feat(focus): Add support for FindFirstFocusableElement

src/Uno.UI/Generated/3.0.0.0/Windows.UI.Xaml.Input/FocusManager.cs

@@ -50,7 +50,7 @@ public static bool TryMoveFocus( global::Windows.UI.Xaml.Input.FocusNavigationDi
 			throw new global::System.NotImplementedException("The member DependencyObject FocusManager.FindNextElement(FocusNavigationDirection focusNavigationDirection) is not implemented in Uno.");
 		}
 		#endif
-		#if __ANDROID__ || __IOS__ || NET461 || __WASM__ || __MACOS__
+		#if false || false || false || false || false
 		[global::Uno.NotImplemented]
 		public static global::Windows.UI.Xaml.DependencyObject FindFirstFocusableElement( global::Windows.UI.Xaml.DependencyObject searchScope)
 		{

src/Uno.UI/UI/Xaml/Input/FocusManager.Android.cs

@@ -214,6 +214,26 @@ public static View InnerFindNextFocusableElement(FocusNavigationDirection focusN
 			}
 		}
 
+		public static DependencyObject InnerFindFirstFocusableElement(DependencyObject searchScope)
+		{
+			if (searchScope == null)
+			{
+				searchScope = Window.Current.Content;
+			}
+
+			if (IsFocusableView(searchScope as View))
+			{
+				return searchScope;
+			}
+
+			if (!(searchScope is ViewGroup searchViewGroup))
+			{
+				return null;
+			}
+
+			return searchViewGroup.EnumerateAllChildren(IsFocusableView, maxDepth: 300).FirstOrDefault() as DependencyObject;			
+		}
+
 		private static void FocusNative(Control control)
 		{
 			control.RequestFocus();

src/Uno.UI/UI/Xaml/Input/FocusManager.cs

@@ -49,6 +49,16 @@ public static UIElement FindNextFocusableElement(FocusNavigationDirection focusN
 			return InnerFindNextFocusableElement(focusNavigationDirection) as UIElement;
 		}
 
+		/// <summary>
+		/// Retrieves the first element that can receive focus based on the specified scope.
+		/// </summary>
+		/// <param name="searchScope">The root object from which to search. If null, the search scope is the current window.</param>
+		/// <returns>The first focusable object.</returns>
+		public static DependencyObject FindFirstFocusableElement(DependencyObject searchScope)
+		{
+			return InnerFindFirstFocusableElement(searchScope);
+		}
+
 		internal static bool SetFocusedElement(DependencyObject newFocus, FocusNavigationDirection focusNavigationDirection, FocusState focusState)
 		{
 			var control = newFocus as Control; // For now only called for Control

src/Uno.UI/UI/Xaml/Input/FocusManager.iOS.cs

@@ -104,7 +104,7 @@ public static UIView InnerFindNextFocusableElement(FocusNavigationDirection focu
 		{
 			var focusedView = GetFocusedElement() as UIView;
 			var absoluteFocusedFrame = focusedView.ConvertRectToView(focusedView.Bounds, UIApplication.SharedApplication.KeyWindow);
-			
+
 			var focusableViews = SearchOtherFocusableViews(focusedView);
 
 			switch (focusNavigationDirection)
@@ -208,6 +208,26 @@ public static UIView InnerFindNextFocusableElement(FocusNavigationDirection focu
 			}
 		}
 
+		public static DependencyObject InnerFindFirstFocusableElement(DependencyObject searchScope)
+		{
+			if (searchScope == null)
+			{
+				searchScope = Window.Current.Content;
+			}
+
+			if (!(searchScope is UIView searchView))
+			{
+				return null;
+			}
+
+			if (IsFocusableView(searchView))
+			{
+				return searchScope;
+			}
+
+			return searchView.FindSubviews(selector: IsFocusableView, maxDepth: 100).FirstOrDefault() as DependencyObject;
+		}
+
 		private static void FocusNative(Control control) => control.BecomeFirstResponder();
 
 		//We need to validate this difference because focused elements don't have the same absolute position once focused

src/Uno.UI/UI/Xaml/Input/FocusManager.macOS.cs

@@ -213,6 +213,26 @@ public static NSView InnerFindNextFocusableElement(FocusNavigationDirection focu
 			}
 		}
 
+		public static DependencyObject InnerFindFirstFocusableElement(DependencyObject searchScope)
+		{
+			if (searchScope == null)
+			{
+				searchScope = Window.Current.Content;
+			}
+
+			if (!(searchScope is NSView searchView))
+			{
+				return null;
+			}
+
+			if (IsFocusableView(searchView))
+			{
+				return searchScope;
+			}
+
+			return searchView.FindSubviews(selector: IsFocusableView, maxDepth: 100).FirstOrDefault() as DependencyObject;
+		}
+
 		private static void FocusNative(Control control) => control.BecomeFirstResponder();
 
 		//We need to validate this difference because focused elements don't have the same absolute position once focused

src/Uno.UI/UI/Xaml/Input/FocusManager.net.cs

@@ -45,6 +45,11 @@ public static View InnerFindNextFocusableElement(FocusNavigationDirection focusN
 			throw new NotImplementedException();
 		}
 
+		public static DependencyObject InnerFindFirstFocusableElement(DependencyObject searchScope)
+		{
+			throw new NotImplementedException();
+		}
+
 		public static void OnFocusChanged(View control, FocusState state)
 		{
 			throw new NotImplementedException();

src/Uno.UI/UI/Xaml/Input/FocusManager.wasm.cs

@@ -113,5 +113,10 @@ private static UIElement InnerFindNextFocusableElement(FocusNavigationDirection
 		{
 			return null;
 		}
+
+		public static DependencyObject InnerFindFirstFocusableElement(DependencyObject searchScope)
+		{
+			return null;
+		}
 	}
 }