[Win] Fix FontAttributes unexpectedly changing a label's size (#325)

3 files changed, 61 insertions, 1 deletions

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla43516.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla43516.cs
new file mode 100644
index 00000000..615f5a09
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla43516.cs
@@ -0,0 +1,56 @@
+using System;
+
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Bugzilla, 43516, "Changing FontAttributes on a label to None changes its font size")]
+	public class Bugzill43516 : TestContentPage
+	{
+		protected override void Init()
+		{
+			var label = new Label
+			{
+				FontAttributes = FontAttributes.Bold
+			};
+			label.BindingContext = label;
+			label.SetBinding(Label.TextProperty, "FontAttributes");
+
+			Content = new StackLayout
+			{
+				Children =
+				{
+					label,
+					new Button
+					{
+						Text = "Click to set FontAttributes.None",
+						Command = new Command(() =>
+						{
+							label.FontAttributes = FontAttributes.None;
+						})
+					},
+					new Button
+					{
+						Text = "Click to set FontAttributes.Bold",
+						Command = new Command(() =>
+						{
+							label.FontAttributes = FontAttributes.Bold;
+						})
+					},
+					new Button
+					{
+						Text = "Click to set Font.SystemFontOfSize to NamedSize.Medium",
+						Command = new Command(() => label.FontSize = Device.GetNamedSize(NamedSize.Medium, typeof(Label)))
+					}
+				}
+			};
+		}
+	}
+}
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index c0f5d33a..adf173df 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -123,6 +123,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla42329.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla42364.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla42519.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla43516.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)CarouselAsync.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla34561.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla34727.cs" />
diff --git a/Xamarin.Forms.Platform.WinRT/LabelRenderer.cs b/Xamarin.Forms.Platform.WinRT/LabelRenderer.cs
index 1f2f861d..3997e7e4 100644
--- a/Xamarin.Forms.Platform.WinRT/LabelRenderer.cs
+++ b/Xamarin.Forms.Platform.WinRT/LabelRenderer.cs
@@ -34,6 +34,7 @@ namespace Xamarin.Forms.Platform.WinRT
 	public class LabelRenderer : ViewRenderer<Label, TextBlock>
 	{
 		bool _fontApplied;
+		bool _isInitiallyDefault;
 
 		protected override Windows.Foundation.Size ArrangeOverride(Windows.Foundation.Size finalSize)
 		{
@@ -71,6 +72,8 @@ namespace Xamarin.Forms.Platform.WinRT
 					SetNativeControl(new TextBlock());
 				}
 
+				_isInitiallyDefault = Element.IsDefault();
+
 				UpdateText(Control);
 				UpdateColor(Control);
 				UpdateAlign(Control);
@@ -134,7 +137,7 @@ namespace Xamarin.Forms.Platform.WinRT
 				return;
 
 #pragma warning disable 618
-			Font fontToApply = label.IsDefault() ? Font.SystemFontOfSize(NamedSize.Medium) : label.Font;
+			Font fontToApply = label.IsDefault() && _isInitiallyDefault ? Font.SystemFontOfSize(NamedSize.Medium) : label.Font;
 #pragma warning restore 618
 
 			textBlock.ApplyFont(fontToApply);