Merge pull request #22714 from ramezgerges/text_trimming_crash

fix: don't use grapheme clusters after they have removed from a line due to TextTrimming or MaxLines

Author: ramezgerges

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_TextBlock.cs

@@ -1871,6 +1871,79 @@ public async Task When_Layered_FlowDirection(string setup)
 				_ => throw new InvalidOperationException()
 			};
 		}
+
+		[TestMethod]
+		[DataRow(TextTrimming.CharacterEllipsis, 0, TextWrapping.NoWrap)]
+		[DataRow(TextTrimming.WordEllipsis, 0, TextWrapping.NoWrap)]
+		[DataRow(TextTrimming.CharacterEllipsis, 1, TextWrapping.Wrap)]
+		[DataRow(TextTrimming.WordEllipsis, 1, TextWrapping.Wrap)]
+		[DataRow(TextTrimming.None, 1, TextWrapping.Wrap)]
+		public async Task When_Pointer_Selection_Lines_Trimmed(TextTrimming textTrimming, int maxLines, TextWrapping textWrapping)
+		{
+			var SUT = new TextBlock
+			{
+				Width = 600,
+				TextTrimming = textTrimming,
+				TextWrapping = textWrapping,
+				MaxLines = maxLines,
+				LineHeight = 20,
+				LineStackingStrategy = LineStackingStrategy.BlockLineHeight,
+				IsTextSelectionEnabled = true,
+				Text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec dignissim interdum sodales. Aliquam diam eros, malesuada a malesuada vel, congue semper enim. Donec justo magna, consectetur eget facilisis tincidunt, luctus sit amet mauris. Suspendisse sed suscipit velit. Donec egestas, lorem a accumsan faucibus, lectus nibh rutrum nisl, in convallis nulla elit nec velit. Maecenas sollicitudin lacus est, in ultrices leo auctor ut. Phasellus eget leo volutpat ante fermentum porttitor at non enim. Donec convallis sem at scelerisque porttitor. Curabitur ac eleifend libero, et blandit turpis. Aliquam erat volutpat. Phasellus eu rhoncus sapien. Nullam non tortor a turpis luctus pulvinar."
+			};
+
+			var bounds = await UITestHelper.Load(new Border { Child = SUT });
+			Assert.AreEqual(bounds.Height, SUT.LineHeight * 1);
+			Assert.IsGreaterThan(100, SUT.DesiredSize.Width); // just to make sure that the layout didn't crash
+
+			var injector = InputInjector.TryCreate() ?? throw new InvalidOperationException("Failed to init the InputInjector");
+			using var mouse = injector.GetMouse();
+
+			mouse.Press(bounds.GetCenter());
+			await UITestHelper.WaitForIdle();
+			mouse.MoveTo(new Point(bounds.Right + 10, bounds.Bottom + 10));
+			await UITestHelper.WaitForIdle();
+			mouse.Release();
+			await UITestHelper.WaitForIdle();
+
+			Assert.IsTrue(SUT.SelectedText.Contains(SUT.Text[^20..])); // selection goes to the end of text
+		}
+
+		[TestMethod]
+		[CombinatorialData]
+		public async Task When_Individual_Run_Has_FlowDirection_Set(FlowDirection flowDirection)
+		{
+			var SUT = new TextBlock
+			{
+				Inlines =
+				{
+					new Run { Text = "english" },
+					new Run { Text = "كلام بالعربي!", FlowDirection = flowDirection },
+					new Run { Text = "english" },
+				}
+			};
+
+			SUT.TextHighlighters.Add(new TextHighlighter
+			{
+				Ranges = { new TextRange { StartIndex = SUT.Text.IndexOf('!'), Length = 1 } },
+				Background = new SolidColorBrush(Colors.Red)
+			});
+
+			await UITestHelper.Load(new Border { Child = SUT });
+			var screenshot = await UITestHelper.ScreenShot(SUT);
+			var leftHalf = new Rectangle(0, 0, screenshot.Width / 2, screenshot.Height);
+			var rightHalf = new Rectangle(screenshot.Width / 2, 0, screenshot.Width / 2, screenshot.Height);
+			if (flowDirection is FlowDirection.LeftToRight)
+			{
+				ImageAssert.HasColorInRectangle(screenshot, rightHalf, Colors.Red);
+				ImageAssert.DoesNotHaveColorInRectangle(screenshot, leftHalf, Colors.Red);
+			}
+			else
+			{
+				ImageAssert.HasColorInRectangle(screenshot, leftHalf, Colors.Red);
+				ImageAssert.DoesNotHaveColorInRectangle(screenshot, rightHalf, Colors.Red);
+			}
+		}
 #endif
 	}
 }

src/Uno.UI/UI/Xaml/Documents/UnicodeText.skia.cs

@@ -593,7 +593,8 @@ internal unsafe UnicodeText(
 		totalHeight += _endingNewLineLineHeight ?? 0;
 
 		float maxLineWidthWithoutTrailingSpaces = 0;
-		_indexToCluster = new List<(int start, int end, LinkedListNode<Cluster> cluster)>(clusterBreaks.Count);
+		_indexToCluster = new List<(int start, int end, LinkedListNode<Cluster> cluster)>();
+		_clustersInLogicalOrder = new();
 		for (var lineIndex = 0; lineIndex < lines.Count; lineIndex++)
 		{
 			var line = lines[lineIndex];
@@ -602,23 +603,14 @@ internal unsafe UnicodeText(
 			{
 				node.Value = node.Value with { lineIndex = lineIndex };
 				_indexToCluster.Add((node.Value.start, node.Value.end, node));
+				_clustersInLogicalOrder.Add(node);
 				if (node == line.clusterLast)
 				{
 					break;
 				}
 			}
 		}
 
-		_clustersInLogicalOrder = new(clusterBreaks.Count);
-		for (var node = clusterBreaks.First; ; node = node!.Next)
-		{
-			_clustersInLogicalOrder.Add(node!);
-			if (node == clusterBreaks.Last)
-			{
-				break;
-			}
-		}
-
 		for (var lineIndex = 0; lineIndex < lines.Count; lineIndex++)
 		{
 			var line = lines[lineIndex];
@@ -739,10 +731,9 @@ private static (IEnumerable<LinkedListNode<Cluster>> possibleTrimPoints, int nex
 		var possibleTrimPoints = new Stack<LinkedListNode<Cluster>>();
 		var currentCluster = line.clusterStart;
 		for (var currentlineBreakOpportunity = lineBreakOpportunities[lineBreakOpportunitiesLookupStart];
-			 lineBreakOpportunitiesLookupStart < lineBreakOpportunities.Count && currentlineBreakOpportunity <= line.end;
+			 lineBreakOpportunitiesLookupStart < lineBreakOpportunities.Count && (currentlineBreakOpportunity = lineBreakOpportunities[lineBreakOpportunitiesLookupStart]) <= line.end;
 			 lineBreakOpportunitiesLookupStart++)
 		{
-			currentlineBreakOpportunity = lineBreakOpportunities[lineBreakOpportunitiesLookupStart];
 			while (currentCluster.Value.end < currentlineBreakOpportunity)
 			{
 				currentCluster = currentCluster.Next!;