--- a/sat/bridge/bridge_constructor/bridge_template.ini	Tue Oct 29 20:24:29 2019 +0100
+++ b/sat/bridge/bridge_constructor/bridge_template.ini	Tue Oct 29 20:38:39 2019 +0100
@@ -909,3 +909,24 @@
 sig_out=a{ss}
 doc=Get a dict to short name => whole namespaces
 doc_return=namespaces mapping
+
+[imageCheck]
+type=method
+category=core
+sig_in=s
+sig_out=s
+doc=Analyze an image a return a report
+doc_return=serialized report
+
+[imageResize]
+async=
+type=method
+category=core
+sig_in=sii
+sig_out=s
+doc=Create a new image with desired size
+doc_param_0=image_path: path of the image to resize
+doc_param_1=width: width of the new image
+doc_param_2=height: height of the new image
+doc_return=path of the new image with desired size
+    the image must be deleted once not needed anymore

--- a/sat/bridge/dbus_bridge.py	Tue Oct 29 20:24:29 2019 +0100
+++ b/sat/bridge/dbus_bridge.py	Tue Oct 29 20:38:39 2019 +0100
@@ -385,6 +385,18 @@
         return self._callback("historyGet", str(from_jid), str(to_jid), limit, between, filters, str(profile), callback=callback, errback=errback)
 
     @dbus.service.method(const_INT_PREFIX+const_CORE_SUFFIX,
+                         in_signature='s', out_signature='s',
+                         async_callbacks=None)
+    def imageCheck(self, arg_0):
+        return self._callback("imageCheck", str(arg_0))
+
+    @dbus.service.method(const_INT_PREFIX+const_CORE_SUFFIX,
+                         in_signature='sii', out_signature='s',
+                         async_callbacks=('callback', 'errback'))
+    def imageResize(self, image_path, width, height, callback=None, errback=None):
+        return self._callback("imageResize", str(image_path), width, height, callback=callback, errback=errback)
+
+    @dbus.service.method(const_INT_PREFIX+const_CORE_SUFFIX,
                          in_signature='s', out_signature='b',
                          async_callbacks=None)
     def isConnected(self, profile_key="@DEFAULT@"):

--- a/sat/core/constants.py	Tue Oct 29 20:24:29 2019 +0100
+++ b/sat/core/constants.py	Tue Oct 29 20:38:39 2019 +0100
@@ -361,6 +361,13 @@
     # internationalisation
     DEFAULT_LOCALE = "en_GB"
 
+    # Contexts
+    # context indicate how things are done (e.g. to who/what a file is transfered)
+    # this is useful to make some decision (e.g. image size)
+
+    # something is done in instant messaging
+    CONTEXT_CHAT = "CONTEXT_CHAT"
+
     ## Misc ##
     SAVEFILE_DATABASE = APP_NAME_FILE + ".db"
     IQ_SET = '/iq[@type="set"]'

--- a/sat/core/sat_main.py	Tue Oct 29 20:24:29 2019 +0100
+++ b/sat/core/sat_main.py	Tue Oct 29 20:38:39 2019 +0100
@@ -40,8 +40,10 @@
 from sat.memory import encryption
 from sat.tools import async_trigger as trigger
 from sat.tools import utils
+from sat.tools import images
 from sat.tools.common import dynamic_import
 from sat.tools.common import regex
+from sat.tools.common import data_format
 from sat.stdui import ui_contact_list, ui_profile_manager
 import sat.plugins
 
@@ -161,6 +163,8 @@
         self.bridge.register_method("loadParamsTemplate", self.memory.load_xml)
         self.bridge.register_method("sessionInfosGet", self.getSessionInfos)
         self.bridge.register_method("namespacesGet", self.getNamespaces)
+        self.bridge.register_method("imageCheck", self._imageCheck)
+        self.bridge.register_method("imageResize", self._imageResize)
 
         self.memory.initialized.addCallback(self._postMemoryInit)
 
@@ -632,6 +636,17 @@
             }
         return defer.succeed(data)
 
+    # images
+
+    def _imageCheck(self, path):
+        report = images.checkImage(self, path)
+        return data_format.serialise(report)
+
+    def _imageResize(self, path, width, height):
+        d = images.resizeImage(path, (width, height))
+        d.addCallback(lambda new_image_path: str(new_image_path))
+        return d
+
     # local dirs
 
     def getLocalPath(self, client, dir_name, *extra_path, **kwargs):

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/tools/images.py	Tue Oct 29 20:38:39 2019 +0100
@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+# SAT: a jabber client
+# Copyright (C) 2009-2019 Jérôme Poisson (goffi@goffi.org)
+
+# 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/>.
+
+"""Methods to manipulate images"""
+
+import tempfile
+from PIL import Image
+from sat.core.constants import Const as C
+from pathlib import Path
+from twisted.internet import threads
+
+
+def checkImage(host, path, context=C.CONTEXT_CHAT):
+    """Analyze image and return a report
+
+    report will indicate if image is too large, and the recommended new size if this is
+    the case
+    @param host: SàT instance
+    @param path(str, pathlib.Path): image to open
+    @param context(str): context in which the image is transfered
+    @return dict: report on image, with following keys:
+        - too_large: true if image is oversized
+        - recommended_size: if too_large is True, recommended size to use
+    """
+    # TODO: context is not used yet
+    report = {}
+    image = Image.open(path)
+    max_size = tuple(host.memory.getConfig(None, "image_max", (1200, 720)))
+    if image.size > max_size:
+        report['too_large'] = True
+        if image.size[0] > max_size[0]:
+            factor = max_size[0] / image.size[0]
+            if image.size[1] * factor > max_size[1]:
+                factor = max_size[1] / image.size[1]
+        else:
+            factor = max_size[1] / image.size[1]
+        report['recommended_size'] = [image.width*factor, image.height*factor]
+    else:
+        report['too_large'] = False
+
+    return report
+
+
+def _resizeImageBlocking(image_path, new_size):
+    im_path = Path(image_path)
+    im = Image.open(im_path)
+    resized = im.resize(new_size, Image.LANCZOS)
+    with tempfile.NamedTemporaryFile(suffix=im_path.suffix, delete=False) as f:
+        resized.save(f, format=im.format)
+    return Path(f.name)
+
+
+def resizeImage(image_path, new_size):
+    """Resize an image to a new temporary file, and return it path
+
+    @param image_path(str, Path): path of the original image
+    @param new_size(tuple[int, int]): size to use for new image
+    @return (Path): path of the resized file. The image at this path must be deleted
+        after use
+    """
+    return threads.deferToThread(_resizeImageBlocking, image_path, new_size)

--- a/sat_frontends/bridge/dbus_bridge.py	Tue Oct 29 20:24:29 2019 +0100
+++ b/sat_frontends/bridge/dbus_bridge.py	Tue Oct 29 20:38:39 2019 +0100
@@ -469,6 +469,29 @@
             error_handler = lambda err:errback(dbus_to_bridge_exception(err))
         return self.db_core_iface.historyGet(from_jid, to_jid, limit, between, filters, profile, timeout=const_TIMEOUT, reply_handler=callback, error_handler=error_handler)
 
+    def imageCheck(self, arg_0, callback=None, errback=None):
+        if callback is None:
+            error_handler = None
+        else:
+            if errback is None:
+                errback = log.error
+            error_handler = lambda err:errback(dbus_to_bridge_exception(err))
+        kwargs={}
+        if callback is not None:
+            kwargs['timeout'] = const_TIMEOUT
+            kwargs['reply_handler'] = callback
+            kwargs['error_handler'] = error_handler
+        return str(self.db_core_iface.imageCheck(arg_0, **kwargs))
+
+    def imageResize(self, image_path, width, height, callback=None, errback=None):
+        if callback is None:
+            error_handler = None
+        else:
+            if errback is None:
+                errback = log.error
+            error_handler = lambda err:errback(dbus_to_bridge_exception(err))
+        return str(self.db_core_iface.imageResize(image_path, width, height, timeout=const_TIMEOUT, reply_handler=callback, error_handler=error_handler))
+
     def isConnected(self, profile_key="@DEFAULT@", callback=None, errback=None):
         if callback is None:
             error_handler = None
@@ -1085,6 +1108,22 @@
         self.db_core_iface.historyGet(from_jid, to_jid, limit, between, filters, profile, timeout=const_TIMEOUT, reply_handler=reply_handler, error_handler=error_handler)
         return fut
 
+    def imageCheck(self, arg_0):
+        loop = asyncio.get_running_loop()
+        fut = loop.create_future()
+        reply_handler = lambda ret=None: loop.call_soon_threadsafe(fut.set_result, ret)
+        error_handler = lambda err: loop.call_soon_threadsafe(fut.set_exception, dbus_to_bridge_exception(err))
+        self.db_core_iface.imageCheck(arg_0, timeout=const_TIMEOUT, reply_handler=reply_handler, error_handler=error_handler)
+        return fut
+
+    def imageResize(self, image_path, width, height):
+        loop = asyncio.get_running_loop()
+        fut = loop.create_future()
+        reply_handler = lambda ret=None: loop.call_soon_threadsafe(fut.set_result, ret)
+        error_handler = lambda err: loop.call_soon_threadsafe(fut.set_exception, dbus_to_bridge_exception(err))
+        self.db_core_iface.imageResize(image_path, width, height, timeout=const_TIMEOUT, reply_handler=reply_handler, error_handler=error_handler)
+        return fut
+
     def isConnected(self, profile_key="@DEFAULT@"):
         loop = asyncio.get_running_loop()
         fut = loop.create_future()

--- a/sat_frontends/bridge/pb.py	Tue Oct 29 20:24:29 2019 +0100
+++ b/sat_frontends/bridge/pb.py	Tue Oct 29 20:38:39 2019 +0100
@@ -375,6 +375,22 @@
             errback = self._generic_errback
         d.addErrback(errback)
 
+    def imageCheck(self, arg_0, callback=None, errback=None):
+        d = self.root.callRemote("imageCheck", arg_0)
+        if callback is not None:
+            d.addCallback(callback)
+        if errback is None:
+            errback = self._generic_errback
+        d.addErrback(errback)
+
+    def imageResize(self, image_path, width, height, callback=None, errback=None):
+        d = self.root.callRemote("imageResize", image_path, width, height)
+        if callback is not None:
+            d.addCallback(callback)
+        if errback is None:
+            errback = self._generic_errback
+        d.addErrback(errback)
+
     def isConnected(self, profile_key="@DEFAULT@", callback=None, errback=None):
         d = self.root.callRemote("isConnected", profile_key)
         if callback is not None:
@@ -773,6 +789,16 @@
         d.addErrback(self._errback)
         return d.asFuture(asyncio.get_event_loop())
 
+    def imageCheck(self, arg_0):
+        d = self.root.callRemote("imageCheck", arg_0)
+        d.addErrback(self._errback)
+        return d.asFuture(asyncio.get_event_loop())
+
+    def imageResize(self, image_path, width, height):
+        d = self.root.callRemote("imageResize", image_path, width, height)
+        d.addErrback(self._errback)
+        return d.asFuture(asyncio.get_event_loop())
+
     def isConnected(self, profile_key="@DEFAULT@"):
         d = self.root.callRemote("isConnected", profile_key)
         d.addErrback(self._errback)