[Interest] QProgressDialog not showing & processEvents()

[Mandeep Sandhu]

> I strongly object to using a thread for something this simple. Threading
> is to be avoided whenever possible, because it's so hard to debug. Use

There's no black magic involved in threads. Though I agree it might be
an overkill in some cases, not so sure about this case.

> the chunks method instead. Something like this:
>
> class FileLoader : public QObject {
>    Q_OBJECT
>
> public:
>    explicit FileLoader(const QString& fileName) {
>      m_file(fileName);
>      m_timer.setSingleShot(false);
>      m_timer.setInterval(0);
>      m_timer.start();
>      connect(&m_timer, SIGNAL(triggered()), SLOT(readChunk()));
>
>      m_file.open(QIODevice::ReadOnly));
>    }
>
> signals:
>    void done(const QByteArray& bytes);
>    void failed();
>    void progress(qreal percent);
>
> private slots:
>    void readChunk() {
>      if (!m_file.isOpen()) {
>        m_timer.stop();
>        emit failed();
>      } else {
>        m_bytes.append(m_file.read(1024));

The read/write chunk size needs to be selected with care. The exact
answer will depend on the underlying filesystem in use. I think it
should not be smaller than the file system block size.

-mandeep