hd-crane-gs/backend/app/utils/captcha_util.py

# -*- coding: utf-8 -*-

import base64
import random
import string
from io import BytesIO
from typing import Tuple
from PIL import Image, ImageDraw, ImageFont

from app.config.setting import settings


class CaptchaUtil:
    """
    验证码工具类
    """
    @classmethod 
    def generate_captcha(cls) -> Tuple[str, str]:
        """
        生成带有噪声和干扰的验证码图片（4位随机字符）。
        
        返回:
        - Tuple[str, str]: [base64图片字符串, 验证码值]。
        """
        # 生成4位随机验证码
        chars = string.digits + string.ascii_letters
        captcha_value = ''.join(random.sample(chars, 4))

        # 创建一张随机颜色背景的图片
        width, height = 160, 60
        background_color = tuple(random.randint(230, 255) for _ in range(3))
        image = Image.new('RGB', (width, height), color=background_color)
        draw = ImageDraw.Draw(image)

        # 使用指定字体
        font = ImageFont.truetype(font=settings.CAPTCHA_FONT_PATH, size=settings.CAPTCHA_FONT_SIZE)

        # 计算文本总宽度和高度
        total_width = sum(draw.textbbox((0, 0), char, font=font)[2] for char in captcha_value)
        text_height = draw.textbbox((0, 0), captcha_value[0], font=font)[3]

        # 计算起始位置,使文字居中
        x_start = (width - total_width) / 2
        y_start = (height - text_height) / 2 - draw.textbbox((0, 0), captcha_value[0], font=font)[1]

        # 绘制字符
        x = x_start
        for char in captcha_value:
            # 使用深色文字,增加对比度
            text_color = tuple(random.randint(0, 80) for _ in range(3))
            
            # 随机偏移,增加干扰
            x_offset = x + random.uniform(-2, 2)
            y_offset = y_start + random.uniform(-2, 2)
            
            # 绘制字符
            draw.text((x_offset, y_offset), char, font=font, fill=text_color)
            
            # 更新x坐标,增加字符间距的随机性
            x += draw.textbbox((0, 0), char, font=font)[2] + random.uniform(1, 5)

        # 添加干扰线
        for _ in range(4):
            line_color = tuple(random.randint(150, 200) for _ in range(3))
            points = [(i, int(random.uniform(0, height))) for i in range(0, width, 20)]
            draw.line(points, fill=line_color, width=1)

        # 添加随机噪点
        for _ in range(width * height // 60):
            point_color = tuple(random.randint(0, 255) for _ in range(3))
            draw.point(
                (random.randint(0, width), random.randint(0, height)),
                fill=point_color
            )

        # 将图像数据保存到内存中并转换为base64
        buffer = BytesIO()
        image.save(buffer, format='PNG', optimize=True)
        base64_string = base64.b64encode(buffer.getvalue()).decode()
        
        return base64_string, captcha_value
    
    @classmethod
    def captcha_arithmetic(cls) -> Tuple[str, int]:
        """
        创建验证码图片（加减乘运算）。
        
        返回:
        - Tuple[str, int]: [base64图片字符串, 计算结果]。
        """
        # 创建空白图像,使用随机浅色背景
        background_color = tuple(random.randint(230, 255) for _ in range(3))
        image = Image.new('RGB', (160, 60), color=background_color)
        draw = ImageDraw.Draw(image)

        # 设置字体
        font = ImageFont.truetype(font=settings.CAPTCHA_FONT_PATH, size=settings.CAPTCHA_FONT_SIZE)

        # 生成运算数字和运算符
        operators = ['+', '-', '*']
        operator = random.choice(operators)
        
        # 对于减法,确保num1大于num2
        if operator == '-':
            num1 = random.randint(6, 10)
            num2 = random.randint(1, 5)
        else:
            num1 = random.randint(1, 9)
            num2 = random.randint(1, 9)
        
        # 计算结果
        result_map = {
            '+': lambda x, y: x + y,
            '-': lambda x, y: x - y,
            '*': lambda x, y: x * y
        }
        captcha_value = result_map[operator](num1, num2)

        # 绘制文本,使用深色增加对比度
        text = f'{num1} {operator} {num2} = ?'
        text_bbox = draw.textbbox((0, 0), text, font=font)
        text_width = text_bbox[2] - text_bbox[0]
        x = (160 - text_width) // 2
        draw.text((x, 15), text, fill=(0, 0, 139), font=font)

        # 添加干扰线
        for _ in range(3):
            line_color = tuple(random.randint(150, 200) for _ in range(3))
            draw.line([
                (random.randint(0, 160), random.randint(0, 60)),
                (random.randint(0, 160), random.randint(0, 60))
            ], fill=line_color, width=1)

        # 将图像数据保存到内存中并转换为base64
        buffer = BytesIO()
        image.save(buffer, format='PNG', optimize=True)
        base64_string = base64.b64encode(buffer.getvalue()).decode()

        return base64_string, captcha_value