Qt4 starting and stopping (pausing) - qt

Question

Ok, so I'm having this problem tonight:
[...]
connect(startButton, SIGNAL(clicked()), this, SLOT(startCalculation()));
connect(stopButton, SIGNAL(clicked()), this, SLOT(stopCalculation()));
[...]
void MainWindow::startCalculation()
{
qDebug() << "hello";
this->startButton->setDisabled(true);
this->stopButton->setEnabled(true);
this->calcStatus = true;
this->calculate();
}
void MainWindow::stopCalculation()
{
this->startButton->setEnabled(true);
this->stopButton->setDisabled(true);
this->calcStatus = false;
}
void MainWindow::calculate()
{
qDebug() << "hello";
while(this->calcStatus)
{
}
}
[...]
I'm trying to make the calculate() procedure stoppable any time, but right after it is started I loose control and I can't press STOP. Of course in my future plans calculate() is going to "calculate" something real (e.g. heat transfer simulation).
Thanks for suggestions.
P.

Answer 1

You would need to look into threading. The calculation locks the ui.

Answer 2

Well, in "Introduction to Design Patterns in C++ with Qt4" they say that
"it is possible to avoid the use of
threads in favor of the Qt Event Loop
combined with QTimers"
but I've never tried it :)
Actually, I've just tried -
add:
QTimer *Timer;
in MainWindow class header and in MainWindow constructor add:
Timer = new QTimer(this);
then change calculate() from function to a signal and modify:
void MainWindow::startCalculation()
{
qDebug() << "hello";
this->startButton->setDisabled(true);
this->stopButton->setEnabled(true);
this->calcStatus = true;
connect(Timer, SIGNAL(timeout()), this, SLOT(calculate()));
Timer->start(0);
}
void MainWindow::stopCalculation()
{
this->startButton->setEnabled(true);
this->stopButton->setDisabled(true);
this->calcStatus = false;
Timer->stop();
Timer->disconnect(this,SLOT(calculate()));
}
This should work as long as you dont pass any arguments into calculate().