Tkinter Listbox

Introduction to the Tkinter Listbox

A Listbox widget displays a list of single-line text items. A Listbox allows you to browse through the items and select one or multiple items at once.

To create a Listbox, you use the tk.Listbox class like this:

listbox = tk.Listbox(container, listvariable, height)Code language: Python (python)

In this syntax:

  • The container is the parent component of the Listbox.
  • The listvariable links to a tkinter.Variable object. More explanation on this later.
  • The height is the number of items that the Listbox will display without scrolling.

List items

To populate items to a Listbox, you first create a Variable object that is initialized with a list of items. And then you assign this Variable object to the listvariable option as follows:

list_items = tk.Variable(value=items)
listbox = tk.Listbox(
    container,
    height,
    listvariable=list_items
)Code language: Python (python)

To add, remove, or rearrange items in the Listbox, you just need to modify the list_items variable.

Select mode

The selectmode option determines how many you can select and how the mouse drags will affect the items:

  • tk.BROWSE – allows a single selection. If you select an item and drag it to a different line, the selection will follow the mouse. This is the default.
  • tk.EXTENDED – select any adjacent group of items at once by clicking the first item and dragging to the last line.
  • tk.SINGLE – allow you to select one line and you cannot drag the mouse.
  • tk.MULTIPLE – select any number of lines at once. Clicking on any line toggles whether it is selected or not.

Binding the selected event

To execute a function when the selected items change, you bind that function to the <<ListboxSelect>> event:

listbox.bind('<<ListboxSelect>>', callback)Code language: Python (python)

Tkinter Listbox widget example

The following program displays a Listbox that contains a list of programming languages. When you select one or more items, the program displays the selected ones in a message box:

import tkinter as tk
from tkinter import ttk
from tkinter.messagebox import showinfo

# create the root window
root = tk.Tk()
root.title('Listbox')


# create a list box
langs = ('Java', 'C#', 'C', 'C++', 'Python',
         'Go', 'JavaScript', 'PHP', 'Swift')

var = tk.Variable(value=langs)

listbox = tk.Listbox(
    root,
    listvariable=var,
    height=6,
    selectmode=tk.EXTENDED
)

listbox.pack(expand=True, fill=tk.BOTH)


def items_selected(event):
    # get all selected indices
    selected_indices = listbox.curselection()
    # get selected items
    selected_langs = ",".join([listbox.get(i) for i in selected_indices])
    msg = f'You selected: {selected_langs}'
    showinfo(title='Information', message=msg)


listbox.bind('<<ListboxSelect>>', items_selected)

root.mainloop()
Code language: Python (python)

Output:

How it works.

First, create a Variable that holds a list of programming languages:

langs = ('Java', 'C#', 'C', 'C++', 'Python',
        'Go', 'JavaScript', 'PHP', 'Swift')

var = tk.Variables(value=langs)Code language: Python (python)

Second, create a new Listbox widget and assign the var object to the listvariable:

listbox = tk.Listbox(
    root,
    listvariable=var,
    height=6,
    selectmode=tk.EXTENDED
)Code language: Python (python)

The height shows six programming languages without scrolling. The selectmode=tk.EXTENDED allows multiple selections.

Third, define a function that will be invoked when one or more items are selected. The items_selected() function shows a list of currently selected list items:

def items_selected(event):
    # get all selected indices
    selected_indices = listbox.curselection()

    # get selected items
    selected_langs = ",".join([listbox.get(i) for i in selected_indices])
    msg = f'You selected: {selected_langs}'
    showinfo(title='Information', message=msg)Code language: Python (python)

Finally, bind the items_selected function with the '<<ListboxSelect>>' event:

listbox.bind('<<ListboxSelect>>', items_selected)Code language: Python (python)

Adding a scrollbar to the Listbox

The following program illustrates how to add a scrollbar to a Listbox:

import tkinter as tk
from tkinter import ttk
from tkinter.messagebox import showinfo

# create the root window
root = tk.Tk()

root.title('Listbox')


# create a list box
langs = ('Java', 'C#', 'C', 'C++', 'Python',
         'Go', 'JavaScript', 'PHP', 'Swift')

var = tk.Variable(value=langs)

listbox = tk.Listbox(
    root,
    listvariable=var,
    height=6,
    selectmode=tk.EXTENDED)

listbox.pack(expand=True, fill=tk.BOTH, side=tk.LEFT)

# link a scrollbar to a list
scrollbar = ttk.Scrollbar(
    root,
    orient=tk.VERTICAL,
    command=listbox.yview
)

listbox['yscrollcommand'] = scrollbar.set

scrollbar.pack(side=tk.LEFT, expand=True, fill=tk.Y)


def items_selected(event):
    # get selected indices
    selected_indices = listbox.curselection()
    # get selected items
    selected_langs = ",".join([listbox.get(i) for i in selected_indices])
    msg = f'You selected: {selected_langs}'

    showinfo(title='Information', message=msg)


listbox.bind('<<ListboxSelect>>', items_selected)

root.mainloop()Code language: Python (python)

Output:

For more information on how to link a scrollbar to a scrollable widget, check out the scrollbar widget tutorial.

Summary

  • Use the tk.Listbox(container, height, listvariable) to create a Listbox widget; a listvariable should be a tk.StringVar(value=items).
  • Bind a callback function to the '<<ListboxSelect>>' event to execute the function when one or more list items are selected.
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