Gui.py

import tkinter as tk
from tkinter import ttk
from tkinter import Menu
from tkinter import filedialog
from tkinter import messagebox as mb


class App:

    def __init__(self):
        # create window
        self.__app = tk.Tk()
        # set title
        self.__app.title = "Text Editor App"
        # create menu
        self.__menuBar = Menu(self.__app)
        # set menu
        self.__app.config(menu=self.__menuBar)
        # file menu
        self.__fileMenu = Menu(self.__menuBar, tearoff=0)
        self.__fileMenu.add_command(label="New", command=self.__newFile)
        self.__fileMenu.add_separator()
        self.__fileMenu.add_command(label="Open", command=self.__browseFile)
        self.__fileMenu.add_separator()
        self.__fileMenu.add_command(label="Save", command=self.__saveFile)
        self.__menuBar.add_cascade(label="File", menu=self.__fileMenu)
        # edit menu
        self.__editMenu = Menu(self.__menuBar, tearoff=0)
        self.__editMenu.add_command(label="Copy", command=self.__copyText)
        self.__editMenu.add_separator()
        self.__editMenu.add_command(label="Cut", command=self.__cutTest)
        self.__editMenu.add_separator()
        self.__editMenu.add_command(label="Paste", command=self.__pasteText)
        self.__menuBar.add_cascade(label="Edit", menu=self.__editMenu)
        # text viewer
        self.__textArea = tk.Text(self.__app, height=50, width=100)
        self.__textArea.pack()

        # font size
        # self.__fontSize = ttk.Combobox(self.__app,text="Change Font Size")
        # self.__menuBar.add_cascade()
        # application variables
        self.__currentFile = None
        self.__clipBoard = ""

    def __call__(self, *args, **kwargs):
        self.__app.mainloop()

    def exit(self):
        self.__app.quit()
        self.__app.destrory()
        exit()

    def __browseFile(self):
        self.__currentFile = filedialog.askopenfilename(
            initialdir="/",
            title="Select a File",
            filetypes=(("Text files", "*.txt*"),
                       ("all files", "*.*")))
        # open file
        if self.__currentFile:
            with open(self.__currentFile, mode="r") as inputFile:
                data = inputFile.readlines()
                # clear text area
                self.__textArea.delete("1.0", tk.END)
                # load lines to text area
                for line in data:
                    self.__textArea.insert(tk.END, line)

    def __saveFile(self):
        if not self.__currentFile:
            self.__currentFile = filedialog.asksaveasfilename(
                initialdir="/",
                title="Select a File",
                filetypes=(("Text files", "*.txt*"),
                           ("all files", "*.*")))
        self.__currentFile += ".txt"
        with open(self.__currentFile, mode="w") as outputFile:
            data = self.__textArea.get("1.0", tk.END)
            outputFile.write(data)

        self.__currentFile = None

    def __newFile(self):
        if len((str.strip(self.__textArea.get("1.0", tk.END)))) > 0:
            if mb.askyesno("Data Loss Warning", "Continuing will clear the text area. "
                                                "Do You want to continue?"):
                self.__textArea.delete("1.0", tk.END)

    def __copyText(self):
        self.__clipBoard = self.__textArea.selection_get()
        print(self.__clipBoard)

    def __cutTest(self):
        self.__copyText()
        self.__textArea.delete(tk.SEL_FIRST, tk.SEL_LAST)

    def __pasteText(self):
        self.__textArea.insert(tk.INSERT, self.__clipBoard)