web/captcha.py
author Adrien Di Mascio <Adrien.DiMascio@logilab.fr>
Mon, 08 Mar 2010 19:11:47 +0100
changeset 4830 10e8bc190695
parent 4722 9c13d5db03d9
child 5037 7778a2bbdf9d
permissions -rw-r--r--
[javascript] fix #736185: add_onload / jQuery.bind() vs. jQuery.one() This patch introduces a new 'server-response' event and deprecates the 'ajax-loaded' event. - 'server-response' is triggered by postAjaxLoad() (instead of 'ajax-loaded'). - 'server-response' is also triggered on document.ready(). - The add_onload() method binds the javascript code the 'server-response' event whether or not it's an ajax request, thus removing the need of the jsoncall hackish parameter. The binding is done with jQuery.one() instead of jQuery.bind(). - The javascript callbacks will be passed two extra parameters : a boolean to indicate if it's an ajax request or not, the DOM node (result of the HTTP query). As javascript is what it is, callbacks can safely ignore those two parameters if they don't need them. Backward compatibility is maintained by triggerring an 'ajax-loaded' event when a 'server-response' is emitted.

"""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 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))
        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)