Making Python/Tkinter Label Widget Update

Update Tkinter Label from variable

The window is only displayed once the mainloop is entered. So you won't see any changes you make in your while True block preceding the line root.mainloop().

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GUI interfaces work by reacting to events while in the mainloop. Here's an example where the StringVar is also connected to an Entry widget. When you change the text in the Entry widget it automatically changes in the Label.

from tkinter import *

root = Tk()
var = StringVar()
var.set('hello')

l = Label(root, textvariable = var)
l.pack()

t = Entry(root, textvariable = var)
t.pack()

root.mainloop() # the window is now displayed

I like the following reference: tkinter 8.5 reference: a GUI for Python

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Here is a working example of what you were trying to do:

from tkinter import *
from time import sleep

root = Tk()
var = StringVar()
var.set('hello')

l = Label(root, textvariable = var)
l.pack()

for i in range(6):
    sleep(1) # Need this to slow the changes down
    var.set('goodbye' if i%2 else 'hello')
    root.update_idletasks()

root.update Enter event loop until all pending events have been processed by Tcl.

How to Update text in Tkinter Label/Canvas widget using for loop?

import tkinter as tk
root = tk.Tk()
root.attributes("-fullscreen", True)
root.bind("<F11>", lambda event: root.attributes("-fullscreen", not root.attributes("-fullscreen")))
root.bind("<Escape>", lambda event: root.attributes("-fullscreen", False))
root.bind("<F1>", lambda event: os.exit(0))

w = tk.StringVar()

labelFlash = tk.Label(root, bg='Black', width=root.winfo_screenwidth(), height=root.winfo_screenheight(),
                      anchor="center", text="Sample", fg="White", font="Times " , textvariable=w)
labelFlash.pack()
MSG="Hello World"
str_list=[]
for i in range(len(MSG)):
    str_list.append(MSG[:i+1])
words=str_list

indx=0
def update():
    global indx
    if indx>=len(words):
        indx=0
    w.set(words[indx])
    labelFlash.config(text=words[indx])
    indx+=1
    root.after(500, update)#500 ms

update()
root.mainloop()

Update Label Text in Python TkInter

You cannot do precisely what you ask -- you can't associate both a static string and a variable to a label at the same time. There are things you can do to get the desired effect, but all you're doing is adding complexity with no real gain. For example, you can assign an instance of StringVar to the textvariable attribute of the Label widget. When you do that, any update to the variable will update the label. However, you end up having to make a function call to update the variable, so you don't really gain anything over making a function call to update the label directly.

Another option is to use two labels -- one for the static text and one for the variable. Put them side-by side with no border so the user won't notice. Then, when you update the variable you'll get the desired effect. However, you're still having to make a function call to set the variable so you don't really gain much.

Yet another option is to use two instances of StringVar -- one for the label, and another for the name. You can put a trace on the name variable so that when it changes, you automatically update the other variable with the static string and the value of the name variable, and that will cause the label to be automatically updated. Again, however, you're having to make a function call to put everything in motion

So, as you can see, there are options, but they all add complexity to your code with no real gain over simply updating the label directly. The only time these other methods gain you an advantage is when the value needs to appear in more than one widget at once. In that case you can associate the variable with two or more widgets, and a single function call will update all associated widgets.

Update label elements in Tkinter

Basically you don't need to create the Label each iteration, there are several ways of how to update Label in tkinter.

For example:

1.

window = tkinter.Tk()
text = tkinter.StringVar()
text.set('old')
lb = tkinter.Label(window, textvariable=text)
...
text.set('new')

2.

lb = tkinter.Label(window, text="What is " + str(number1) + "x" + str(number2) + " ?")
lb['text'] = 'new'

3.

lb = tkinter.Label(window, text="What is " + str(number1) + "x" + str(number2) + " ?")
lb.config(text='new')

How to update Tkinter Label Text before executing some other function?

Seems to work for me after changing a couple of things (others were mostly just little optimizations).

1. Changed func() to not use time.sleep() as shown below—the after() universal widget method can (also) be used to do this and using it doesn't interfere with the mainloop() running the way calling sleep() would.
2. Called the universal widget method update() instead of update_idletasks() after destruction of the widgets—but still before the counting loop runs.

Here's some documentation describing how to use the universal widget method after() this way (as well as what the update() method does).

FWIW: You'll be able see what's happening better if you add something like a root.geometry('600x400') line following the root = tk.Tk() statement in the initialization section of the example code in your question (not shown here) which will prevent the window from resizing after the widgets are destroyed and the display is updated.

def func():
    widgets = root.grid_slaves()
    for widget in widgets:
        if widget.grid_info()['row']:  # Don't need all that int() != 0 stuff.
            widget.destroy()

    startPrompt.configure(text="Updated Text")  # Only need to call once.
    root.update()  # Update display (startPrompt.update() also works here)

    # Just an example of something running, to verify that the loop executes
    # AFTER the tkinter window has been updated.
    for i in range(10):
        print(i)
#        time.sleep(0.5)  # Don't use sleep in tkiner programs.
        root.after(500)  # Pause 500 millisecs.

Adding and updating new widget in tkinter in runtime

You are getting the error because every thing you retrieve from Text widget is a string and you cannot directly pass an string to .config method, you need a keyword and then you can assign value which can be string.

According to your question and the comments on the question, what i have figured out is:

• You want to run lable.config(bg='red') from the Text widget.
• You want to change the property of specific widget.

Here's what you can do:

1. To run Tkinter code form Text widget, you can use:

• getattr method
• eval method

4. Just to change property of widget:

def update_Frame():
    global bcd
    a = u_text_wid.get("1.0", "end-1c")
    b=a.split(",")
    c=[tuple(i.split("=")) if "=" in i else i for i in b]
    d=dict(i for i in c)
    for key,value in d.items():
        bcd[key]=value

• We can use string to change property only in this format widget_name[key]=value.

Some Useful Links:

• Eval()
• Getattr()

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