使用Python和Tkinter制作倒数计时器？

Question

我想使用倒数计时器功能在Tkinter中设置标签.现在它所做的就是在达到10时将标签设置为"10"并且我真的不明白为什么.此外,即使我将计时器打印到终端而不是"时间到了!" 有点从不打印.

import time
import tkinter as tk

class App():
    def __init__(self):
        self.root = tk.Tk()
        self.label = tk.Label(text="null")
        self.label.pack()
        self.countdown()
        self.root.mainloop()

    # Define a timer.
    def countdown(self):
        p = 10.00
        t = time.time()
        n = 0
        # Loop while the number of seconds is less than the integer defined in "p"
        while n - t < p: 
            n = time.time()
            if n == t + p:
                self.label.configure(text="Time's up!")
            else:
                self.label.configure(text=round(n - t))

app=App()

Answer 1

Tkinter已经有一个无限循环运行(事件循环),以及一种在一段时间过后(使用after)安排运行的方法.您可以通过编写一个每秒调用一次以更新显示的函数来利用这一点.您可以使用类变量来跟踪剩余时间.

import Tkinter as tk

class ExampleApp(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.label = tk.Label(self, text="", width=10)
        self.label.pack()
        self.remaining = 0
        self.countdown(10)

    def countdown(self, remaining = None):
        if remaining is not None:
            self.remaining = remaining

        if self.remaining <= 0:
            self.label.configure(text="time's up!")
        else:
            self.label.configure(text="%d" % self.remaining)
            self.remaining = self.remaining - 1
            self.after(1000, self.countdown)

if __name__ == "__main__":
    app = ExampleApp()
    app.mainloop()