+
−"""Simple captcha library, based on PIL. Monkey patch functions in this module
+
−if you want something better...
+
−
+
−:organization: Logilab
+
−:copyright: 2009-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
+
−:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
+
−:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
+
−"""
+
−__docformat__ = "restructuredtext en"
+
−
+
−from random import randint, choice
+
−from cStringIO import StringIO
+
−
+
−import Image, ImageFont, ImageDraw, ImageFilter
+
−
+
−
+
−from time import time
+
−
+
−from cubicweb import tags
+
−from cubicweb.web import ProcessFormError, formwidgets as fw
+
−
+
−
+
−def pil_captcha(text, fontfile, fontsize):
+
−    """Generate a captcha image. Return a PIL image object.
+
−
+
−    adapted from http://code.activestate.com/recipes/440588/
+
−    """
+
−    # randomly select the foreground color
+
−    fgcolor = randint(0, 0xffff00)
+
−    # make the background color the opposite of fgcolor
+
−    bgcolor = fgcolor ^ 0xffffff
+
−    # create a font object
+
−    font = ImageFont.truetype(fontfile, fontsize)
+
−    # determine dimensions of the text
+
−    dim = font.getsize(text)
+
−    # create a new image slightly larger that the text
+
−    img = Image.new('RGB', (dim[0]+5, dim[1]+5), bgcolor)
+
−    draw = ImageDraw.Draw(img)
+
−    # draw 100 random colored boxes on the background
+
−    x, y = img.size
+
−    for num in xrange(100):
+
−        draw.rectangle((randint(0, x), randint(0, y),
+
−                        randint(0, x), randint(0, y)),
+
−                       fill=randint(0, 0xffffff))
+
−    # add the text to the image
+
−    draw.text((3, 3), text, font=font, fill=fgcolor)
+
−    img = img.filter(ImageFilter.EDGE_ENHANCE_MORE)
+
−    return img
+
−
+
−
+
−def captcha(fontfile, fontsize, size=5, format='JPEG'):
+
−    """Generate an arbitrary text, return it together with a buffer containing
+
−    the captcha image for the text
+
−    """
+
−    text = u''.join(choice('QWERTYUOPASDFGHJKLZXCVBNM') for i in range(size))
+
−    img = pil_captcha(text, fontfile, fontsize)
+
−    out = StringIO()
+
−    img.save(out, format)
+
−    out.seek(0)
+
−    return text, out
+
−
+
−
+
−class CaptchaWidget(fw.TextInput):
+
−    def render(self, form, field, renderer=None):
+
−        # t=int(time()*100) to make sure img is not cached
+
−        src = form._cw.build_url('view', vid='captcha', t=int(time()*100),
+
−                                 captchakey=field.input_name(form))
+
−        img = tags.img(src=src, alt=u'captcha')
+
−        img = u'<div class="captcha">%s</div>' % img
+
−        return img + super(CaptchaWidget, self).render(form, field, renderer)
+
−
+
−    def process_field_data(self, form, field):
+
−        captcha = form._cw.session.data.pop(field.input_name(form), None)
+
−        val = super(CaptchaWidget, self).process_field_data(form, field)
+
−        if val is None:
+
−            return val # required will be checked by field
+
−        if captcha is None:
+
−            msg = form._cw._('unable to check captcha, please try again')
+
−            raise ProcessFormError(msg)
+
−        elif val.lower() != captcha.lower():
+
−            msg = form._cw._('incorrect captcha value')
+
−            raise ProcessFormError(msg)
+
−        return val