How to create a QInputDialog in a new thread? - c++

Question

Basically I'm calling a function from another thread using QtConcurrent.
Working as expected but once I create a QInputDialog within the called function, I'm getting an assertion exception telling me that I have to create the Dialog in the Main GUI Thread.
To be more specific this line:
password = QInputDialog::getText( this , tr( "Password" ) , tr( "Enter Password:" ) , QLineEdit::Password , selectedPassword , &ok );
Now the question would be how can I call the Dialog from a new thread without too much extra work.

Answer 1

You can't create widgets outside from main thread. You can emit signal from network thread and create dialog in main thread.
Or do something like this (pseudo-code):
class NotificationManager : public QObject
{
Q_OBJECT
//...
public slots:
void showMessage( const QString& text )
{
if ( QThread::currendThread() != this->thread() )
{
QMetaObject::invoke( this, "showMessage", Qt::QueuedConnection, Q_ARG( QString, text );
// Or use Qt::BlockingQueuedConnection to freeze caller thread, until dialog will be closed
return;
}
QMessageBox::information( nullptr, QString(), text );
}
};
class ThreadedWorker : public QRunnable
{
ThreadedWorker( NotificationManager *notifications )
: _notifications( notifications )
{}
void run() override
{
// Do some work;
notifications->showMessage( "Show this in GUI thread" );
}
private:
NotificationManager *_notifications;
}