Tkinter 实时更新变量

Question

我有这个代码显示一个页面，然后当按下 PAGE1 按钮时转到其他框架。在这里，我想在任何标签中显示时间，但我希望它自动更新。我不能自己做

import Tkinter as tk
from Tkinter import *
import time
import datetime

def clock():
    time = datetime.datetime.now().strftime("Time: %H:%M:%S")
    print time

class MainApp(tk.Tk):

    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)

        container = tk.Frame(self)
        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.frames = {}
        for F in (MainPage, page1, help):
            page_name = F.__name__
            frame = F(parent=container, controller=self)
            self.frames[page_name] = frame
            frame.grid(row=0, column=0, columnspan=12,sticky="nsew")
            frame.grid_columnconfigure(0, weight=1)
            frame.grid_columnconfigure(1, weight=1)
            frame.grid_columnconfigure(2, weight=1)
            frame.grid_columnconfigure(3, weight=1)
            frame.grid_columnconfigure(4, weight=1)
            frame.grid_columnconfigure(5, weight=1)
            frame.grid_columnconfigure(6, weight=1)
            frame.grid_columnconfigure(7, weight=1)
            frame.grid_columnconfigure(8, weight=1)
            frame.grid_columnconfigure(9, weight=1)
            frame.grid_columnconfigure(10, weight=1)
            frame.grid_columnconfigure(11, weight=1)

        self.show_frame("MainPage")
        clock()
    def show_frame(self, page_name):
        frame = self.frames[page_name]
        frame.tkraise()


class MainPage(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller

        # line 0
        label00 = tk.Label(self, text='00', height=2)
        label00.configure(relief='raised')
        label00.grid(row=0, column=0, sticky='nsew', columnspan=12)
        # line 1
        label10 = tk.Label(self, text='10')
        label10.configure(relief='raised')
        label10.grid(row=1, column=0, sticky='nsew')
        label11 = tk.Label(self, text='LOGO')
        label11.configure(relief='raised')
        label11.grid(row=1, column=1, sticky='nsew', columnspan=4, rowspan=2)
        label12 = tk.Label(self, text='12')
        label12.configure(relief='raised')
        label12.grid(row=1, column=5, sticky='nsew')
        label13 = tk.Label(self, text='TITLE')
        label13.configure(relief='raised')
        label13.grid(row=1, column=6, sticky='nsew', columnspan=5)
        label14 = tk.Label(self, text='14')
        label14.configure(relief='raised')
        label14.grid(row=1, column=11, sticky='nsew')
        # line 2
        label20 = tk.Label(self, text='20')
        label20.configure(relief='raised')
        label20.grid(row=2, column=0, sticky='nsew')
        label21 = tk.Label(self, text='21')
        label21.configure(relief='raised')
        label21.grid(row=2, column=5, sticky='nsew')
        label22 = tk.Label(self, text='Desc')
        label22.configure(relief='raised')
        label22.grid(row=2, column=6, sticky='nsew', columnspan=5)
        label23 = tk.Label(self, text='23')
        label23.configure(relief='raised')
        label23.grid(row=2, column=11, sticky='nsew')
        # line 3
        label30 = tk.Label(self, text='30', height=2)
        label30.configure(relief='raised')
        label30.grid(row=3, column=0, sticky='nsew', columnspan=12)
        #line 4
        label40 = tk.Label(self, text='40', width=10)
        label40.configure(relief='raised')
        label40.grid(row=4, column=0, sticky='nsew')
        label41 = tk.Label(self, text='STATUS', font=("Helvetica", 16), justify='center', fg="blue")
        label41.configure(relief='raised')
        label41.grid(row=4, column=1, columnspan=10)
        label42 = tk.Label(self, text='42', width=10)
        label42.configure(relief='raised')
        label42.grid(row=4, column=11, sticky='nsew')
        #line 5
        label50 = tk.Label(self, text='50', height=2)
        label50.configure(relief='raised')
        label50.grid(row=5, column=0, columnspan=12, sticky="nsew")
        #line 6
        label60 = tk.Label(self, text='60', height=2)
        label60.configure(relief='raised')
        label60.grid(row=6, column=0, sticky='nsew')
        buttonauto = tk.Button(self, text="PAGE1", font=("Helvetica", 16), justify='center', width=40, height=5,
                              command=lambda: controller.show_frame("page1"))
        buttonauto.grid(row=6, column=1, columnspan=4)
        label61 = tk.Label(self, text='61', height=2)
        label61.configure(relief='raised')
        label61.grid(row=6, column=5, sticky='nsew')
        label62 = tk.Label(self, text='62', height=2)
        label62.configure(relief='raised')
        label62.grid(row=6, column=6, sticky='nsew')
        buttoncam = tk.Button(self, text="HELP",font=("Helvetica", 16), justify='center', width=40, height=5,
                              command=lambda: controller.show_frame("help"))
        buttoncam.grid(row=6 , column=7, columnspan=4)
        label63 = tk.Label(self, text='63', height=2)
        label63.configure(relief='raised')
        label63.grid(row=6, column=11, sticky='nsew')
        # line 7
        label70 = tk.Label(self, text='70', height=2)
        label70.configure(relief='raised')
        label70.grid(row=7, column=0, sticky='nsew', columnspan=12)

        #line 13
        label13 = tk.Label(self, text='', height=2)
        label13.configure(relief='raised')
        label13.grid(row=13, column=0, columnspan=12, sticky="nsew")
        #line 14
        label14 = tk.Label(self, text='', width=10)
        label14.grid(row=14, column=0, sticky='w')
        buttonhlp = tk.Button(self, text="Help", width=20, height = 3,
                              command=lambda: controller.show_frame("help"))
        buttonhlp.grid(row=14, column=1, columnspan=4)
        label14 = tk.Label(self, text='')
        label14.grid(row=14, column=5, columnspan=2)
        buttonquit = tk.Button(self, text="Quit", width=20, height = 3, command=close_window)
        buttonquit.grid(row=14, column=7, columnspan=4)
        label14 = tk.Label(self, text='', width=10)
        label14.grid(row=14, column=11, sticky='e')
        #line 15
        label15 = tk.Label(self, text='', height=5)
        label15.grid(row=15, column=0, columnspan=12, sticky="nsew")


class page1(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller

        #line 0
        label00 = tk.Label(self, text='PAGE1', height=2)
        label00.configure(relief='raised')
        label00.grid(row=13, column=0, columnspan=12, sticky="nsew")
        #line 1
        label10 = tk.Label(self, text='', width=10)
        label10.grid(row=14, column=0, sticky='w')
        buttonback = tk.Button(self, text="Back", width=20, height = 3,
                              command=lambda: controller.show_frame("MainPage"))
        buttonback.grid(row=14, column=1, columnspan=4)
        label10= tk.Label(self, text='')
        label10.grid(row=14, column=5, columnspan=2)
        buttonquit = tk.Button(self, text="Quit", width=20, height = 3, command=close_window)
        buttonquit.grid(row=14, column=7, columnspan=4)
        label10 = tk.Label(self, text='', width=10)
        label10.grid(row=14, column=11, sticky='e')
        #line 2
        label20 = tk.Label(self, text='', height=5)
        label20.grid(row=15, column=0, columnspan=12, sticky="nsew")

class help(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller

        #line 0
        label00 = tk.Label(self, text='HELP', height=2)
        label00.configure(relief='raised')
        label00.grid(row=13, column=0, columnspan=12, sticky="nsew")
        #line 1
        label10 = tk.Label(self, text='', width=10)
        label10.grid(row=14, column=0, sticky='w')
        buttonback = tk.Button(self, text="Back", width=20, height = 3,
                              command=lambda: controller.show_frame("MainPage"))
        buttonback.grid(row=14, column=1, columnspan=4)
        label10= tk.Label(self, text='')
        label10.grid(row=14, column=5, columnspan=2)
        buttonquit = tk.Button(self, text="Quit", width=20, height = 3, command=close_window)
        buttonquit.grid(row=14, column=7, columnspan=4)
        label10 = tk.Label(self, text='', width=10)
        label10.grid(row=14, column=11, sticky='e')
        #line 2
        label20 = tk.Label(self, text='', height=5)
        label20.grid(row=15, column=0, columnspan=12, sticky="nsew")


def close_window ():
    app.destroy()


if __name__ == "__main__":
    app = MainApp()

    app.overrideredirect(True)
    app.geometry("{0}x{1}+0+0".format(app.winfo_screenwidth(), app.winfo_screenheight()))
    app.focus_set()  # <-- move focus to this widget


    app.mainloop()

所以实际上我希望在打开 page1 框架时，在 label00 中我想看到我在代码开头打印的时间。

Answer 1

You should use the after method, so as to periodically update the label displaying the time. The following post provides in-depth explanations on how to do so: How to use the after method to make a callback run periodically?

Let's build a minimal example. First off, I need a root, and a label:

import tkinter as tk
root = tk.Tk()
label = tk.Label(root, text="placeholder")
label.pack()

Now, I need a function that will set the current time in the label. As explained in the Q/A I linked to, I need this function to call itself. Since I want the label to be refreshed as fast as possible, I will ask the function to call itself after one millisecond. The time module could be used, but the datetime module wraps the latter so as to provide human-readable time.

import datetime
def set_label():
    currentTime = datetime.datetime.now()
    label['text'] = currentTime
    root.after(1, set_label)

Now I will call the set_label function, in order to start the loop, and then call root.mainloop so as to enter the application's loop:

set_label()
root.mainloop()

All together:

import tkinter as tk
import time

def set_label():
    currentTime = datetime.datetime.now()
    label['text'] = currentTime
    root.after(1, set_label)

root = tk.Tk()
label = tk.Label(root, text="placeholder")
label.pack()

set_label()
root.mainloop()