python image verification code generation code

#!/usr/bin/env python
# -*- coding: UTF-8 -*-
 
import random
from PIL import Image, ImageDraw, ImageFont, ImageFilter
 
try:
  import cStringIO as StringIO
except ImportError:
  import StringIO
 
_letter_cases = "abcdefghjkmnpqrstuvwxy"            # 小写字母
_upper_cases = "ABCDEFGHJKLMNPQRSTUVWXY"            # 大写字母
_numbers = "1234567890"                     # 数字
init_chars = ''.join((_letter_cases, _upper_cases, _numbers))  # 生成允许的字符集合
default_font = "./DejaVuSans.ttf"                # 验证码字体
 
 
# 生成验证码接口
def generate_verify_image(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=default_font,
             length=4,
             draw_lines=True,
             n_line=(1, 2),
             draw_points=True,
             point_chance=2,
             save_img=False):
 
  """
  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 DejaVuSans.ttf
  :param length: 验证码字符个数
  :param draw_lines: 是否划干扰线
  :param n_line: 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]
  :param save_img: 是否保存为图片
  :return: [0]: 验证码字节流, [1]: 验证码图片中的字符串
  """
 
  width, height = size # 宽， 高
  img = Image.new(mode, size, bg_color) # 创建图形
  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 xrange(width):
      for h in xrange(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_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）
 
  mstream = StringIO.StringIO()
  img.save(mstream, img_type)
 
  if save_img:
    img.save("validate.gif", img_type)
 
  return mstream, strs
 
 
if __name__ == "__main__":
  mstream, strs = generate_verify_image(save_img=True)
  print strs