--- a/src/core/constants.py	Fri Mar 02 17:53:19 2018 +0100
+++ b/src/core/constants.py	Fri Mar 02 17:53:31 2018 +0100
@@ -352,6 +352,11 @@
     ACCESS_TYPES = (ACCESS_TYPE_PUBLIC, ACCESS_TYPE_WHITELIST)
 
 
+    ## Common data keys ##
+    KEY_THUMBNAILS = u'thumbnails'
+    KEY_PROGRESS_ID = u'progress_id'
+
+
     ## Misc ##
     SAVEFILE_DATABASE = APP_NAME_FILE + ".db"
     IQ_SET = '/iq[@type="set"]'

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/plugins/plugin_xep_0264.py	Fri Mar 02 17:53:31 2018 +0100
@@ -0,0 +1,181 @@
+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+# SAT plugin for managing xep-0264
+# Copyright (C) 2009-2018 Jérôme Poisson (goffi@goffi.org)
+# Copyright (C) 2014 Emmanuel Gil Peyrot (linkmauve@linkmauve.fr)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from sat.core.i18n import _
+from sat.core.constants import Const as C
+from sat.core.log import getLogger
+log = getLogger(__name__)
+from twisted.internet import threads
+from twisted.python.failure import Failure
+
+from zope.interface import implements
+
+from wokkel import disco, iwokkel
+
+from sat.core import exceptions
+import hashlib
+try:
+    from PIL import Image
+except:
+    raise exceptions.MissingModule(u"Missing module pillow, please download/install it from https://python-pillow.github.io")
+
+try:
+    from twisted.words.protocols.xmlstream import XMPPHandler
+except ImportError:
+    from wokkel.subprotocols import XMPPHandler
+
+
+MIME_TYPE = u'image/jpeg'
+SAVE_FORMAT = u'JPEG' # (cf. Pillow documentation)
+
+NS_THUMBS = 'urn:xmpp:thumbs:1'
+
+PLUGIN_INFO = {
+    C.PI_NAME: "XEP-0264",
+    C.PI_IMPORT_NAME: "XEP-0264",
+    C.PI_TYPE: "XEP",
+    C.PI_MODES: C.PLUG_MODE_BOTH,
+    C.PI_PROTOCOLS: ["XEP-0264"],
+    C.PI_DEPENDENCIES: ["XEP-0234"],
+    C.PI_MAIN: "XEP_0264",
+    C.PI_HANDLER: "yes",
+    C.PI_DESCRIPTION: _("""Thumbnails handling""")
+}
+
+
+class XEP_0264(object):
+    SIZE_SMALL = (250, 250)
+    SIZE_MEDIUM = (1024, 1024)
+
+    def __init__(self, host):
+        log.info(_(u"Plugin XEP_0264 initialization"))
+        self.host = host
+        host.trigger.add("XEP-0234_buildFileElement", self._addFileThumbnails)
+        host.trigger.add("XEP-0234_parseFileElement", self._getFileThumbnails)
+
+    def getHandler(self, client):
+        return XEP_0264_handler()
+
+    ## triggers ##
+
+    def _addFileThumbnails(self, file_elt, extra_args):
+        try:
+            thumbnails = extra_args[u'extra'][C.KEY_THUMBNAILS]
+        except KeyError:
+            return
+        for thumbnail in thumbnails:
+            thumbnail_elt = file_elt.addElement((NS_THUMBS, u'thumbnail'))
+            thumbnail_elt['uri'] = u'cid:' + thumbnail['id']
+            thumbnail_elt['media-type'] = MIME_TYPE
+            width, height = thumbnail['size']
+            thumbnail_elt['width'] = unicode(width)
+            thumbnail_elt['height'] = unicode(height)
+
+    def _getFileThumbnails(self, file_elt, file_data):
+        thumbnails = []
+        for thumbnail_elt in file_elt.elements(NS_THUMBS, u'thumbnail'):
+            uri = thumbnail_elt['uri']
+            if uri.startswith ('cid:'):
+                thumbnail = {'id': uri[4:]}
+            width = thumbnail_elt.getAttribute('width')
+            height = thumbnail_elt.getAttribute('height')
+            if width and height:
+                try:
+                    thumbnail['size'] = int(width), int(height)
+                except ValueError:
+                    pass
+            try:
+                thumbnail['mime_type'] = thumbnail_elt['media-type']
+            except KeyError:
+                pass
+            thumbnails.append(thumbnail)
+
+        if thumbnails:
+            file_data.setdefault('extra', {})[C.KEY_THUMBNAILS] = thumbnails
+
+    ## thumbnails generation ##
+
+    def getThumbId(self, image_uid, size):
+        """return an ID unique for image/size combination
+
+        @param image_uid(unicode): unique id of the image
+            can be a hash
+        @param size(tuple(int)): requested size of thumbnail
+        @return (unicode): unique id for this image/size
+        """
+        return hashlib.sha256(repr((image_uid, size))).hexdigest()
+
+    def _blockingGenThumb(self, source_path, size=None, max_age=None, image_uid=None):
+        """Generate a thumbnail for image
+
+        This is a blocking method and must be executed in a thread
+        params are the same as for [generateThumbnail]
+        """
+        if size is None:
+            size = self.SIZE_SMALL
+        try:
+            img = Image.open(source_path)
+        except IOError:
+            return Failure(exceptions.DataError(u"Can't open image"))
+
+        img.thumbnail(size)
+        uid = self.getThumbId(image_uid or source_path, size)
+
+        with self.host.common_cache.cacheData(
+            PLUGIN_INFO[C.PI_IMPORT_NAME],
+            uid,
+            MIME_TYPE,
+            max_age,
+            ) as f:
+            img.save(f, SAVE_FORMAT)
+
+        return img.size, uid
+
+    def generateThumbnail(self, source_path, size=None, max_age=None, image_uid=None):
+        """Generate a thumbnail of image
+
+        @param source_path(unicode): absolute path to source image
+        @param size(int, None): max size of the thumbnail
+            can be one of self.SIZE_*
+            None to use default value (i.e. self.SIZE_SMALL)
+        @param max_age(int, None): same as for [memory.cache.Cache.cacheData])
+        @param image_uid(unicode, None): unique ID to identify the image
+            use hash whenever possible
+            if None, source_path will be used
+        @return D(tuple[tuple[int,int], unicode]): tuple with:
+            - size of the thumbnail
+            - unique Id of the thumbnail
+        """
+
+        d = threads.deferToThread(
+                self._blockingGenThumb, source_path, size, max_age, image_uid=image_uid)
+        d.addErrback(lambda failure_:
+            log.error(u"thumbnail generation error: {}".format(failure_)))
+        return d
+
+
+class XEP_0264_handler(XMPPHandler):
+    implements(iwokkel.IDisco)
+
+    def getDiscoInfo(self, requestor, target, nodeIdentifier=''):
+        return [disco.DiscoFeature(NS_THUMBS)]
+
+    def getDiscoItems(self, requestor, target, nodeIdentifier=''):
+        return []