Question

Basically, I’m doing some image processing and using a QImage in a QLabel to display the current frame in a video sequence. Let’s say I want to update the QImage to the next frame at 30 fps (or if some processing is not done by the 30 fps interval, wait until it’s done), but I don’t want the whole program to stop during that 30 fps.

So the flow is…

if (done_some_work && 30fps_interval_has_passed)
{
   updateQImage();
}

How is this done in Qt? Thanks!

Answer 1

And use a QTimer to send a signal repaint the frame every 1000/30 ms

myTimer= new QTimer(this);
myTimer->setInterval(1000/fps); // ms
connect(myTimer, SIGNAL(timeout()), this, SLOT(doNextFrame())); 

// where
public slots:
    virtual void doNextFrame() {repaint();}