calling QMessageBox from a worker thread

[prkhr4u]

I am emitting a signal from a worker thread and connecting it to a slot in GUI thread of MainWindow.
In the slot I am invoking a QMessageBox and displaying some error message.
Now I want the worker thread to stop working until I click OK on the QMessageBox.
Here is how I am doing it:

//worker thread

emit CameraDisconnectSignal("no camera present");

emit CameraDisconnectSignal("no camera present");

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//GUI thread

void MainWindow::CameraDisconnectSlot(QString q)
{
           QMessageBox messageBox;
           messageBox.critical(0,"Error",q);
           messageBox.setFixedSize(500,200);
}

void MainWindow::CameraDisconnectSlot(QString q)
{
           QMessageBox messageBox;
           messageBox.critical(0,"Error",q);
           messageBox.setFixedSize(500,200);
}

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First of all I am not able to get any MessageBox and secondly I want to stop worker thread till the user clicks OK on GUI thread.
How can I acheive this??

[Lesiok]

First of all You don't show message box. Add this line :

messageBox.exec();

messageBox.exec();

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Second : read about QObject::connect and especially about third parameter.

[anda_skoa]

And you probably want to use one of the static helper methods of QMessageBox, e.g.

QMessageBox::critical(this, "Error", q);

QMessageBox::critical(this, "Error", q);

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Cheers,
_

[prkhr4u]

Thanks to both of you,I am able to get MessageBox now.
But I am still unable to stop the thread processing on displaying QMessageBox and resuming it on its OK button click.
how to achieve that?

[Lesiok]

Did You read doc for QObject::connect method ?

[prkhr4u]

thank you @Lesiok,I didn't get it in the first time,but Qt::BlockingQueuedConnection did the job for me.