Fixed Label Span font property inheritance when applied via Style

src/Controls/src/Core/FontExtensions.cs

@@ -34,5 +34,20 @@ public static Font ToFont(this IFontElement element, double? defaultSize = null)
 
 			return Font.OfSize(element.FontFamily, size, enableScaling: element.FontAutoScalingEnabled).WithAttributes(element.FontAttributes);
 		}
+
+		internal static Font GetEffectiveFont(this Span span, double defaultFontSize, Font? defaultFont)
+		{
+			var fontFamily = span.IsSet(Span.FontFamilyProperty) ? span.FontFamily : defaultFont?.Family;
+			var fontSize = span.IsSet(Span.FontSizeProperty) ? span.FontSize : defaultFontSize;
+			var fontAttributes = span.IsSet(Span.FontAttributesProperty)
+				? span.FontAttributes
+				: (defaultFont?.GetFontAttributes() ?? FontAttributes.None);
+			var autoScaling = span.IsSet(Span.FontAutoScalingEnabledProperty)
+				? span.FontAutoScalingEnabled
+				: (defaultFont?.AutoScalingEnabled ?? true);
+
+			return Font.OfSize(fontFamily, fontSize, enableScaling: autoScaling)
+				.WithAttributes(fontAttributes);
+		}
 	}
 }

src/Controls/src/Core/Platform/Android/Extensions/FormattedStringExtensions.cs

@@ -90,10 +90,7 @@ public static SpannableString ToSpannableString(
 				if (characterSpacing >= 0)
 					spannable.SetSpan(new PlatformFontSpan(characterSpacing.ToEm()), start, end, SpanTypes.InclusiveInclusive);
 
-				// Font
-				var font = span.ToFont(defaultFontSize);
-				if (font.IsDefault && defaultFont.HasValue)
-					font = defaultFont.Value;
+				var font = span.GetEffectiveFont(defaultFontSize, defaultFont);
 				if (!font.IsDefault)
 					spannable.SetSpan(new PlatformFontSpan(context ?? AAplication.Context, font.ToTypeface(fontManager), font.AutoScalingEnabled, (float)fontManager.GetFontSize(font).Value), start, end, SpanTypes.InclusiveInclusive);
 

src/Controls/src/Core/Platform/Windows/Extensions/FormattedStringExtensions.cs

@@ -127,9 +127,7 @@ public static Tuple<Run, Color, Color> ToRunAndColorsTuple(
 
 			var run = new Run { Text = text ?? string.Empty };
 
-			var font = span.ToFont(defaultFontSize);
-			if (font.IsDefault && defaultFont.HasValue)
-				font = defaultFont.Value;
+			var font = span.GetEffectiveFont(defaultFontSize, defaultFont);
 
 			if (!font.IsDefault)
 			{

src/Controls/src/Core/Platform/iOS/Extensions/FormattedStringExtensions.cs

@@ -91,10 +91,7 @@ public static NSAttributedString ToNSAttributedString(
 				_ => UITextAlignment.Left
 			};
 
-			var font = span.ToFont(defaultFontSize);
-			if (font.IsDefault && defaultFont.HasValue)
-				font = defaultFont.Value;
-
+			var font = span.GetEffectiveFont(defaultFontSize, defaultFont);
 			var hasUnderline = false;
 			var hasStrikethrough = false;
 			if (span.IsSet(Span.TextDecorationsProperty))

src/Controls/tests/TestCases.HostApp/Issues/Issue21326.cs

@@ -0,0 +1,100 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 21326, "Span does not inherit text styling from Label if that styling is applied using Style", PlatformAffected.All)]
+public partial class Issue21326 : ContentPage
+{
+	public Issue21326()
+	{
+		var Issue21326resourceDictionary = new ResourceDictionary();
+
+		var headingStyle = new Style(typeof(Label));
+		headingStyle.Setters.Add(new Setter { Property = Label.FontFamilyProperty, Value = "MontserratBold" });
+		headingStyle.Setters.Add(new Setter { Property = Label.FontSizeProperty, Value = 20.0 });
+		Issue21326resourceDictionary.Add("HeadingStyle", headingStyle);
+
+		Resources = Issue21326resourceDictionary;
+
+		// Test 1: FontFamily inheritance (original test)
+		var Issue21326testLabel = new Label
+		{
+			Style = headingStyle,
+			AutomationId = "Issue21326Label"
+		};
+
+		var formattedString = new FormattedString();
+		formattedString.Spans.Add(new Span
+		{
+			Text = "SHOULD BE MONTSERRATBOLD from Style"
+		});
+		Issue21326testLabel.FormattedText = formattedString;
+
+		// Test 2: Span with explicit Bold attribute (should render as Bold)
+		var boldSpanLabel = new Label
+		{
+			AutomationId = "BoldSpanLabel"
+		};
+
+		var boldFormattedString = new FormattedString();
+		boldFormattedString.Spans.Add(new Span
+		{
+			Text = "This text should be BOLD",
+			FontAttributes = FontAttributes.Bold
+		});
+		boldSpanLabel.FormattedText = boldFormattedString;
+
+		// Test 3: Span with explicit Italic attribute (should render as Italic)
+		var italicSpanLabel = new Label
+		{
+			AutomationId = "ItalicSpanLabel"
+		};
+
+		var italicFormattedString = new FormattedString();
+		italicFormattedString.Spans.Add(new Span
+		{
+			Text = "This text should be ITALIC",
+			FontAttributes = FontAttributes.Italic
+		});
+		italicSpanLabel.FormattedText = italicFormattedString;
+
+		// Test 4: Span with Bold+Italic (should render as Bold Italic)
+		var boldItalicSpanLabel = new Label
+		{
+			AutomationId = "BoldItalicSpanLabel"
+		};
+
+		var boldItalicFormattedString = new FormattedString();
+		boldItalicFormattedString.Spans.Add(new Span
+		{
+			Text = "This text should be BOLD + ITALIC",
+			FontAttributes = FontAttributes.Bold | FontAttributes.Italic
+		});
+		boldItalicSpanLabel.FormattedText = boldItalicFormattedString;
+
+		Content = new VerticalStackLayout
+		{
+			Padding = 10,
+			Spacing = 20,
+			Children =
+			{
+				new Label { Text = "Test 1: FontFamily inheritance from Style", FontAttributes = FontAttributes.Bold },
+				Issue21326testLabel,
+
+				new Label { Text = "Test 2: Span with FontAttributes='Bold'", FontAttributes = FontAttributes.Bold },
+				boldSpanLabel,
+
+				new Label { Text = "Test 3: Span with FontAttributes='Italic'", FontAttributes = FontAttributes.Bold },
+				italicSpanLabel,
+
+				new Label { Text = "Test 4: Span with Bold + Italic", FontAttributes = FontAttributes.Bold },
+				boldItalicSpanLabel,
+
+				new Label
+				{
+					Text = "If any Span above looks Regular (not Bold/Italic), the FontAttributes are being dropped!",
+					TextColor = Colors.Green,
+					FontSize = 12
+				}
+			}
+		};
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue21326.cs

@@ -0,0 +1,20 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue21326 : _IssuesUITest
+{
+	public override string Issue => "Span does not inherit text styling from Label if that styling is applied using Style";
+
+	public Issue21326(TestDevice device) : base(device) { }
+
+	[Test]
+	[Category(UITestCategories.Label)]
+	public void SpanShouldInheritStyleFromLabel()
+	{
+		App.WaitForElement("Issue21326Label");
+		VerifyScreenshot();
+	}
+}