Implement text-autocompletion in Python/Tkinter based text editor

Text autocompletion is a useful feature that enhances productivity and improves the user experience in text editors. It automatically suggests completions for partially typed words or phrases, reducing the effort required for manual typing.

In this article, we will explore how to implement text autocompletion in a Python text editor using the Tkinter library. We will walk through the process step by step, including setting up the user interface, handling user input, and implementing the autocompletion functionality.

Prerequisites

To follow along with this tutorial, you should have a basic understanding of Python programming and the Tkinter library. Additionally, make sure you have Python and Tkinter installed on your system.

Setting Up the User Interface

Import Required Modules

First, import the necessary modules for GUI operations and regular expressions ?

import tkinter as tk
import re

Create the Main Window

Create the main window and configure its properties ?

import tkinter as tk

window = tk.Tk()
window.title("Text Editor with Autocompletion")
window.geometry("700x400")

Add Text Widget

Create a text widget where users can input text ?

import tkinter as tk

window = tk.Tk()
window.title("Text Editor with Autocompletion")
window.geometry("700x400")

text_widget = tk.Text(window, wrap=tk.WORD, font=("Arial", 12))
text_widget.pack(fill=tk.BOTH, expand=True, padx=10, pady=10)

window.mainloop()

Implementing Autocompletion Logic

Dictionary Setup

Define a dictionary of words for autocompletion suggestions ?

# Sample dictionary of words
dictionary = [
    "apple", "application", "banana", "cherry", "computer", 
    "development", "dog", "elephant", "fruit", "grape", 
    "house", "internet", "javascript", "keyboard", "language",
    "mouse", "network", "orange", "programming", "python"
]

Input Handler Function

Create a function to handle user input and provide autocompletion ?

import tkinter as tk
import re

def handle_input(event):
    # Get current line text up to cursor position
    current_text = text_widget.get("insert linestart", "insert")
    
    # Extract the current word being typed
    words = re.findall(r'\w+', current_text)
    current_word = words[-1].lower() if words else ""
    
    # Skip autocompletion for very short words
    if len(current_word) < 2:
        return
    
    # Find matching suggestions
    suggestions = [word for word in dictionary if word.lower().startswith(current_word)]
    
    # Auto-complete with first suggestion
    if suggestions and suggestions[0].lower() != current_word:
        autocomplete = suggestions[0]
        remaining_text = autocomplete[len(current_word):]
        
        # Insert the remaining part
        text_widget.insert("insert", remaining_text)
        
        # Select the inserted text for easy replacement
        text_widget.tag_add("sel", f"insert-{len(remaining_text)}c", "insert")
        text_widget.mark_set("insert", f"insert-{len(remaining_text)}c")

Complete Implementation

Full Working Example

Here's the complete text editor with autocompletion functionality ?

import tkinter as tk
import re

# Dictionary of words for autocompletion
dictionary = [
    "apple", "application", "banana", "cherry", "computer", 
    "development", "dog", "elephant", "fruit", "grape", 
    "house", "internet", "javascript", "keyboard", "language",
    "mouse", "network", "orange", "programming", "python"
]

def handle_input(event):
    # Get current line text up to cursor position
    current_text = text_widget.get("insert linestart", "insert")
    
    # Extract the current word being typed
    words = re.findall(r'\w+', current_text)
    current_word = words[-1].lower() if words else ""
    
    # Skip autocompletion for very short words
    if len(current_word) < 2:
        return
    
    # Find matching suggestions
    suggestions = [word for word in dictionary if word.lower().startswith(current_word)]
    
    # Auto-complete with first suggestion
    if suggestions and suggestions[0].lower() != current_word:
        autocomplete = suggestions[0]
        remaining_text = autocomplete[len(current_word):]
        
        # Insert the remaining part
        text_widget.insert("insert", remaining_text)
        
        # Select the inserted text for easy replacement
        text_widget.tag_add("sel", f"insert-{len(remaining_text)}c", "insert")
        text_widget.mark_set("insert", f"insert-{len(remaining_text)}c")

# Create main window
window = tk.Tk()
window.title("Text Editor with Autocompletion")
window.geometry("700x400")

# Create text widget
text_widget = tk.Text(window, wrap=tk.WORD, font=("Arial", 12))
text_widget.pack(fill=tk.BOTH, expand=True, padx=10, pady=10)

# Bind the autocompletion handler
text_widget.bind("<KeyRelease>", handle_input)

# Add instructions
instructions = tk.Label(window, text="Start typing words like 'app', 'prog', or 'comp' to see autocompletion in action!", 
                       bg="lightblue", pady=5)
instructions.pack(fill=tk.X)

# Start the application
window.mainloop()

How It Works

The autocompletion system works through these key components:

Event Binding: The <KeyRelease> event triggers the autocompletion function whenever a key is released.

Word Extraction: Regular expressions extract the current word being typed from the text widget.

Suggestion Matching: The system searches the dictionary for words that start with the current partial word.

Text Insertion: When a match is found, the remaining characters are inserted and selected for easy replacement.

Key Features

This implementation includes several important features:

• Real-time autocompletion as you type

• Case-insensitive matching

• Minimum word length requirement (2 characters)

• Text selection for easy replacement

• Customizable word dictionary

Conclusion

We have successfully implemented text autocompletion in a Python/Tkinter text editor. The system provides real-time word suggestions based on a customizable dictionary, improving typing efficiency and user experience. You can enhance this further by adding features like multiple suggestions, context-aware completion, or loading dictionaries from external files.