diff --git a/ckan/controllers/package.py b/ckan/controllers/package.py
index c7082617732..4106f7ee611 100644
--- a/ckan/controllers/package.py
+++ b/ckan/controllers/package.py
@@ -30,6 +30,7 @@
 import ckan.rating
 import ckan.misc
 import ckan.lib.accept as accept
+import ckan.lib.helpers as helpers
 from home import CACHE_PARAMETERS
 
 from ckan.lib.plugins import lookup_package_plugin
@@ -1335,15 +1336,18 @@ def resource_datapreview(self, id, resource_id):
                                                      {'id': resource_id})
             c.package = get_action('package_show')(context, {'id': id})
 
+            data_dict = {'resource': c.resource, 'package': c.package}
+            data_dict = helpers._add_whether_on_same_domain(data_dict)
+
             plugins = ckanplugins.PluginImplementations(ckanplugins.IResourcePreview)
-            plugins_that_can_preview = [p for p in plugins if p.can_preview(c.resource)]
+            plugins_that_can_preview = [p for p in plugins if p.can_preview(data_dict)]
             if len(plugins_that_can_preview) == 0:
                 abort(409, _('No preview has been defined.'))
             if len(plugins_that_can_preview) > 1:
                 log.warn('Multiple previews are possible. {0}'.format(plugins_that_can_preview))
 
             plugin = plugins_that_can_preview[0]
-            plugin.setup_template_variables(context, {'resource': c.resource, 'package': c.package})
+            plugin.setup_template_variables(context, data_dict)
 
             c.resource_json = json.dumps(c.resource)
 
diff --git a/ckan/lib/helpers.py b/ckan/lib/helpers.py
index ff411d96deb..859658eb3e3 100644
--- a/ckan/lib/helpers.py
+++ b/ckan/lib/helpers.py
@@ -1265,23 +1265,29 @@ def format_resource_items(items):
     return sorted(output, key=lambda x: x[0])
 
 
-def _can_be_previewed(resource):
-    '''
-    Determines whether there is an extension that can preview the resource.
+def _add_whether_on_same_domain(data_dict):
+    ''' sets the ``on_same_domain`` flag to a resource dictionary
     '''
     # compare CKAN domain and resource URL
     import ckan.plugins.toolkit as toolkit
     ckan_domain = toolkit.request.environ['HTTP_HOST'].lower()
     request_protocol = toolkit.request.environ['SERVER_PROTOCOL'].lower()
 
-    parsed = urlparse.urlparse(resource['url'])
+    parsed = urlparse.urlparse(data_dict['resource']['url'])
     resource_domain = (parsed.hostname + ':' + str(parsed.port)).lower()
 
-    resource['on_same_domain'] = (ckan_domain == resource_domain
+    data_dict['resource']['on_same_domain'] = (ckan_domain == resource_domain
             and parsed.scheme.lower() in request_protocol)
+    return data_dict
 
+
+def _can_be_previewed(data_dict):
+    '''
+    Determines whether there is an extension that can preview the resource.
+    '''
+    data_dict = _add_whether_on_same_domain(data_dict)
     plugins = ckanplugins.PluginImplementations(ckanplugins.IResourcePreview)
-    return any(plugin.can_preview(resource) for plugin in plugins)
+    return any(plugin.can_preview(data_dict) for plugin in plugins)
 
 
 def resource_preview(resource, pkg_id):
@@ -1302,7 +1308,9 @@ def resource_preview(resource, pkg_id):
     directly = False
     url = ''
 
-    if _can_be_previewed(resource):
+    data_dict = {'resource': resource, 'package': None}
+
+    if _can_be_previewed(data_dict):
         url = url = url_for(controller='package', action='resource_datapreview',
             resource_id=resource['id'], id=pkg_id, qualified=True)
     elif format_lower in DIRECT_EMBEDS:
diff --git a/ckan/plugins/interfaces.py b/ckan/plugins/interfaces.py
index b067b41b181..fcaeea39d0c 100644
--- a/ckan/plugins/interfaces.py
+++ b/ckan/plugins/interfaces.py
@@ -198,9 +198,10 @@ class IResourcePreview(Interface):
     create custom previews for example for xml files.
     """
 
-    def can_preview(self, resource):
+    def can_preview(self, data_dict):
         '''
-        Return True if the extension can preview the resource.
+        Return True if the extension can preview the resource. The ``data_dict``
+        contains the resource and the package.
 
         Make sure you also make sure to ckeck the ``on_same_domain`` value of the
         resource or the url if your preview requires the resource to be on
@@ -210,6 +211,7 @@ def can_preview(self, resource):
     def setup_template_variables(self, context, data_dict):
         '''
         Add variables to c just prior to the template being rendered.
+        The ``data_dict`` contains the resource and the package.
 
         Change the url to a proxied domain if necessary.
         '''