How to use an OptionMenu in Python Tkinter to set the justify option in a text box

Question

I am creating a word editor in which I would like a taskbar at the top which has an OptionMenu widget with 3 possible choices - "right", "left", and "center". When one of these choices are chosen, it should take the value of that choice and set a text box window to each of those values using .tag_add, .insert, and .tag_config. Here is my code so far. All of it is inside of a frame called Task1, and the text box itself is inside a frame called label_frame. Next, the taskbar and the OptionMenu widget is inside a frame called Taskbar1. Here is my full code, which makes the GUI work.

from tkinter import *
from tkinter import ttk
from tkinter.scrolledtext import ScrolledText
import tkinter as tk
from tkinter import Menu, filedialog

root = Tk()

class ToDoList(tk.Frame):
    def __init__(self, master):
        root.columnconfigure(2, weight=1)
        root.rowconfigure(1, weight=1)


root.title("To - Do List")
root.geometry("1200x600")
root.configure(background = "white")
# Variable list:

style = ttk.Style()                     
current_theme =style.theme_use()
style.theme_settings(current_theme, {"TNotebook.Tab": {"configure": {"padding": [20, 5], "background" : "white"}}})
style.theme_settings(current_theme, {"TNotebook" : {"configure" : {"tabposition" : "wn", "padding" : (0, 5)}}})
style.theme_settings(current_theme, {"TNotebook.Window" : {"configure" : {"width" : 500}}})

TasksList = ttk.Notebook(root)
Task1 = tk.Frame(TasksList, bg='white', height = 1000, width = 3000)

Taskbar1 = tk.Frame(Task1, bg="white", width=176)
Taskbar1.pack()
Button(Taskbar1, text="Hello", highlightthickness=0, borderwidth=0, highlightbackground = "white").pack(pady=[4, 5], padx=[3,3], ipadx = [2], ipady = [2], side = LEFT)


JustifyOptionList = ["right", "center", "left"]
JustifyDefaultOption=StringVar(Taskbar1)
JustifyDefaultOption.set(JustifyOptionList[0]) # default choice
JustifyOption= OptionMenu(Taskbar1, JustifyDefaultOption, *JustifyOptionList)
JustifyOption.pack(side = LEFT)

JustifyDefaultOption



entry1 = Entry(Task1, width = 60, font = "Calibri 20", highlightthickness = 0, justify = "center", selectborderwidth = 0, bd = 1, borderwidth = 0, relief = FLAT)
entry1.pack()

label_frame = tk.Frame(Task1, width=1000,height=550,bg="blue")
label_frame.pack()
label_frame.columnconfigure(0, weight=2)  
label_frame.rowconfigure(0, weight = 1)
label_frame.pack_propagate(0)



# create a Text widget
root.txt = tk.Text(label_frame)
root.txt.config(font=("TkMenuFont"), undo=True, wrap='word', highlightthickness=0, borderwidth=0, bd = 1, highlightbackground = "white", spacing1 = 5, spacing2 = 5, spacing3 = 5)
root.txt.tag_config(JustifyDefaultOption.get(), justify = JustifyDefaultOption.get())
root.txt.insert("1.0", "Please enter your notes here")
root.txt.tag_add(JustifyDefaultOption.get(), "1.0", "end")
root.txt.pack(expand=TRUE, fill = "both", side = LEFT)

# create a Scrollbar and associate it with txt
scrollb = tk.Scrollbar(label_frame, command=root.txt.yview, width = 16, bg = "white", troughcolor = "white", highlightbackground = "white")
scrollb.pack(fill = Y, side = RIGHT)
root.txt['yscrollcommand'] = scrollb.set






Task2 = tk.Frame(TasksList, bg='white')
text=ScrolledText(Task2, width = 176, height = 120, font = "TkMenuFont")
text.grid(row = 2, column = 0)
entry2 = Entry(Task2, width = 179, font = "TkMenuFont")
entry2.grid(row=0, column=0, sticky = W)


Task3 = tk.Frame(TasksList, bg = "white")
text=ScrolledText(Task3, width = 176, height = 120, font = "TkMenuFont")
text.grid(row = 2, column = 0)
entry3 = Entry(Task3, width = 179, font = "TkMenuFont")
entry3.grid(row=0, column=0, sticky = W)


TasksList.add(Task1,text = 'Click Here In Order To Read The Instructions')
TasksList.add(Task2, text = 'Two Two Two Two Two Two'[0: 40] + '...')
TasksList.add(Task3, text = "Three Three Three Three Three Three Three Extra"[0 : 40] + '...')
TasksList.grid(row=1, column=0, sticky=N+W, columnspan=3)


Button(root, text = "WELCOME", borderwidth=0, highlightthickness=0).grid(row=0, column=1, sticky=E, ipady = [5])



Label(text="HELLO", borderwidth=0, highlightthickness=0).grid(row=0, column=0, sticky=W, ipady = [5])

root.mainloop()

The part that I am confused about regarding this is the fact that even though I have a OptionList that records the option that the user selects, this option is not set in the justify settings even though I am using a .get function to take the user's justify setting and apply it to the text box.

score 0 · Accepted Answer · answered Jul 17 '18 at 08:11

The problem is that you do not change the justify setting each time the option changes. Initializing with .get does not make the value update when the StringVar value changes.

One way of applying the new justify setting to the text is to use the command option of the OptionMenu to do it:

import tkinter as tk

def justify_text(option):
    """Change text justify setting."""
    text.tag_configure('justify', justify=option)
    # make sure all text has the tag
    text.tag_add('justify', '1.0', 'end')

root = tk.Tk()

options = ["right", "center", "left"]
var = tk.StringVar(root, options[0])

menu = tk.OptionMenu(root, var, *options, command=justify_text)
menu.pack()

text = tk.Text(root)
text.insert('1.0',  "Please enter your notes here", 'justify')
text.tag_configure('justify', justify=options[0])

text.pack()

root.mainloop()

How to use an OptionMenu in Python Tkinter to set the justify option in a text box

1 Answers1