Fix TextWrapping in combination with TextEndOfLine runs (#18523)

Author: Gillibald

src/Avalonia.Base/Media/TextFormatting/TextFormatterImpl.cs

@@ -574,10 +574,11 @@ private static int MeasureLength(IReadOnlyList<TextRun> textRuns, double paragra
         {
             var measuredLength = 0;
             var currentWidth = 0.0;
+            var runIndex = 0;
 
-            for (var i = 0; i < textRuns.Count; ++i)
+            for (; runIndex < textRuns.Count; ++runIndex)
             {
-                var currentRun = textRuns[i];
+                var currentRun = textRuns[runIndex];
 
                 switch (currentRun)
                 {
@@ -630,7 +631,14 @@ private static int MeasureLength(IReadOnlyList<TextRun> textRuns, double paragra
                                             runLength = clusterLength;
                                         }
 
-                                        return measuredLength + runLength;
+                                        measuredLength += runLength;
+
+                                        if (runIndex < textRuns.Count - 1 && runLength == currentRun.Length && textRuns[runIndex + 1] is TextEndOfLine endOfLine)
+                                        {
+                                            measuredLength += endOfLine.Length;
+                                        }
+
+                                        return measuredLength;
                                     }
 
                                     currentWidth += clusterWidth;

tests/Avalonia.Skia.UnitTests/Media/TextFormatting/TextLayoutTests.cs

@@ -1160,6 +1160,30 @@ public void Should_Measure_TextLayoutSymbolWithAndWidthIncludingTrailingWhitespa
             }
         }
 
+        [Fact]
+        public void Should_Wrap_With_LineEnd()
+        {
+            using (Start())
+            {
+                var defaultProperties =
+                   new GenericTextRunProperties(Typeface.Default, 72, foregroundBrush: Brushes.Black);
+
+                var paragraphProperties = new GenericTextParagraphProperties(defaultProperties, textWrap: TextWrapping.Wrap);
+
+                var textLayout = new TextLayout(new SingleBufferTextSource("01", defaultProperties, true), paragraphProperties, maxWidth: 36);
+
+                Assert.Equal(2, textLayout.TextLines.Count);
+
+                var lastLine = textLayout.TextLines.Last();
+
+                Assert.Equal(2, lastLine.TextRuns.Count);
+
+                var lastRun = lastLine.TextRuns.Last();
+
+                Assert.IsAssignableFrom<TextEndOfLine>(lastRun);
+            }
+        }
+
         private static IDisposable Start()
         {
             var disposable = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface