'Return an interpolated size between pixmap1.size()
and pixmap2.size()'

def sizeHint(self):

    if (self.pixmap1 and self.pixmap2):
        size1 = self.pixmap1.size()
        size2 = self.pixmap2.size()
        return (size1 + (self.blendingFactor_ * (size2 - size1)))
    else:
        return QWidget.sizeHint(self)
