Qt でノンブロッキング コピーと名前変更操作を実装するにはどうすればよいですか?

class CopyHelper : public QObject {
    Q_OBJECT
    Q_PROPERTY(qreal progress READ progress WRITE setProgress NOTIFY progressChanged)
public:
    CopyHelper(QString sPath, QString dPath, quint64 bSize = 1024 * 1024) :
        isCancelled(false), bufferSize(bSize), prog(0.0), source(sPath), destination(dPath), position(0) { }
    ~CopyHelper() { free(buff); }

    qreal progress() const { return prog; }
    void setProgress(qreal p) {
        if (p != prog) {
            prog = p;
            emit progressChanged();
        }
    }

public slots:
    void begin() {
        // File opening, size checking, and buffer allocation
        QMetaObject::invokeMethod(this, "step", Qt::QueuedConnection);
    }
    void step() {
        // Read, write, and progress tracking
        if (isCancelled) {
            // Delete the copied portion and emit done signal
        }
        else if (position < fileSize) {
            QMetaObject::invokeMethod(this, "step", Qt::QueuedConnection);
        } else {
            // Emit done signal
        }
    }
    void cancel() { isCancelled = true; }

signals:
    void progressChanged();
    void done();

private:
    bool isCancelled;
    quint64 bufferSize;
    qreal prog;
    QFile source, destination;
    quint64 fileSize, position;
    char * buff;
};