title: Qt : draw triangle image
body: <p>I need to do something similar to <code>QPainter::drawImage</code>, but drawing a triangle part of the given picture (into a triangular region of my widget) instead of working with rectangles.</p>
  
  <p>Any idea how I could do that, besides painfully trying to redraw every pixel?</p>
  
  <p>Thanks for your insights!</p>