如何在 tkinter 中显示加载消息

Question

我是 tkinter 的新手。我制作了所需的对话框。我的一项功能需要一些时间来处理。所以我想在该函数开始执行之前显示“正在加载...”消息。

b1 = Button(text = "Compare",command = compare)
b1.pack()

当点击此按钮时 compare() 函数开始执行。我想在该功能启动之前显示加载消息。我尝试使用 label ，以便在 compare() 函数开始时为其设置一个值。但只有在函数执行完成后才会生效。

我该怎么做？请帮帮我..

Answer 1

看看manual for widgets。 w.wait_visibility(window) 等到小部件可见。事情的“正常”方式（在所有 GUI 工具包中）是将所有绘图命令（例如您的标签）放在等待列表中，并在有时间时进行实际绘图，优先考虑其他事件）。从页面：

等待给定的小部件变得可见。这通常用于等到屏幕上出现新的顶层窗口。喜欢 wait_variable，这个方法进入一个本地事件循环，所以其他部分 的应用程序仍将照常工作。

wait_visibility 的使用示例来自 test_widgets.py 代码，其中 setup 等待小部件真正显示：

class WidgetTest(unittest.TestCase):
    """Tests methods available in every ttk widget."""

    def setUp(self):
        support.root_deiconify()
        self.widget = ttk.Button(width=0, text="Text")
        self.widget.pack()
        self.widget.wait_visibility()

当然，compare 函数确实需要一些可观的时间 - 否则标签可能会在屏幕上真正看到之前消失。您的屏幕每秒重绘 60 次，因此如果比较时间少于 16 毫秒，您可能什么都看不到。

编辑：更好的方法实际上是使用update_idletasks。这是一些代码：

import tkinter as tk
import time

class SampleApp(tk.Tk):
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        self.frame = tk.Frame(self)
        self.frame.pack(side="top", fill = "both", expand=True)

        self.label = tk.Label(self, text = "Hello, world")
        button1 = tk.Button(self, text = "Start to do something",
                                  command = self.do_something)
        self.label.pack(in_=self.frame)
        button1.pack(in_=self.frame)

    def do_something(self):
        self.label.config(text = "Wait till I'm done...")
        self.label.update_idletasks()
        time.sleep(2)
        print ("end sleep")
        self.label.config(text = "I'm done doing...")

def main():
    app = SampleApp()
    app.mainloop()  
    return 0
    
if __name__ == '__main__':
    main()

do_something 中的 time.sleep 模拟您想做的任何事情。点击按钮开始进程。

Answer 2

只要给定的函数正在运行，就会出现一个带有不确定进度条的弹出窗口和给定的消息。

from tkinter import *
import tkinter.ttk as ttk
import threading


# the given message with a bouncing progress bar will appear for as long as func is running, returns same as if func was run normally
# a pb_length of None will result in the progress bar filling the window whose width is set by the length of msg
# Ex:  run_func_with_loading_popup(lambda: task('joe'), photo_img)  
def run_func_with_loading_popup(func, msg, window_title = None, bounce_speed = 8, pb_length = None):
    func_return_l = []

    class Main_Frame(object):
        def __init__(self, top, window_title, bounce_speed, pb_length):
            print('top of Main_Frame')
            self.func = func
            # save root reference
            self.top = top
            # set title bar
            self.top.title(window_title)

            self.bounce_speed = bounce_speed
            self.pb_length = pb_length

            self.msg_lbl = Label(top, text=msg)
            self.msg_lbl.pack(padx = 10, pady = 5)

            # the progress bar will be referenced in the "bar handling" and "work" threads
            self.load_bar = ttk.Progressbar(top)
            self.load_bar.pack(padx = 10, pady = (0,10))

            self.bar_init()


        def bar_init(self):
            # first layer of isolation, note var being passed along to the self.start_bar function
            # target is the function being started on a new thread, so the "bar handler" thread
            self.start_bar_thread = threading.Thread(target=self.start_bar, args=())
            # start the bar handling thread
            self.start_bar_thread.start()

        def start_bar(self):
            # the load_bar needs to be configured for indeterminate amount of bouncing
            self.load_bar.config(mode='indeterminate', maximum=100, value=0, length = self.pb_length)
            # 8 here is for speed of bounce
            self.load_bar.start(self.bounce_speed)            
#             self.load_bar.start(8)            

            self.work_thread = threading.Thread(target=self.work_task, args=())
            self.work_thread.start()

            # close the work thread
            self.work_thread.join()


            self.top.destroy()
#             # stop the indeterminate bouncing
#             self.load_bar.stop()
#             # reconfigure the bar so it appears reset
#             self.load_bar.config(value=0, maximum=0)

        def work_task(self):
            func_return_l.append(func())


    # create root window
    root = Tk()

    # call Main_Frame class with reference to root as top
    Main_Frame(root, window_title, bounce_speed, pb_length)
    root.mainloop() 
    return func_return_l[0]

if __name__ == '__main__':
    import time
    def task(i):
        # The window will stay open until this function call ends.
        for x in range(10):
            print('hi: ' + i)
            time.sleep(.5) # Replace this with the code you want to run
        return "this is the func return"

    msg = 'running func...'        

    bounc_speed = 9
    pb_length = 200
    window_title = "Wait"

    r = run_func_with_loading_popup(lambda: task('joe'), msg, window_title, bounc_speed, pb_length)

    print('return of test: ', r)