[GameStudio] FIX for #1913 - Make "Add Component" button functional with multiple entities selected

sources/editor/Stride.Assets.Presentation/NodePresenters/Keys/EntityHierarchyData.cs

@@ -12,10 +12,9 @@ namespace Stride.Assets.Presentation.NodePresenters.Keys
     public static class EntityHierarchyData
     {
         public const string EntityComponentAvailableTypes = nameof(EntityComponentAvailableTypes);
-        public static readonly PropertyKey<IEnumerable<AbstractNodeType>> EntityComponentAvailableTypesKey = new PropertyKey<IEnumerable<AbstractNodeType>>(EntityComponentAvailableTypes, typeof(EntityHierarchyData), new PropertyCombinerMetadata(AbstractNodeEntryData.CombineProperty));
-
+        public static readonly PropertyKey<IEnumerable<AbstractNodeType>> EntityComponentAvailableTypesKey = new PropertyKey<IEnumerable<AbstractNodeType>>(EntityComponentAvailableTypes, typeof(EntityHierarchyData), new PropertyCombinerMetadata(AbstractNodeEntryData.CombineProperties<AbstractNodeType>));
 
         public const string EntityComponentAvailableTypeGroups = nameof(EntityComponentAvailableTypeGroups);
-        public static readonly PropertyKey<IEnumerable<AbstractNodeTypeGroup>> EntityComponentAvailableTypeGroupsKey = new PropertyKey<IEnumerable<AbstractNodeTypeGroup>>(EntityComponentAvailableTypeGroups, typeof(EntityHierarchyData), new PropertyCombinerMetadata(AbstractNodeEntryData.CombineProperty));
+        public static readonly PropertyKey<IEnumerable<AbstractNodeTypeGroup>> EntityComponentAvailableTypeGroupsKey = new PropertyKey<IEnumerable<AbstractNodeTypeGroup>>(EntityComponentAvailableTypeGroups, typeof(EntityHierarchyData), new PropertyCombinerMetadata(AbstractNodeEntryData.CombineProperties<AbstractNodeTypeGroup>));
     }
 }

sources/editor/Stride.Core.Assets.Editor/Quantum/NodePresenters/Keys/AbstractNodeEntryData.cs

@@ -10,8 +10,9 @@ namespace Stride.Core.Assets.Editor.Quantum.NodePresenters.Keys
     public static class AbstractNodeEntryData
     {
         public const string AbstractNodeMatchingEntries = nameof(AbstractNodeMatchingEntries);
-        public static readonly PropertyKey<IEnumerable<AbstractNodeEntry>> Key = new PropertyKey<IEnumerable<AbstractNodeEntry>>(AbstractNodeMatchingEntries, typeof(AbstractNodeEntryData), new PropertyCombinerMetadata(CombineProperty));
-
+        public static readonly PropertyKey<IEnumerable<AbstractNodeEntry>> Key = new PropertyKey<IEnumerable<AbstractNodeEntry>>(AbstractNodeMatchingEntries, typeof(AbstractNodeEntryData), new PropertyCombinerMetadata(CombineProperties<AbstractNodeEntry>));
+
+        [Obsolete("Use the generic version of CombineProperties instead, which allows to specify the type of the properties to combine. This method is kept for backward compatibility, but it is recommended to use the generic version instead.")]
         public static object CombineProperty(IEnumerable<object> properties)
         {
             var result = new HashSet<AbstractNodeEntry>();
@@ -25,5 +26,29 @@ public static object CombineProperty(IEnumerable<object> properties)
             }
             return result.OrderBy(x => x.Order).ThenBy(x => x.DisplayValue);
         }
+
+        /// <summary>
+        /// Combines the properties of type <typeparamref name="TAbstractNodeEntry"/> by intersecting them and ordering them by their order and display value.
+        /// This method allows to specify the type of the properties to combine, which can be useful when the properties are of a more specific type than <see cref="AbstractNodeEntry"/>.
+        /// E.g. WPF cannot coerce IEnumerable&lt;AbstractNodeEntry&gt; into IEnumerable&lt;AbstractNodeType&gt; since covariance only goes the other direction — you can widen to AbstractNodeEntry, not narrow back to AbstractNodeType.
+        /// In those cases, the binding would silently fall back to the DependencyProperty's default value: null.
+        /// </summary>
+        /// <param name="properties"></param>
+        /// <typeparam name="TAbstractNodeEntry"></typeparam>
+        /// <returns></returns>
+        public static IEnumerable<TAbstractNodeEntry> CombineProperties<TAbstractNodeEntry>(IEnumerable<object> properties)
+            where TAbstractNodeEntry : AbstractNodeEntry
+        {
+            var result = new HashSet<TAbstractNodeEntry>();
+            var hashSets = new List<HashSet<TAbstractNodeEntry>>();
+            hashSets.AddRange(properties.Cast<IEnumerable<TAbstractNodeEntry>>().Select(x => new HashSet<TAbstractNodeEntry>(x)));
+            result = hashSets[0];
+            // We display only component types that are available for all entities
+            for (var i = 1; i < hashSets.Count; ++i)
+            {
+                result.IntersectWith(hashSets[i]);
+            }
+            return result.OrderBy(x => x.Order).ThenBy(x => x.DisplayValue);
+        }
     }
 }