Create First GUI Application using Python-Tkinter

Tkinter is a Python Package for creating GUI applications. Python has a lot of GUI frameworks, but Tkinter is the only framework that’s built into the Python standard library. Tkinter has several strengths; it’s cross-platform, so the same code works on Windows, macOS, and Linux. Tkinter is lightweight and relatively painless to use compared to other frameworks. This makes it a compelling choice for building GUI applications in Python, especially for applications where a modern shine is unnecessary, and the top priority is to build something that’s functional and cross-platform quickly.  

To understand Tkinter better, we will create a simple GUI. 

Getting Started

1. Import tkinter package and all of its modules.
2. Create a root window. Give the root window a title(using title()) and dimension(using geometry()).  All other widgets will be inside the root window. 
3. Use mainloop() to call the endless loop of the window. If you forget to call this nothing will appear to the user. The window will wait for any user interaction till we close it.

Example:

Python3

# Import Module
from tkinter import *

# create root window
root = Tk()

# root window title and dimension
root.title("Welcome to GeekForGeeks")
# Set geometry (widthxheight)
root.geometry('350x200')

# all widgets will be here
# Execute Tkinter
root.mainloop()

Output: 

Root Window

4. We’ll add a label using the Label Class and change its text configuration as desired.  The grid() function is a geometry manager which keeps the label in the desired location inside the window. If no parameters are mentioned by default it will place it in the empty cell; that is 0,0 as that is the first location. 

Example:

Python3

# Import Module
from tkinter import *

# create root window
root = Tk()

# root window title and dimension
root.title("Welcome to GeekForGeeks")
# Set geometry(widthxheight)
root.geometry('350x200')

#adding a label to the root window
lbl = Label(root, text = "Are you a Geek?")
lbl.grid()

# Execute Tkinter
root.mainloop()

Output:

Label inside root window

5.  Now add a button to the root window. Changing the button configurations gives us a lot of options.  In this example we will make the button display a text once it is clicked and also change the color of the text inside the button. 

Example:

Python3

# Import Module
from tkinter import *

# create root window
root = Tk()

# root window title and dimension
root.title("Welcome to GeekForGeeks")
# Set geometry(widthxheight)
root.geometry('350x200')

# adding a label to the root window
lbl = Label(root, text = "Are you a Geek?")
lbl.grid()

# function to display text when
# button is clicked
def clicked():
    lbl.configure(text = "I just got clicked")

# button widget with red color text
# inside
btn = Button(root, text = "Click me" ,
             fg = "red", command=clicked)
# set Button grid
btn.grid(column=1, row=0)

# Execute Tkinter
root.mainloop()

Output:  

Button added

After clicking “Click me”

6. Using the Entry() class we will create a text box for user input. To display the user input text, we’ll make changes to the function clicked(). We can get the user entered text using the get() function. When the Button after entering of the text, a default text concatenated with the user text. Also change button grid location to column 2 as Entry() will be column 1.

Example:

Python3

# Import Module
from tkinter import *

# create root window
root = Tk()

# root window title and dimension
root.title("Welcome to GeekForGeeks")
# Set geometry(widthxheight)
root.geometry('350x200')

# adding a label to the root window
lbl = Label(root, text = "Are you a Geek?")
lbl.grid()

# adding Entry Field
txt = Entry(root, width=10)
txt.grid(column =1, row =0)


# function to display user text when
# button is clicked
def clicked():

    res = "You wrote" + txt.get()
    lbl.configure(text = res)

# button widget with red color text inside
btn = Button(root, text = "Click me" ,
             fg = "red", command=clicked)
# Set Button Grid
btn.grid(column=2, row=0)

# Execute Tkinter
root.mainloop()

Output: 

Entry Widget at column 2 row 0

Displaying user input text. 

7. To add a menu bar, you can use Menu class. First, we create a menu, then we add our first label, and finally, we assign the menu to our window. We can add menu items under any menu by using add_cascade().

Example:

Python3

# Import Module
from tkinter import *

# create root window
root = Tk()

# root window title and dimension
root.title("Welcome to GeekForGeeks")
# Set geometry(widthxheight)
root.geometry('350x200')

# adding menu bar in root window
# new item in menu bar labelled as 'New'
# adding more items in the menu bar
menu = Menu(root)
item = Menu(menu)
item.add_command(label='New')
menu.add_cascade(label='File', menu=item)
root.config(menu=menu)

# adding a label to the root window
lbl = Label(root, text = "Are you a Geek?")
lbl.grid()

# adding Entry Field
txt = Entry(root, width=10)
txt.grid(column =1, row =0)


# function to display user text when
# button is clicked
def clicked():

    res = "You wrote" + txt.get()
    lbl.configure(text = res)

# button widget with red color text inside
btn = Button(root, text = "Click me" ,
             fg = "red", command=clicked)
# Set Button Grid
btn.grid(column=2, row=0)

# Execute Tkinter
root.mainloop()

Output : 

Menu bar

This simple GUI covers the basics of Tkinter package. Similarly, you can add more widgets and change their configurations as desired. 

Widgets

Tkinter provides various controls, such as buttons, labels and text boxes used in a GUI application. These controls are commonly called Widgets.  The list of commonly used Widgets are mentioned below –

S No.	Widget	Description
1	Label	The Label widget is used to provide a single-line caption for other widgets. It can also contain images.
2	Button	The Button widget is used to display buttons in your application.
3	Entry	The Entry widget is used to display a single-line text field for accepting values from a user.
4	Menu	The Menu widget is used to provide various commands to a user. These commands are contained inside Menubutton.
5	Canvas	The Canvas widget is used to draw shapes, such as lines, ovals, polygons and rectangles, in your application.
6	Checkbutton	The Checkbutton widget is used to display a number of options as checkboxes. The user can select multiple options at a time.
7	Frame	The Frame widget is used as a container widget to organize other widgets.
8	Listbox	The Listbox widget is used to provide a list of options to a user.
9	Menubutton	The Menubutton widget is used to display menus in your application.
10	Message	The Message widget is used to display multiline text fields for accepting values from a user.
11	Radiobutton	The Radiobutton widget is used to display a number of options as radio buttons. The user can select only one option at a time.
12	Scale	The Scale widget is used to provide a slider widget.
13	Scrollbar	The Scrollbar widget is used to add scrolling capability to various widgets, such as list boxes.
14	Text	The Text widget is used to display text in multiple lines.
15	Toplevel	The Toplevel widget is used to provide a separate window container.
16	LabelFrame	A labelframe is a simple container widget. Its primary purpose is to act as a spacer or container for complex window layouts.
17	tkMessageBox	This module is used to display message boxes in your applications.
18	Spinbox	The Spinbox widget is a variant of the standard Tkinter Entry widget, which can be used to select from a fixed number of values.
19	PanedWindow	A PanedWindow is a container widget that may contain any number of panes, arranged horizontally or vertically.

Geometry Management

All Tkinter widgets have access to specific geometry management methods, which have the purpose of organizing widgets throughout the parent widget area. Tkinter exposes the following geometry manager classes: pack, grid, and place. Their description is mentioned below –

S No.	Widget	Description
1	pack()	This geometry manager organizes widgets in blocks before placing them in the parent widget.
2	grid()	This geometry manager organizes widgets in a table-like structure in the parent widget.
3	place()	This geometry manager organizes widgets by placing them in a specific position in the parent widget.