[PyQt] Yet another examples fix

[Dmitry Shachnev]

This time for elasticnodes.py:

Traceback (most recent call last):
  File "./graphicsview/elasticnodes.py", line 348, in keyPressEvent
    self.scaleView(1.2)
  File "./graphicsview/elasticnodes.py", line 412, in scaleView
    factor = self.matrix().scale(scaleFactor,
scaleFactor).mapRect(QRectF(0, 0, 1, 1)).width()
AttributeError: 'GraphWidget' object has no attribute 'matrix'

Patch attached.

--
Dmitry Shachnev
-------------- next part --------------
--- a/examples/graphicsview/elasticnodes.py
+++ b/examples/graphicsview/elasticnodes.py
@@ -409,7 +409,7 @@
         painter.drawText(textRect, message)
 
     def scaleView(self, scaleFactor):
-        factor = self.matrix().scale(scaleFactor, scaleFactor).mapRect(QRectF(0, 0, 1, 1)).width()
+        factor = self.transform().scale(scaleFactor, scaleFactor).mapRect(QRectF(0, 0, 1, 1)).width()
 
         if factor < 0.07 or factor > 100:
             return