[Assets] Added a new KeepReferences flag to AssetCloner

sources/assets/Xenko.Core.Assets.Tests/TestAssetCloner.cs

@@ -11,6 +11,15 @@
 
 namespace Xenko.Core.Assets.Tests
 {
+    [DataContract, ReferenceSerializer, DataSerializerGlobal(typeof(ReferenceSerializer<TestContent>), Profile = "Content")]
+    public class TestContent { }
+
+    [DataContract("TestAssetClonerContent")]
+    public class TestAssetClonerContent
+    {
+        public TestContent Content;
+    }
+
     [DataContract("TestAssetClonerObject")]
     public class TestAssetClonerObject
     {
@@ -38,6 +47,14 @@ public class TestObjectReference
 
     public class TestAssetCloner
     {
+        [Fact]
+        public void TestAssetClonerContent()
+        {
+            var obj1 = new TestAssetClonerContent { Content = new TestContent() };
+            var obj2 = AssetCloner.Clone(obj1, AssetClonerFlags.KeepReferences);
+            Assert.Equal(obj1.Content, obj2.Content);
+        }
+
         [Fact]
         public void TestHash()
         {

sources/assets/Xenko.Core.Assets/AssetCloner.cs

@@ -31,6 +31,7 @@ public class AssetCloner
         private Dictionary<Guid, Guid> cloningIdRemapping;
         public static SerializerSelector ClonerSelector { get; internal set; }
         public static PropertyKey<List<object>> InvariantObjectListProperty = new PropertyKey<List<object>>("InvariantObjectList", typeof(AssetCloner));
+        private List<object> cloneReferences;
 
         static AssetCloner()
         {
@@ -62,11 +63,8 @@ private AssetCloner(object value, AssetClonerFlags flags, IEnumerable<IIdentifia
                 var stream = new MemoryStream();
                 var writer = new BinarySerializationWriter(stream);
                 writer.Context.SerializerSelector = ClonerSelector;
-                var refFlag = (flags & AssetClonerFlags.ReferenceAsNull) != 0
-                    ? ContentSerializerContext.AttachedReferenceSerialization.AsNull
-                    : ContentSerializerContext.AttachedReferenceSerialization.AsSerializableVersion;
                 writer.Context.Set(InvariantObjectListProperty, invariantObjects);
-                writer.Context.Set(ContentSerializerContext.SerializeAttachedReferenceProperty, refFlag);
+                writer.Context.Set(ContentSerializerContext.SerializeAttachedReferenceProperty, GenerateContentSerializerFlags(flags));
                 if (externalIdentifiables != null)
                 {
                     this.externalIdentifiables = new Dictionary<Guid, IIdentifiable>();
@@ -80,6 +78,9 @@ private AssetCloner(object value, AssetClonerFlags flags, IEnumerable<IIdentifia
                 writer.SerializeExtended(value, ArchiveMode.Serialize);
                 writer.Flush();
 
+                if ((flags & AssetClonerFlags.KeepReferences) != 0)
+                    cloneReferences = writer.Context.Get(ReferenceSerializer.CloneReferences);
+
                 // Retrieve back all object references that were discovered while serializing
                 // They will be used layer by OnObjectDeserialized when cloning ShadowObject datas
                 var objectRefs = writer.Context.Get(MemberSerializer.ObjectSerializeReferences);
@@ -113,18 +114,17 @@ private object Clone([NotNull] out Dictionary<Guid, Guid> idRemapping)
                 stream.Position = 0;
                 var reader = new BinarySerializationReader(stream);
                 reader.Context.SerializerSelector = ClonerSelector;
-                var refFlag = (flags & AssetClonerFlags.ReferenceAsNull) != 0
-                    ? ContentSerializerContext.AttachedReferenceSerialization.AsNull
-                    : ContentSerializerContext.AttachedReferenceSerialization.AsSerializableVersion;
                 reader.Context.Set(InvariantObjectListProperty, invariantObjects);
-                reader.Context.Set(ContentSerializerContext.SerializeAttachedReferenceProperty, refFlag);
+                reader.Context.Set(ContentSerializerContext.SerializeAttachedReferenceProperty, GenerateContentSerializerFlags(flags));
                 if (externalIdentifiables != null)
                 {
                     if ((flags & AssetClonerFlags.ClearExternalReferences) != 0)
                         externalIdentifiables.Clear();
 
                     reader.Context.Set(MemberSerializer.ExternalIdentifiables, externalIdentifiables);
                 }
+                if ((flags & AssetClonerFlags.KeepReferences) != 0)
+                    reader.Context.Set(ReferenceSerializer.CloneReferences, cloneReferences);
                 reader.Context.Set(MemberSerializer.ObjectDeserializeCallback, OnObjectDeserialized);
                 object newObject = null;
                 reader.SerializeExtended(ref newObject, ArchiveMode.Deserialize);
@@ -317,6 +317,18 @@ internal static ObjectId ComputeHash(object asset, AssetClonerFlags flags = Asse
             return result;
         }
 
+        private static ContentSerializerContext.AttachedReferenceSerialization GenerateContentSerializerFlags(AssetClonerFlags flags)
+        {
+            ContentSerializerContext.AttachedReferenceSerialization refFlag;
+            if ((flags & AssetClonerFlags.ReferenceAsNull) != 0)
+                refFlag = ContentSerializerContext.AttachedReferenceSerialization.AsNull;
+            else if ((flags & AssetClonerFlags.KeepReferences) != 0)
+                refFlag = ContentSerializerContext.AttachedReferenceSerialization.Clone;
+            else
+                refFlag = ContentSerializerContext.AttachedReferenceSerialization.AsSerializableVersion;
+            return refFlag;
+        }
+
         private class UnloadableCloneSerializer<T> : DataSerializer<T> where T : class, IUnloadable
         {
             private DataSerializer parentSerializer;

sources/assets/Xenko.Core.Assets/AssetClonerFlags.cs

@@ -40,5 +40,10 @@ public enum AssetClonerFlags
         /// Clears any external references in the cloned object
         /// </summary>
         ClearExternalReferences = 16,
+
+        /// <summary>
+        /// Attached references will be kept as is
+        /// </summary>
+        KeepReferences = 32,
     }
 }

sources/core/Xenko.Core.Serialization/Serialization/Contents/ContentSerializerContext.cs

@@ -22,6 +22,7 @@ public enum AttachedReferenceSerialization
             Unset,
             AsSerializableVersion,
             AsNull,
+            Clone,
         }
 
         public static PropertyKey<ContentSerializerContext> ContentSerializerContextProperty = new PropertyKey<ContentSerializerContext>("ContentSerializerContext", typeof(ContentSerializerContext));

sources/core/Xenko.Core.Serialization/Serialization/Contents/ReferenceSerializer.cs

@@ -2,11 +2,17 @@
 // Distributed under the MIT license. See the LICENSE.md file in the project root for more information.
 
 using System;
+using System.Collections.Generic;
 using Xenko.Core.Assets;
 using Xenko.Core.Reflection;
 
 namespace Xenko.Core.Serialization.Contents
 {
+    public static class ReferenceSerializer
+    {
+        public static readonly PropertyKey<List<object>> CloneReferences = new PropertyKey<List<object>>("CloneReferences", typeof(SerializerExtensions), DefaultValueMetadata.Delegate(delegate { return new List<object>(); }));
+    }
+
     /// <summary>
     /// Serialize object with its underlying Id and Location, and use <see cref="ContentManager"/> to generate a separate chunk.
     /// </summary>
@@ -95,6 +101,19 @@ public override void Serialize(ref T obj, ArchiveMode mode, SerializationStream
                     obj = (T)AttachedReferenceManager.CreateProxyObject(type, id, url);
                 }
             }
+            else if (referenceSerialization == ContentSerializerContext.AttachedReferenceSerialization.Clone)
+            {
+                var cloneReferences = stream.Context.Get(ReferenceSerializer.CloneReferences);
+                if (mode == ArchiveMode.Serialize)
+                {
+                    stream.Write(cloneReferences.Count);
+                    cloneReferences.Add(obj);
+                }
+                else
+                {
+                    obj = (T)cloneReferences[stream.ReadInt32()];
+                }
+            }
             else
             {
                 // This case will happen when serializing build engine command hashes: we still want Location to still be written