Cannot queue argument of type "QTextBlock"

Cobra91151

Hi! I have decided to use QProgressDialog to monitor loading of big text file, but I have some issue with QProgressBar.

Code:

    QProgressDialog progressDialog;
    progressDialog.setWindowTitle(QObject::tr("Test"));
    progressDialog.setFixedSize(350, 100);
    progressDialog.setWindowFlags(Qt::Window | Qt::WindowTitleHint | Qt::CustomizeWindowHint);
    progressDialog.setCancelButton(false);

    QProgressBar *progressBar = new QProgressBar(&progressDialog);
    progressBar->setTextVisible(false);
    progressDialog.setBar(progressBar);
    progressDialog.setMinimum(0);
    progressDialog.setValue(0);
    progressDialog.setMaximum(100);
    progressDialog.setLabelText(QObject::tr("Loading data. Please wait..."));
    QFutureWatcher<void> watcher;
    connect(&progressDialog, &QProgressDialog::canceled, &watcher, &QFutureWatcher<void>::cancel);
    connect(&watcher, &QFutureWatcher<void>::finished, &progressDialog, &QProgressDialog::reset);
    //connect(&watcher, &QFutureWatcher<void>::progressRangeChanged, &progressDialog, &QProgressDialog::setRange);
    connect(&watcher, &QFutureWatcher<void>::progressValueChanged, &progressDialog, &QProgressDialog::setValue);
    QFuture<void> future = QtConcurrent::run(this, &Test::loadDataFile);
    watcher.setFuture(future);
    progressDialog.exec();
    watcher.waitForFinished();

void Test::loadDataFile()
{
    ui->plainTextEdit->setPlainText(dbTextStream.readAll());
}

The problem is that it displays empty progress or when I use connect(&watcher, &QFutureWatcher<void>::progressRangeChanged, &progressDialog, &QProgressDialog::setRange); it displays a busy indicator. I want to display standard progressbar, like in the image below. Also I get warnings: QObject::connect: Cannot queue arguments of type 'QTextBlock' (Make sure 'QTextBlock' is registered using qRegisterMetaType().) QObject: Cannot create children for a parent that is in a different thread. (Parent is QTextDocument(0x5a28e48), parent's thread is QThread(0x8dbcc0), current thread is QThread(0x5a1f700) QObject::connect: Cannot queue arguments of type 'QTextCursor' (Make sure 'QTextCursor' is registered using qRegisterMetaType().) How to fix it?

Image:
alt text

SGaist

Hi,

That question was unrelated to your other topic so I moved to its own thread.

The error itself is pretty clear: QTextBlock is unknown to the Qt meta type system so you have to make it known to it.

You should take a look at Qt's documentation for qRegisterMetaType for more information.

Cobra91151

@SGaist

I have set but the progress in still not moving.

qRegisterMetaType<QTextBlock>("QTextBlock");
qRegisterMetaType<QTextCursor>("QTextCursor");

SGaist

Did you forgot the Q_DECLARE_METATYPE ?

By the way, remove the string parameter from your qRegisterMetaType calls. That version of the function should only be used to register aliases.

Cobra91151

@SGaist

I have changed to:

qRegisterMetaType<QTextBlock>();
qRegisterMetaType<QTextCursor>();

but now I need to declare Q_DECLARE_METATYPE

I have set it outsize the class in a header:

Q_DECLARE_METATYPE(QTextBlock)

But it displays error: Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system

Where I should declare Q_DECLARE_METATYPE?

SGaist

Before your calls to qRegisterMetaType. You can do it in your main.cpp file before the main implementation.

Cobra91151

@SGaist

Ok. I have registered it before class declaration in a header.
Thanks.

Cobra91151

Hi! I have fixed it by implementing QThread with worker class and passing the file name argument to QMetaObject::invokeMethod function and now I don't need to display the QProgressDialog.