Develop Notepad using Tkinter in python

Tkinter is a GUI library from python from which we can create multiple GUI apps. Here, using tkinter we will develop a notepad like text editor. This notepad will have the menu where we can create new file, open existing file, save the file, editing, cut and paste, all functionality will there.
Prerequisite
Python installed.
Tkinter installed.
Note: tkinter comes as a standard library with python 3.x.
Our notepad will have four main menu items: File, Edit, Commands & Help. Our file menu item will have four sub-items- New, Open, Save & Exit.
Our edit menu item will have three sub-items- cut, copy & paste
Our commands menu item will have one subitem – About commands,
And our help menu will have one subitem- About notepad
We are going to give these many menu-item & subitem by using below code −
# To open new file
      self.__thisFileMenu.add_command(label="New",
   command=self.__newFile)
      # To open a already existing file
      self.__thisFileMenu.add_command(label="Open",
   command=self.__openFile)
      # To save current file
      self.__thisFileMenu.add_command(label="Save",
   command=self.__saveFile)
      # To create a line in the dialog
      self.__thisFileMenu.add_separator()
      self.__thisFileMenu.add_command(label="Exit",
   command=self.__quitApplication)
      self.__thisMenuBar.add_cascade(label="File", menu=self.__thisFileMenu)
      # To give a feature of cut
      self.__thisEditMenu.add_command(label="Cut",
   command=self.__cut)
      # to give a feature of copy
      self.__thisEditMenu.add_command(label="Copy",
   command=self.__copy)
      # To give a feature of paste
      self.__thisEditMenu.add_command(label="Paste",
   command=self.__paste)
      # To give a feature of editing
      self.__thisMenuBar.add_cascade(label="Edit", menu=self.__thisEditMenu)
      # To create a feature of description of the notepad
      self.__thisHelpMenu.add_command(label="About Notepad",
   command=self.__showAbout)
      self.__thisCommandMenu.add_command(label = "About Commands", command=self.__showCommand)
      self.__thisMenuBar.add_cascade(label="Commands", menu=self.__thisCommandMenu)
      self.__thisMenuBar.add_cascade(label="Help", menu=self.__thisHelpMenu)
Now we have the menu items ready, now we are going to add functionality to each of the menu items. Below the list of functionality, we going to add to this notepad (of course you can add many others too).
Open file
New file
Save file
Quit Application
Show About
Show Commands
Cut
Copy
Paste
Below is the code to implement, above mentioned functionality −
def __quitApplication(self):
   self.__root.destroy()
   # exit()
def __showAbout(self):
   showinfo("About Notepad","Simple text editor like notepad using Python")
def __showCommand(self):
   showinfo("Notepad", "Just Another TextPad \n Copyright \n with BSD license you can use it'")
def __openFile(self):
   self.__file = askopenfilename(defaultextension=".txt", filetypes=[("All Files","*.*"),("Text Documents","*.txt")])
   if self.__file == "":
      # no file to open
      self.__file = None
   else:
   # Try to open the file
   # set the window title
   self.__root.title(os.path.basename(self.__file) + " - Notepad")
   self.__thisTextArea.delete(1.0,END)
   file = open(self.__file,"r")
   self.__thisTextArea.insert(1.0,file.read())
   file.close()
def __newFile(self):
   self.__root.title("Untitled Notepad")
   self.__file = None
   self.__thisTextArea.delete(1.0,END)
def __saveFile(self):
   if self.__file == None:
      # Save as new file
   self.__file = asksaveasfilename(initialfile='Untitled.txt', defaultextension=".txt", filetypes=[("All Files","*.*"), ("Text Documents","*.txt")])
   if self.__file == "":
      self.__file = None
   else:
      # Try to save the file
      file = open(self.__file,"w")
      file.write(self.__thisTextArea.get(1.0,END))
      file.close()
      # Change the window title
      self.__root.title(os.path.basename(self.__file) + " - Notepad")
   else:
      file = open(self.__file,"w")
      file.write(self.__thisTextArea.get(1.0,END))
      file.close()
   def __cut(self):
      self.__thisTextArea.event_generate("<<Cut>>")
   def __copy(self):
      self.__thisTextArea.event_generate("<<Copy>>")
   def __paste(self):
      self.__thisTextArea.event_generate("<<Paste>>")
Now we have added the required package, add a menu item and the required functionality we’re going to see in this notepad-like text editor using tkinter library.
Below is the complete program to create a notepad text editor using tkinter −
#Import os library
import os
#import everything from tkinter
from tkinter import *
#To get the space above the message
from tkinter.messagebox import *
#To get the dialog box to open when required
from tkinter.filedialog import *
class Notepad:
   # Set up the root widget
   __root = Tk()
   __thisWidth = 500
   __thisHeight = 700
   __thisTextArea = Text(__root)
   __thisMenuBar = Menu(__root)
   __thisFileMenu = Menu(__thisMenuBar, tearoff=0)
   __thisEditMenu = Menu(__thisMenuBar, tearoff=0)
   __thisHelpMenu = Menu(__thisMenuBar, tearoff=0)
   __thisCommandMenu = Menu(__thisMenuBar, tearoff=0)
   # To add scrollbar
   __thisScrollBar = Scrollbar(__thisTextArea)
   __file = None
   def __init__(self,**kwargs):
      # icon
      try:
         self.__root.wm_iconbitmap("Notepad.ico")
      except:
         pass
   # Set window size as mentioned above (the default is 300x300)
   try:
      self.__thisWidth = kwargs['width']
      except KeyError:
      pass
   try:
      self.__thisHeight = kwargs['height']
      except KeyError:
      pass
      # the window text
      self.__root.title("Untitled-Notepad")
      # Center the window
      screenWidth = self.__root.winfo_screenwidth()
      screenHeight = self.__root.winfo_screenheight()
      # For left-alling
      left = (screenWidth / 2) - (self.__thisWidth / 2)
      # For right-allign
      top = (screenHeight / 2) - (self.__thisHeight /2)
      # For top and bottom
      self.__root.geometry('%dx%d+%d+%d' % (self.__thisWidth, self.__thisHeight, left, top))
      # To make the textarea auto resizable
      self.__root.grid_rowconfigure(0, weight=1)
      self.__root.grid_columnconfigure(0, weight=1)
      # Add controls (widget)
      self.__thisTextArea.grid(sticky = N + E + S + W)
      # To open new file
      self.__thisFileMenu.add_command(label="New",
   command=self.__newFile)
      # To open a already existing file
      self.__thisFileMenu.add_command(label="Open",
   command=self.__openFile)
      # To save current file
      self.__thisFileMenu.add_command(label="Save",
   command=self.__saveFile)
      # To create a line in the dialog
      self.__thisFileMenu.add_separator()
      self.__thisFileMenu.add_command(label="Exit",
   command=self.__quitApplication)
      self.__thisMenuBar.add_cascade(label="File", menu=self.__thisFileMenu)
      # To give a feature of cut
      self.__thisEditMenu.add_command(label="Cut",
   command=self.__cut)
      # to give a feature of copy
      self.__thisEditMenu.add_command(label="Copy",
   command=self.__copy)
      # To give a feature of paste
      self.__thisEditMenu.add_command(label="Paste",
   command=self.__paste)
      # To give a feature of editing
      self.__thisMenuBar.add_cascade(label="Edit", menu=self.__thisEditMenu)
      # To create a feature of description of the notepad
      self.__thisHelpMenu.add_command(label="About Notepad",
   command=self.__showAbout)
      self.__thisCommandMenu.add_command(label = "About Commands", command=self.__showCommand)
      self.__thisMenuBar.add_cascade(label="Commands", menu=self.__thisCommandMenu)
      self.__thisMenuBar.add_cascade(label="Help", menu=self.__thisHelpMenu)
      self.__root.config(menu=self.__thisMenuBar)
      self.__thisScrollBar.pack(side=RIGHT,fill=Y)
      # Scrollbar will adjust automatically according to the content
      self.__thisScrollBar.config(command=self.__thisTextArea.yview)
      self.__thisTextArea.config(yscrollcommand=self.__thisScrollBar.set)
   def __quitApplication(self):
      self.__root.destroy()
      # exit()
   def __showAbout(self):
      showinfo("About Notepad","Simple text editor like notepad using Python")
   def __showCommand(self):
      showinfo("Notepad", "Just Another TextPad \n Copyright \n with BSD license you can use it'")
   def __openFile(self):
      self.__file = askopenfilename(defaultextension=".txt", filetypes=[("All Files","*.*"),("Text Documents","*.txt")])
      if self.__file == "":
         # no file to open
         self.__file = None
      else:
         # Try to open the file
         # set the window title
         self.__root.title(os.path.basename(self.__file) + " - Notepad")
         self.__thisTextArea.delete(1.0,END)
         file = open(self.__file,"r")
         self.__thisTextArea.insert(1.0,file.read())
         file.close()
   def __newFile(self):
      self.__root.title("Untitled Notepad")
      self.__file = None
      self.__thisTextArea.delete(1.0,END)
   def __saveFile(self):
      if self.__file == None:
         # Save as new file
         self.__file = asksaveasfilename(initialfile='Untitled.txt', defaultextension=".txt", filetypes=[("All Files","*.*"), ("Text Documents","*.txt")])
      if self.__file == "":
         self.__file = None
      else:
         # Try to save the file
         file = open(self.__file,"w")
         file.write(self.__thisTextArea.get(1.0,END))
         file.close()
         # Change the window title
         self.__root.title(os.path.basename(self.__file) + " - Notepad")
      else:
         file = open(self.__file,"w")
         file.write(self.__thisTextArea.get(1.0,END))
         file.close()
   def __cut(self):
      self.__thisTextArea.event_generate("<<Cut>>")
   def __copy(self):
      self.__thisTextArea.event_generate("<<Copy>>")
   def __paste(self):
      self.__thisTextArea.event_generate("<<Paste>>")
   def run(self):
      # Run main application
      self.__root.mainloop()
# Run main application
notepad = Notepad(width=600,height=400)
notepad.run()
On running above program, we’ll get a pop-up notepad text editor, something like
In this notepad, we can write into it, save it and can open our saved file(or any other file). We can create cut, copy & paste from the open file contents. You can use all the menu items of this newly created notepad.