Fix TextLayout.Width calculation (#18305) (#18310)

* Fix TextLayout.Width calculation (#18305)

* Use WinSymbols3.ttf

Author: xoofx

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

@@ -679,20 +679,47 @@ private TextLine[] CreateTextLines()
 
         private void UpdateMetrics(TextLineImpl currentLine, ref bool first)
         {
-            _metrics.InkBounds = _metrics.InkBounds.Union(new Rect(new Point(0, _metrics.Bounds.Bottom) + currentLine.InkBounds.Position, currentLine.InkBounds.Size));
-            _metrics.Bounds = _metrics.Bounds.Union(new Rect(new Point(0, _metrics.Bounds.Bottom) + currentLine.Bounds.Position, currentLine.Bounds.Size));
+            // 1) Offset each line’s bounding rectangles by the total height so far,
+            //    so we keep an overall bounding box for the entire text block.
+            var lineTop = _metrics.Height;
 
-            _metrics.MinTextWidth = Math.Max(_metrics.MinTextWidth, currentLine.Bounds.Width);
-            _metrics.MinTextWidth = Math.Max(_metrics.MinTextWidth, currentLine.InkBounds.Width);
+            // Offset the line's Bounds
+            var lineBoundsRect = new Rect(
+                currentLine.Bounds.X,
+                lineTop + currentLine.Bounds.Y,
+                currentLine.Bounds.Width,
+                currentLine.Bounds.Height);
 
-            _metrics.Height = _metrics.Bounds.Height;
-            _metrics.Width = _metrics.InkBounds.Width;
-            _metrics.WidthIncludingTrailingWhitespace = _metrics.Bounds.Width;
-            _metrics.Extent = _metrics.InkBounds.Height;
-            _metrics.OverhangLeading = Math.Max(0, _metrics.Bounds.Left - _metrics.InkBounds.Left);
-            _metrics.OverhangTrailing = Math.Max(0, _metrics.InkBounds.Right - _metrics.Bounds.Right);
-            _metrics.OverhangAfter = Math.Max(0, _metrics.InkBounds.Bottom - _metrics.Bounds.Bottom);
+            _metrics.Bounds = _metrics.Bounds.Union(lineBoundsRect);
 
+            // Offset the line's InkBounds
+            var lineInkRect = new Rect(
+                currentLine.InkBounds.X,
+                lineTop + currentLine.InkBounds.Y,
+                currentLine.InkBounds.Width,
+                currentLine.InkBounds.Height);
+
+            _metrics.InkBounds = _metrics.InkBounds.Union(lineInkRect);
+
+            // 2) Accumulate total layout height by adding the line’s Height.
+            _metrics.Height += currentLine.Height;
+
+            // 3) For the layout’s Width and WidthIncludingTrailingWhitespace,
+            //    use the maximum of the line widths rather than the bounding box.
+            _metrics.Width = Math.Max(_metrics.Width, currentLine.Width);
+            _metrics.WidthIncludingTrailingWhitespace = Math.Max(_metrics.WidthIncludingTrailingWhitespace, currentLine.WidthIncludingTrailingWhitespace);
+
+            // 4) Extent is the max black-pixel extent among lines.
+            _metrics.Extent = Math.Max(_metrics.Extent, currentLine.Extent);
+
+            // 5) We can track min-text-width or overhangs similarly if needed.
+            _metrics.MinTextWidth = Math.Max(_metrics.MinTextWidth, currentLine.Width);
+
+            _metrics.OverhangLeading = Math.Max(_metrics.OverhangLeading, currentLine.OverhangLeading);
+            _metrics.OverhangTrailing = Math.Max(_metrics.OverhangTrailing, currentLine.OverhangTrailing);
+            _metrics.OverhangAfter = Math.Max(_metrics.OverhangAfter, currentLine.OverhangAfter);
+
+            // 6) Capture the baseline from the first line.
             if (first)
             {
                 _metrics.Baseline = currentLine.Baseline;

tests/Avalonia.Skia.UnitTests/Avalonia.Skia.UnitTests.csproj

@@ -12,8 +12,10 @@
     <EmbeddedResource Include="..\Avalonia.RenderTests\*\*.ttf" />
     <None Remove="Fonts\DejaVuSans.ttf" />
     <None Remove="Fonts\Manrope-Light.ttf" />
+    <None Remove="Fonts\WinSymbols3.ttf" />
     <EmbeddedResource Include="Fonts\DejaVuSans.ttf" />
     <EmbeddedResource Include="Fonts\Manrope-Light.ttf" />
+    <EmbeddedResource Include="Fonts\WinSymbols3.ttf" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\Avalonia.Base\Avalonia.Base.csproj" />

tests/Avalonia.Skia.UnitTests/Fonts/WinSymbols3.ttf

@@ -1147,6 +1147,19 @@ public void Should_Handle_TextStyle_With_Ligature()
             }
         }
 
+        [Fact]
+        public void Should_Measure_TextLayoutSymbolWithAndWidthIncludingTrailingWhitespace()
+        {
+            const string symbolsFont = "resm:Avalonia.Skia.UnitTests.Fonts?assembly=Avalonia.Skia.UnitTests#Symbols";
+            using (Start())
+            {
+                var textLayout = new TextLayout("\ue971", new Typeface(symbolsFont), 12.0, Brushes.White);
+
+                Assert.Equal(new Size(12.0, 12.0), new Size(textLayout.Width, textLayout.Height));
+                Assert.Equal(12.0, textLayout.WidthIncludingTrailingWhitespace);
+            }
+        }
+
         private static IDisposable Start()
         {
             var disposable = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface