根据Qfont中的family 得到字体文件的路径和文件名称

转载：https://www.zhihu.com/question/25834024
根据Qfont中的family 得到字体文件的路径和文件名称；

源码：
//头文件
#include
#include
#include
#include
#include
#include
#include

源码：

std::string GetFontPathFromQFont::GetSystemFontFile(const std::string &faceName) {
	static const LPWSTR fontRegistryPath = L"Software\\Microsoft\\Windows NT\\CurrentVersion\\Fonts";
    HKEY hKey;
    LONG result;
    std::wstring wsFaceName(faceName.begin(), faceName.end());
  
    // Open Windows font registry key
    result = RegOpenKeyEx(HKEY_LOCAL_MACHINE, fontRegistryPath, 0, KEY_READ, &hKey);
    if (result != ERROR_SUCCESS) {
        return "";
    }

    DWORD maxValueNameSize, maxValueDataSize;
    result = RegQueryInfoKey(hKey, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, &maxValueNameSize, &maxValueDataSize, nullptr, nullptr);
    if (result != ERROR_SUCCESS) {
        return "";
    }

    DWORD valueIndex = 0;
    LPWSTR valueName = new WCHAR[maxValueNameSize];
    LPBYTE valueData = new BYTE[maxValueDataSize];
    DWORD valueNameSize, valueDataSize, valueType;
    std::wstring wsFontFile;

    // Look for a matching font name
    do {

        wsFontFile.clear();
        valueDataSize = maxValueDataSize;
        valueNameSize = maxValueNameSize;

        result = RegEnumValue(hKey, valueIndex, valueName, &valueNameSize, nullptr, &valueType, valueData, &valueDataSize);

        valueIndex++;

        if (result != ERROR_SUCCESS || valueType != REG_SZ) {
            continue;
        }

        std::wstring wsValueName(valueName, valueNameSize);

        // Found a match
        if (_wcsnicmp(wsFaceName.c_str(), wsValueName.c_str(), wsFaceName.length()) == 0) {

            wsFontFile.assign((LPWSTR)valueData, valueDataSize);
            break;
        }
    }
    while (result != ERROR_NO_MORE_ITEMS);

    delete[] valueName;
    delete[] valueData;

    RegCloseKey(hKey);

    if (wsFontFile.empty()) {
        return "";
    }

    // Build full font file path
    WCHAR winDir[MAX_PATH];
    GetWindowsDirectory(winDir, MAX_PATH);

    std::wstringstream ss;
    ss << winDir << "\\Fonts\\" << wsFontFile;
    wsFontFile = ss.str();

    return std::string(wsFontFile.begin(), wsFontFile.end());
}

```cpp
#define MAKE_TAG(ch1, ch2, ch3, ch4) (\
    (((quint32)(ch4)) << 24) | \
    (((quint32)(ch3)) << 16) | \
    (((quint32)(ch2)) << 8) | \
    ((quint32)(ch1)) \
    )

quint16 GetFontPathFromQFont::getUShort(const unsigned char *p)
{
    quint16 val;
    val = static_cast<quint16>(*p++ << 8);
    val |= *p;

    return val;
}

QString GetFontPathFromQFont::getEnglishName(const uchar *table, quint32 bytes)
{
    QString i18n_name;
    enum {
        NameRecordSize = 12,
        FamilyId = 1,
        MS_LangIdEnglish = 0x009
    };

    // get the name table
    quint16 count;
    quint16 string_offset;
    const unsigned char *names;

    int microsoft_id = -1;
    int apple_id = -1;
    int unicode_id = -1;

    if(getUShort(table) != 0)
        goto error;

    count = getUShort(table+2);
    string_offset = getUShort(table+4);
    names = table + 6;

    if(string_offset >= bytes || 6 + count*NameRecordSize > string_offset)
        goto error;

    for(int i = 0; i < count; ++i) {
        // search for the correct name entry

        quint16 platform_id = getUShort(names + i*NameRecordSize);
        quint16 encoding_id = getUShort(names + 2 + i*NameRecordSize);
        quint16 language_id = getUShort(names + 4 + i*NameRecordSize);
        quint16 name_id = getUShort(names + 6 + i*NameRecordSize);

        if(name_id != FamilyId)
            continue;

        enum {
            PlatformId_Unicode = 0,
            PlatformId_Apple = 1,
            PlatformId_Microsoft = 3
        };

        quint16 length = getUShort(names + 8 + i*NameRecordSize);
        quint16 offset = getUShort(names + 10 + i*NameRecordSize);
        if(DWORD(string_offset + offset + length) >= bytes)
            continue;

        if ((platform_id == PlatformId_Microsoft
            && (encoding_id == 0 || encoding_id == 1))
            && (language_id & 0x3ff) == MS_LangIdEnglish
            && microsoft_id == -1)
            microsoft_id = i;
        // not sure if encoding id 4 for Unicode is utf16 or ucs4...
        else if(platform_id == PlatformId_Unicode && encoding_id < 4 && unicode_id == -1)
            unicode_id = i;
        else if(platform_id == PlatformId_Apple && encoding_id == 0 && language_id == 0)
            apple_id = i;
    }
    {
        bool unicode = false;
        int id = -1;
        if(microsoft_id != -1) {
            id = microsoft_id;
            unicode = true;
        } else if(apple_id != -1) {
            id = apple_id;
            unicode = false;
        } else if (unicode_id != -1) {
            id = unicode_id;
            unicode = true;
        }
        if(id != -1) {
            quint16 length = getUShort(names + 8 + id*NameRecordSize);
            quint16 offset = getUShort(names + 10 + id*NameRecordSize);
            if(unicode) {
                // utf16

                length /= 2;
                i18n_name.resize(length);
                QChar *uc = (QChar *) i18n_name.unicode();
                const unsigned char *string = table + string_offset + offset;
                for(int i = 0; i < length; ++i)
                    uc[i] = getUShort(string + 2*i);
            } else {
                // Apple Roman
                i18n_name.resize(length);
                QChar *uc = (QChar *) i18n_name.unicode();
                const unsigned char *string = table + string_offset + offset;
                for(int i = 0; i < length; ++i)
                    uc[i] = QLatin1Char(string[i]);
            }
        }
    }
error:
    //qDebug("got i18n name of '%s' for font '%s'", i18n_name.latin1(), familyName.toLocal8Bit().data());
    return i18n_name;
}

QString GetFontPathFromQFont::getEnglishName(const QString &familyName)
{
    QString i18n_name;

    HDC hdc = GetDC( nullptr );
    LOGFONT lf;
    memset(&lf, 0, sizeof(LOGFONT));
    memcpy(lf.lfFaceName, familyName.utf16(), qMin(LF_FACESIZE, familyName.length()) * sizeof(wchar_t));
    lf.lfCharSet = DEFAULT_CHARSET;
    HFONT hfont = CreateFontIndirect(&lf);
    if(!hfont) {
        ReleaseDC(nullptr, hdc);
        return QString();
    }

    HGDIOBJ oldobj = SelectObject( hdc, hfont );

    const DWORD name_tag = MAKE_TAG( 'n', 'a', 'm', 'e' );

    // get the name table
    unsigned char *table = nullptr;

    DWORD bytes = GetFontData( hdc, name_tag, 0, nullptr, 0 );
    if ( bytes == GDI_ERROR ) {
        // ### Unused variable
        /* int err = GetLastError(); */
        goto error;
    }

    table = new unsigned char[bytes];
    GetFontData(hdc, name_tag, 0, table, bytes);
    if ( bytes == GDI_ERROR )
        goto error;

    i18n_name = getEnglishName(table, bytes);
error:
    delete [] table;
    SelectObject( hdc, oldobj );
    DeleteObject( hfont );
    ReleaseDC( nullptr, hdc );

    //qDebug("got i18n name of '%s' for font '%s'", i18n_name.latin1(), familyName.toLocal8Bit().data());
    return i18n_name;
}

使用方法：
std::string path = GetFontPathFromQFont::GetSystemFontFile(GetFontPathFromQFont::getEnglishName(font.family()).toStdString());
    QString fontPath = QString().fromLocal8Bit(path.c_str());//根据字体得到字体文件名和路径

结果输入 根据QFontComboBox 选择字体宋体
结果输出 C:\\Windows\\Fonts\\simsun.ttc