Tkinter GUI QR code scanner using pyzbar library and supporting loading codes from image and pasting from clipboard

qr-scanner.py

"""
Author: limafresh <https://github.com/limafresh>
License: CC0 <https://creativecommons.org/publicdomain/zero/1.0/>
"""

import tkinter as tk
from tkinter import filedialog, ttk
from PIL import Image, ImageTk, ImageGrab
from pyzbar.pyzbar import decode


def upload_image():
    file_path = filedialog.askopenfilename()
    if file_path:
        try:
            global img
            img = Image.open(file_path)
            scan_code()
        except Exception as e:
            error()
            tk.messagebox.showinfo("Error", e)


def paste_image():
    try:
        global img
        img = ImageGrab.grabclipboard()
        scan_code()
    except Exception as e:
        error()
        tk.messagebox.showinfo("Error", e)


def scan_code():
    image_canvas.delete("all")
    img_resized = img.resize((image_canvas.winfo_width(), image_canvas.winfo_height()))
    img_tk = ImageTk.PhotoImage(img_resized)

    image_canvas.create_image(0, 0, anchor=tk.NW, image=img_tk)
    image_canvas.image = img_tk

    decoded_data = decode(img)

    if decoded_data:
        global link
        link = decoded_data[0].data.decode("utf-8")
        copy_button.config(state=tk.NORMAL)
        link_entry.config(state=tk.NORMAL)
        link_entry.delete(0, tk.END)
        link_entry.insert(0, link)
    else:
        error()
        tk.messagebox.showinfo("Error", "Failed to recognize QR code")


def error():
    image_canvas.delete("all")
    link_entry.delete(0, tk.END)
    copy_button.config(state=tk.DISABLED)
    link_entry.config(state=tk.DISABLED)


def copy_to_clipboard():
    root.clipboard_clear()
    root.clipboard_append(link)
    root.update()


root = tk.Tk()
root.title("QR code scanner")

upload_frame = ttk.Frame(root)
upload_frame.pack(padx=10, pady=10)

upload_button = ttk.Button(upload_frame, text="Upload QR image", command=upload_image)
upload_button.grid(row=1, column=1, padx=10, pady=10)

paste_button = ttk.Button(upload_frame, text="Paste QR image", command=paste_image)
paste_button.grid(row=1, column=2, padx=10, pady=10)

image_canvas = tk.Canvas(
    root,
    width=300,
    height=300,
    bg="white",
    highlightthickness=2,
    highlightbackground="blue",
)
image_canvas.pack(padx=10, pady=10)

link_frame = ttk.Frame(root)
link_frame.pack(padx=10, pady=10)

link_label = ttk.Label(link_frame, text="Link")
link_label.grid(row=1, column=1, padx=10, pady=10)

link_entry = ttk.Entry(link_frame, state=tk.DISABLED)
link_entry.grid(row=1, column=2, padx=10, pady=10)

copy_button = ttk.Button(
    link_frame, text="Copy", command=copy_to_clipboard, state=tk.DISABLED
)
copy_button.grid(row=1, column=3, padx=10, pady=10)

root.mainloop()