Access violation error in QtConcurrent updating QLabel

azadsagar

hello i have this 'access violation reading..." error in QtConcurrent thread when am i terminating my application. My thread is updating some status in QLabel. it seems like when i exit my application QLabel object is being destroyed and my thread is working on it. how can i resolve it ? here is my source

@
void Sparsh::connectCam()
{
QString str[]={"Connecting.","Connecting..","Connecting..."};
unsigned int i=1;

while(!mycam.Connect(FIRST_AVAILABLE))
{
if(ui.lblStatus) // i tried this but no help :(
ui.lblStatus->setText(str[i%3]);

Sleep(1000);
i++;
}

camconnected=true;

ui.lblStatus->setText("Device Connected...!");

}

@

JKSH

Hi,

Qt's GUI classes are not thread-safe. You can only update them in the main thread.

If you want to trigger an update from a secondary thread, your secondary thread must invoke a slot in the main thread to update your QLabel.

Use "QMetaObject::invokeMethod()":http://qt-project.org/doc/qt-5/qmetaobject.html#invokeMethod with a Queued Connection, OR
Emit a signal to invoke the slot.