Fix missing focalPoint in ActivityPub JSON (#6609)

app/serializers/activitypub/note_serializer.rb

@@ -90,6 +90,7 @@ class ActivityPub::NoteSerializer < ActiveModel::Serializer
     include RoutingHelper
 
     attributes :type, :media_type, :url, :name
+    attribute :focal_point, if: :focal_point?
 
     def type
       'Document'
@@ -106,6 +107,14 @@ class ActivityPub::NoteSerializer < ActiveModel::Serializer
     def url
       object.local? ? full_asset_url(object.file.url(:original, false)) : object.remote_url
     end
+
+    def focal_point?
+      object.file.meta.is_a?(Hash) && object.file.meta['focus'].is_a?(Hash)
+    end
+
+    def focal_point
+      [object.file.meta['focus']['x'], object.file.meta['focus']['y']]
+    end
   end
 
   class MentionSerializer < ActiveModel::Serializer

spec/lib/activitypub/activity/create_spec.rb

@@ -202,7 +202,7 @@ RSpec.describe ActivityPub::Activity::Create do
           attachment: [
             {
               type: 'Document',
-              mime_type: 'image/png',
+              mediaType: 'image/png',
               url: 'http://example.com/attachment.png',
             },
           ],
@@ -217,6 +217,31 @@ RSpec.describe ActivityPub::Activity::Create do
       end
     end
 
+    context 'with media attachments with focal points' do
+      let(:object_json) do
+        {
+          id: [ActivityPub::TagManager.instance.uri_for(sender), '#bar'].join,
+          type: 'Note',
+          content: 'Lorem ipsum',
+          attachment: [
+            {
+              type: 'Document',
+              mediaType: 'image/png',
+              url: 'http://example.com/attachment.png',
+              focalPoint: [0.5, -0.7],
+            },
+          ],
+        }
+      end
+
+      it 'creates status' do
+        status = sender.statuses.first
+
+        expect(status).to_not be_nil
+        expect(status.media_attachments.map(&:focus)).to include('0.5,-0.7')
+      end
+    end
+
     context 'with media attachments missing url' do
       let(:object_json) do
         {
@@ -226,7 +251,7 @@ RSpec.describe ActivityPub::Activity::Create do
           attachment: [
             {
               type: 'Document',
-              mime_type: 'image/png',
+              mediaType: 'image/png',
             },
           ],
         }