为什么我的标签不更新来自不同函数的变量？ Tkinter

Question

我正在写一个时钟程序。我已经构建了代码，但在围绕它创建 GUI 时遇到了问题。我有接受输入并将它们发送到外部函数的条目，并带有用于计算的按钮事件处理。

运行程序，我没有得到更新时间的标签。我想知道这是否与我的文本变量有关。

from tkinter import *
import time
import os


def show_entry_fields():
    hr= hrvar.get()
    mn = minvar.get()
    sc = secvar.get()
    counter = int(hr)*3600+int(mn)*60+ int(sc)

    mins = int(counter/60)
    hours = int(mins/60)

    hours = IntVar()
    mins = IntVar()
    secs = IntVar()

    while counter > 0:
       counter -= 1
       hours, sec = divmod(counter, 3600)
       mins, sec = divmod(sec, 60)
       printv = StringVar()




       printv = (" %d Hr:, %d Min: %d Sec" % (hours, mins, sec))
       win1 = Tk()
       timeLabel = Label(win1, textvariable= printv).grid(row=7)
       mins= int(counter/60)
       hours = int(mins/60)
       time.sleep(1)
       os.system('cls')
       return
   else:
       finishedLabel = Label(master, text="Time is Up").grid(row=7)
       return


  master = Tk()
  Label(master, text="Enter Hour(s)").grid(row=0)
  Label(master, text="Enter Mins(s)").grid(row=1)
  Label(master, text="Enter Second(s)").grid(row=2)

  hrvar = IntVar()
  minvar = IntVar()
  secvar = IntVar()
  e1 = Entry(master, textvariable = hrvar)
  e2 = Entry(master, textvariable = minvar)
  e3 = Entry(master, textvariable = secvar)

  e1.grid(row=0, column=1)
  e2.grid(row=1, column=1)
  e3.grid(row=2, column=1)

  Button(master, text='Quit', command=master.quit).grid(row=3, column=0, 
  sticky=W, pady=4)
  Button(master, text='Show', command=show_entry_fields).grid(row=3, 
  column=1, 
  sticky=W, pady=4)

  mainloop( )

更新代码。

class Timer:

   def __init__(self, master):
       #self.seconds = 0
       self.time = StringVar()
       self.hr = StringVar()
       self.mins = StringVar()
       self.secs = StringVar()

       self.hr_label = Label(master, text='Enter Hours').pack()
       self.entry_hr = Entry(master, textvariable = self.hr )
       self.entry_hr.pack()

       self.min_label = Label(master, text='Enter Minutes').pack()
       self.entry_min = Entry(master, textvariable = self.mins)
       self.entry_min.pack()



       self.time_label = Label(master, relief='flat', font=("Cambria", 20),
                              textvariable=self.time)
       self.set_time(hours= self.entry_hr.get(), minutes=self.entry_min.get(), seconds = 0)

       self.time.set('00:00:00')
       self.start_button = Button(master, text='Start')
       self.start_button.bind('<Button-1>', self.start_countdown)

       self.time_label.pack(padx=30, pady=10)
       self.start_button.pack(pady=(10,20))

   def set_time(self, hours, minutes, seconds):
       self.seconds = hours * 3600 + minutes * 60 + seconds
       self.time.set(self.format_time(self.seconds))

   def start_countdown(self, event):
       self.countdown()

   def countdown(self):
       if self.seconds <= 0:
           return
       self.seconds -= 1
       self.time.set(self.format_time(self.seconds))
       self.time_label.after(1000, self.countdown)

   def format_time(self, seconds):
       h = seconds // 3600
       m = (seconds - h*3600) // 60
       s = seconds - h*3600 - m*60
       return '{:0>2}:{:0>2}:{:0>2}'.format(h,m,s)

if __name__ == '__main__':
    root = Tk()
    timer = Timer(root)
    #timer.set_time(hours=0, minutes=20, seconds=0)
    root.mainloop()

Answer 1

您的代码有几个问题。您正在重新定义 printv、timeLabel，并在 while 循环的每一步创建一个新的 Tk() 对象。更重要的是，您将 printv 定义为 StringVar，但立即将其重新定义为字符串。您应该在 while 循环的外部定义它们中的每一个，然后使用 printv.

的 set() 方法

这是 Tkinter 中一个非常基本的计时器。首先，您应该 而不是 使用 time.sleep 或 while 循环。 mainloop 函数已经是一个 while 循环，大多数 tkinter 对象都有一个 .after() 方法，允许您在 window 时间（以毫秒为单位）后调用事件。

请注意，我创建了一个 class 来封装我的整个 UI。所有变量都存储在 class 中并从其方法中更新。时间是在脚本本身中设置的（目前为 1 小时 20 分钟 10 秒），尽管很容易修改它以接受来自命令行或 UI.[=22= 中的文本字段的参数]

from tkinter import Tk, Label, StringVar
from tkinter.ttk import Button, Entry

class Timer:
    def __init__(self, master):
        self.seconds = 0
        self.time = StringVar()
        self.time_label = Label(master, relief='flat', font=("Cambria", 20),
                                textvariable=self.time)

        self.hr = StringVar()
        self.hr_label = Label(master, text='Hours:').grid(row=1, column=1, padx=5, pady=1)
        self.entry_hr = Entry(master, textvariable=self.hr, width=4)
        self.entry_hr.grid(row=1, column=2)

        self.mins = StringVar()
        self.min_label = Label(master, text='Minutes:').grid(row=2, column=1, padx=5, pady=1)
        self.entry_min = Entry(master, textvariable=self.mins, width=4)
        self.entry_min.grid(row=2, column=2)

        self.secs = StringVar()
        self.secs_label = Label(master, text='Seconds:').grid(row=3, column=1, padx=5, pady=1)
        self.entry_sec = Entry(master, textvariable=self.secs, width=4)
        self.entry_sec.grid(row=3, column=2)

        self.time.set('00:00:00')
        self.start_button = Button(master, text='Start')
        self.start_button.bind('<Button-1>', self.start_countdown)

        self.time_label.grid(row=0, columnspan=4, padx=30, pady=10)
        self.start_button.grid(row=4, columnspan=4, pady=(10,20))

    def set_time(self, hours, minutes, seconds):
        self.seconds = hours * 3600 + minutes * 60 + seconds
        self.time.set(self.format_time(self.seconds))

    def start_countdown(self, event):
        h = self.entry_hr.get()
        m = self.entry_min.get()
        s = self.entry_sec.get()
        h,m,s = map(lambda x: int(x) if x else 0, (h,m,s))
        self.set_time(h,m,s)
        self.countdown()

    def countdown(self):
        if self.seconds <= 0:
            return
        self.time.set(self.format_time(self.seconds))
        self.seconds -= 1
        self.time_label.after(1000, self.countdown)

    def format_time(self, seconds):
        h = seconds // 3600
        m = (seconds - h*3600) // 60
        s = seconds - h*3600 - m*60
        return '{:0>2}:{:0>2}:{:0>2}'.format(h,m,s)

if __name__ == '__main__':
    root = Tk()
    timer = Timer(root)
    root.mainloop()

为什么我的标签不更新来自不同函数的变量？ Tkinter

Why is my label not updating variable from different function? Tkinter

python

tk

tkinter