Python使用PIL库实现验证码图片的方法

#!/usr/bin/env python
#coding=utf-8
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,font_size=18,font_type="ae_AlArabiya.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
  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[1]))
      draw.line([begin,end],fill=(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),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)) / 100,1 - float(random.randint(1,10)) / 100,float(random.randint(1,2)) / 500,0.001,2)) / 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）
  return img,strs
if __name__ == "__main__":
  code_img = create_validate_code()
  code_img.save("validate.gif","GIF")

try:
  import cStringIO as StringIO
except ImportError:
  import StringIO
mstream = StringIO.StringIO()
img = create_validate_code()[0]
img.save(mstream,"GIF") 

from django.conf.urls.defaults import *
urlpatterns = patterns('example.views',url(r'^validate/$','validate',name='validate'),)

from django.shortcuts import HttpResponse
from validate import create_validate_code
def validate(request):
  mstream = StringIO.StringIO()
  validate_code = create_validate_code()
  img = validate_code[0]
  img.save(mstream,"GIF")
  request.session['validate'] = validate_code[1]
  return HttpResponse(mstream.getvalue(),"image/gif")