Tkinter 标签未跨类更新（另一个）

Question

目标：跨类显示变量

问题：更新标签，特别是第 99 行

错误：仅逻辑

环境： Python 3.6.9、Tk 8.6.8、操作系统 Ubuntu 18.04

写下来：

我试图在包含代码的第 99 行的 pViewSettings 类中显示变量 pPanelSettings.cutLength，但是我无法让它更新/刷新。在我的任何标签中包含textvariable 会使它显示为空白，即使我给它们一个初始值。在包含的尝试中，我留下了一个无效的刷新命令（第 106 行）以及一个无效的跟踪尝试（第 107 行）。其他尝试包括：

update_idletasks, 创建一个额外的字符串变量，它只是重新格式化整数变量以确认这不是问题， 在彼此内部引用pViewSettings 和pPanelSettings（导致循环）， 以及我现在忘记的其他一些内容。

我最感兴趣的是找出我遗漏的“原因”，因为我将来会再次重复这个过程。很抱歉用另一个新手标签问题填满论坛，但我自己在这一点上不知所措。我相信这是一个我完全错过的简单修复。

理想情况下，我想了解textvariable 哪里出了问题，因为这似乎是最简单的解决方案，但与在线示例相比，我仍然看不出我错在哪里。

我：

我不打算在明年初之前进行 GUI 学习，但是我的这个项目的时间表加快了，所以我不得不快速投入。

我看过的帖子：

What are the arguments to Tkinter variable trace method callbacks?

Update Tkinter Label from variable

https://yagisanatode.com/2018/02/26/how-to-display-and-entry-in-a-label-tkinter-python-3/

许多其他人，但只是丢失了我所有的书签。

代码：

import tkinter as tk
import time as time
import math as math

#create main window
root = tk.Tk()
root.title('machine')

#create main container
mainFrame = tk.Frame(root)

#layout main container, grow with window size
mainFrame.pack(fill=tk.BOTH, expand=True)

#create globals
inchesInFeet = tk.IntVar()
answerReset = tk.IntVar()

#set globals
answerReset.set(0)

#create classes
class Page(tk.Frame):
    def __init__(self, *args, **kwargs):
        tk.Frame.__init__(self, *args, **kwargs)
    def show(self):
        self.lift()

class pPanelSettings(Page):
    def __init__(self, *args, **kwargs):
        Page.__init__(self, *args, **kwargs)
        #create variables
        self.cutFeet = tk.IntVar()
        self.cutInches = tk.IntVar()
        self.cutLength = tk.IntVar()
        self.panelCutConfirm = tk.BooleanVar()
        #set variables
        self.cutFeet.set(0)
        self.cutInches.set(0)
        self.cutLength.set(0)
        self.panelCutConfirm.set(0)
        #widgets
        self.pageTitle = tk.Label(self, text='PANEL SETTINGS')
        self.panelBlock = tk.LabelFrame(self, padx=5, pady=5)
        self.panelLabel = tk.Label(self.panelBlock, text='CURRENT PANEL SET LENGTH')
        self.panelSetting = tk.Label(self.panelBlock, text=self.cutLength.get())
        self.messageDisplay = tk.Label(self, text='Set cut length (feet):')
        self.wYesNo = tk.LabelFrame(self, padx=5, pady=5)
        self.bYes = tk.Button(self.wYesNo, text='ENTER', command=self.setCutFeet, height=4, activebackground='green1', background='green2')
        self.response = tk.Entry(self, justify='center')
        #layout
        self.pageTitle.pack(side='top', fill='x')
        self.panelBlock.pack(side='top', fill='x', pady=5)
        self.panelLabel.pack(side='left', fill='x', padx=50)
        self.panelSetting.pack(side='right', fill='x')
        self.messageDisplay.pack(side='top', fill='x', pady=60)
        self.wYesNo.pack(side='bottom', fill='x', padx=20, pady=20, expand=True)
        self.bYes.pack(side='left', fill='both', padx=10, expand=True)
        self.response.pack(side='bottom', fill='x', padx=20, pady=60)
        #settings
        self.response.focus_set()

    def clearText(self):
        self.response.delete(0, 'end')

    def transition(self):
        self.after(2000, self.pageReset)
        
    def pageReset(self): #resets widgets to initial view
        self.response.delete(0, 'end')
        self.messageDisplay.config(text='Set cut length (feet):')
        self.response.pack(side='bottom', fill='x', padx=20, pady=60)
        self.wYesNo.pack(side='bottom', fill='x', padx=20, pady=20, expand=True)
        self.bYes.config(command=self.setCutFeet)
        self.panelSetting.pack(side='right', fill='x')
      
    def setCutFeet(self):
        self.cutFeet.set(int(self.response.get()))
        self.setCutConfirm()
     
    def setCutConfirm(self):
        self.panelCutConfirm.set(True)
        self.cutLength.set(self.cutFeet.get())
        self.panelSetting.config(text=self.cutLength.get())
        print(self.cutLength.get())  ##verification test point using shell
        self.messageDisplay.config(text='Panel cut length set.')
        self.wYesNo.pack_forget()
        self.transition()
        
class pViewSettings(Page): ##this page needs auto update/refresh to display current settings from other pages
    def __init__(self, *args, **kwargs):
        Page.__init__(self, *args, **kwargs)
        #pages to objects
        oPanelSettings = pPanelSettings(self)
        #widgets
        self.pageTitle = tk.Label(self, text='VIEW SETTINGS')
        self.panelBlock = tk.LabelFrame(self, padx=5, pady=5)
        self.panelLabel = tk.Label(self.panelBlock, text='PANEL LENGTH')
        self.panelSetting = tk.Label(self.panelBlock, text=oPanelSettings.cutLength.get())
        #layout
        self.pageTitle.pack(side='top', fill='x')
        self.panelBlock.pack(side='top', fill='x', pady=5)
        self.panelLabel.pack(side='left', fill='x', padx=50)
        self.panelSetting.pack(side='right', fill='x')
        #actions
        self.refreshSelf() ##i know that this doesn't work, but i do not understand why
        oPanelSettings.cutLength.trace('r', self.refreshSelf) ##i really feel like this should work though

    def refreshSelf(self):
        #pages to objects
        oPanelSettings = pPanelSettings(self)
        #action
        self.after(1000, self.refreshSelf)
        self.panelSetting.config(text=oPanelSettings.cutLength.get())

class pMainView(tk.Frame):
    def __init__(self, *args, **kwargs):
        tk.Frame.__init__(self, *args, **kwargs)
        #pages to objects
        oPanelSettings = pPanelSettings(self)
        oViewSettings = pViewSettings(self)

        #create menu and view windows
        buttonFrame = tk.Frame(self)
        container = tk.Frame(self)
        buttonFrame.pack(side='left', fill='both', expand=False) #menu column
        container.pack(side='right', fill='both', expand=True) #main view window

        #place page objects into main view window
        oPanelSettings.place(in_=container, x=0, y=0, relwidth=1, relheight=1)
        oViewSettings.place(in_=container, x=0, y=0, relwidth=1, relheight=1)
        
        #create menu buttons
        bPanelSettings = tk.Button(buttonFrame, text='Panel Settings', command=oPanelSettings.lift)
        bViewSettings = tk.Button(buttonFrame, text='View Settings', command=oViewSettings.lift)
        
        #menu layout
        bPanelSettings.pack(side='top', fill='both', expand=True)
        bViewSettings.pack(side='top', fill='both', expand=True)
        
        #startup display page
        oViewSettings.show()

if __name__ == '__main__':
    root = tk.Tk()
    oMainView = pMainView(root)
    oMainView.pack(side='top', fill='both', expand=True)
    root.wm_geometry('1024x600')
    root.mainloop()

非常感谢任何和所有帮助。有人打电话给布莱恩奥克利来救我！ :) :)

编辑 #1：缩短代码以实现最少的复制。

Answer 1

使用StringVar更新标签的正确方法如下：

这是一个最小的示例，您可以单击“添加”按钮来增加值并在“红色”和“青色”之间更改标签颜色。

import tkinter as tk


root = tk.Tk()
value = 0
labelVar = tk.StringVar()
labelVar.set(f"Current value: {value}")


def add_text():
    global value
    value += 1
    labelVar.set(f"Current value: {value}")
    if value % 2:
        newcolor = 'red'
    else:
        newcolor = 'cyan'
    label.config(bg=newcolor)


label = tk.Label(root, textvariable=labelVar, bg='cyan')
label.pack()

tk.Button(root, text='Add', command=add_text).pack()

root.mainloop()

Answer 2

对于任何可能在未来找到它的人——我最终只使用了全局变量并添加了一个自循环刷新。附加的代码不是“最小复制”，因为我不想把它擦掉，但它就在那里。我有点理解，最好从设置变量的位置提取变量，但我不明白全局变量与使用此处给出的共享数据示例有何不同（只需吸收 Bryan Oakley 发布的任何内容）How to access variables from different classes in tkinter?。

第 16/19 行 - 定义和初始设置全局变量

第 123 行 - 更新全局变量（类 pPanelSettings）

第 148 行 - 初始显示（类 pViewSettings）

第 155 行 - 开始刷新（pViewSettings 类）

第 159 行 - 只是 L148 的副本

import tkinter as tk
import time as time
import math as math

#create main window
root = tk.Tk()
root.title('Fabric Marker')

#create main container
mainFrame = tk.Frame(root)

#layout main container, grow with window size
mainFrame.pack(fill=tk.BOTH, expand=True)

#define variables
cutLength = tk.IntVar()

#set variables
cutLength.set(0)

#define constants
answerReset = tk.IntVar()

inchesInFeet = tk.IntVar()
inch = tk.IntVar()

#set constants
answerReset.set(0)

inchesInFeet.set(12)
inch.set(1)

#create classes
class Page(tk.Frame): ###I NEED NOTES TO UNDERSTAND THIS ONE ENTIRELY###
    def __init__(self, *args, **kwargs):
        tk.Frame.__init__(self, *args, **kwargs)
    def show(self):
        self.lift()

class pPanelSettings(Page):
    def __init__(self, *args, **kwargs):
        Page.__init__(self, *args, **kwargs)
        #define variables
        self.cutFeet = tk.IntVar()
        self.cutInches = tk.IntVar()
        self.setCutConfirm = tk.BooleanVar()
        #set variables
        self.cutFeet.set(0)
        self.cutInches.set(0)
        self.setCutConfirm.set(False)
        #widgets
        self.pageTitle = tk.Label(self, text='PANEL SETTINGS')
        self.panelBlock = tk.LabelFrame(self, padx=5, pady=5)
        self.panelLabel = tk.Label(self.panelBlock, text='CURRENT PANEL SET LENGTH')
        self.panelSetting = tk.Label(self.panelBlock, text=(str(str(cutLength.get()) + '" / ' + str(self.cutFeet.get()) + '\' ' + str(self.cutInches.get()) + '"')))
        self.messageDisplay = tk.Label(self, text='Set cut length (feet):')
        self.outputDisplay = tk.Label(self)
        self.wYesNo = tk.LabelFrame(self, padx=5, pady=5)
        self.bYes = tk.Button(self.wYesNo, text='ENTER', command=self.setCutFeet, height=4, activebackground='green1', background='green2')
        self.bNo = tk.Button(self.wYesNo, text='CLEAR', command=self.clearText, height=4, activebackground='red1', background='red2')
        self.response = tk.Entry(self, justify='center')
        #layout
        self.pageTitle.pack(side='top', fill='x')
        self.panelBlock.pack(side='top', fill='x', pady=5)
        self.panelLabel.pack(side='left', fill='x', padx=50)
        self.panelSetting.pack(side='right', fill='x')
        self.messageDisplay.pack(side='top', fill='x', pady=60)
        self.wYesNo.pack(side='bottom', fill='x', padx=20, pady=20, expand=True)
        self.bYes.pack(side='left', fill='both', padx=10, expand=True)
        self.bNo.pack(side='right', fill='both', padx=10, expand=True)
        self.response.pack(side='bottom', fill='x', padx=20, pady=60)
        #settings
        self.response.focus_set()

    def clearText(self):
        self.response.delete(0, 'end')

    def confirmTransition(self):
        self.after(2000, self.pageReset)
        
    def pageReset(self):
        self.cutFeet.set(answerReset.get())
        self.cutInches.set(answerReset.get())
        self.response.delete(0, 'end')
        self.outputDisplay.pack_forget()
        self.messageDisplay.config(text='Set cut length (feet):')
        self.wYesNo.pack(side='bottom', fill='x', padx=20, pady=20, expand=True)
        self.bYes.config(command=self.setCutFeet)
        self.bNo.config(command=self.clearText)
        self.response.pack(side='bottom', fill='x', padx=20, pady=60)
        self.outputDisplay.config(foreground='black')
        self.panelSetting.pack(side='right', fill='x')
      
    def setCutFeet(self):
        self.cutFeet.set(int(self.response.get()))
        self.enterCutInches()

    def enterCutInches(self):
        self.response.delete(0, 'end')
        self.bYes.config(command=self.verifyInches)
        self.messageDisplay.config(text='Set cut length (inches):')

    def verifyInches(self):
        if (int(self.response.get()) >= (inchesInFeet.get())):
            self.response.delete(0, 'end')
            self.messageDisplay.config(text='Enter a number less than 12')
            return
        else:
            self.setCutInches()

    def setCutInches(self):
        self.cutInches.set(int(self.response.get()))
        self.response.delete(0, 'end')
        self.response.pack_forget()
        self.messageDisplay.config(text='Is this the correct cut length?')
        self.bYes.config(command=self.setPanelCut)
        self.bNo.config(command=self.pageReset)
        self.outputDisplay.config(text=str(str((self.cutFeet.get() * inchesInFeet.get()) + self.cutInches.get()) + '" / ' + str(self.cutFeet.get()) + '\' ' + str(self.cutInches.get()) + '"'))
        self.outputDisplay.pack(side='bottom', fill='x', padx=20, pady=60)
        
    def setPanelCut(self):
        self.setCutConfirm.set(True)
        cutLength.set((self.cutFeet.get() * inchesInFeet.get()) + self.cutInches.get())
        self.panelSetting.config(text=(str(str(cutLength.get()) + '" / ' + str(self.cutFeet.get()) + '\' ' + str(self.cutInches.get()) + '"')))
        print(cutLength.get())  ##verification test point using shell
        self.messageDisplay.config(text='Panel cut length set.')
        self.outputDisplay.config(foreground='green1', pady=120)
        self.bNo.config(command=self.pageReset)
        self.wYesNo.pack_forget()
        self.confirmTransition()

class pViewSettings(Page):
    #confirm setting options on this page
    def __init__(self, *args, **kwargs):
        Page.__init__(self, *args, **kwargs)
        #define variables
        setMarkConfirm = tk.BooleanVar()
        setJobConfirm = tk.BooleanVar()
        #set variables
        setMarkConfirm.set(0)
        setJobConfirm.set(0)
        #widgets
        self.pageTitle = tk.Label(self, text='VIEW SETTINGS')
        self.panelBlock = tk.LabelFrame(self, padx=5, pady=5)
        self.panelLabel = tk.Label(self.panelBlock, text='PANEL LENGTH')
        self.panelSetting = tk.Label(self.panelBlock, text=str(cutLength.get()) + '" / ' + str(math.trunc(cutLength.get()/inchesInFeet.get())) + '\' ' + str(cutLength.get() - ((math.trunc(cutLength.get()/inchesInFeet.get())) * inchesInFeet.get())) + '"')
        #layout
        self.pageTitle.pack(side='top', fill='x')
        self.panelBlock.pack(side='top', fill='x', pady=5)
        self.panelLabel.pack(side='left', fill='x', padx=50)
        self.panelSetting.pack(side='right', fill='x')
        #action
        self.refreshSelf()

    def refreshSelf(self):
        #action
        self.panelSetting.config(text=str(cutLength.get()) + '" / ' + str(math.trunc(cutLength.get()/inchesInFeet.get())) + '\' ' + str(cutLength.get() - ((math.trunc(cutLength.get()/inchesInFeet.get())) * inchesInFeet.get())) + '"')
        self.after(10, self.refreshSelf)

class pMainView(tk.Frame):
    def __init__(self, *args, **kwargs):
        tk.Frame.__init__(self, *args, **kwargs)
        #pages to objects
        oPanelSettings = pPanelSettings(self)
        oViewSettings = pViewSettings(self)

        #create menu and view windows
        buttonFrame = tk.Frame(self)
        container = tk.Frame(self)
        buttonFrame.pack(side='left', fill='both', expand=False) #menu column
        container.pack(side='right', fill='both', expand=True) #main view window

        #place page objects into main view window
        oPanelSettings.place(in_=container, x=0, y=0, relwidth=1, relheight=1)
        oViewSettings.place(in_=container, x=0, y=0, relwidth=1, relheight=1)
        
        #create menu buttons
        bPanelSettings = tk.Button(buttonFrame, text='Panel Settings', command=oPanelSettings.lift)
        bViewSettings = tk.Button(buttonFrame, text='View Settings', command=oViewSettings.lift)
        
        #menu layout
        bPanelSettings.pack(side='top', fill='both', expand=True)
        bViewSettings.pack(side='top', fill='both', expand=True)

        #startup display page
        oViewSettings.show()

if __name__ == '__main__':
    root = tk.Tk()
    oMainView = pMainView(root)
    oMainView.pack(side='top', fill='both', expand=True)
    root.wm_geometry('1024x600')
    root.mainloop()