editor4.py

#!/usr/bin/python3

from guizero import App,TextBox,PushButton,Box,Combo,Slider,MenuBar,CheckBox
from tkinter import filedialog

revertText = ""

def OpenFile():
    global revertText
    filepath = filedialog.askopenfilename()
    file_name.value = filepath
    f = open(filepath,"r")
    editor.value = f.read()
    revertText = editor.value
    save_button.hide()
    f.close()

def SaveFile():
    global revertText
    filepath = filedialog.asksaveasfile()
    if filepath:
        f = open(filepath.name,"w")
        f.write(editor.value)
        revertText = editor.value
        save_button.hide()
        open_button.enable()
        revert_button.disable()
        f.close()

def ChangeFont():
    editor.font = font.value

def ChangeTextSize():
    editor.text_size = size.value
    editor.resize(1,1)
    editor.resize("fill","fill")

def ChangeColor():
    editor.text_color = color.value

def TextChanged():
    global revertText

    editText = editor.value
    compareText = revertText
    if editText == compareText:
        save_button.hide()
        open_button.enable()
        revert_button.disable()
    else:
        save_button.show()
        open_button.disable()
        revert_button.enable()

def Revert():
    global revertText

    editor.value = revertText
    revertText = editor.value # weird guizero artificat if not done
    save_button.hide()
    open_button.enable()
    revert_button.disable()

# A new function that closes the app
def ExitApp():
    global revertText

    if revertText != editor.value:
        quitNow = app.yesno('Warning!',
                           'Quit without saving changes?')
        if not quitNow:
            return

    app.destroy()

def DarkMode():
    if darkMode.value:
        app.bg = "black"
        editor.saved_text_color = editor.text_color
        app.text_color = "white"
        editor.text_color = editor.saved_text_color
    else:
        app.bg = "white"
        editor.saved_text_color = editor.text_color
        app.text_color = "black"
        editor.text_color = editor.saved_text_color

app = App(title="texteditor")

# The new MenuBar
menubar = MenuBar(app,
                  toplevel=["File","Edit"],
                  options=[[["open",OpenFile],["save",SaveFile],
                            ["exit",ExitApp]],
                           [["revert",Revert]]])

# create a box to house the controls, we want the box to span the entire width of the app
file_controls = Box(app, align="top", width="fill")

# create a TextBox for the file name
file_name = TextBox(file_controls, text="text_file.txt", width=32, align="left")

# create a save button which uses the save_file function
save_button = PushButton(file_controls,text="Save",align="right",
                         visible=False,command=SaveFile)

# create an open button which uses the open_file function
open_button = PushButton(file_controls,text="Open",align="right",
                         command=OpenFile)

revert_button = PushButton(file_controls,text="Revert",align="right",
                           enabled=False,command=Revert)

preferences_controls = Box(app, align="top", width="fill", border=True)
font = Combo(preferences_controls, options=["courier", "times new roman", "verdana"],
             align="left", command=ChangeFont)
color = Combo(preferences_controls, options=["black", "red", "blue", "green"],
             align="left", command=ChangeColor)
size = Slider(preferences_controls,  align="left",
              start = 8, end = 42, command=ChangeTextSize)
darkMode = CheckBox(preferences_controls,text="Dark Mode",
                    align="left",command=DarkMode)

# create a TextBox which is not in the box and fills the rest of the GUI
editor = TextBox(app, multiline=True, height="fill", width="fill",command=TextChanged)


app.display()