Merge pull request #2327 from LarsVoxen/master

Update PColorMeshItem.py

pyqtgraph/graphicsItems/PColorMeshItem.py

@@ -205,9 +205,6 @@ def setData(self, *args):
                          matplotlib.pyplot.pcolormesh.html>".
         """
 
-        # Prepare data
-        self._prepareData(args)
-
         # Has the view bounds changed
         shapeChanged = False
         if self.qpicture is None:
@@ -219,6 +216,10 @@ def setData(self, *args):
             if np.any(self.x != args[0]) or np.any(self.y != args[1]):
                 shapeChanged = True
 
+        # Prepare data
+        self._prepareData(args)
+
+
         self.qpicture = QtGui.QPicture()
         painter = QtGui.QPainter(self.qpicture)
         # We set the pen of all polygons once