title: Qt, widget refresh, and ui interactability
body: <p>I'm sparkling brand new to Qt, and am finding it very rewarding to learn. I'm trying to merge some existing C++ code with a new Qt GUI. Basically, the idea is to have images that are extracted from an .avi file be processed in the backend and then displayed in a <code>QLabel</code> on-screen. I have managed to get the following bit of code to display the frames correctly:</p>
  
  <pre><code>while (frame = cvQueryFrame(capture))
  {
      // Some processing code...
  
      QImage qImageFrame((uchar*) frame-&gt;imageData, frame-&gt;width, frame-&gt;height, frame-&gt;widthStep, QImage::Format_RGB888);
      qImageFrame = qImageFrame.rgbSwapped();
      QPixmap qFrame;
  
      qFrame.convertFromImage(qImageFrame);
      label-&gt;setPixmap(qFrame);
      label-&gt;repaint();
  
      cvWaitKey(10);
  }
  </code></pre>
  
  <p>Now, however, this obviously means that the UI stops being responsive to user input until all the frames from the movie are displayed. How is something like this done?</p>
  
  <p>NB: I am performing the processing using the openCV library, which expects the images in a certain format. One thing which I think I cannot do, for example, is work with the .avi file directly in the Qt domain.</p>