math_captcha.py

import base64
from io import BytesIO
from random import choice, randint, uniform

from PIL import Image, ImageDraw, ImageFont


def random_color(start: int, end: int):
    red = randint(start, end)
    green = randint(start, end)
    blue = randint(start, end)
    return red, green, blue


def draw_rotated_text(draw, image, text, position, font, color):
    left, top, right, bottom = draw.textbbox((0, 0), text, font=font)
    w = int((right - left) * 1.7) or 1
    h = int((bottom - top) * 1.7) or 1

    dx1 = randint(0, 4)
    dy1 = randint(0, 6)

    text_image = Image.new('RGBA', (w + dx1, h + dy1))
    text_draw = ImageDraw.Draw(text_image)

    # Place text in the center of the image
    dx1 = randint(0, 4)
    dy1 = randint(0, 6)
    text_draw.text((dx1, dy1), text, font=font, fill=color)

    # Rotate picture
    rotated_image = text_image.rotate(uniform(-10, 10), Image.BILINEAR, expand=True)
    image.paste(rotated_image, position, rotated_image)


def generate_captcha(width, height, save):

    operators = {"+": lambda x, y: x + y, "-": lambda x, y: x - y, "×": lambda x, y: x * y, "÷": lambda x, y: x / y}

    x = randint(1, 10)
    y = randint(1, 10)
    operator = choice(list(operators.keys()))

    # Make sure the result of division is an integer.
    if operator == "÷":
        x *= y
    if operator == "-":
        x += y

    question = f"{x} {operator} {y} = ?"
    answer = int(operators[operator](x, y))

    image = Image.new("RGB", (width, height), color=(random_color(238, 255)))

    draw = ImageDraw.Draw(image)

    font = ImageFont.truetype("Arial Bold.ttf", 35)
    # font = ImageFont.load_default(35)

    for i, char in enumerate(question):
        x = int(len(question) / 2) + i * (int((width - 15) / len(question)))
        y = randint(int((height / 2 / 2 / 2) * 1.5), int(height / 2 / 2 / 2) * 3)
        draw_rotated_text(draw, image, char, (x, y), font, color=random_color(0, 200))
    
    # Draw random lines
    for _ in range(5):
        start = (randint(0, image.width), randint(0, image.height))
        end = (randint(0, image.width), randint(0, image.height))
        draw.line([start, end], fill=random_color(0, 255))
    
    # Add random points
    for _ in range(100):
        dot = (randint(0, image.width), randint(0, image.height))
        draw.point(dot, fill=random_color(0, 255))

    if save:
        image.save("blurry_captcha.png")
        return answer, question
    else:
        out = BytesIO()
        image.save(out, format="png")
        out.seek(0)

        bytes_like = out.read()
        return answer, base64.b64encode(bytes_like)


answer, question = generate_captcha(width=150, height=70, save=True)
print(answer)
print(question)