使 python/tkinter 标签小部件更新？

Question

I'm working on getting a python/tkinter label widget to update its contents. Per an earlier thread today, I followed instructions on how to put together the widgets. At runtime, however, the label widget does NOT change contents, but simply retains its original content. As far as I can tell, decrement_widget() is never called at all. Any ideas?

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

You'll want to set the label's textvariable with a StringVar ; when the StringVar changes (by you calling myStringVar.set("text here") ), then the label's text also gets updated. And yes, I agree, this is a strange way to do things.

See the Tkinter Book for a little more information on this:

You can associate a Tkinter variable with a label. When the contents of the variable changes, the label is automatically updated:

 v = StringVar() Label(master, textvariable=v).pack() v.set("New Text!")

Answer 2

I think you're getting a "referenced before assignment" error because Python thinks remaining is in the local scope.

In Python 3, you can say nonlocal remaining . But in Python 2, I don't believe there's a way to refer to a non-local, non-global scope. This worked for me:

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

To update text in a label you can try the following:

from tkinter import *

root = Tk()
root.title("Title")
root.geometry('300x300')


def clear_text(self):
    txtE.delete(0, 'end')


def new_label(event=None):
    Entree = txtE.get()
    lbl1['text'] = Entree.title()
    clear_text(txtE)


lbl1 = Label(root, text='Hello There')
lbl1.pack()
txtE = Entry(root)
txtE.focus()
txtE.pack()

Button(root, text='Enter', command=new_label).pack()
Button(root, text='Quit', command=root.destroy).pack(side=BOTTOM)
root.bind('<Return>', new_label)
root.mainloop()

Answer 4

    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()

Answer 5

I think you have to call snooze(secs) function

After that if your code again not works try this

Set a variable

Variable = StringVar()

In the label widget you can set "textvariable" argument to the above mentioned "Variable".

Eg: label1 = Label(root,textvariable = Variable).pack()

And you can update by setting a new value to "Variable"

Eg: Variable.set("hi")

Hope you got it !!!