title: Qt image move/rotation
body: <p>I just want to move the image by the widget's axises and rotate around the widget's center(like a canvas in any digital painting software), but it's rotating around its left top point... </p>
  
  <pre><code>QPainter p(this);
  QTransform trans; 
  
  trans.translate(width()/2, -height()/2);
  trans.rotate(angle); 
  
  QTransform inverse = trans.inverted();
  inverse.translate(-canvas.width()/2, -canvas.height()/2); 
  
  p.setTransform(trans);
  p.drawImage(inverse.map(canvasPos), canvas);
  </code></pre>
  
  <p>How to get it to rotate correctly?</p>