#!/usr/bin/env python
#coding=utf-8
import random
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))
fontType="/usr/share/fonts/truetype/freefont/FreeSans.ttf"
 
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=fontType,
               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
 if draw_lines:
  create_lines(draw,n_line,width,height)
 if draw_points:
  create_points(draw,point_chance,width,height)
 strs = create_strs(draw,chars,length,font_type, font_size,width,height,fg_color)
 
 # 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）
 
 return img, strs
 
 
def create_lines(draw,n_line,width,height):
 '''绘制干扰线'''
 line_num = random.randint(n_line[0],n_line[1]) # 干扰线条数
 for i in range(line_num):
  # 起始点
  begin = (random.randint(0, width), random.randint(0, height))
  #结束点
  end = (random.randint(0, width), random.randint(0, height))
  draw.line([begin, end], fill=(0, 0, 0))
 
def create_points(draw,point_chance,width,height):
 '''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(draw,chars,length,font_type, font_size,width,height,fg_color):
 '''绘制验证码字符'''
 '''生成给定长度的字符串，返回列表格式'''
 c_chars = random.sample(chars, length)
 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 __name__ == "__main__":
  code_img = create_validate_code()
  code_img[0].save("validate.gif", "GIF")
  print code_img[1]