在Qt中列出所有serial port

由於QSettings不能利用含有反斜線的key，來找到值。
所以只好和winapi交互利用。

要注意的是QSettings得到的鍵值是斜線，可是winapi是反斜線

const QStringList WinDongle::getComPort()
{
    QStringList comports;
    QString keyPath = "HARDWARE\\DEVICEMAP\\SERIALCOMM";
    HKEY comsKey;
    LPCWSTR winKeyPath = (LPCWSTR)keyPath.constData();
    if(RegOpenKey(HKEY_LOCAL_MACHINE, winKeyPath, &comsKey) != ERROR_SUCCESS)
    {
        error = UNKNOW;
        RegCloseKey(comsKey);
        return comports;
    }

    QSettings settings(QString("HKEY_LOCAL_MACHINE\\")+keyPath, QSettings::NativeFormat);
    QStringList keys = settings.allKeys();
    foreach( const QString & key, keys )
    {
        QString newKey(key);
        newKey.replace(QString("/"), QString("\\"));
        LPCWSTR winKey = (LPCWSTR)newKey.constData();
        char *szData= new char[101];
        DWORD dwType, dwLen=100;
        if (RegQueryValueEx(comsKey, winKey,
                            NULL, &dwType, (unsigned char *)szData, &dwLen) == ERROR_SUCCESS)
        {
            comports.append( QString::fromUtf16((ushort*)szData) );
        }
        delete[] szData;
    }
    RegCloseKey(comsKey);
    return comports;
}

參考資料:在 Win32 下 Serial Port 的通訊