def mouseMoveEvent(self, ev):
        if not self.left_button_down:
            return
        pos = ev.globalPos()
        delta_x = pos.x() - self.last_pos.x()
        delta_y = self.last_pos.y() - pos.y()
        #log.debug('%d %d' % (delta_x, delta_y))
        
        v = self.verticalScrollBar()
        v.setValue(v.value() - delta_y)     # Opposite to slider direction
        h = self.horizontalScrollBar()
        h.setValue(h.value() - delta_x)     # Opposite to slider direction
        
        self.last_pos = pos
dataset/ETHPy150Open hbprotoss/weii/app/widget/picture_viewer.py/ScrollArea.mouseMoveEvent/swapped operands of `-`