QProgressDialog doubt

dasmoeh

You can use exec to show your dialog. But it works only for me if i use a new Thread for my function. I'm looking for a solution without threads, but can't find something.

@
QProgressDialog dlg("Running...", QString(), 0, 0, this, Qt::CustomizeWindowHint | Qt::WindowTitleHint);
dlg.setRange(0,0);
MyThread* work = new MyThread();
connect(work, SIGNAL(statusText(QString)), &dlg, SLOT(setLabelText(QString)));
connect(work, SIGNAL(finished()), &dlg, SLOT(cancel()));
connect(work, SIGNAL(errorText(QString,QWaitCondition*)), this, SLOT(workError(QString,QWaitCondition*)));
work->start();
dlg.exec();
@

DenisKormalev

Use single @ tag before and after code. I've fixed it in this comment, but don't forget about it in future posts.

What do you mean by "solution without threads"?

goetz

If you do your work in the main thread, then that thread is blocked with your work. You want to process the pending events from time to time, eg. with "QCoreApplication::processEvents() ":http://doc.qt.nokia.com/4.7/qcoreapplication.html#processEvents

If you do the work in a separate thread, the main thread's event loop continues to run and everything is updated automatically.

dasmoeh

As long as i am waiting for a TIMEOUT
@
_tcpSocket.waitForConnected(TIMEOUT)
@
i want to show the QProgressDialog.

Something like
@
QProgressDialog dlg("Running...", QString(), 0, 0, this, Qt::CustomizeWindowHint | Qt::WindowTitleHint);
dlg.setRange(0,0);
//dlg.exec()
_tcpSocket.waitForConnected(TIMEOUT)
dlg.cancel()
@
but if i use exec only the ProgressBar is running forever.

Thank u for helping with the code tag. Hope its better now.

goetz

this snippet works for me:

@
QProgressDialog pd;
pd.setLabelText("waiting for connect");

pd.setWindowModality(Qt::WindowModal);
pd.setRange(0,0);
// always show the dialog
// do no assumed time calculation
pd.setMinimumDuration(0);
// disable the cancel button at all
pd.setCancelButton(0);
// eventually show the dialog
pd.setValue(1);

QTcpSocket sock;
connect(&_tcpScoket, SIGNAL(connected()), &pd, SLOT(cancel()));
_tcpScoket.connectToHost("host", 80);
_tcpScoket.waitForConnected(30000);
@

Be aware that there is no need to explicitly exec the progress dialog (in contrary to an "ordinary" QDialog).

dasmoeh

@Volker: Thank you. With processEvents() i can get the dialog visible. But it doesn't show title or progressbar. Only blank window. Some time ago i tried to put the tcpsocket in another thread, but it wasn't easy so it remained in the main thread. Is there a way to start the progressdialog in a new thread?

edit: Just seen your answer. I will try it.

goetz

No, you must start gui elements in the main thread.

It depends on you application what to do exactly. If the app should block until the connection is done you can try something like this:

@
QProgressDialog pd;
// setup the dialog like posted

QEventLoop el;
connect(&_tcpScoket, SIGNAL(connected()), &el, SLOT(quit()));

QTcpSocket sock;
connect(&_tcpScoket, SIGNAL(connected()), &pd, SLOT(cancel()));
_tcpScoket.connectToHost("host", 80);
el.run();
pd.cancel();
@

This runs a local event loop, it keeps the QApplication running, but blocks the flow of control in the method until the socket is connected (and thus the event loop stops).

You will have to add some error handling (eg. connect to the error signal of the socket) and/or add a QTimer to setup a timeout.

dasmoeh

I tried your code, but it did not work.
The first shows only for a second a pop-up after it finished waiting.
With the second i don't know where to call @_tcpScoket.waitForConnected(30000) @? I think el.run() should be el.exec()?

goetz

Ahm. The progress dialog is only shown until the initial TCP connection has been set up. This usually takes less than a second on a decent internet connection... How long do you expect that to last in your case?

dasmoeh

Mh, i tried to connect to a not given IP. I want to see the dialog while
@
_tcpScoket.waitForConnected(30000)
@
is active till it times out. At 30000 ms.

In not working code:
@
dlg.show()
_tcpScoket.waitForConnected(30000)
dlg.cancel()
@

But in this 30000ms i don't get updates to my gui. Like i expected. But i'm looking for a way, to have my progressdialog running during this 30000 ms without calling waitForConnected from another thread because i don't want to move my socket from the main thread.
I think it's not possible?