自动更新不直接访问的tkinter标签b

Question

我想创建一个简单的图形用户界面，用于通过串口传输的常量数据。我决定用tkinter。值reading将被更新，并应显示在标签中。我为容器和其他页面创建了单独的类。我将容器定义为：

class Gui(Tk):
def __init__(self, *args, **kwargs):
    Tk.__init__(self, *args, **kwargs)
    container = Frame(self)
    container.pack(side="top", fill = "both", expand = TRUE)
    container.grid_rowconfigure(0, weight = 1)

    self.frames={}

    for F in (StartPage, PageOne):
        frame = F(container, self)
        self.frames[F] = frame
        frame.grid(row = 0, column = 0, sticky = "nsew")
        frame.UpdateMe()

    self.show_frame(StartPage)


def show_frame(self, cont):
    frame = self.frames[cont]
    frame.tkraise()

以及显示标签的页面：

class PageOne(Frame):
def __init__(self, parent, controller):
    Frame.__init__(self,parent)
    global reading
    self.label1text = StringVar()
    self.label1 = Label(self, textvariable = label1text)
    self.label1.pack()
    button1 = Button (self, text = "Show Start Page", command = lambda: controller.show_frame(StartPage))
    button1.pack()
    self.label1text.set(reading)


def UpdateMe(self):
    global reading
    self.lable1text.set(reading)

现在，要初始化GUI：

root = Gui()
root.mainloop()

但是，因为mainloop()是阻塞的，所以后面的任何参数都不会被执行；我可以用update和update_idletasks来绕过它。但是，当我只创建了Gui()的实例化时，我仍然不知道如何调用UpdateMe()内的函数PageOne()。有没有办法解决这个问题或者修正我对类和对象编程的理解？你知道吗

Answer 1

因为在没有初始化Tk()的情况下无法创建StringVar（对于您的情况，它是Gui()），所以您需要在Gui()内创建reading变量，并且PageOne.label1使用它作为它的textvariable。以下是基于您的代码的示例：

from tkinter import *
from random import randint

class Gui(Tk):
    def __init__(self, *args, **kwargs):
        Tk.__init__(self, *args, **kwargs)
        container = Frame(self)
        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.reading = StringVar() # create the StringVar for PageOne

        self.frames = {}
        for F in (StartPage, PageOne):
            frame = F(container, self)
            frame.grid(row=0, column=0, sticky="nsew")
            self.frames[F] = frame
        self.show_frame(StartPage)

    def show_frame(self, cont):
        self.frames[cont].tkraise()

class StartPage(Frame):
    def __init__(self, parent, controller):
        Frame.__init__(self, parent)
        button1 = Button (self, text="Show Page 1", command=lambda: controller.show_frame(PageOne))
        button1.pack(fill="both", expand=True)

class PageOne(Frame):
    def __init__(self, parent, controller):
        Frame.__init__(self, parent)
        self.label1 = Label(self, textvariable=controller.reading) # refer to Gui.reading StringVar
        self.label1.pack(fill='x')
        button1 = Button (self, text="Show Start Page", command=lambda: controller.show_frame(StartPage))
        button1.pack(fill='x')


# use .after() to simulate the update of reading variable periodically
def update_reading():
    app.reading.set(randint(0, 10000))
    print('reading:', app.reading.get())
    app.after(1000, update_reading)

app = Gui()
update_reading() # start the simulation task of updating reading variable
app.mainloop()

注意，我创建了一个函数update_reading()，用after()函数来模拟reading变量的周期性更新。你知道吗