1 """Simple captcha library, based on PIL. Monkey patch functions in this module

     2 if you want something better...

     3 

     4 :organization: Logilab

     5 :copyright: 2009-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.

     6 :contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

     7 :license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses

     8 """

     9 __docformat__ = "restructuredtext en"

    10 

    11 from random import randint, choice

    12 from cStringIO import StringIO

    13 

    14 import Image, ImageFont, ImageDraw, ImageFilter

    15 

    16 

    17 from time import time

    18 

    19 from cubicweb import tags

    20 from cubicweb.view import StartupView

    21 from cubicweb.web import httpcache, formwidgets as fw, formfields as ff

    22 

    23 

    24 def pil_captcha(text, fontfile, fontsize):

    25     """Generate a captcha image. Return a PIL image object.

    26 

    27     adapted from http://code.activestate.com/recipes/440588/

    28     """

    29     # randomly select the foreground color

    30     fgcolor = randint(0, 0xffff00)

    31     # make the background color the opposite of fgcolor

    32     bgcolor = fgcolor ^ 0xffffff

    33     # create a font object

    34     font = ImageFont.truetype(fontfile, fontsize)

    35     # determine dimensions of the text

    36     dim = font.getsize(text)

    37     # create a new image slightly larger that the text

    38     img = Image.new('RGB', (dim[0]+5, dim[1]+5), bgcolor)

    39     draw = ImageDraw.Draw(img)

    40     # draw 100 random colored boxes on the background

    41     x, y = img.size

    42     for num in range(100):

    43         draw.rectangle((randint(0, x), randint(0, y),

    44                         randint(0, x), randint(0, y)),

    45                        fill=randint(0, 0xffffff))

    46     # add the text to the image

    47     draw.text((3, 3), text, font=font, fill=fgcolor)

    48     img = img.filter(ImageFilter.EDGE_ENHANCE_MORE)

    49     return img

    50 

    51 

    52 def captcha(fontfile, fontsize, size=5, format='JPEG'):

    53     """Generate an arbitrary text, return it together with a buffer containing

    54     the captcha image for the text

    55     """

    56     text = u''.join(choice('QWERTYUOPASDFGHJKLZXCVBNM') for i in range(size))

    57     img = pil_captcha(text, fontfile, fontsize)

    58     out = StringIO()

    59     img.save(out, format)

    60     out.seek(0)

    61     return text, out

    62 

    63 

    64 class CaptchaView(StartupView):

    65     __regid__ = 'captcha'

    66 

    67     http_cache_manager = httpcache.NoHTTPCacheManager

    68     binary = True

    69     templatable = False

    70     content_type = 'image/jpg'

    71 

    72     def call(self):

    73         text, data = captcha.captcha(self._cw.vreg.config['captcha-font-file'],

    74                                      self._cw.vreg.config['captcha-font-size'])

    75         self._cw.set_session_data('captcha', text)

    76         self.w(data.read())

    77 

    78 

    79 class CaptchaWidget(fw.TextInput):

    80     def render(self, form, field, renderer=None):

    81         # t=int(time()*100) to make sure img is not cached

    82         src = form._cw.build_url('view', vid='captcha', t=int(time()*100))

    83         img = tags.img(src=src, alt=u'captcha')

    84         img = u'<div class="captcha">%s</div>' % img

    85         return img + super(CaptchaWidget, self).render(form, field, renderer)