如何在Kivy中创建倒计时计时器的圈速函数

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.clock import Clock
from kivy.properties import NumericProperty

class CountdownTimer(Widget):
    time_remaining = NumericProperty(60)  # 设置初始倒计时时间为60秒

    def __init__(self, **kwargs):
        super(CountdownTimer, self).__init__(**kwargs)
        Clock.schedule_interval(self.update, 1)  # 每秒钟调用一次update函数

    def update(self, dt):
        self.time_remaining -= dt  # 每秒钟减少1秒

        if self.time_remaining <= 0:
            self.time_remaining = 0  # 倒计时结束

    def get_progress(self):
        return 1 - self.time_remaining / 60  # 返回圈速函数的进度值

class CountdownApp(App):
    def build(self):
        return CountdownTimer()

if __name__ == '__main__':
    CountdownApp().run()