From d87f3aa42e7e1c67a2d35aa87693a03b67308dc3 Mon Sep 17 00:00:00 2001
From: Matthew Leibowitz <mattleibow@live.com>
Date: Thu, 18 Jan 2024 02:36:51 +0200
Subject: [PATCH] Fix Label Multiline Truncation
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Javier Suárez <javiersuarezruiz@hotmail.com>
---
 .../Pages/Controls/LabelPage.xaml             |  7 ++
 src/Controls/src/Core/Label/Label.Android.cs  |  1 -
 src/Controls/src/Core/Label/Label.Windows.cs  |  5 +-
 src/Controls/src/Core/Label/Label.iOS.cs      |  2 +-
 .../Android/Extensions/TextViewExtensions.cs  | 23 +++--
 .../Windows/Extensions/TextBlockExtensions.cs | 83 ++++++++++---------
 .../Platform/iOS/Extensions/TextExtensions.cs |  9 +-
 .../Elements/Label/LabelTests.Android.cs      | 22 +++++
 .../DeviceTests/Elements/Label/LabelTests.cs  | 60 +++++++++++++-
 .../Elements/Label/LabelTests.iOS.cs          | 26 +++++-
 10 files changed, 179 insertions(+), 59 deletions(-)

diff --git a/src/Controls/samples/Controls.Sample/Pages/Controls/LabelPage.xaml b/src/Controls/samples/Controls.Sample/Pages/Controls/LabelPage.xaml
index f98559ce3e39..7fab8e0d6405 100644
--- a/src/Controls/samples/Controls.Sample/Pages/Controls/LabelPage.xaml
+++ b/src/Controls/samples/Controls.Sample/Pages/Controls/LabelPage.xaml
@@ -231,6 +231,13 @@
             <Label
                 LineBreakMode ="TailTruncation"
                 Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat." />
+            <Label
+                Text="TailTruncation (with 2 MaxLines)"
+                Style="{StaticResource Headline}" />
+            <Label
+                MaxLines="2"
+                LineBreakMode ="TailTruncation"
+                Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat." />
             <Label
                 Text="CharacterWrap"
                 Style="{StaticResource Headline}" />
diff --git a/src/Controls/src/Core/Label/Label.Android.cs b/src/Controls/src/Core/Label/Label.Android.cs
index 46adaaf2e0b9..8392c9820379 100644
--- a/src/Controls/src/Core/Label/Label.Android.cs
+++ b/src/Controls/src/Core/Label/Label.Android.cs
@@ -36,7 +36,6 @@ private protected override void OnHandlerChangedCore()
 		public static void MapText(LabelHandler handler, Label label) => MapText((ILabelHandler)handler, label);
 		public static void MapLineBreakMode(LabelHandler handler, Label label) => MapLineBreakMode((ILabelHandler)handler, label);
 
-
 		public static void MapText(ILabelHandler handler, Label label)
 		{
 			Platform.TextViewExtensions.UpdateText(handler.PlatformView, label);
diff --git a/src/Controls/src/Core/Label/Label.Windows.cs b/src/Controls/src/Core/Label/Label.Windows.cs
index f843e0b3d7a2..ed89c6aa56b5 100644
--- a/src/Controls/src/Core/Label/Label.Windows.cs
+++ b/src/Controls/src/Core/Label/Label.Windows.cs
@@ -8,7 +8,6 @@ public partial class Label
 		public static void MapDetectReadingOrderFromContent(LabelHandler handler, Label label) => MapDetectReadingOrderFromContent((ILabelHandler)handler, label);
 		public static void MapText(LabelHandler handler, Label label) => MapText((ILabelHandler)handler, label);
 
-
 		public static void MapDetectReadingOrderFromContent(ILabelHandler handler, Label label) =>
 			Platform.TextBlockExtensions.UpdateDetectReadingOrderFromContent(handler.PlatformView, label);
 
@@ -16,9 +15,9 @@ public static void MapText(ILabelHandler handler, Label label) =>
 			Platform.TextBlockExtensions.UpdateText(handler.PlatformView, label);
 
 		public static void MapLineBreakMode(ILabelHandler handler, Label label) =>
-			handler.PlatformView?.UpdateLineBreakMode(label.LineBreakMode);
+			handler.PlatformView?.UpdateLineBreakMode(label);
 
 		public static void MapMaxLines(ILabelHandler handler, Label label) =>
 			handler.PlatformView?.UpdateMaxLines(label);
 	}
-}
+}
\ No newline at end of file
diff --git a/src/Controls/src/Core/Label/Label.iOS.cs b/src/Controls/src/Core/Label/Label.iOS.cs
index 4a6b43822ae8..4c843c7280da 100644
--- a/src/Controls/src/Core/Label/Label.iOS.cs
+++ b/src/Controls/src/Core/Label/Label.iOS.cs
@@ -1,4 +1,4 @@
-#nullable disable
+#nullable disable
 using System;
 using Microsoft.Maui.Controls.Platform;
 
diff --git a/src/Controls/src/Core/Platform/Android/Extensions/TextViewExtensions.cs b/src/Controls/src/Core/Platform/Android/Extensions/TextViewExtensions.cs
index 719a525c7475..db6dd6edd28b 100644
--- a/src/Controls/src/Core/Platform/Android/Extensions/TextViewExtensions.cs
+++ b/src/Controls/src/Core/Platform/Android/Extensions/TextViewExtensions.cs
@@ -2,6 +2,7 @@
 using System;
 using Android.Text;
 using Android.Widget;
+using AndroidX.AppCompat.Widget;
 using Microsoft.Maui.Controls.Internals;
 
 namespace Microsoft.Maui.Controls.Platform
@@ -31,14 +32,21 @@ public static void UpdateLineBreakMode(this TextView textView, Label label)
 
 		public static void UpdateMaxLines(this TextView textView, Label label)
 		{
-			// Linebreak mode also handles settng MaxLines
+			// Linebreak mode also handles setting MaxLines
 			textView.SetLineBreakMode(label.LineBreakMode, label.MaxLines);
 		}
 
 		internal static void SetLineBreakMode(this TextView textView, LineBreakMode lineBreakMode, int? maxLines = null)
 		{
 			if (!maxLines.HasValue || maxLines <= 0)
-				maxLines = int.MaxValue;
+			{
+				// Without setting the MaxLines property, to equalize behaviors across platforms
+				// we set the max to 1.
+				if (lineBreakMode == LineBreakMode.TailTruncation)
+					maxLines = 1;
+				else
+					maxLines = int.MaxValue;
+			}
 
 			bool singleLine = false;
 			bool shouldSetSingleLine = !OperatingSystem.IsAndroidVersionAtLeast(23);
@@ -67,12 +75,11 @@ internal static void SetLineBreakMode(this TextView textView, LineBreakMode line
 					break;
 				case LineBreakMode.TailTruncation:
 
-					// Leaving this in for now to preserve existing behavior
-					// Technically, we don't _need_ this for Labels; they will handle Ellipsization at the end just fine, even with multiple lines
-					// But we don't have a mechanism for setting MaxLines on other controls (e.g., Button) right now, so we need to force it here or
-					// they will potentially exceed a single line. Also, changing this behavior the for Labels would technically be breaking (though
-					// possibly less surprising than what happens currently).
-					maxLines = 1;
+					// We don't have a mechanism for setting MaxLines on other controls (e.g., Button) right now, so we need to force it here or
+					// they will potentially exceed a single line. 
+					if (textView is AppCompatButton)
+						maxLines = 1;
+
 					textView.Ellipsize = TextUtils.TruncateAt.End;
 					break;
 				case LineBreakMode.MiddleTruncation:
diff --git a/src/Controls/src/Core/Platform/Windows/Extensions/TextBlockExtensions.cs b/src/Controls/src/Core/Platform/Windows/Extensions/TextBlockExtensions.cs
index 2e33c3a6abc7..8530b4311bc7 100644
--- a/src/Controls/src/Core/Platform/Windows/Extensions/TextBlockExtensions.cs
+++ b/src/Controls/src/Core/Platform/Windows/Extensions/TextBlockExtensions.cs
@@ -12,44 +12,11 @@ namespace Microsoft.Maui.Controls.Platform
 	internal static class TextBlockExtensions
 	{
 		public static void UpdateLineBreakMode(this TextBlock textBlock, Label label) =>
-			textBlock.UpdateLineBreakMode(label.LineBreakMode);
+			textBlock.SetLineBreakMode(label.LineBreakMode, label.MaxLines);
 
 		public static void UpdateLineBreakMode(this TextBlock textBlock, LineBreakMode lineBreakMode)
 		{
-			if (textBlock == null)
-				return;
-
-			switch (lineBreakMode)
-			{
-				case LineBreakMode.NoWrap:
-					textBlock.TextTrimming = TextTrimming.Clip;
-					textBlock.TextWrapping = TextWrapping.NoWrap;
-					break;
-				case LineBreakMode.WordWrap:
-					textBlock.TextTrimming = TextTrimming.None;
-					textBlock.TextWrapping = TextWrapping.Wrap;
-					break;
-				case LineBreakMode.CharacterWrap:
-					textBlock.TextTrimming = TextTrimming.WordEllipsis;
-					textBlock.TextWrapping = TextWrapping.Wrap;
-					break;
-				case LineBreakMode.HeadTruncation:
-					// TODO: This truncates at the end.
-					textBlock.TextTrimming = TextTrimming.WordEllipsis;
-					DetermineTruncatedTextWrapping(textBlock);
-					break;
-				case LineBreakMode.TailTruncation:
-					textBlock.TextTrimming = TextTrimming.CharacterEllipsis;
-					DetermineTruncatedTextWrapping(textBlock);
-					break;
-				case LineBreakMode.MiddleTruncation:
-					// TODO: This truncates at the end.
-					textBlock.TextTrimming = TextTrimming.WordEllipsis;
-					DetermineTruncatedTextWrapping(textBlock);
-					break;
-				default:
-					throw new ArgumentOutOfRangeException();
-			}
+			textBlock.SetLineBreakMode(lineBreakMode, null);
 		}
 
 		static void DetermineTruncatedTextWrapping(TextBlock textBlock) =>
@@ -87,10 +54,8 @@ public static double FindDefaultLineHeight(this TextBlock control, Inline inline
 
 		public static void UpdateMaxLines(this TextBlock platformControl, Label label)
 		{
-			if (label.MaxLines >= 0)
-				platformControl.MaxLines = label.MaxLines;
-			else
-				platformControl.MaxLines = 0;
+			// Linebreak mode also handles setting MaxLines
+			platformControl.SetLineBreakMode(label.LineBreakMode, label.MaxLines);
 		}
 
 		public static void UpdateDetectReadingOrderFromContent(this TextBlock platformControl, Label label)
@@ -99,6 +64,46 @@ public static void UpdateDetectReadingOrderFromContent(this TextBlock platformCo
 				platformControl.SetTextReadingOrder(label.OnThisPlatform().GetDetectReadingOrderFromContent());
 		}
 
+		internal static void SetLineBreakMode(this TextBlock textBlock, LineBreakMode lineBreakMode, int? maxLines = null)
+		{
+			if (maxLines.HasValue && maxLines >= 0)
+				textBlock.MaxLines = maxLines.Value;
+			else
+				textBlock.MaxLines = 0;
+
+			switch (lineBreakMode)
+			{
+				case LineBreakMode.NoWrap:
+					textBlock.TextTrimming = TextTrimming.Clip;
+					textBlock.TextWrapping = TextWrapping.NoWrap;
+					break;
+				case LineBreakMode.WordWrap:
+					textBlock.TextTrimming = TextTrimming.None;
+					textBlock.TextWrapping = TextWrapping.Wrap;
+					break;
+				case LineBreakMode.CharacterWrap:
+					textBlock.TextTrimming = TextTrimming.WordEllipsis;
+					textBlock.TextWrapping = TextWrapping.Wrap;
+					break;
+				case LineBreakMode.HeadTruncation:
+					// TODO: This truncates at the end.
+					textBlock.TextTrimming = TextTrimming.WordEllipsis;
+					DetermineTruncatedTextWrapping(textBlock);
+					break;
+				case LineBreakMode.TailTruncation:
+					textBlock.TextTrimming = TextTrimming.CharacterEllipsis;
+					DetermineTruncatedTextWrapping(textBlock);
+					break;
+				case LineBreakMode.MiddleTruncation:
+					// TODO: This truncates at the end.
+					textBlock.TextTrimming = TextTrimming.WordEllipsis;
+					DetermineTruncatedTextWrapping(textBlock);
+					break;
+				default:
+					throw new ArgumentOutOfRangeException();
+			}
+		}
+	
 		internal static void SetTextReadingOrder(this TextBlock platformControl, bool detectReadingOrderFromContent) =>
 			platformControl.TextReadingOrder = detectReadingOrderFromContent
 				? TextReadingOrder.DetectFromContent
diff --git a/src/Controls/src/Core/Platform/iOS/Extensions/TextExtensions.cs b/src/Controls/src/Core/Platform/iOS/Extensions/TextExtensions.cs
index 948c18531e89..6b34f6febe60 100644
--- a/src/Controls/src/Core/Platform/iOS/Extensions/TextExtensions.cs
+++ b/src/Controls/src/Core/Platform/iOS/Extensions/TextExtensions.cs
@@ -72,8 +72,14 @@ public static void UpdateMaxLines(this UILabel platformLabel, Label label)
 		internal static void SetLineBreakMode(this UILabel platformLabel, Label label)
 		{
 			int maxLines = label.MaxLines;
+
 			if (maxLines < 0)
-				maxLines = 0;
+			{
+				if (label.LineBreakMode == LineBreakMode.TailTruncation)
+					maxLines = 1;
+				else
+					maxLines = 0;
+			}
 
 			switch (label.LineBreakMode)
 			{
@@ -97,7 +103,6 @@ internal static void SetLineBreakMode(this UILabel platformLabel, Label label)
 					break;
 				case LineBreakMode.TailTruncation:
 					platformLabel.LineBreakMode = UILineBreakMode.TailTruncation;
-					maxLines = 1;
 					break;
 			}
 
diff --git a/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.Android.cs b/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.Android.cs
index f16c7557d904..22bced4d0afb 100644
--- a/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.Android.cs
+++ b/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.Android.cs
@@ -66,6 +66,28 @@ public async Task VerticalTextAlignedWhenRtlIsFalse()
 			Assert.True(platformLabel.Gravity.HasFlag(GravityFlags.CenterVertical), "Label should only have the CenterVertical flag.");
 		}
 
+		// https://github.com/dotnet/maui/issues/18059
+		[Fact(DisplayName = "Using TailTruncation LineBreakMode with 2 MaxLines")]
+		public async Task UsingTailTruncationWith2MaxLines()
+		{
+			var label = new Label()
+			{
+				Text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit",
+				LineBreakMode = LineBreakMode.TailTruncation,
+				MaxLines = 2
+			};
+
+			var handler = await CreateHandlerAsync<LabelHandler>(label);
+
+			var platformLabel = GetPlatformLabel(handler);
+
+			await InvokeOnMainThreadAsync((System.Action)(() =>
+			{
+				Assert.Equal(2, GetPlatformMaxLines(handler));
+				Assert.Equal(LineBreakMode.TailTruncation.ToPlatform(), GetPlatformLineBreakMode(handler));
+			}));
+		}
+
 		TextView GetPlatformLabel(LabelHandler labelHandler) =>
 			labelHandler.PlatformView;
 
diff --git a/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.cs b/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.cs
index 659d3140011c..922f7b0eb537 100644
--- a/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.cs
+++ b/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.cs
@@ -1,4 +1,5 @@
-using System.Threading.Tasks;
+using System;
+using System.Threading.Tasks;
 #if __IOS__
 using Foundation;
 #endif
@@ -26,6 +27,37 @@ void SetupBuilder()
 				});
 			});
 		}
+		
+		[Fact(DisplayName = "Does Not Leak")]
+		public async Task DoesNotLeak()
+		{
+			SetupBuilder();
+
+			WeakReference viewReference = null;
+			WeakReference platformViewReference = null;
+			WeakReference handlerReference = null;
+
+			await InvokeOnMainThreadAsync(() =>
+			{
+				var layout = new Grid();
+
+				var label = new Label
+				{
+					Text = "Test"
+				};
+
+				layout.Add(label);
+				var handler = CreateHandler<LayoutHandler>(layout);
+				viewReference = new WeakReference(label);
+				handlerReference = new WeakReference(label.Handler);
+				platformViewReference = new WeakReference(label.Handler.PlatformView);
+			});
+
+			await AssertionExtensions.WaitForGC(viewReference, handlerReference, platformViewReference);
+			Assert.False(viewReference.IsAlive, "Label should not be alive!");
+			Assert.False(handlerReference.IsAlive, "Handler should not be alive!");
+			Assert.False(platformViewReference.IsAlive, "PlatformView should not be alive!");
+		}
 
 		[Theory]
 		[ClassData(typeof(TextTransformCases))]
@@ -204,6 +236,32 @@ await InvokeOnMainThreadAsync((System.Action)(() =>
 			}));
 		}
 
+		[Fact(DisplayName = "LineBreakMode TailTruncation does not affect MaxLines")]
+		public async Task TailTruncationDoesNotAffectMaxLines()
+		{
+			var label = new Label()
+			{
+				Text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit",
+				MaxLines = 3,
+				LineBreakMode = LineBreakMode.TailTruncation,
+			};
+
+			var handler = await CreateHandlerAsync<LabelHandler>(label);
+			var platformLabel = GetPlatformLabel(handler);
+
+			await InvokeOnMainThreadAsync(() =>
+			{
+				Assert.Equal(3, GetPlatformMaxLines(handler));
+				Assert.Equal(LineBreakMode.TailTruncation.ToPlatform(), GetPlatformLineBreakMode(handler));
+
+				label.LineBreakMode = LineBreakMode.CharacterWrap;
+				platformLabel.UpdateLineBreakMode(label);
+
+				Assert.Equal(3, GetPlatformMaxLines(handler));
+				Assert.Equal(LineBreakMode.CharacterWrap.ToPlatform(), GetPlatformLineBreakMode(handler));
+			});
+		}
+
 		[Fact(DisplayName = "MaxLines Initializes Correctly")]
 		public async Task MaxLinesInitializesCorrectly()
 		{
diff --git a/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.iOS.cs b/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.iOS.cs
index 503a216bf79a..a6f3d77cbc4c 100644
--- a/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.iOS.cs
+++ b/src/Controls/tests/DeviceTests/Elements/Label/LabelTests.iOS.cs
@@ -1,7 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using Microsoft.Maui.Controls;
 using Microsoft.Maui.Handlers;
@@ -12,6 +9,27 @@ namespace Microsoft.Maui.DeviceTests
 {
 	public partial class LabelTests
 	{
+
+		[Fact(DisplayName = "Using TailTruncation LineBreakMode changes MaxLines")]
+		public async Task UsingTailTruncationSetMaxLines()
+		{
+			var label = new Label()
+			{
+				Text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit",
+				LineBreakMode = LineBreakMode.TailTruncation,
+			};
+
+			var handler = await CreateHandlerAsync<LabelHandler>(label);
+
+			var platformLabel = GetPlatformLabel(handler);
+
+			await InvokeOnMainThreadAsync((System.Action)(() =>
+			{
+				Assert.Equal(1, GetPlatformMaxLines(handler));
+				Assert.Equal(LineBreakMode.TailTruncation.ToPlatform(), GetPlatformLineBreakMode(handler));
+			}));
+		}
+				
 		UILabel GetPlatformLabel(LabelHandler labelHandler) =>
 			(UILabel)labelHandler.PlatformView;