title: How to get click position on QPixmap
body: <p>There is a <strong>QLabel</strong>:</p>
  
  <pre><code>self.image_label = QtGui.QLabel(self.centralwidget)
  self.image_label.setSizePolicy(sizePolicy)
  </code></pre>
  
  <p>to which I put <strong>QPixmap</strong> (generated dynamically):</p>
  
  <pre><code>pixmap = QtGui.QPixmap(os.getcwd() + '\\deafult_title.png')
  self.image_label.setPixmap(pixmap)
  </code></pre>
  
  <p>How to get xy coordinates of click, but in respect to image top-left corner? 
  I know how to get position on label:</p>
  
  <pre><code>self.image_label.mousePressEvent = self.map_clicked
  </code></pre>
  
  <p>But label has some margin that changes when I move window.</p>
  
  <p>I have also tried aligning <strong>QPixmap</strong> in label:</p>
  
  <pre><code>self.image_label.setAlignment(QtCore.Qt.AlignLeft)
  </code></pre>
  
  <p>And now there is constant offset in x,y position, but I not sure if this is the best way to do this.</p>
  
  <p>Is there some easy way to get click position in image coordination system?</p>