[Android] Enable MaxLines and TextDecorations on fast renderers (#3878)

* enable MaxLines on fast renderers

* added text decoration functionality

* include test in project

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Github3856.cs

@@ -0,0 +1,61 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+#if UITEST
+using Xamarin.Forms.Core.UITests;
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+#if UITEST
+	[Category(UITestCategories.ManualReview)]
+#endif
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 3856, "[Android] MaxLines on Label not working with FastRenderers 3.3.0-pre1", PlatformAffected.Android)]
+	public class Github3856 : TestContentPage // or TestMasterDetailPage, etc ...
+	{
+		protected override void Init()
+		{
+			var label1 = new Label
+			{
+				MaxLines = 4,
+				LineBreakMode = LineBreakMode.TailTruncation,
+				Text = "You should see 4 lines of text and truncation at the end. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam mattis quam non enim pellentesque, ut placerat purus finibus. Nulla quis tincidunt ante. Ut mauris lectus, aliquam a sagittis vitae, consequat eget elit. Interdum et malesuada fames ac ante ipsum primis in faucibus. Pellentesque convallis nunc nisi, a imperdiet elit efficitur et. Duis in lectus mollis, interdum ipsum et, tincidunt orci. Fusce ipsum metus, imperdiet non lacus vitae, facilisis feugiat magna. Nulla volutpat nisl tortor, a consectetur felis consectetur non. Curabitur in enim vulputate sem volutpat bibendum id nec lorem. Mauris laoreet lacus ac volutpat tempus."
+			};
+
+			var label2 = new Label
+			{
+				TextDecorations = TextDecorations.Underline,
+				Text = "Label/Span Underline"
+			};
+
+			var label3 = new Label
+			{
+				TextDecorations = TextDecorations.Strikethrough,
+				Text = "Label/Span Strikethrough"
+			};
+
+			var label4 = new Label
+			{
+				TextDecorations = TextDecorations.Underline | TextDecorations.Strikethrough,
+				Text = "Label/Span Underline and Strikethrough"
+			};
+
+			var stackLayout = new StackLayout
+			{
+				Spacing = 10,
+				Orientation = StackOrientation.Vertical,
+				HorizontalOptions = LayoutOptions.CenterAndExpand,
+				VerticalOptions = LayoutOptions.CenterAndExpand
+			};
+			stackLayout.Children.Add(label1);
+			stackLayout.Children.Add(label2);
+			stackLayout.Children.Add(label3);
+			stackLayout.Children.Add(label4);
+
+			Content = stackLayout;
+		}
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -9,6 +9,7 @@
     <Import_RootNamespace>Xamarin.Forms.Controls.Issues</Import_RootNamespace>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="$(MSBuildThisFileDirectory)Github3856.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue3788.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue2894.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue3524.cs" />

Xamarin.Forms.Platform.Android/FastRenderers/LabelRenderer.cs

@@ -220,11 +220,13 @@ namespace Xamarin.Forms.Platform.Android.FastRenderers
 				SkipNextInvalidate();
 				UpdateText();
 				UpdateLineHeight();
+				UpdateTextDecorations();
 				if (e.OldElement?.LineBreakMode != e.NewElement.LineBreakMode)
 					UpdateLineBreakMode();
-				if (e.OldElement?.HorizontalTextAlignment != e.NewElement.HorizontalTextAlignment
+				if (e.OldElement?.HorizontalTextAlignment != e.NewElement.HorizontalTextAlignment || e.OldElement?.VerticalTextAlignment != e.NewElement.VerticalTextAlignment)
-				 || e.OldElement?.VerticalTextAlignment != e.NewElement.VerticalTextAlignment)
 					UpdateGravity();
+				if (e.OldElement?.MaxLines != e.NewElement.MaxLines)
+					UpdateMaxLines();
 
 				ElevationHelper.SetElevation(this, e.NewElement);
 			}
@@ -242,10 +244,14 @@ namespace Xamarin.Forms.Platform.Android.FastRenderers
 				UpdateText();
 			else if (e.PropertyName == Label.LineBreakModeProperty.PropertyName)
 				UpdateLineBreakMode();
+			else if (e.PropertyName == Label.TextDecorationsProperty.PropertyName)
+				UpdateTextDecorations();
 			else if (e.PropertyName == Label.TextProperty.PropertyName || e.PropertyName == Label.FormattedTextProperty.PropertyName)
 				UpdateText();
 			else if (e.PropertyName == Label.LineHeightProperty.PropertyName)
 				UpdateLineHeight();
+			else if (e.PropertyName == Label.MaxLinesProperty.PropertyName)
+				UpdateMaxLines();
 		}
 
 		void UpdateColor()
@@ -315,6 +321,12 @@ namespace Xamarin.Forms.Platform.Android.FastRenderers
 			_lastSizeRequest = null;
 		}
 
+		void UpdateMaxLines()
+		{
+			SetSingleLine(Element.MaxLines == 1);
+			SetMaxLines(Element.MaxLines > 0 ? Element.MaxLines : 1);
+		}
+
 		void UpdateText()
 		{
 			if (Element.FormattedText != null)

Xamarin.Forms.Platform.Android/Renderers/LabelRenderer.cs

@@ -226,16 +226,8 @@ namespace Xamarin.Forms.Platform.Android
 
 		void UpdateMaxLines()
 		{
-			if (Element.MaxLines > 0)
+			Control.SetSingleLine(Element.MaxLines == 1);
-			{
+			Control.SetMaxLines(Element.MaxLines > 0 ? Element.MaxLines : 1);
-				Control.SetSingleLine(Element.MaxLines == 1);
-				Control.SetMaxLines(Element.MaxLines);
-			}
-			else
-			{
-				Control.SetSingleLine(false);
-				Control.SetMaxLines(1);
-			}
 		}
 
 		void UpdateText()