Python tkinter:如何确保每次单击按钮时只创建一个子窗口而不是新窗口? [英] Python tkinter: How can I ensure only ONE child window is created onclick and not a new window every time the button is clicked?

问题描述

目前正在学习tkinter，已经走到了尽头.每次我单击 GUI 中的一个按钮(在登录屏幕中输入用户名"和密码"后)都会创建并出现一个新的子窗口.正如它应该.我现在想要做的是确保只创建一个窗口，并且任何后续单击都不会创建更多窗口.这怎么可能?

Currently learning tkinter and have come to a dead end. Each time I click one of the buttons in my GUI (after typing 'username' and 'password' into the log in screen) a new child window is created and appears. As it should. What I would now like to do is to ensure that only one window is created and any subsequent clicks do not create yet more windows. How could this be done?

from tkinter import *

class Main():

    def __init__(self, master):
        self.master = master
        self.master.title("Main Window")

        self.button1 = Button(self.master, text="Click Me 1", command = self.Open1)
        self.button1.grid(row=0, column=0, sticky=W)
        self.button2 = Button(self.master, text="Click Me 2", command = self.Open2)
        self.button2.grid(row=0, column=2, sticky=W)
        self.button3 = Button(self.master, text="Close", command = self.Close)
        self.button3.grid(row=1, column=0, sticky=W)

    def Login(self):

        login_win = Toplevel(self.master)
        login_window = Login(login_win)
        login_window.Focus()
        #main_window.Hide()


    def Open1(self):
        second_window = Toplevel(self.master)
        window2 = Second(second_window)

    def Open2(self):
        third_window = Toplevel(self.master)
        window3 = Third(third_window)

    def Close(self):
        self.master.destroy()

    #def Hide(self):
        #self.master.withdraw()

    #def Appear(self):
        #self.master.deiconify()


class Second():

    def __init__(self, master):
        self.master = master
        self.master.title("Child 1 of Main")
        self.master.geometry("300x300")
        self.button4 = Button(self.master, text="Click Me 1", command = self.Open_Child)
        self.button4.grid(row=0, column=0, sticky=W)


    def Open_Child(self):
        second_child_window = Toplevel(self.master)
        window4 = Second_Child(second_child_window)

class Third():
    def __init__(self, master):
        self.master = master
        self.master.geometry("300x300")
        self.master.title("Child 2 of Main")

class Second_Child():
    def __init__(self, master):
        self.master = master
        self.master.geometry("400x300")
        self.master.title("Child of 'Child 1 of Main'")

class Login():
    def __init__(self, window):

        self.window = window
        self.window.title("Current Library")

        Label(self.window, text="Log in to use this program:").grid(row=0, column=0, sticky=W)

        self.userbox=Entry(self.window, width=20, bg="light green")
        self.userbox.grid(row=1, column=0, sticky=W)

        self.passbox=Entry(self.window, width=20, bg="light green")
        self.passbox.grid(row=2, column=0, sticky=W)

        Button(self.window, text="Submit", width=5, command=self.clicked).grid(row=3, column=0, sticky=W)

    def Focus(self):
        self.window.attributes('-topmost', 1)
        self.window.grab_set()

    def clicked(self):
        username = self.userbox.get()
        password = self.passbox.get()
        if password == "password" and username == "username":
            self.correct = True
            self.window.grab_release()
            self.window.destroy()
        else:
            pass

root_window = Tk()
root_window.iconbitmap(default='transparent.ico')
root_window.geometry("200x100")

main_window = Main(root_window)
main_window.Login()

root_window.mainloop()

在单击按钮时调用的函数中，我可以添加一条 IF 语句吗?:IF 窗口对象不存在，然后实例化窗口对象 ELSE 传递.

Inside the functions which are called when the buttons are clicked could I add an IF statement?: IF window object does not exist then instantiate window object ELSE pass.

def Open1(self):
    if window2 == False:
        second_window = Toplevel(self.master)
        window2 = Second(second_window)
    else:
        pass

如果这是正确的逻辑，那么我如何检查窗口对象是否已经创建，因为上面的方法不起作用，因为我在创建对象之前引用了该对象?

If this is the correct logic then how can I check if a window object has already been created because the above doesn't work as I am referencing the object before it is created?

非常感谢.

推荐答案

在 Main 的 __init__ 中初始化子窗口变量.

Initialize the child window variable in Main's __init__.

self.child_window = None

然后你可以检查它是否存在于Open1中.

Then you can check whether it exists in Open1.

def Open1(self):
    if not self.child_window:
        self.child_window = Second(Toplevel(self.master))

顺便说一句，如果您打算让 Second 像它自己的窗口一样运行，那么每次要创建 Second 时都必须创建一个 Toplevel，这有点尴尬.按照惯例，您会将 Second 设为 Toplevel 的子类，这样它就可以自己创建了.类似的东西:

By the way, if you intend for Second to act like its own window, it's a bit awkward that you have to create a Toplevel every time you want to create a Second. Conventionally, you would make Second a subclass of Toplevel, so it can be created on its own. Something like:

class Second(Toplevel):
    def __init__(self, master, *args, **kargs):
        Toplevel.__init__(self, master, *args, **kargs)
        #rest of initialization goes here. 
        #Use `self` everywhere you previously used `self.master`.

现在你可以这样做:

def Open1(self):
    if not self.child_window:
        self.child_window = Second(self.master)

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