.hasSeen(familyNameCF)) {
                fallbackFamilies << familyName;
            }
        }
        FcFontSetDestroy(fontSet);
    }
//    qDebug() << "fallbackFamilies for:" << family << style << styleHint << script << fallbackFamilies;

    return fallbackFamilies;
}

static FcPattern *queryFont(const FcChar8 *file, const QByteArray &data, int id, FcBlanks *blanks, int *count)
{
#if FC_VERSION < 20402
    Q_UNUSED(data);
    return FcFreeTypeQuery(file, id, blanks, count);
#else
    if (data.isEmpty())
        return FcFreeTypeQuery(file, id, blanks, count);

    FT_Library lib = qt_getFreetype();

    FcPattern *pattern = nullptr;

    FT_Face face;
    if (!FT_New_Memory_Face(lib, (const FT_Byte *)data.constData(), data.size(), id, &face)) {
        *count = face->num_faces;

        pattern = FcFreeTypeQueryFace(face, file, id, blanks);

        FT_Done_Face(face);
    }

    return pattern;
#endif
}

QStringList QFontconfigDatabase::addApplicationFont(const QByteArray &fontData, const QString &fileName, QFontDatabasePrivate::ApplicationFont *applicationFont)
{
    QStringList families;

    if (applicationFont != nullptr)
        applicationFont->properties.clear();

    FcFontSet *set = FcConfigGetFonts(nullptr, FcSetApplication);
    if (!set) {
        FcConfigAppFontAddFile(nullptr, (const FcChar8 *)":/non-existent");
        set = FcConfigGetFonts(nullptr, FcSetApplication); // try again
        if (!set)
            return families;
    }

    int id = 0;
    FcBlanks *blanks = FcConfigGetBlanks(nullptr);
    int count = 0;

    FcPattern *pattern;
    do {
        pattern = queryFont((const FcChar8 *)QFile::encodeName(fileName).constData(),
                            fontData, id, blanks, &count);
        if (!pattern)
            return families;

        FcChar8 *fam = nullptr;
        if (FcPatternGetString(pattern, FC_FAMILY, 0, &fam) == FcResultMatch) {
            QString family = QString::fromUtf8(reinterpret_cast<const char *>(fam));
            families << family;
        }
        populateFromPattern(pattern, applicationFont);

        FcFontSetAdd(set, pattern);

        ++id;
    } while (id < count);

    return families;
}

QString QFontconfigDatabase::resolveFontFamilyAlias(const QString &family) const
{
    QString resolved = QFreeTypeFontDatabase::resolveFontFamilyAlias(family);
    if (!resolved.isEmpty() && resolved != family)
        return resolved;
    FcPattern *pattern = FcPatternCreate();
    if (!pattern)
        return family;

    if (!family.isEmpty()) {
        const QByteArray cs = family.toUtf8();
        FcPatternAddString(pattern, FC_FAMILY, (const FcChar8 *) cs.constData());
    }
    FcConfigSubstitute(nullptr, pattern, FcMatchPattern);
    FcDefaultSubstitute(pattern);

    FcChar8 *familyAfterSubstitution = nullptr;
    FcPatternGetString(pattern, FC_FAMILY, 0, &familyAfterSubstitution);
    resolved = QString::fromUtf8((const char *) familyAfterSubstitution);
    FcPatternDestroy(pattern);

    return resolved;
}

QFont QFontconfigDatabase::defaultFont() const
{
    // Hack to get system default language until FcGetDefaultLangs()
    // is exported (https://bugs.freedesktop.org/show_bug.cgi?id=32853)
    // or https://bugs.freedesktop.org/show_bug.cgi?id=35482 is fixed
    FcPattern *dummy = FcPatternCreate();
    FcDefaultSubstitute(dummy);
    FcChar8 *lang = nullptr;
    FcResult res = FcPatternGetString(dummy, FC_LANG, 0, &lang);

    FcPattern *pattern = FcPatternCreate();
    if (res == FcResultMatch) {
        // Make defaultFont pattern matching locale language aware, because
        // certain FC_LANG based custom rules may happen in FcConfigSubstitute()
        FcPatternAddString(pattern, FC_LANG, lang);
    }
    FcConfigSubstitute(nullptr, pattern, FcMatchPattern);
    FcDefaultSubstitute(pattern);

    FcChar8 *familyAfterSubstitution = nullptr;
    FcPatternGetString(pattern, FC_FAMILY, 0, &familyAfterSubstitution);
    QString resolved = QString::fromUtf8((const char *) familyAfterSubstitution);
    FcPatternDestroy(pattern);
    FcPatternDestroy(dummy);

    return QFont(resolved);
}

void QFontconfigDatabase::setupFontEngine(QFontEngineFT *engine, const QFontDef &fontDef) const
{
    bool antialias = !(fontDef.styleStrategy & QFont::NoAntialias);
    bool forcedAntialiasSetting = !antialias || QHighDpiScaling::isActive();

    const QPlatformServices *services = QGuiApplicationPrivate::platformIntegration()->services();
    bool useXftConf = false;

    if (services) {
        const QList<QByteArray> desktopEnv = services->desktopEnvironment().split(':');
        useXftConf = desktopEnv.contains("GNOME") || desktopEnv.contains("UNITY") || desktopEnv.contains("XFCE");
    }

    if (useXftConf && !forcedAntialiasSetting) {
        void *antialiasResource =
                QGuiApplication::platformNativeInterface()->nativeResourceForScreen("antialiasingEnabled",
                                                                                    QGuiApplication::primaryScreen());
        int antialiasingEnabled = int(reinterpret_cast<qintptr>(antialiasResource));
        if (antialiasingEnabled > 0)
            antialias = antialiasingEnabled - 1;
    }

    QFontEngine::GlyphFormat format;
    // try and get the pattern
    FcPattern *pattern = FcPatternCreate();

    FcValue value;
    value.type = FcTypeString;
    QByteArray cs = fontDef.families.first().toUtf8();
    value.u.s = (const FcChar8 *)cs.data();
    FcPatternAdd(pattern,FC_FAMILY,value,true);

    QFontEngine::FaceId fid = engine->faceId();

    if (!fid.filename.isEmpty()) {
        value.u.s = (const FcChar8 *)fid.filename.data();
        FcPatternAdd(pattern,FC_FILE,value,true);

        value.type = FcTypeInteger;
        value.u.i = fid.index;
        FcPatternAdd(pattern,FC_INDEX,value,true);
    }

    if (fontDef.pixelSize > 0.1)
        FcPatternAddDouble(pattern, FC_PIXEL_SIZE, fontDef.pixelSize);

    FcResult result;

    FcConfigSubstitute(nullptr, pattern, FcMatchPattern);
    FcDefaultSubstitute(pattern);

    FcPattern *match = FcFontMatch(nullptr, pattern, &result);
    if (match) {
        engine->setDefaultHintStyle(defaultHintStyleFromMatch((QFont::HintingPreference)fontDef.hintingPreference, match, useXftConf));

        FcBool fc_autohint;
        if (FcPatternGetBool(match, FC_AUTOHINT,0, &fc_autohint) == FcResultMatch)
            engine->forceAutoHint = fc_autohint;

#if defined(FT_LCD_FILTER_H)
        int lcdFilter;
        if (FcPatternGetInteger(match, FC_LCD_FILTER, 0, &lcdFilter) == FcResultMatch)
            engine->lcdFilterType = lcdFilter;
#endif

        if (!forcedAntialiasSetting) {
            FcBool fc_antialias;
            if (FcPatternGetBool(match, FC_ANTIALIAS,0, &fc_antialias) == FcResultMatch)
                antialias = fc_antialias;
        }

        if (antialias) {
            QFontEngine::SubpixelAntialiasingType subpixelType = QFontEngine::Subpixel_None;
            if (!(fontDef.styleStrategy & QFont::NoSubpixelAntialias))
                subpixelType = subpixelTypeFromMatch(match, useXftConf);
            engine->subpixelType = subpixelType;

            format = (subpixelType == QFontEngine::Subpixel_None)
                    ? QFontEngine::Format_A8
                    : QFontEngine::Format_A32;
        } else
            format = QFontEngine::Format_Mono;

        FcPatternDestroy(match);
    } else
        format = antialias ? QFontEngine::Format_A8 : QFontEngine::Format_Mono;

    FcPatternDestroy(pattern);

    engine->antialias = antialias;
    engine->defaultFormat = format;
    engine->glyphFormat = format;
}

QT_END_NAMESPACE