Python GUI Program: Font size control with Tkinter scale widget

Last update on April 25 2025 12:57:47 (UTC/GMT +8 hours)

Write a Python GUI program to create a Scale widget that controls the font size of a label using tkinter module.

Sample Solution:

Python Code:

import tkinter as tk
from tkinter import ttk

def update_font_size(value):
    try:
        new_font_size = int(float(value))
        label.config(font=("Roboto", new_font_size))
    except ValueError:
        pass  # Ignore non-integer values
parent = tk.Tk()
parent.title("Font Size Control")
# Create a Scale widget for font size control
font_size_scale = ttk.Scale(parent, from_=10, to=36, orient="horizontal", length=200, command=update_font_size)
font_size_scale.pack(pady=10)
# Create a label with initial font size
initial_font_size = 16
label = ttk.Label(parent, text="Font Size", font=("Roboto", initial_font_size))
label.pack(pady=10)
parent.mainloop()

Explanation:

In the exercise above -

First we create a Tkinter main window using tk.Tk() and set its title.
Next we create a ttk.Scale widget named 'font_size_scale' that allows users to select font sizes from 10 to 36.
Create a label widget named label with an initial font size of 16 and display the text "Font Size."
The "update_font_size()" function updates the font size of the label based on the value of the Scale widget. It converts the value to an integer and sets the font size accordingly.
A Scale widget and a Label widget are packed into the main window.
The main event loop, root.mainloop(), starts the Tkinter application.

Sample Output:

Flowchart:

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