尽管update_idletasks（），tkinter游标在行动之后才会改变

Question

我正在尝试更改我的tkinter程序中的光标以显示程序正在运行，但是光标只会更改为工作光标，直到工作完成后，这就像我可以制作代码一样压缩

警告：为了演示工作，当你按第一页时，它将计为99,999,999

import tkinter as tk                # python 3
from tkinter import font  as tkfont # python 3
#import Tkinter as tk     # python 2
#import tkFont as tkfont  # python 2

class SampleApp(tk.Tk):
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        self.title_font = tkfont.Font(family='Helvetica', size=18, weight="bold", slant="italic")

        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 (StartPage, PageOne):
            page_name = F.__name__
            frame = F(parent=container, controller=self)
            self.frames[page_name] = frame

            frame.grid(row=0, column=0, sticky="nsew")
        self.show_frame("StartPage")

    def show_frame(self, page_name):
        '''Show a frame for the given page name'''
        frame = self.frames[page_name]
        frame.tkraise()


class StartPage(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="This is the start page", font=controller.title_font)
        label.pack(side="top", fill="x", pady=10)

        button1 = tk.Button(self, text="Go to Page One",
                            command=self.go)
        button1.pack()

    def go(self):
        # do something for like 5 seconds to demonstrate working
        working(True)
        l = [x for x in range(99999999)]
        self.controller.show_frame('PageOne')


class PageOne(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        label = tk.Label(self, text="This is page 1", font=controller.title_font)
        label.pack(side="top", fill="x", pady=10)
        button = tk.Button(self, text="Go to the start page",
                           command=self.back)
        button.pack()

    def back(self):
        working(False)
        self.controller.show_frame('StartPage')


def working(yesorno):
    if yesorno==True:
        app.config(cursor='wait')
    else:
        app.config(cursor='')
    app.update_idletasks()


if __name__ == "__main__":
    app = SampleApp()
    app.mainloop()

编辑：我要感谢tkinter中两个帧之间切换这个应用程序布局示例

Answer 1

我怀疑所有事件都需要继续更改游标的外观，因为游标依赖于操作系统并且有一些事件要处理（我假设），因为update_idletask没有效果 - 只有在代码流时你的光标才真正改变到达mainloop 。 因为您可以将update视为mainloop(1) （非常粗略的比较） - 如果您知道自己在做什么，这是一个很好的选择，因为没有人想要在代码中无限循环。

代表想法的小片段：

try:
    import tkinter as tk
except ImportError:
    import Tkinter as tk
import time


class App(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.button = tk.Button(self, text='Toggle cursor', command=self.toggle_business)
        self.button.pack()

    def toggle_business(self):
        if self['cursor']:
            self.config(cursor='')
        else:
            self.config(cursor='wait')


        # self.update_idletasks()   # have no effect at all
        # self.update()             # "local" mainloop(1)

        # simulate work with time.sleep
        # time.sleep(3)

        # also your work can be scheduled so code flow can reach a mainloop
        # self.after(500, lambda: time.sleep(3))


app = App()
app.mainloop()

要解决此问题，您可以使用：

• update方法（注意警告）

• after计划工作的方法after （到达代码流的mainloop机会）

• threading “线程”工作（另一个机会，但GUI响应，你可以处理其他事件甚至模拟无响应，另一方面， threading增加了复杂性，所以如果你真的需要它，请使用它）。

注意：Windows平台上的通用游标和本机游标之间的行为没有区别。

Answer 2

此代码在Windows 10和Python 3中进行了测试。我发现在将控件返回到mainloop之前光标不会改变。 此处的代码概述了如何在长时间运行的任务期间始终显示忙碌光标。 此外，此代码演示了如何从长时间运行的任务中检索数据（如数据库查询的结果）。

#! python3
'''
Everything you need to run I/O in a separate thread and make the cursor show busy
Summary:
    1. Set up to call the long running task, get data from windows etc.
        1a. Issue a callback to the routine that will process the data
    2. Do the long running task - absolutely no tkinter access, return the data
    3. Get the data from the queue and process away. tkinter as you will
'''

import tkinter as tk
import tkinter.ttk as ttk
from threading import Thread
from threading import Event
import queue


class SimpleWindow(object):
    def __init__(self):

        self._build_widgets()

    def _build_widgets(self):
        # *************************************************************************************************
        # * Build buttons and some entry boxes
        # *************************************************************************************************
        g_col = 0
        g_row = 0
        WaiterFrame = ttk.Frame()
        WaiterFrame.pack( padx=50)

        i = 0
        g_row += 1
        longWaitButton = ttk.Button(WaiterFrame, text='Long Wait',command=self.setup_for_long_running_task)
        longWaitButton.grid(row = g_row, column = i, pady=4, padx=25)
        i += 1
        QuitButton = ttk.Button(WaiterFrame, text='Quit', command=self.quit)
        QuitButton.grid(row = g_row, column = i,pady=4, padx=25)
        i += 1
        self.Parm1Label = ttk.Label(WaiterFrame, text="Parm 1 Data")
        self.Parm1Label.grid(row = g_row-1, column = i, pady=4, padx=2)
        self.Parm1 = ttk.Entry(WaiterFrame)
        self.Parm1.grid(row = g_row, column = i, pady=4, padx=2)

        i += 1
        self.Parm2Label = ttk.Label(WaiterFrame, text="Parm 2 Data")
        self.Parm2Label.grid(row = g_row-1, column = i, pady=4, padx=2)
        self.Parm2 = ttk.Entry(WaiterFrame)
        self.Parm2.grid(row = g_row, column = i, pady=4, padx=2)

        i += 1
        self.Parm3Label = ttk.Label(WaiterFrame, text="Parm 3 Data")
        self.Parm3Label.grid(row = g_row-1, column = i, pady=4, padx=2)
        self.Parm3 = ttk.Entry(WaiterFrame)
        self.Parm3.grid(row = g_row, column = i, pady=4, padx=2)

        i += 1
        self.Parm4Label = ttk.Label(WaiterFrame, text="Parm 4 Data")
        self.Parm4Label.grid(row = g_row-1, column = i, pady=4, padx=2)
        self.Parm4 = ttk.Entry(WaiterFrame)
        self.Parm4.grid(row = g_row, column = i, pady=4, padx=2)

    def quit(self):
        root.destroy()
        root.quit()

    def setup_for_long_running_task(self):
        # ********************************************************************************************************
        # * Do what needs to be done before starting the long running task in a thread
        # ********************************************************************************************************
        Parm1, Parm2, Parm3, Parm4 = self.Get_Parms()

        root.config(cursor="wait")  # Set the cursor to busy

        # ********************************************************************************************************
        # * Set up a queue for thread communication
        # * Invoke the long running task (ie. database calls, etc.) in a separate thread
        # ********************************************************************************************************
        return_que = queue.Queue(1)
        workThread = Thread(target=lambda q, w_self, p_1, p_2, p_3, p_4: \
                            q.put(self.long_running_task(Parm1, Parm2, Parm3, Parm4)),
                            args=(return_que, self, Parm1, Parm2, Parm3, Parm4))
        workThread.start()
        # ********************************************************************************************************
        # * Busy cursor won't appear until this function returns, so schedule a callback to accept the data
        # * from the long running task. Adjust the wait time according to your situation
        # ********************************************************************************************************
        root.after(500,self.use_results_of_long_running_task,workThread,return_que)  # 500ms is half a second

    # ********************************************************************************************************
    # * This is run in a thread so the cursor can be changed to busy. NO tkinter ALLOWED IN THIS FUNCTION
    # ********************************************************************************************************
    def long_running_task(self, p1,p2,p3,p4):

        Event().wait(3.0)  # Simulate long running task

        p1_out = f'New {p1}'
        p2_out = f'New {p2}'
        p3_out = f'New {p3}'
        p4_out = f'New {p4}'

        return [p1_out, p2_out, p3_out, p4_out]

    # ********************************************************************************************************
    # * Waits for the thread to complete, then gets the data out of the queue for the listbox
    # ********************************************************************************************************
    def use_results_of_long_running_task(self, workThread,return_que):
        ThreadRunning = 1
        while ThreadRunning:
            Event().wait(0.1)  # this is set to .1 seconds. Adjust for your process
            ThreadRunning = workThread.is_alive()

        while not return_que.empty():
            return_list = return_que.get()

        self.LoadWindow(return_list)
        root.config(cursor="")  # reset the cursor to normal

    def LoadWindow(self, data_list):

        self.Parm1.delete(0, tk.END)
        self.Parm2.delete(0, tk.END)
        self.Parm3.delete(0, tk.END)
        self.Parm4.delete(0, tk.END)

        i=0; self.Parm1.insert(0,data_list[i])
        i+=1; self.Parm2.insert(0,data_list[i])
        i+=1; self.Parm3.insert(0,data_list[i])
        i+=1; self.Parm4.insert(0,data_list[i])

    # ********************************************************************************************************
    # * The long running task thread can't get to the tkinter self object, so pull these parms
    # * out of the window and into variables in the main process
    # ********************************************************************************************************
    def Get_Parms(self):
        p1 = self.Parm1Label.cget("text")
        p2 = self.Parm2Label.cget("text")
        p3 = self.Parm3Label.cget("text")
        p4 = self.Parm4Label.cget("text")
        return p1,p2,p3,p4

def WaitForBigData():
    global root

    root = tk.Tk()
    root.title("Wait with busy cursor")
    waitWindow = SimpleWindow()
    root.mainloop()

if __name__ == '__main__':

    WaitForBigData()