【Python百日进阶-WEB开发】Day177 - Django案例：09图形验证码(一)

八、图形验证码

8.1 图形验证码逻辑分析

UUID 是 通用唯一识别码（Universally Unique Identifier）的缩写，是一种软件建构的标准，亦为开放软件基金会组织在分布式计算环境领域的一部分。其目的，是让分布式系统中的所有元素，都能有唯一的辨识信息，而不需要通过中央控制端来做辨识信息的指定。如此一来，每个人都可以创建不与其它人冲突的UUID。在这样的情况下，就不需考虑数据库创建时的名称重复问题。目前最广泛应用的UUID，是微软公司的全局唯一标识符（GUID），而其他重要的应用，则有Linux ext2/ext3文件系统、LUKS加密分区、GNOME、KDE、Mac OS X等等。另外我们也可以在e2fsprogs包中的UUID库找到实现。
UUID（Universally Unique Identifier）全局唯一标识符，定义为一个字符串主键，采用32位数字组成，编码采用16进制，定义了在时间和空间都完全惟一的系统信息。

8.2 图形验证码接口设计和定义

8.3 图形验证码后端逻辑

8.3.1 新建子应用

8.3.1 创建子应用

(meiduo_mall) PS E:\meiduo_project\meiduo_mall> cd meiduo_mall/apps
(meiduo_mall) PS E:\meiduo_project\meiduo_mall\meiduo_mall\apps> python ../../manage.py startapp verifications
(meiduo_mall) PS E:\meiduo_project\meiduo_mall\meiduo_mall\apps> cd ..
(meiduo_mall) PS E:\meiduo_project\meiduo_mall\meiduo_mall> cd..
(meiduo_mall) PS E:\meiduo_project\meiduo_mall> 
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8.3.2 meiduo_mall.settings.dev.py中注册验证子应用，也可以不注册

注册的子应用一般需要迁移或模板，但验证模块既不需要迁移也没有模板

8.3.3 主路由中添加首页子路由转向和命名空间

from django.contrib import admin
from django.urls import path, include
from meiduo_mall.apps.users import urls as users_urls
from meiduo_mall.apps.contents import urls as contents_urls
from meiduo_mall.apps.verifications import urls as verifications_urls

urlpatterns = [
    path('admin/', admin.site.urls),

    # users
    path('', include(users_urls, namespace='users')),

    # contents
    path('', include(contents_urls, namespace='contents')),
    
    # verifications
    path('', include(verifications_urls, namespace='verifications')),
]

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8.3.4 新建子路由contents.urls.py文件

from django.urls import path, re_path
from . import views

app_name = 'verifications'

urlpatterns = [
    # 图形验证码，re_path路由正则校验，响应json数据，不需要重定向，也就不需要命名空间
    re_path(r'^image_codes/(?P[\w-]+)/', views.ImageCodeView.as_view()),

]
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8.3.5 首页子应用view.py文件

from django.views import View
from meiduo_mall.apps.users.models import User
from meiduo_mall.utils.response_code import RETCODE


class ImageCodeView(View):
    """  图形验证码 """
    def get(self, request, uuid):
        """
        参数：uuid通用唯一识别码，用于唯一识别图形验证码属于哪个用户的
        返回值：image/jpg
        """
        pass
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8.3.2 准备captcha扩展包

1. 先安装前置包Pillow：pip install -i https://pypi.tuna.tsinghua.edu.cn/simple Pillow
2. verifictions子应用中新建libs包，包含 init.py文件，用于存放扩展包文件；内部新建captcha包，captcha包内新建fonts包和captcha.py文件，复制字体文件到fonts包中。结构如下
   
   captcha.py文件

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# refer to `https://bitbucket.org/akorn/wheezy.captcha`

import random
import string
import os.path
from io import BytesIO

from PIL import Image
from PIL import ImageFilter
from PIL.ImageDraw import Draw
from PIL.ImageFont import truetype


class Bezier:       # 贝塞尔曲线
    def __init__(self):
        self.tsequence = tuple([t / 20.0 for t in range(21)])
        self.beziers = {}

    def pascal_row(self, n):
        """ Returns n-th row of Pascal's triangle
        """
        result = [1]
        x, numerator = 1, n
        for denominator in range(1, n // 2 + 1):
            x *= numerator
            x /= denominator
            result.append(x)
            numerator -= 1
        if n & 1 == 0:
            result.extend(reversed(result[:-1]))
        else:
            result.extend(reversed(result))
        return result

    def make_bezier(self, n):
        """ Bezier curves:
            http://en.wikipedia.org/wiki/B%C3%A9zier_curve#Generalization
        """
        try:
            return self.beziers[n]
        except KeyError:
            combinations = self.pascal_row(n - 1)
            result = []
            for t in self.tsequence:
                tpowers = (t ** i for i in range(n))
                upowers = ((1 - t) ** i for i in range(n - 1, -1, -1))
                coefs = [c * a * b for c, a, b in zip(combinations,
                                                      tpowers, upowers)]
                result.append(coefs)
            self.beziers[n] = result
            return result


class Captcha(object):
    def __init__(self):
        self._bezier = Bezier()
        self._dir = os.path.dirname(__file__)
        # self._captcha_path = os.path.join(self._dir, '..', 'static', 'captcha')

    @staticmethod
    def instance():
        if not hasattr(Captcha, "_instance"):
            Captcha._instance = Captcha()
        return Captcha._instance

    def initialize(self, width=200, height=75, color=None, text=None, fonts=None):
        # self.image = Image.new('RGB', (width, height), (255, 255, 255))
        self._text = text if text else random.sample(string.ascii_uppercase + string.ascii_uppercase + '3456789', 4)
        self.fonts = fonts if fonts else \
            [os.path.join(self._dir, 'fonts', font) for font in ['Arial.ttf', 'Georgia.ttf', 'actionj.ttf']]
        self.width = width
        self.height = height
        self._color = color if color else self.random_color(0, 200, random.randint(220, 255))

    @staticmethod
    def random_color(start, end, opacity=None):
        red = random.randint(start, end)
        green = random.randint(start, end)
        blue = random.randint(start, end)
        if opacity is None:
            return red, green, blue
        return red, green, blue, opacity

    # draw image

    def background(self, image):
        Draw(image).rectangle([(0, 0), image.size], fill=self.random_color(238, 255))
        return image

    @staticmethod
    def smooth(image):
        return image.filter(ImageFilter.SMOOTH)

    def curve(self, image, width=4, number=6, color=None):
        dx, height = image.size
        dx /= number
        path = [(dx * i, random.randint(0, height))
                for i in range(1, number)]
        bcoefs = self._bezier.make_bezier(number - 1)
        points = []
        for coefs in bcoefs:
            points.append(tuple(sum([coef * p for coef, p in zip(coefs, ps)])
                                for ps in zip(*path)))
        Draw(image).line(points, fill=color if color else self._color, width=width)
        return image

    def noise(self, image, number=50, level=2, color=None):
        width, height = image.size
        dx = width / 10
        width -= dx
        dy = height / 10
        height -= dy
        draw = Draw(image)
        for i in range(number):
            x = int(random.uniform(dx, width))
            y = int(random.uniform(dy, height))
            draw.line(((x, y), (x + level, y)), fill=color if color else self._color, width=level)
        return image

    def text(self, image, fonts, font_sizes=None, drawings=None, squeeze_factor=0.75, color=None):
        color = color if color else self._color
        fonts = tuple([truetype(name, size)
                       for name in fonts
                       for size in font_sizes or (65, 70, 75)])
        draw = Draw(image)
        char_images = []
        for c in self._text:
            font = random.choice(fonts)
            c_width, c_height = draw.textsize(c, font=font)
            char_image = Image.new('RGB', (c_width, c_height), (0, 0, 0))
            char_draw = Draw(char_image)
            char_draw.text((0, 0), c, font=font, fill=color)
            char_image = char_image.crop(char_image.getbbox())
            for drawing in drawings:
                d = getattr(self, drawing)
                char_image = d(char_image)
            char_images.append(char_image)
        width, height = image.size
        offset = int((width - sum(int(i.size[0] * squeeze_factor)
                                  for i in char_images[:-1]) -
                      char_images[-1].size[0]) / 2)
        for char_image in char_images:
            c_width, c_height = char_image.size
            mask = char_image.convert('L').point(lambda i: i * 1.97)
            image.paste(char_image,
                        (offset, int((height - c_height) / 2)),
                        mask)
            offset += int(c_width * squeeze_factor)
        return image

    # draw text
    @staticmethod
    def warp(image, dx_factor=0.27, dy_factor=0.21):
        width, height = image.size
        dx = width * dx_factor
        dy = height * dy_factor
        x1 = int(random.uniform(-dx, dx))
        y1 = int(random.uniform(-dy, dy))
        x2 = int(random.uniform(-dx, dx))
        y2 = int(random.uniform(-dy, dy))
        image2 = Image.new('RGB',
                           (width + abs(x1) + abs(x2),
                            height + abs(y1) + abs(y2)))
        image2.paste(image, (abs(x1), abs(y1)))
        width2, height2 = image2.size
        return image2.transform(
            (width, height), Image.QUAD,
            (x1, y1,
             -x1, height2 - y2,
             width2 + x2, height2 + y2,
             width2 - x2, -y1))

    @staticmethod
    def offset(image, dx_factor=0.1, dy_factor=0.2):
        width, height = image.size
        dx = int(random.random() * width * dx_factor)
        dy = int(random.random() * height * dy_factor)
        image2 = Image.new('RGB', (width + dx, height + dy))
        image2.paste(image, (dx, dy))
        return image2

    @staticmethod
    def rotate(image, angle=25):
        return image.rotate(
            random.uniform(-angle, angle), Image.BILINEAR, expand=1)

    def captcha(self, path=None, fmt='JPEG'):
        """Create a captcha.

        Args:
            path: save path, default None.
            fmt: image format, PNG / JPEG.
        Returns:
            A tuple, (name, text, StringIO.value).
            For example:
                ('fXZJN4AFxHGoU5mIlcsdOypa', 'JGW9', '\x89PNG\r\n\x1a\n\x00\x00\x00\r...')

        """
        image = Image.new('RGB', (self.width, self.height), (255, 255, 255))
        image = self.background(image)
        image = self.text(image, self.fonts, drawings=['warp', 'rotate', 'offset'])
        image = self.curve(image)
        image = self.noise(image)
        image = self.smooth(image)
        # name = "".join(random.sample(string.ascii_lowercase + string.ascii_uppercase + '3456789', 24))
        text = "".join(self._text)
        out = BytesIO()
        image.save(out, format=fmt)
        # if path:
        #     image.save(os.path.join(path, name), fmt)
        # return name, text, out.getvalue()
        return text, out.getvalue()

    def generate_captcha(self):
        self.initialize()
        return self.captcha("")

captcha = Captcha.instance()

if __name__ == '__main__':
    print(captcha.generate_captcha())
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