Python | ToDo GUI Application using Tkinter

Last Updated : 10 Jun, 2021

Prerequisites : Introduction to tkinter

Python offers multiple options for developing GUI (Graphical User Interface). Out of all the GUI methods, Tkinter is the most commonly used method. In this article, we will learn how to create a ToDo GUI application using Tkinter, with a step-by-step guide.

To create a tkinter :

Importing the module – tkinter
Create the main window (container)
Add any number of widgets to the main window.
Apply the event Trigger on the widgets.

The GUI would look like below:

Let’s create a GUI based simple ToDo application in which you can add and delete the Task.

Below is the implementation :

Python3

# import all functions from the tkinter   
from tkinter import *
 
# import messagebox class from tkinter
from tkinter import messagebox
 
# global list is declare for storing all the task
tasks_list = []
 
# global variable is declare for counting the task
counter = 1
 
# Function for checking input error when
# empty input is given in task field
def inputError() :
     
    # check for enter task field is empty or not
    if enterTaskField.get() == "" :
         
        # show the error message
        messagebox.showerror("Input Error")
         
        return 0
     
    return 1
 
# Function for clearing the contents
# of task number text field
def clear_taskNumberField() :
     
    # clear the content of task number text field
    taskNumberField.delete(0.0, END)
 
# Function for clearing the contents
# of task entry field   
def clear_taskField() :
 
    # clear the content of task field entry box
    enterTaskField.delete(0, END)
     
# Function for inserting the contents
# from the task entry field to the text area 
def insertTask():
 
    global counter
     
    # check for error
    value = inputError()
 
    # if error occur then return
    if value == 0 :
        return
 
    # get the task string concatenating
    # with new line character
    content = enterTaskField.get() + "\n"
 
    # store task in the list
    tasks_list.append(content)
 
    # insert content of task entry field to the text area
    # add task one by one in below one by one
    TextArea.insert('end -1 chars', "[ " + str(counter) + " ] " + content)
 
    # incremented
    counter += 1
 
    # function calling for deleting the content of task field
    clear_taskField()
 
# function for deleting the specified task
def delete() :
     
    global counter
     
    # handling the empty task error
    if len(tasks_list) == 0 :
        messagebox.showerror("No task")
        return
 
    # get the task number, which is required to delete
    number = taskNumberField.get(1.0, END)
 
    # checking for input error when
    # empty input in task number field
    if number == "\n" :
        messagebox.showerror("input error")
        return
     
    else :
        task_no = int(number)
 
    # function calling for deleting the
    # content of task number field
    clear_taskNumberField()
     
    # deleted specified task from the list
    tasks_list.pop(task_no - 1)
 
    # decremented 
    counter -= 1
     
    # whole content of text area widget is deleted
    TextArea.delete(1.0, END)
 
    # rewriting the task after deleting one task at a time
    for i in range(len(tasks_list)) :
        TextArea.insert('end -1 chars', "[ " + str(i + 1) + " ] " + tasks_list[i])
     
 
# Driver code 
if __name__ == "__main__" :
 
    # create a GUI window
    gui = Tk()
 
    # set the background colour of GUI window 
    gui.configure(background = "light green")
 
    # set the title of GUI window
    gui.title("ToDo App")
 
    # set the configuration of GUI window 
    gui.geometry("250x300")
 
    # create a label : Enter Your Task
    enterTask = Label(gui, text = "Enter Your Task", bg = "light green")
 
    # create a text entry box 
    # for typing the task
    enterTaskField = Entry(gui)
 
    # create a Submit Button and place into the root window
    # when user press the button, the command or 
    # function affiliated to that button is executed 
    Submit = Button(gui, text = "Submit", fg = "Black", bg = "Red", command = insertTask)
 
    # create a text area for the root
    # with lunida 13 font
    # text area is for writing the content
    TextArea = Text(gui, height = 5, width = 25, font = "lucida 13")
 
    # create a label : Delete Task Number
    taskNumber = Label(gui, text = "Delete Task Number", bg = "blue")
                        
    taskNumberField = Text(gui, height = 1, width = 2, font = "lucida 13")
 
    # create a Delete Button and place into the root window
    # when user press the button, the command or 
    # function affiliated to that button is executed .
    delete = Button(gui, text = "Delete", fg = "Black", bg = "Red", command = delete)
 
    # create a Exit Button and place into the root window
    # when user press the button, the command or 
    # function affiliated to that button is executed .
    Exit = Button(gui, text = "Exit", fg = "Black", bg = "Red", command = exit)
 
    # grid method is used for placing 
    # the widgets at respective positions 
    # in table like structure.
    enterTask.grid(row = 0, column = 2)
 
    # ipadx attributed set the entry box horizontal size               
    enterTaskField.grid(row = 1, column = 2, ipadx = 50)
                        
    Submit.grid(row = 2, column = 2)
         
    # padx attributed provide x-axis margin 
    # from the root window to the widget.
    TextArea.grid(row = 3, column = 2, padx = 10, sticky = W)
                        
    taskNumber.grid(row = 4, column = 2, pady = 5)
                        
    taskNumberField.grid(row = 5, column = 2)
 
    # pady attributed provide y-axis
    # margin from the widget.                  
    delete.grid(row = 6, column = 2, pady = 5)
                        
    Exit.grid(row = 7, column = 2)
 
    # start the GUI 
    gui.mainloop()