tkinter_text_viewer_with_scrollable_line_numbers.py

import tkinter as tk
from tkinter import scrolledtext
from tkinter import filedialog

class TextViewer:
    def __init__(self, root):
        self.root = root
        self.root.title("Text Viewer")

        self.line_numbers = tk.Text(root, width=4, height=30, bg="lightgray", state="disabled", padx=5)
        self.line_numbers.pack(side="left", fill="y")

        self.text_area = scrolledtext.ScrolledText(root, wrap=tk.WORD, width=80, height=30, font=("Courier New", 12))
        self.text_area.pack(expand=True, fill="both")

        self.text_area.bind("<Key>", self.update_line_numbers)
        self.text_area.bind("<MouseWheel>", self.update_line_numbers)
        self.text_area.bind("<Button-4>", self.update_line_numbers)
        self.text_area.bind("<Button-5>", self.update_line_numbers)
        self.text_area.bind("<Configure>", self.update_line_numbers_on_configure)

        menu_bar = tk.Menu(root)
        root.config(menu=menu_bar)

        file_menu = tk.Menu(menu_bar, tearoff=0)
        menu_bar.add_cascade(label="File", menu=file_menu)
        file_menu.add_command(label="Open", command=self.open_file)

    def open_file(self):
        file_path = filedialog.askopenfilename(title="Open Text File", filetypes=[("Text files", "*.txt"), ("All files", "*.*")])

        if file_path:
            with open(file_path, 'r') as file:
                content = file.read()
                self.text_area.delete(1.0, tk.END)
                self.text_area.insert(tk.END, content)

            self.update_line_numbers()

    def update_line_numbers(self, event=None):
        lines = self.text_area.get(1.0, tk.END).split('\n')[:-1]  # Exclude last empty line
        line_numbers_text = "\n".join(str(i) for i in range(1, len(lines) + 1))
        self.line_numbers.config(state="normal")
        self.line_numbers.delete(1.0, tk.END)
        self.line_numbers.insert(tk.END, line_numbers_text)
        self.line_numbers.config(state="disabled")

        # Synchronize line numbers with text area scrolling
        y_scroll_fraction = self.text_area.yview()[0]
        self.line_numbers.yview_moveto(y_scroll_fraction)

    def update_line_numbers_on_configure(self, event=None):
        # Update line numbers when the text area is resized
        self.update_line_numbers()


if __name__ == "__main__":
    root = tk.Tk()
    text_viewer = TextViewer(root)
    root.mainloop()