Add Start Canvas

app/services/manifest_builder/manifest_service_locator.rb

@@ -78,6 +78,13 @@ def record_property_builder
         ManifestBuilder::RecordPropertyBuilder
       end
 
+      def start_canvas_builder
+        IIIFManifest::ManifestServiceLocator::InjectedFactory.new(
+          ::ManifestBuilder::StartCanvasBuilder,
+          canvas_builder: canvas_builder
+        )
+      end
+
       ##
       # Objects are either in 'manifests' or 'collections' depending on if the
       # child resource is a IIIF::Manifest or a IIIF::Collection. This special
@@ -109,7 +116,8 @@ def sequence_builder
         IIIFManifest::ManifestServiceLocator::InjectedFactory.new(
           ::ManifestBuilder::SequenceBuilder, # This whole method is overridden just for this constant.
           canvas_builder_factory: canvas_builder_factory,
-          sequence_factory: sequence_factory
+          sequence_factory: sequence_factory,
+          start_canvas_builder: start_canvas_builder
         )
       end
 

app/services/manifest_builder/sequence_builder.rb

@@ -1,8 +1,15 @@
 # frozen_string_literal: true
 class ManifestBuilder
   class SequenceBuilder < IIIFManifest::ManifestBuilder::SequenceBuilder
+    attr_reader :start_canvas_builder
+    def initialize(work, canvas_builder_factory:, sequence_factory:, start_canvas_builder:)
+      super(work, canvas_builder_factory: canvas_builder_factory, sequence_factory: sequence_factory)
+      @start_canvas_builder = start_canvas_builder
+    end
+
     def apply(manifest)
       sequence["viewingHint"] = manifest["viewingHint"]
+      start_canvas_builder.new(work).apply(sequence)
       super
     end
   end

app/services/manifest_builder/start_canvas_builder.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+class ManifestBuilder
+  class StartCanvasBuilder
+    attr_reader :resource, :canvas_builder
+
+    # @param [Valhalla::Resource] resource the Resource being viewed
+    def initialize(resource, canvas_builder:)
+      @resource = resource
+      @canvas_builder = canvas_builder
+    end
+
+    def apply(manifest)
+      return manifest unless start_canvas_id && file_set
+      manifest['startCanvas'] = path
+      manifest
+    end
+
+    private
+
+      def path
+        canvas_builder.new(file_set, resource).path
+      end
+
+      def file_set
+        @file_set ||= query_service.find_by(id: start_canvas_id)
+      rescue Valkyrie::Persistence::ObjectNotFoundError
+        nil
+      end
+
+      def query_service
+        Valkyrie.config.metadata_adapter.query_service
+      end
+
+      def start_canvas_id
+        Array.wrap(resource.resource.try(:start_canvas)).first
+      end
+  end
+end

spec/services/manifest_builder_spec.rb

@@ -29,6 +29,7 @@
   let(:metadata_adapter) { Valkyrie.config.metadata_adapter }
   let(:query_service) { metadata_adapter.query_service }
   let(:file) { fixture_file_upload('files/example.tif', 'image/tiff') }
+  let(:start_canvas) { nil }
 
   def logical_structure(file_set_id)
     [
@@ -61,7 +62,7 @@ def logical_structure(file_set_id)
       file_set.local_identifier = "p79409x97p"
       metadata_adapter.persister.save(resource: file_set)
       change_set = ScannedResourceChangeSet.new(output)
-      change_set.validate(logical_structure: logical_structure(file_set_id))
+      change_set.validate(logical_structure: logical_structure(file_set_id), start_canvas: start_canvas || file_set_id)
       change_set.sync
       change_set_persister.save(change_set: change_set)
     end
@@ -92,6 +93,7 @@ def logical_structure(file_set_id)
       expect(output["thumbnail"]).not_to be_blank
       expect(output["thumbnail"]["@id"]).to eq "#{first_image['resource']['service']['@id']}/full/!200,150/0/default.jpg"
       expect(output["thumbnail"]["service"]["@id"]).to eq first_image["resource"]["service"]["@id"]
+      expect(output["sequences"][0]["startCanvas"]).to eq canvas_id
     end
 
     context "when there's no derivative_file" do
@@ -129,6 +131,15 @@ def logical_structure(file_set_id)
       end
     end
 
+    context "when a start_canvas doesn't exist" do
+      let(:start_canvas) { Valkyrie::ID.new("blablabla") }
+      it "doesn't set a startCanvas" do
+        output = manifest_builder.build
+        first_sequence = output["sequences"][0]
+        expect(first_sequence["startCanvas"]).to be_nil
+      end
+    end
+
     context "when in staging" do
       it "generates cantaloupe links" do
         allow(Rails.env).to receive(:development?).and_return(false)