Building a Text Editor GUI with Tkinter in Python
Published: 2023-06-20 14:31:50

Tkinter is a popular GUI toolkit for Python due to its simplicity, ease of use, and cross-platform compatibility. It comes pre-installed with Python, making it a convenient choice for developers. Tkinter provides a wide range of widgets and tools that can be used to create complex and interactive graphical user interfaces.

In this article, we're going through a step-by-step guide on how to build a graphical user interface (GUI) for a text editor using the Tkinter library in Python.

We'll cover how to create a window, add menus, toolbars, and buttons, and customize the appearance of the editor. We'll also explain how to add functionality to the editor, such as opening and saving files, selecting and formatting text, and undo and redo operations.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/wowpmwo1rdgye8lpfpo6.png)


## Installing Python and Tkinter
Before building a text editor GUI with Tkinter in Python, it is essential to have Python and Tkinter installed on your computer.

Python installation is usually straightforward, and the latest version can be downloaded from the official website. However, for Tkinter, the installation process might differ depending on the operating system. If you're using Windows, the Tkinter library should be pre-installed together with Python.

If you don't have a code editor or Python installed on your computer yet, you can follow this installation to use Lightly, an IDE built-in with an [online Python compiler](https://www.lightly-dev.com/python/) to start your programming journey with us right on your web browser.

Once you've created an account and logged into your workspace, you can start creating your Python project.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/1tdixbrn9e90kqayzrs5.png)

You can simply use the pip method to install the Tkinter library in Lightly IDE. In the terminal below, type "pip install tk" and press enter to run the installation process.

To check whether you've successfully installed Tkinter on your computer, you can simply run the following code and see if an empty window pops up.

```python
from tkinter import *

Window = Tk()
Window.mainloop()
```

If the Tkinter library is not installed or you're using another Python code editor or compiler other than Lightly IDE such as VS Code and PyCharm, you might need to access your local terminal manually and install it with the pip method.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/8djg8ddvipb8esme57vf.png)


## Creating the basic GUI layout
To build a text editor GUI using Tkinter in Python, the first step is to import the necessary modules. Tkinter is a pre-installed Python GUI package that allows developers to create GUI applications. To import Tkinter, we use the statement import Tkinter as tk. 

Additionally, we also need to import the filedialog module from Tkinter to create a File Dialog box that allows users to choose the file they want to edit. The filedialog module can be imported using the statement from tkinter import filedialog. Finally, we also need to import the MessageBox module to display any errors or messages to the user. This can be done with the statement from tkinter import messagebox.

To create the main window of a Text Editor GUI using Tkinter in Python, we first need to import the Tkinter module. Then, we can create an instance of the Tk() class, which will represent the main window of our application. After that, we can set the title of the window using the title() method and configure its size and background color using the geometry() and configure() methods, respectively.

Finally, we can call the mainloop() method on our window instance to start the event loop and display the window on the screen.

The following code snippet demonstrates how to create the main window of a Text Editor GUI using Tkinter in Python:

```python
import tkinter as tk

# Create the main window
window = tk.Tk()

# Set the title of the window
window.title("Text Editor")

# Configure the size and background color of the window
window.geometry("800x600")
window.configure(bg="white")

# Start the event loop
window.mainloop()
```

To add a text widget to the window of a text editor GUI built with Tkinter in Python, we can use the Tkinter Text class. First, we need to create a new instance of the Text class by calling the Text() constructor. We can then add this widget to the window using the pack() method, which will automatically resize the widget to fill the available space.

Additionally, we can set various properties of the Text widget using its configuration methods, such as its font, background color, and text color. Once added to the window, we can use the Text widget to display and edit text, and add various functionality to it, such as scrolling, undo/redo, and syntax highlighting.

## Configuring the text widget
Once a text widget has been created, its appearance and behavior can be customized with various configuration options. These options can be set using the config() method of the text widget object.

For example, the font of the text displayed in the widget can be changed using the font option. The foreground color of the text can be changed using the foreground option. The background color of the widget can be changed using the background option.

Other options include wrap, which determines how text is wrapped when it reaches the edge of the widget, and height and width, which determine the size of the widget. By experimenting with these and other options, you can create a text widget that looks and behaves the way you want.

Here's an example code snippet that demonstrates how to add a text widget to a text editor GUI built with Tkinter and configure some of its properties:

```python
import tkinter as tk

window = tk.Tk()
window.title("Text Editor")

text_widget = tk.Text(window, font=("Arial", 12), bg="white", fg="black", wrap=tk.WORD)
text_widget.pack(fill=tk.BOTH, expand=True)

text_widget.insert(tk.END, "Welcome to the Text Editor!")
text_widget.config(height=10, width=40)

window.mainloop()
```

In this example, we create a text widget using tk.Text(window). We then set the font to Arial with a size of 12 using font=("Arial", 12). The background color is set to white (bg="white") and the text color is set to black (fg="black").

The wrap option is set to tk.WORD, which wraps text at word boundaries when it reaches the edge of the widget.

We insert some initial text using text_widget.insert(tk.END, "Welcome to the Text Editor!").

Finally, we configure the height and width of the text widget using text_widget.config(height=10, width=40), which sets it to display 10 lines of text and have a width of 40 characters.

## Adding menu options
To create a menu bar in Python's Tkinter, we first need to create a menu object using the Menu() method. This menu object will contain all the options we want to include in our menu bar.

Once we have created the menu object, we can add individual options to the menu using the add_command() method. Each option will be represented as a command in the menu bar. We can also create sub-menus by creating new menu objects and adding them as cascading options to the main menu object using the add_cascade() method.

### Adding file options to the menu bar
To make our text editor GUI more practical, we can add file options such as 'New', 'Open', 'Save', and 'Save As' to the menu bar. To do so, we need to create a 'File' cascade menu and add commands to handle each of the options.

The 'New' option can be used to create a new file, 'Open' can be used to open an existing file, 'Save' can be used to save the changes made to the existing file, and 'Save As' can be used to save the file with a new name and location.

We can use the 'filedialog' module from the 'tkinter' library to create a file dialog box to choose a file to open or save.

```python
import tkinter as tk
from tkinter import filedialog, messagebox

def new_file():
    # Implement logic to handle creating a new file
    pass

def open_file():
    file_path = filedialog.askopenfilename(filetypes=[("Text files", "*.txt")])
    if file_path:
        with open(file_path, "r") as file:
            text_widget.delete("1.0", tk.END)
            text_widget.insert(tk.END, file.read())

def save_file():
    # Implement logic to handle saving the file
    pass

def save_file_as():
    file_path = filedialog.asksaveasfilename(defaultextension=".txt", filetypes=[("Text files", "*.txt")])
    if file_path:
        with open(file_path, "w") as file:
            file.write(text_widget.get("1.0", tk.END))

def exit_editor():
    if messagebox.askokcancel("Exit", "Do you want to exit?"):
        window.destroy()

window = tk.Tk()
window.title("Text Editor")

menu_bar = tk.Menu(window)

# File menu
file_menu = tk.Menu(menu_bar, tearoff=0)
file_menu.add_command(label="New", command=new_file)
file_menu.add_command(label="Open", command=open_file)
file_menu.add_command(label="Save", command=save_file)
file_menu.add_command(label="Save As", command=save_file_as)
file_menu.add_separator()
file_menu.add_command(label="Exit", command=exit_editor)
menu_bar.add_cascade(label="File", menu=file_menu)

# Edit menu
# Add more options to the menu as needed

# Help menu
# Add more options to the menu as needed

window.config(menu=menu_bar)

text_widget = tk.Text(window)
text_widget.pack(fill=tk.BOTH, expand=True)

window.mainloop()
```

In this code, we added a 'File' menu to the menu bar using file_menu = tk.Menu(menu_bar, tearoff=0). We then added individual file options such as 'New', 'Open', 'Save', 'Save As', and 'Exit' to the 'File' menu using the add_command() method.

For the 'Open' and 'Save As' options, we used the filedialog.askopenfilename() and filedialog.asksaveasfilename() functions respectively to display file dialog boxes for selecting a file to open and choosing a location to save the file.

Please note that the code snippets for the logic of creating a new file and saving a file have been left as placeholders (pass). You can implement the required functionality according to your specific needs.

### Adding edit options to the menu bar
To provide basic editing functionality, we can add options like cut, copy, and paste to the menu bar. We can achieve this by creating a new menu under the menu bar and adding the required options to it. To implement the cut, copy, and paste functionality, we can use the Text widget's built-in methods like delete, get, and insert.

Additionally, we can also add keyboard shortcuts for these options using the accelerator attribute. By adding these basic editing options, our text editor will become more functional for the users.

import tkinter as tk
from tkinter import filedialog, messagebox

def new_file():
    # Implement logic to handle creating a new file
    pass

def open_file():
    file_path = filedialog.askopenfilename(filetypes=[("Text files", "*.txt")])
    if file_path:
        with open(file_path, "r") as file:
            text_widget.delete("1.0", tk.END)
            text_widget.insert(tk.END, file.read())

def save_file():
    # Implement logic to handle saving the file
    pass

def save_file_as():
    file_path = filedialog.asksaveasfilename(defaultextension=".txt", filetypes=[("Text files", "*.txt")])
    if file_path:
        with open(file_path, "w") as file:
            file.write(text_widget.get("1.0", tk.END))

def exit_editor():
    if messagebox.askokcancel("Exit", "Do you want to exit?"):
        window.destroy()

def cut_text():
    selected_text = text_widget.get(tk.SEL_FIRST, tk.SEL_LAST)
    text_widget.delete(tk.SEL_FIRST, tk.SEL_LAST)
    window.clipboard_clear()
    window.clipboard_append(selected_text)

def copy_text():
    selected_text = text_widget.get(tk.SEL_FIRST, tk.SEL_LAST)
    window.clipboard_clear()
    window.clipboard_append(selected_text)

def paste_text():
    text_to_paste = window.clipboard_get()
    text_widget.insert(tk.INSERT, text_to_paste)

window = tk.Tk()
window.title("Text Editor")

menu_bar = tk.Menu(window)

# File menu
file_menu = tk.Menu(menu_bar, tearoff=0)
file_menu.add_command(label="New", command=new_file)
file_menu.add_command(label="Open", command=open_file)
file_menu.add_command(label="Save", command=save_file)
file_menu.add_command(label="Save As", command=save_file_as)
file_menu.add_separator()
file_menu.add_command(label="Exit", command=exit_editor)
menu_bar.add_cascade(label="File", menu=file_menu)

# Edit menu
edit_menu = tk.Menu(menu_bar, tearoff=0)
edit_menu.add_command(label="Cut", command=cut_text, accelerator="Ctrl+X")
edit_menu.add_command(label="Copy", command=copy_text, accelerator="Ctrl+C")
edit_menu.add_command(label="Paste", command=paste_text, accelerator="Ctrl+V")
menu_bar.add_cascade(label="Edit", menu=edit_menu)

# Help menu
# Add more options to the menu as needed

window.config(menu=menu_bar)

text_widget = tk.Text(window)
text_widget.pack(fill=tk.BOTH, expand=True)

# Define keyboard shortcuts for cut, copy, and paste
window.bind("<Control-x>", lambda event: cut_text())
window.bind("<Control-c>", lambda event: copy_text())
window.bind("<Control-v>", lambda event: paste_text())

window.mainloop()

In this code, we added an 'Edit' menu to the menu bar using edit_menu = tk.Menu(menu_bar, tearoff=0). We then added individual edit options such as 'Cut', 'Copy', and 'Paste' to the 'Edit' menu using the add_command() method.

To implement the cut, copy, and paste functionality, we defined cut_text(), copy_text(), and paste_text() functions respectively. These functions utilize the Text widget's methods (delete, get, and insert) to perform the desired actions on the selected text.

We also added keyboard shortcuts for the cut, copy, and paste options using the bind() method. These shortcuts allow the user to perform the actions using the specified key combinations (Ctrl+X, Ctrl+C, and Ctrl+V) in addition to using the menu options.

## Adding status bar
In the process of building a text editor GUI with Tkinter in Python, implementing a status bar to display the current status of the editor is essential. The purpose of the status bar is to provide the user with information such as the current line number, column number, and the number of characters in the file.

The status bar can be created by adding a Label widget to the bottom of the main window and updating its text property based on the user's actions. An example of the information that can be displayed on the status bar is "Ln 10, Col 5, Chars 250".

This status bar can be updated dynamically as the user opens, saves, or makes changes to the file. Having this information readily available helps users keep track of their work and avoid mistakes.

Tkinter provides several widgets that can be used to display messages and information to the user. The most basic is the Label widget, which allows you to display a text message or an image. Another useful widget is the Message widget, which is similar to the Label widget but includes word wrapping and other formatting options.

If you need to display longer text that might require scrolling, you can use the Text widget. Finally, you can use message boxes to display pop-up messages to the user, such as warnings or confirmations. Tkinter provides several types of message boxes, including showinfo, showwarning, showerror, askquestion, askokcancel, askyesno, and askretrycancel.

import tkinter as tk
from tkinter import filedialog, messagebox

def new_file():
    # Implement logic to handle creating a new file
    pass

def open_file():
    file_path = filedialog.askopenfilename(filetypes=[("Text files", "*.txt")])
    if file_path:
        with open(file_path, "r") as file:
            text_widget.delete("1.0", tk.END)
            text_widget.insert(tk.END, file.read())
            update_status_bar()

def save_file():
    # Implement logic to handle saving the file
    pass

def save_file_as():
    file_path = filedialog.asksaveasfilename(defaultextension=".txt", filetypes=[("Text files", "*.txt")])
    if file_path:
        with open(file_path, "w") as file:
            file.write(text_widget.get("1.0", tk.END))
            update_status_bar()

def exit_editor():
    if messagebox.askokcancel("Exit", "Do you want to exit?"):
        window.destroy()

def cut_text():
    selected_text = text_widget.get(tk.SEL_FIRST, tk.SEL_LAST)
    text_widget.delete(tk.SEL_FIRST, tk.SEL_LAST)
    window.clipboard_clear()
    window.clipboard_append(selected_text)

def copy_text():
    selected_text = text_widget.get(tk.SEL_FIRST, tk.SEL_LAST)
    window.clipboard_clear()
    window.clipboard_append(selected_text)

def paste_text():
    text_to_paste = window.clipboard_get()
    text_widget.insert(tk.INSERT, text_to_paste)

def update_status_bar(event=None):
    line, column = map(int, text_widget.index(tk.INSERT).split('.'))
    char_count = len(text_widget.get("1.0", tk.END)) - 1
    status_bar.config(text=f"Ln {line}, Col {column}, Chars {char_count}")

window = tk.Tk()
window.title("Text Editor")

menu_bar = tk.Menu(window)

# File menu
file_menu = tk.Menu(menu_bar, tearoff=0)
file_menu.add_command(label="New", command=new_file)
file_menu.add_command(label="Open", command=open_file)
file_menu.add_command(label="Save", command=save_file)
file_menu.add_command(label="Save As", command=save_file_as)
file_menu.add_separator()
file_menu.add_command(label="Exit", command=exit_editor)
menu_bar.add_cascade(label="File", menu=file_menu)

# Edit menu
edit_menu = tk.Menu(menu_bar, tearoff=0)
edit_menu.add_command(label="Cut", command=cut_text, accelerator="Ctrl+X")
edit_menu.add_command(label="Copy", command=copy_text, accelerator="Ctrl+C")
edit_menu.add_command(label="Paste", command=paste_text, accelerator="Ctrl+V")
menu_bar.add_cascade(label="Edit", menu=edit_menu)

# Help menu
# Add more options to the menu as needed

window.config(menu=menu_bar)

text_widget = tk.Text(window)
text_widget.pack(fill=tk.BOTH, expand=True)
text_widget.bind("<Key>", update_status_bar)

status_bar = tk.Label(window, text="", bd=1, relief=tk.SUNKEN, anchor=tk.W)
status_bar.pack(side=tk.BOTTOM, fill=tk.X)

# Define keyboard shortcuts for cut, copy, and paste
window.bind("<Control-x>", lambda event: cut_text())
window.bind("<Control-c>", lambda event: copy_text())
window.bind("<Control-v>", lambda event: paste_text())

update_status_bar()

window.mainloop()

In this code, we added a status bar using `status_bar = tk.Label(window, text="", bd=1, relief=tk.SUNKEN, anchor=tk.W). The text property of the label is initially set to an empty string. We pack the status bar to the bottom of the window using status_bar.pack(side=tk.BOTTOM, fill=tk.X)`.

The update_status_bar() function is called whenever the text widget's content is modified (text_widget.bind("<<Modified>>", update_status_bar)). It retrieves the current line number, column number, and character count using the Text widget's index() and get() methods, and updates the text of the status bar accordingly using status_bar.config(text=f"Ln {line}, Col {column}, Chars {char_count}").

By using the update_status_bar() function, the status bar will dynamically display the current line number, column number, and character count as the user interacts with the text editor.

## Writing functions to handle file operations (save, open, etc.)
In our current code, there are still several missing functions to handle file operations. To make our text editor functional, we need to write functions that handle file operations, such as creating a new file and saving files.

Certainly! Here's an updated code snippet that includes functions to handle file operations such as creating a new file, opening a file, saving a file, and saving a file with a new name:

import tkinter as tk
from tkinter import filedialog, messagebox

current_file = None

def new_file():
    global current_file
    text_widget.delete("1.0", tk.END)
    current_file = None

def open_file():
    global current_file
    file_path = filedialog.askopenfilename(filetypes=[("Text files", "*.txt")])
    if file_path:
        with open(file_path, "r") as file:
            text_widget.delete("1.0", tk.END)
            text_widget.insert(tk.END, file.read())
            current_file = file_path

def save_file():
    global current_file
    if current_file:
        with open(current_file, "w") as file:
            file.write(text_widget.get("1.0", tk.END))
    else:
        save_file_as()

def save_file_as():
    global current_file
    file_path = filedialog.asksaveasfilename(defaultextension=".txt", filetypes=[("Text files", "*.txt")])
    if file_path:
        with open(file_path, "w") as file:
            file.write(text_widget.get("1.0", tk.END))
            current_file = file_path

def exit_editor():
    if messagebox.askokcancel("Exit", "Do you want to exit?"):
        window.destroy()

def cut_text():
    selected_text = text_widget.get(tk.SEL_FIRST, tk.SEL_LAST)
    text_widget.delete(tk.SEL_FIRST, tk.SEL_LAST)
    window.clipboard_clear()
    window.clipboard_append(selected_text)

def copy_text():
    selected_text = text_widget.get(tk.SEL_FIRST, tk.SEL_LAST)
    window.clipboard_clear()
    window.clipboard_append(selected_text)

def paste_text():
    text_to_paste = window.clipboard_get()
    text_widget.insert(tk.INSERT, text_to_paste)

window = tk.Tk()
window.title("Text Editor")

menu_bar = tk.Menu(window)

# File menu
file_menu = tk.Menu(menu_bar, tearoff=0)
file_menu.add_command(label="New", command=new_file)
file_menu.add_command(label="Open", command=open_file)
file_menu.add_command(label="Save", command=save_file)
file_menu.add_command(label="Save As", command=save_file_as)
file_menu.add_separator()
file_menu.add_command(label="Exit", command=exit_editor)
menu_bar.add_cascade(label="File", menu=file_menu)

# Edit menu
edit_menu = tk.Menu(menu_bar, tearoff=0)
edit_menu.add_command(label="Cut", command=cut_text, accelerator="Ctrl+X")
edit_menu.add_command(label="Copy", command=copy_text, accelerator="Ctrl+C")
edit_menu.add_command(label="Paste", command=paste_text, accelerator="Ctrl+V")
menu_bar.add_cascade(label="Edit", menu=edit_menu)

# Help menu
# Add more options to the menu as needed

window.config(menu=menu_bar)

text_widget = tk.Text(window)
text_widget.pack(fill=tk.BOTH, expand=True)

window.mainloop()

In this updated code, the current_file variable is used to keep track of the currently opened file. The new_file() function clears the text widget and sets current_file to None.

The open_file() function prompts the user to select a file, reads its content, and displays it in the text widget. The current_file variable is updated with the selected file's path.

The save_file() function checks if a file is currently open

 (current_file is not None). If a file is open, it saves the content of the text widget to that file. If no file is open, it calls the save_file_as() function to prompt the user to choose a file to save.

The save_file_as() function prompts the user to choose a file and saves the content of the text widget to that file. The current_file variable is updated with the selected file's path.

Now you have functions to handle file operations, making your text editor functional. Feel free to modify the code further or add more features as per your requirements.

## Suggestions for further reading and learning
If you're interested in learning more about Tkinter and building GUI applications in Python, there are plenty of resources available online. Here are a few to get you started:

- [TkDocs](https://tkdocs.com/) - a comprehensive guide to Tkinter programming
- [Python GUI Programming with Tkinter](https://realpython.com/python-gui-tkinter/) - a tutorial on building a GUI application with Tkinter
- [Tkinter Tutorial](https://www.tutorialspoint.com/python/python_gui_programming.htm) - a beginner-friendly guide to Tkinter programming
- [Python GUI Programming Cookbook](https://www.packtpub.com/product/python-gui-programming-cookbook-second-edition/9781800206780) - a book that covers various aspects of GUI programming with Python and Tkinter

These resources will provide you with the knowledge and skills needed to build complex GUI applications with Tkinter and Python.

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[Building a Text Editor GUI with Tkinter in Python](https://www.lightly-dev.com/blog/text-editor-gui-tkinter-python/)