--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/captcha.py	Tue Feb 16 10:33:48 2010 +0100
@@ -0,0 +1,85 @@
+"""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.view import StartupView
+from cubicweb.web import httpcache, formwidgets as fw, formfields as ff
+
+
+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 range(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 CaptchaView(StartupView):
+    __regid__ = 'captcha'
+
+    http_cache_manager = httpcache.NoHTTPCacheManager
+    binary = True
+    templatable = False
+    content_type = 'image/jpg'
+
+    def call(self):
+        text, data = captcha.captcha(self._cw.vreg.config['captcha-font-file'],
+                                     self._cw.vreg.config['captcha-font-size'])
+        self._cw.set_session_data('captcha', text)
+        self.w(data.read())
+
+
+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)