Lesson 7 · 7 of 20

Checkboxes · tkinter

tkinter checkboxes (Checkbutton), each with its own BooleanVar: some checked at the start and a summary that changes on every click.

tkinter · Checkboxes in DMarlon Studio: the example's code and the window it opens when run

A Checkbutton is a box you tick and untick. Its state lives in a variable: here, a `BooleanVar`, which is True when checked and False when not.

The toppings dictionary says which boxes start checked. For every topping the loop creates tk.BooleanVar(value=checked) and the checkbox with variable=choices[name]. The variables are kept in the choices dictionary to read them later: if a tkinter variable is lost, the checkbox loses its state.

command=update runs on every click. update goes through choices, keeps the names whose var.get() is True and joins them with ", ".join(...); if there are none, it writes none.

The summary label is created before the loop so update can use it, but it is packed afterwards, below the checkboxes: the position depends on the order of pack, not on the order of creation.

In DMarlon Studio this is the Checkbox in the palette: in the inspector you set its text and whether it starts *Checked*. The studio binds it to an IntVar named self.<Name>_var, which is 1 when checked and 0 when not.

Code · main.py

import tkinter as tkfrom tkinter import ttkroot = tk.Tk()root.title("Pizza toppings")root.geometry("400x270")ttk.Label(root, text="Choose your toppings",          font=("Helvetica", 16, "bold")).pack(anchor="w", padx=24, pady=(20, 8))summary = ttk.Label(root, foreground="#1d4ed8")toppings = {"Cheese": True, "Mushrooms": False, "Olives": True,            "Pepperoni": False, "Pineapple": False}choices = {}  # name -> BooleanVardef update():    chosen = [name for name, var in choices.items() if var.get()]    summary.config(text="Selected: " + (", ".join(chosen) or "none"))# One BooleanVar per checkbox: True while it is checked.for name, checked in toppings.items():    choices[name] = tk.BooleanVar(value=checked)    ttk.Checkbutton(root, text=name, variable=choices[name],                    command=update).pack(anchor="w", padx=36, pady=2)summary.pack(anchor="w", padx=24, pady=14)update()root.mainloop()

Key points

Every checkbox has its own variable (BooleanVar or IntVar).
The variable's initial value decides whether it starts checked.
command runs every time the box is ticked or unticked.
Keep the variables: if they are lost, the checkbox loses its state.

Exercise

Give each topping a price and show the total of the checked ones in the summary.