chore: Address review comments on DependencyPropertyHelper PR

src/Uno.UI.RuntimeTests/Tests/Uno_Helpers/Given_DependencyPropertyHelper.cs

@@ -122,7 +122,7 @@ public void When_GetPropertyType()
 		var property = TestClass.TestProperty;
 
 		// Act
-		var propertyType = DependencyPropertyHelper.GetValueType(property);
+		var propertyType = DependencyPropertyHelper.GetPropertyType(property);
 
 		// Assert
 		propertyType.Should().Be(typeof(string));

src/Uno.UI/UI/Xaml/DependencyProperty.Dictionary.PropertiesRegistry.cs

@@ -18,12 +18,18 @@ namespace Microsoft.UI.Xaml
 {
 	public sealed partial class DependencyProperty
 	{
-		private class DependencyPropertyRegistry
+		internal class DependencyPropertyRegistry
 		{
+			public static DependencyPropertyRegistry Instance { get; } = new DependencyPropertyRegistry();
+
 			// This dictionary has a single static instance that is kept for the lifetime of the whole app.
 			// So we don't use pooling to not cause pool exhaustion by renting without returning.
 			private readonly HashtableEx _entries = new HashtableEx(FastTypeComparer.Default, usePooling: false);
 
+			private DependencyPropertyRegistry()
+			{
+			}
+
 			internal bool TryGetValue(Type type, string name, out DependencyProperty? result)
 			{
 				if (TryGetTypeTable(type, out var typeTable))
@@ -39,8 +45,6 @@ internal bool TryGetValue(Type type, string name, out DependencyProperty? result
 				return false;
 			}
 
-			internal void Clear() => _entries.Clear();
-
 			internal void Add(Type type, string name, DependencyProperty property)
 			{
 				if (!TryGetTypeTable(type, out var typeTable))
@@ -63,7 +67,7 @@ internal void AppendPropertiesForType(Type type, List<DependencyProperty> proper
 				}
 			}
 
-			private bool TryGetTypeTable(Type type, out HashtableEx? table)
+			internal bool TryGetTypeTable(Type type, out HashtableEx? table)
 			{
 				if (_entries.TryGetValue(type, out var dictionaryObject))
 				{

src/Uno.UI/UI/Xaml/DependencyProperty.cs

@@ -36,7 +36,7 @@ namespace Microsoft.UI.Xaml
 	[DebuggerDisplay("Name={Name}, Type={Type.FullName}, Owner={OwnerType.FullName}")]
 	public sealed partial class DependencyProperty
 	{
-		private readonly static DependencyPropertyRegistry _registry = new DependencyPropertyRegistry();
+		private readonly static DependencyPropertyRegistry _registry = DependencyPropertyRegistry.Instance;
 
 		private readonly static TypeToPropertiesDictionary _getPropertiesForType = new TypeToPropertiesDictionary();
 		private readonly static NameToPropertyDictionary _getPropertyCache = new NameToPropertyDictionary();
@@ -416,17 +416,6 @@ internal static DependencyProperty[] GetFrameworkPropertiesForType(Type type, Fr
 			return result;
 		}
 
-		/// <summary>
-		/// Clears all the property registrations, when used in unit tests.
-		/// </summary>
-		internal static void ClearRegistry()
-		{
-			_registry.Clear();
-			_getPropertiesForType.Clear();
-			_getPropertyCache.Clear();
-			_getFrameworkPropertiesForType.Clear();
-		}
-
 		private static void RegisterProperty(Type ownerType, string name, DependencyProperty newProperty)
 		{
 			ResetGetPropertyCache(ownerType, name);
@@ -469,7 +458,7 @@ private static DependencyProperty[] InternalGetPropertiesForType(Type type)
 		///
 		/// See: http://stackoverflow.com/questions/6729841/why-did-the-beforefieldinit-behavior-change-in-net-4
 		/// </remarks>
-		private static void ForceInitializeTypeConstructor(Type type)
+		internal static void ForceInitializeTypeConstructor(Type type)
 		{
 			do
 			{

src/Uno.UI/UI/Xaml/Internal/DependencyPropertyHelper.cs

@@ -67,7 +67,7 @@ internal static class DependencyPropertyHelper
 	/// </summary>
 	public static IReadOnlyCollection<DependencyProperty>? GetDependencyPropertiesForType<T>()
 		where T : DependencyObject
-		=> DependencyProperty.GetPropertiesForType(typeof(T));
+		=> GetPropertiesForTypeCore(typeof(T));
 
 	/// <summary>
 	/// Try to get all the <see cref="DependencyProperty"/> defined for a given type.
@@ -84,14 +84,45 @@ public static bool TryGetDependencyPropertiesForType(
 			return false;
 		}
 
-		properties = DependencyProperty.GetPropertiesForType(forType);
+		properties = GetPropertiesForTypeCore(forType);
 		return true;
 	}
 
+	private static DependencyProperty[] GetPropertiesForTypeCore(Type type)
+	{
+		DependencyProperty.ForceInitializeTypeConstructor(type);
+
+		var results = new List<DependencyProperty>();
+
+		var currentType = type;
+
+		do
+		{
+			if (DependencyProperty.DependencyPropertyRegistry.Instance.TryGetTypeTable(currentType, out var typeTable))
+			{
+				foreach (var value in typeTable!.Values)
+				{
+					results.Add((DependencyProperty)value);
+				}
+			}
+
+			// Dependency properties are inherited
+			currentType = currentType.BaseType;
+		}
+		while (currentType != typeof(object) && currentType != null);
+
+		var array = results.ToArray();
+
+		// Produce a pre-sorted list, aligned with the initial behavior of DependencyPropertyDetailsCollection
+		Array.Sort(array, (l, r) => l.UniqueId - r.UniqueId);
+
+		return array;
+	}
+
 	/// <summary>
-	/// Get the value type of the property. 
+	/// Get the type of the property. 
 	/// </summary>
-	public static Type GetValueType(DependencyProperty dependencyProperty)
+	public static Type GetPropertyType(DependencyProperty dependencyProperty)
 		=> dependencyProperty.Type;
 
 	/// <summary>
@@ -105,7 +136,6 @@ public static string GetName(DependencyProperty dependencyProperty)
 	/// </summary>
 	/// <remarks>
 	/// This is the property that defines the property, not the type that uses it.
-	/// It may also be overridden by a derived type.
 	/// </remarks>
 	public static Type GetOwnerType(DependencyProperty dependencyProperty)
 		=> dependencyProperty.OwnerType;
@@ -147,13 +177,15 @@ public static (object? value, DependencyPropertyValuePrecedences precedence) Get
 			return (valueFromImplicitStyle, DependencyPropertyValuePrecedences.ImplicitStyle);
 		}
 
-		if (obj is IDependencyObjectStoreProvider { Store: { } store } && store.GetPropertyDetails(dependencyProperty) is { } details)
+		if (obj is IDependencyObjectStoreProvider { Store: { } store })
 		{
+			var details = store.GetPropertyDetails(dependencyProperty);
+
 			// 3rd: Check inherited value
 			var inheritedValue = details.GetInheritedValue();
 			if (inheritedValue != DependencyProperty.UnsetValue)
 			{
-				return (details.GetInheritedValue(), DependencyPropertyValuePrecedences.Inheritance);
+				return (inheritedValue, DependencyPropertyValuePrecedences.Inheritance);
 			}
 
 			// 4th: Check default value
@@ -164,9 +196,8 @@ public static (object? value, DependencyPropertyValuePrecedences precedence) Get
 			}
 		}
 
-		// 5th: Return default value of the type (should not happen)
-		var propertyType = dependencyProperty.Type;
-		return (propertyType.IsValueType ? Activator.CreateInstance(propertyType) : null, DependencyPropertyValuePrecedences.DefaultValue);
+		// 5th: Return default value of the DP (should not happen)
+		return (dependencyProperty.GetDefaultValue(obj, obj.GetType()), DependencyPropertyValuePrecedences.DefaultValue);
 	}
 
 	/// <summary>
@@ -186,24 +217,20 @@ public static void SetValueForPrecedence(
 	/// Get if the property value is inherited through the visual tree. 
 	/// </summary>
 	public static bool GetIsInherited(DependencyProperty dependencyProperty)
-		=> dependencyProperty.GetMetadata(dependencyProperty.OwnerType) is FrameworkPropertyMetadata metadata
-		   && metadata.Options.HasFlag(FrameworkPropertyMetadataOptions.Inherits);
+		=> dependencyProperty.IsInherited;
 
 	/// <summary>
 	/// Get the multiple aspects of a given property at the same time.
 	/// </summary>
-	public static (Type ValueType, Type OwnerType, string Name, bool IsTypeNullable, bool IsAttached, bool IsInherited, object? defaultValue) GetDetails(
+	public static (Type PropertyType, Type OwnerType, string Name, bool IsTypeNullable, bool IsAttached, bool IsInherited, object? defaultValue) GetDetails(
 		DependencyProperty property)
 	{
-		var propertyMetadata = property.GetMetadata(property.OwnerType);
-
 		return (property.Type,
 			property.OwnerType,
 			property.Name,
 			property.IsTypeNullable,
 			property.IsAttached,
-			propertyMetadata is FrameworkPropertyMetadata metadata &&
-			metadata.Options.HasFlag(FrameworkPropertyMetadataOptions.Inherits),
-			propertyMetadata?.DefaultValue);
+			property.IsInherited,
+			property.GetDefaultValue(referenceObject: null, property.Type));
 	}
 }