Tkinter Button

Summary: in this tutorial, you’ll learn about the Tkinter Button widget and how to use it to create various kinds of buttons.

Introduction to the Tkinter Button widget #

Button widgets represent a clickable item in the applications. Typically, you use text or an image to display the action that will be performed when clicked.

Buttons can display text in a single font. However, the text can span multiple lines. On top of that, you can make one of the characters underline to mark a keyboard shortcut.

To invoke a function or a method of a class automatically when the button is clicked, you assign its command option to the function or method. This is called the command binding in Tkinter.

To create a button, you use the ttk.Button constructor as follows:

button = ttk.Button(master, **option)Code language: Python (python)

A button has many options. However, the typical ones are like this:

button = ttk.Button(master, text, command)Code language: Python (python)

In this syntax:

• The master is the parent widget on which you place the button.
• The text is the label of the button.
• The command specifies a callback function that will be called automatically when the button is clicked.

Command callback #

The command option associates the button’s action with a function or a method of a class. When you click or press the button, it’ll automatically invoke a callback function.

To assign a callback to the command option, you can use a lambda expression:

def callback():
    # do something


ttk.Button(
   root, 
   text="Demo Button", 
   command=callback
)Code language: Python (python)

If the function contains one expression, you use a lambda expression:

ttk.Button(
   root, 
   text="Demo Button", 
   command=lambda_expression
)Code language: Python (python)

Button states #

The default state of a button is normal. In the normal state, the button will respond to the mouse events and keyboard presses by invoking the callback function assigned to its command option.

The button can also have the disabled state. In the disabled state, a button is greyed out and doesn’t respond to the mouse events and keyboard presses.

To control the state of a button, you use the state() method:

# set the disabled flag
button.state(['disabled'])

# remove the disabled flag
button.state(['!disabled'])Code language: Python (python)

Tkinter button examples #

Let’s take some examples of using button widgets.

1) Simple Tkinter button example #

The following program shows how to display a Exit button. When you click it, the program is terminated.

import tkinter as tk
from tkinter import ttk

# root window
root = tk.Tk()
root.geometry('300x200')
root.resizable(False, False)
root.title('Button Demo')

# exit button
exit_button = ttk.Button(
    root,
    text='Exit',
    command=lambda: root.quit()
)

exit_button.pack(
    ipadx=5,
    ipady=5,
    expand=True
)

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

Output:

How it works.

The following creates the Exit button:

exit_button = ttk.Button(
    root,
    text='Exit',
    command=lambda: root.quit()
)Code language: Python (python)

The command of the button is assigned to a lambda expression that closes the root window.

2) Tkinter image button example #

The following program shows how to display an image button. To practice this example, you need to download the following image first:

Just right-click and save it into a folder that is accessible from the following program e.g., assets folder:

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


# root window
root = tk.Tk()
root.geometry('300x200')
root.resizable(False, False)
root.title('Image Button Demo')


# download button
def download_clicked():
    showinfo(
        title='Information',
        message='Download button clicked!'
    )


download_icon = tk.PhotoImage(file='./assets/download.png')
download_button = ttk.Button(
    root,
    image=download_icon,
    command=download_clicked
)

download_button.pack(
    ipadx=5,
    ipady=5,
    expand=True
)


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

Output:

How it works.

• First, create a new instance of the tk.PhotoImage class that references the image file './assets/download.png'.
• Second, create the ttk.Button whose image option is assigned to the image.
• Third, assign a function to the command option. When you click the button, it’ll call the download_clicked function that displays a message box.

3) Displaying an image button #

To display both text and image on a button, you need to use the compound option. If you don’t, the button will display the text only, not the image.

The following shows how to display both text and image on a button:

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


# root window
root = tk.Tk()
root.geometry('300x200')
root.resizable(False, False)
root.title('Image Button Demo')


# download button handler
def download_clicked():
    showinfo(
        title='Information',
        message='Download button clicked!'
    )


download_icon = tk.PhotoImage(file='./assets/download.png')

download_button = ttk.Button(
    root,
    image=download_icon,
    text='Download',
    compound=tk.LEFT,
    command=download_clicked
)

download_button.pack(
    ipadx=5,
    ipady=5,
    expand=True
)


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

Output:

Summary #

• Use the ttk.Button() class to create a button.
• Assign a lambda expression or a function to the command option to respond to the button click event.
• Assign the tk.PhotoImage() to the image property to display an image on the button.
• Use the compound option if you want to display both text and image on a button.