title: How to check if QImage is valid?
body: <p>I wanted to know if there was a way to determine if a <code>QImage</code> is valid. I am displaying that image as a pixmap in <code>QLabel</code> and sometimes when the image is not valid. It is not displayed in the <code>QLabel</code>, then.</p>
  
  <p>The reason for not being valid sometimes is that the image is loaded from external data and that data can be corrupted at times.</p>
  
  <p>Thereby, I wished to know if it is possible to actually determine whether a <code>QImage</code> is valid.</p>