Show a messagebox until a thread emits a Signal

dualfaces

Hello,

if I loose a connection to device I want to open a message box which says that the application waits for the connection to be reestablished.
Therefore, when i recognize the lost connection i start a thread which will run until the connection is established again. Then it emits a Signal which says that the connection is established.
This signal is connected to a slot of my gui thread, but unfortunately it does not close the messagebox, cause the thread is stuck in showing the messagebox.
Is there a proper way to do this? Here is a snippet of my code
@
QMessageBox* m_box; //private class variable of gui thread

public void on_ConnectionLost() {
m_box = new QMessageBox();
m_box->setText("Wait for connection to return");
m_box->show();
}

public void on_ConnectionEstablished() {
if (m_box != nullptr) {
m_box->close();
delete m_box;
m_box = nullptr;
}
//restart processing
}
@

Thank you!

Regards

SGaist

Hi,

AFAIK, calling show() should not block anything, are you sure on_ConnectionEstablished is called ?

Jeroentjehome

What happens to your thread after it has re-established the connection? Do you terminate it? If so, use deleteLater() instead of delete(). This way your event queue will be finished before deletion.

dualfaces

So the m_box->show() call is indeed not blocking. And on_connectionEstablished is executed. When stepping through with the debugger the message box is successfully closed, when i run it without breakpoints the box does not disappear.
Since i run it on an android device the problem might also stem from the cross-platform debugger.
The thread itself (the run() function) terminates after establishing the connection, but the object stays alive.

regards

SGaist

When running without the debugger, are you sure the message box is still there and not only painted ? Can you click on a button of it ?

dualfaces

Hi,

it was just the problem that the Qmessagebox was not removed from the screen, the application was working normally behind it.
Now i uses m_box->done(0); and the box disappears.
Now i struggle with adding a button to cancel waiting and close the box and getting the fired signal.
Therefore I modified my m_box to
@
m_box = new QMessageBox();
m_box->setText("Wait");
m_box->setStandardButtons(QMessageBox::Cancel);
m_box->setButtonText(QMessageBox::Cancel, "Do not Wait");
connect(m_box, SIGNAL(buttonClicked(QAbstractButton*)), this, SLOT(on_cancelWaitingClicked(QAbstractButton*)));
@

The button is added (although it is no renamed, it's text is still Cancel. But when i click the button the slot is not executed.
The messagebox is still shown via m_box->show().
Isn't it possible to connect a slot this way?

Regards

SGaist

Then why not use a QProgressDialog ? I would be more suited to your needs