Function example code of django implementing verification code in python

import random
from PIL import Image, ImageDraw, ImageFont, ImageFilter

_letter_cases = "abcdefghjkmnpqrstuvwxy" # 小写字母，去除可能干扰的i，l，o，z
_upper_cases = _letter_cases.upper() # 大写字母
_numbers = ''.join(map(str, range(3, 10))) # 数字
init_chars = ''.join((_letter_cases, _upper_cases, _numbers))

def create_validate_code(size=(120, 30),
       chars=init_chars,
       img_type="GIF",
       mode="RGB",
       bg_color=(255, 255, 255),
       fg_color=(0, 0, 255),
       font_size=18,
       font_type="Monaco.ttf",
       length=4,
       draw_lines=True,
       n_line=(1, 2),
       draw_points=True,
       point_chance=2):
 """
 @todo: 生成验证码图片
 @param size: 图片的大小，格式（宽，高），默认为(120, 30)
 @param chars: 允许的字符集合，格式字符串
 @param img_type: 图片保存的格式，默认为GIF，可选的为GIF，JPEG，TIFF，PNG
 @param mode: 图片模式，默认为RGB
 @param bg_color: 背景颜色，默认为白色
 @param fg_color: 前景色，验证码字符颜色，默认为蓝色#0000FF
 @param font_size: 验证码字体大小
 @param font_type: 验证码字体，默认为 ae_AlArabiya.ttf
 @param length: 验证码字符个数
 @param draw_lines: 是否划干扰线
 @param n_lines: 干扰线的条数范围，格式元组，默认为(1, 2)，只有draw_lines为True时有效
 @param draw_points: 是否画干扰点
 @param point_chance: 干扰点出现的概率，大小范围[0, 100]
 @return: [0]: PIL Image实例
 @return: [1]: 验证码图片中的字符串
 """

 width, height = size # 宽高
 # 创建图形
 img = Image.new(mode, size, bg_color)
 draw = ImageDraw.Draw(img) # 创建画笔

 def get_chars():
  """生成给定长度的字符串，返回列表格式"""
  return random.sample(chars, length)

 def create_lines():
  """绘制干扰线"""
  line_num = random.randint(*n_line) # 干扰线条数

  for i in range(line_num):
   # 起始点
   begin = (random.randint(0, size[0]), random.randint(0, size[1]))
   # 结束点
   end = (random.randint(0, size[0]), random.randint(0, size[1]))
   draw.line([begin, end], fill=(0, 0, 0))

 def create_points():
  """绘制干扰点"""
  chance = min(100, max(0, int(point_chance))) # 大小限制在[0, 100]

  for w in range(width):
   for h in range(height):
    tmp = random.randint(0, 100)
    if tmp > 100 - chance:
     draw.point((w, h), fill=(0, 0, 0))

 def create_strs():
  """绘制验证码字符"""
  c_chars = get_chars()
  strs = ' %s ' % ' '.join(c_chars) # 每个字符前后以空格隔开

  # font = ImageFont.truetype(font_type, font_size)
  font = ImageFont.load_default().font
  font_width, font_height = font.getsize(strs)

  draw.text(((width - font_width) / 3, (height - font_height) / 3),
     strs, font=font, fill=fg_color)

  return ''.join(c_chars)

 if draw_lines:
  create_lines()
 if draw_points:
  create_points()
 strs = create_strs()

 # 图形扭曲参数
params = [1 - float(random.randint(1, 2)) / 100,0, 0, 0,1 - float(random.randint(1, 10)) / 100,float(random.randint(1, 2)) / 500, 0.001,float(random.randint(1, 2)) / 500] 
img = img.transform(size, Image.PERSPECTIVE, params) # 创建扭曲 
img = img.filter(ImageFilter.EDGE_ENHANCE_MORE) # 滤镜，边界加强（阈值更大）