Add XamlObjectCreationFactory to improve the performance of XAML creation of objects

src/Microsoft.DotNet.Wpf/src/System.Xaml/System/Xaml/Schema/XamlObjectCreationFactory.cs

@@ -0,0 +1,52 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Concurrent;
+
+namespace System.Xaml.Schema
+{
+    public static class XamlObjectCreationFactory
+    {
+        public static void RegisterCreator<T>(Func<T> creator)
+        {
+            if (creator == null) throw new ArgumentNullException(nameof(creator));
+            RegisterCreator(typeof(T), () => creator());
+        }
+
+        public static void RegisterCreator(Type type, Func<object> creator)
+        {
+            if (type == null) throw new ArgumentNullException(nameof(type));
+            s_xamlObjectCreatorDictionary[type] = creator ?? throw new ArgumentNullException(nameof(creator));
+
+            HasBeenRegister = true;
+        }
+
+        public static void RegisterTypeCreator(Func<Type, Func<object>> typeCreator)
+        {
+            _typeCreator = typeCreator;
+            HasBeenRegister = true;
+        }
+
+        internal static bool HasBeenRegister { get; private set; }
+
+        private static Func<Type, Func<object>> _typeCreator;
+
+        internal static bool TryGetCreator(Type type, out Func<object> creator)
+        {
+            if (_typeCreator != null)
+            {
+               creator = _typeCreator(type);
+               if (creator != null)
+               {
+                  return true;
+               }
+            }
+
+            return s_xamlObjectCreatorDictionary.TryGetValue(type, out creator);
+        }
+
+        private static readonly ConcurrentDictionary<Type, Func<object>> s_xamlObjectCreatorDictionary =
+            new ConcurrentDictionary<Type, Func<object>>();
+    }
+}

src/Microsoft.DotNet.Wpf/src/System.Xaml/System/Xaml/Schema/XamlTypeInvoker.cs

@@ -21,7 +21,7 @@ public class XamlTypeInvoker
         internal MethodInfo EnumeratorMethod { get; set; }
         private XamlType _xamlType;
 
-        private Action<object> _constructorDelegate;
+        private Func<object> _instanceCreatorDelegate;
 
         private ThreeValuedBool _isPublic;
 
@@ -290,20 +290,13 @@ public static object CreateInstance(XamlTypeInvoker type)
                 {
                     return null;
                 }
-                object inst = CallCtorDelegate(type);
+                object inst = type._instanceCreatorDelegate();
                 return inst;
             }
 
 #if TARGETTING35SP1
 #else
 #endif
-            private static object CallCtorDelegate(XamlTypeInvoker type)
-            {
-                object inst = FormatterServices.GetUninitializedObject(type._xamlType.UnderlyingType);
-                InvokeDelegate(type._constructorDelegate, inst);
-                return inst;
-            }
-
             private static void InvokeDelegate(Action<object> action, object argument)
             {
                 action.Invoke(argument);
@@ -315,10 +308,21 @@ private static void InvokeDelegate(Action<object> action, object argument)
             // returns true if a delegate is available, false if not
             private static bool EnsureConstructorDelegate(XamlTypeInvoker type)
             {
-                if (type._constructorDelegate != null)
+                if (type._instanceCreatorDelegate != null)
                 {
                     return true;
                 }
+                Type underlyingType = null;
+                if (XamlObjectCreationFactory.HasBeenRegister)
+                {
+                    underlyingType = type._xamlType.UnderlyingType.UnderlyingSystemType;
+                    if (XamlObjectCreationFactory.TryGetCreator(underlyingType, out Func<object> creator))
+                    {
+                        type._instanceCreatorDelegate = creator;
+                        return true;
+                    }
+                }
+
                 if (!type.IsPublic)
                 {
                     return false;
@@ -333,7 +337,8 @@ private static bool EnsureConstructorDelegate(XamlTypeInvoker type)
                     return false;
                 }
 
-                Type underlyingType = type._xamlType.UnderlyingType.UnderlyingSystemType;
+                underlyingType ??= type._xamlType.UnderlyingType.UnderlyingSystemType;
+
                 // Look up public ctors only, for equivalence with Activator.CreateInstance
                 ConstructorInfo tConstInfo = underlyingType.GetConstructor(Type.EmptyTypes);
                 if (tConstInfo == null)
@@ -352,9 +357,14 @@ private static bool EnsureConstructorDelegate(XamlTypeInvoker type)
                 }
                 IntPtr constPtr = tConstInfo.MethodHandle.GetFunctionPointer();
                 // This requires Reflection Permission
-                Action<object> ctorDelegate = ctorDelegate =
+                Action<object> ctorDelegate = 
                     (Action<object>)s_actionCtor.Invoke(new object[] { null, constPtr });
-                type._constructorDelegate = ctorDelegate;
+                type._instanceCreatorDelegate = () =>
+                {
+                    object inst = FormatterServices.GetUninitializedObject(type._xamlType.UnderlyingType);
+                    InvokeDelegate(ctorDelegate, inst);
+                    return inst;
+                };
                 return true;
             }
         }

src/Microsoft.DotNet.Wpf/src/System.Xaml/ref/System.Xaml.cs

@@ -1106,4 +1106,11 @@ public XamlValueConverter(System.Type converterType, System.Xaml.XamlType target
         public static bool operator !=(System.Xaml.Schema.XamlValueConverter<TConverterBase> converter1, System.Xaml.Schema.XamlValueConverter<TConverterBase> converter2) { throw null; }
         public override string ToString() { throw null; }
     }
+
+    public static class XamlObjectCreationFactory
+    {
+        public static void RegisterCreator<T>(Func<T> creator) { }
+        public static void RegisterCreator(Type type, Func<object> creator) { }
+        public static void RegisterTypeCreator(Func<Type, Func<object>> typeCreator) { }
+    }
 }