使用pyqtgraph添加新数据条的最快方法

I'd like to refresh a candle graph in the fastest way. But following the modified sample, I've got to draw whole chart every time even when I add just one new bar. The reason is that the QPainter object is cleared when I call the object again to draw additional data. It can be slow. Literally I'd like to just "add" a bar data.I'd like to refresh a candle graph in the faste