製作python/tkinter標籤小部件更新？

Question

我正在努力獲取一個python/tkinter標籤小部件來更新其內容。根據今天早些時候的主題，我遵循了關於如何組裝小部件的說明。但是，在運行時，標籤小部件不會更改內容，只是保留其原始內容。據我所知，decrement_widget（）根本不會被調用。有任何想法嗎？

def snooze (secs): 
    """ 
    Snoozes for the given number of seconds. During the snooze, a progress 
    dialog is launched notifying the 
    """ 

    root = Tkinter.Tk() 
    prompt = 'hello' 
    label1 = Tkinter.Label(root, text=prompt, width=len(prompt)) 
    label1.pack() 

    remaining = secs 

    def decrement_label(): 
    text = "Snoozing %d sec(s)" % remaining 
    remaining -= 1 
    label1.config(text=text, width=100) 
    label1.update_idletasks() 

    for i in range(1, secs + 1): 
    root.after(i * 1000, decrement_label) 

    root.after((i+1) * 1000, lambda : root.destroy()) 
    root.mainloop() 

Answer 1

你要設置的標籤的textvariable與StringVar;當StringVar發生變化時（通過您致電myStringVar.set("text here")），標籤的文字也會更新。是的，我同意，這是一種奇怪的做事方式。

關於這一點了更多信息，請參見the Tkinter Book：

您可以用標籤的Tkinter的變量關聯。當該變量的內容發生變化時，標籤會自動更新：

v = StringVar() 
Label(master, textvariable=v).pack() 

v.set("New Text!") 

Answer 2

我覺得因爲Python認爲remaining是在局部範圍內你得到一個「引用賦值之前」的錯誤。

在Python 3中，你可以說nonlocal remaining。但在Python 2中，我不認爲有一種方法可以引用非本地非全局範圍。這爲我工作：

remaining = 0 

def snooze (secs): 
    """ 
    Snoozes for the given number of seconds. During the snooze, a progress 
    dialog is launched notifying the 
    """ 

    global remaining 
    root = Tkinter.Tk() 
    prompt = 'hello' 
    label1 = Tkinter.Label(root, text=prompt, width=len(prompt)) 
    label1.pack() 

    remaining = secs 

    def decrement_label(): 
    global remaining 
    text = "Snoozing %d sec(s)" % remaining 
    remaining -= 1 
    label1.config(text=text, width=100) 
    label1.update_idletasks() 

    for i in range(1, secs + 1): 
    root.after(i * 1000, decrement_label) 

    root.after((i+1) * 1000, lambda : root.destroy()) 
    root.mainloop() 

Answer 3

import tkinter 
    from tkinter import * 

    # just init some vars 
    remaining = 0     
    secs = 0 
    root = tkinter.Tk() 
    prompt = StringVar() 

    def snooze (secs): 
     """ 
     Snoozes for the given number of seconds. During the snooze, a progress 
     dialog is launched notifying the 
     """ 
     def decrement_label(): 
     global remaining, prompt 
     remaining -= 1 
     prompt.set('Snoozing %d sec(s)' % remaining) 
     label1.update_idletasks() 
     if not remaining: 
      print("end ... ") 
      root.destroy() 

     global remaining 
     prompt.set("hello") 
     label1 = tkinter.Label(root, textvariable=prompt, width=30) 
     label1.pack() 

     remaining = secs 
     for i in range(1, secs + 1): 
     root.after(i * 1000, decrement_label) 

    snooze(10) 
    root.mainloop()