diff -r 72293e510f03 -r 240417d006df src/pyams_default_theme/root/opengraph.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/pyams_default_theme/root/opengraph.py	Wed Jan 16 18:56:36 2019 +0100
@@ -0,0 +1,107 @@
+#
+# Copyright (c) 2008-2019 Thierry Florac <tflorac AT ulthar.net>
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+
+__docformat__ = 'restructuredtext'
+
+from zope.interface import Interface
+
+from pyams_content.component.illustration import IIllustration
+from pyams_content.features.share.interfaces import ISocialShareInfo
+from pyams_content.root import ISiteRoot
+from pyams_file.interfaces import IThumbnails
+from pyams_i18n.interfaces import II18n, INegotiator
+from pyams_skin.interfaces.configuration import IConfiguration
+from pyams_skin.interfaces.metas import IHTMLContentMetas
+from pyams_skin.layer import IPyAMSUserLayer
+from pyams_skin.metas import ContentMeta, PropertyMeta, SchemaMeta
+from pyams_utils.adapter import ContextRequestViewAdapter, adapter_config
+from pyams_utils.registry import get_utility
+from pyams_utils.url import absolute_url, canonical_url
+
+
+@adapter_config(name='opengraph', context=(ISiteRoot, IPyAMSUserLayer, Interface), provides=IHTMLContentMetas)
+class SiteRootOpengraphMetasAdapter(ContextRequestViewAdapter):
+    """Opengraph site root metas adapter"""
+
+    order = 15
+
+    def get_metas(self):
+        context = self.context
+        request = self.request
+        i18n = II18n(context)
+        negotiator = get_utility(INegotiator)
+        lang = negotiator.server_language
+
+        configuration = IConfiguration(context)
+        title = configuration.title
+        description = configuration.description
+
+        # main properties
+        yield PropertyMeta('og:type', 'website')
+        if title:
+            yield PropertyMeta('og:title', title)
+        if description:
+            yield PropertyMeta('og:description', description)
+
+        # URL and site name
+        yield PropertyMeta('og:url', canonical_url(context, request))
+        yield PropertyMeta('og:site_name', title)
+
+        # illustration properties
+        registry = request.registry
+        thumbnail = None
+        illustration = registry.queryAdapter(context, IIllustration, name='link')
+        if (illustration is None) or (not illustration.has_data()):
+            illustration = registry.queryAdapter(context, IIllustration)
+        if (illustration is not None) and illustration.has_data():
+            data = II18n(illustration).query_attribute('data', lang=lang, request=request)
+            thumbnail = IThumbnails(data).get_thumbnail('800x600')
+            yield PropertyMeta('og:image', absolute_url(thumbnail, request))
+            if request.scheme == 'https':
+                yield PropertyMeta('og:image:secure_url', absolute_url(thumbnail, request))
+            else:
+                yield PropertyMeta('og:image:url', absolute_url(thumbnail, request))
+            yield PropertyMeta('og:image:type', thumbnail.content_type)
+            image_size = thumbnail.image_size
+            yield PropertyMeta('og:image:width', image_size[0])
+            yield PropertyMeta('og:image:height', image_size[1])
+            alt = II18n(illustration).query_attribute('alt_title', lang=lang, request=request)
+            if alt:
+                yield PropertyMeta('og:image:alt', alt)
+
+        # locales properties
+        yield PropertyMeta('og:locale', lang)
+        for other_lang in negotiator.offered_languages or ():
+            if other_lang != lang:
+                yield PropertyMeta('og:locale:alternate', other_lang)
+
+        # twitter properties
+        share_info = ISocialShareInfo(request.root, None)
+        if (share_info is not None) and share_info.twitter_account:
+            yield ContentMeta('twitter:site', share_info.twitter_account)
+            yield ContentMeta('twitter:creator', share_info.twitter_creator_account or share_info.twitter_account)
+        if illustration is not None:
+            yield ContentMeta('twitter:card', 'summary_large_image')
+        else:
+            yield ContentMeta('twitter:card', 'summary')
+        if title:
+            yield ContentMeta('twitter:title', title)
+        if description:
+            yield ContentMeta('twitter:description', description)
+
+        # Schema.org properties
+        if title:
+            yield SchemaMeta('name', title)
+        if description:
+            yield SchemaMeta('description', description)
+        if thumbnail is not None:
+            yield SchemaMeta('image', absolute_url(thumbnail, request))