Calling QFileDialog in new thread creating problem

Question

1.00/5 (1 vote)

See more:

From main UI thread i am creating new thread(counterThread) and in new thread i am trying to accesss QfileDialog. it gives me error msg No matching function for call.

C#

void MainWindow::on_pushButton_clicked()
{
    //Start Counter Thread
    QThread* workerThread = new QThread;   
    counterThread* worker = new counterThread();  
    worker-&gt;moveToThread(workerThread);
    
    connect(workerThread, SIGNAL(started()), worker, SLOT(processCounter()));
    
    workerThread-&gt;start(); // start the thread with name Workerthread

}

and in counterThread

void counterThread::processCounter()
{
   QString logfileName = QFileDialog::getOpenFileName(this, tr("Open File"),"C://readfiles",tr("Trace files (*.trc)"));
   
}

Posted 3-Dec-15 2:42am

XamBEE

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Jochen Arndt · Answer 1 · 2015-12-03T04:09:00

This won't work in a Qt worker thread.
From http://doc.qt.io/qt-5/thread-basics.html[^]:

Quote:
As mentioned, each program has one thread when it is started. This thread is called the "main thread" (also known as the "GUI thread" in Qt applications). The Qt GUI must run in this thread. All widgets and several related classes, for example QPixmap, don't work in secondary threads. A secondary thread is commonly referred to as a "worker thread" because it is used to offload processing work from the main thread.

You must move the GUI related operations to the main thread and perform only the time consuming operations inside the worker thread. Especially things like asking the user to select a file should be performed before starting the worker thread. In your case I would also open the file in the main thread and pass the file handle to the worker thread. But note that there must be some kind of synchronization or locking when shared objects may be used at the same time by multiple threads.