From 74bbfd8509c34c82d7f73f9bd1e85f9e1801414a Mon Sep 17 00:00:00 2001
From: Benedikt Stebner <Gillibald@users.noreply.github.com>
Date: Wed, 11 Jan 2023 15:35:07 +0100
Subject: [PATCH] Support intercepts for all location but
 TextDecorationLocation.Strikethrough

---
 src/Avalonia.Base/Media/TextDecoration.cs | 19 +++++++++----------
 tests/Avalonia.Benchmarks/NullGlyphRun.cs |  8 +++++++-
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/Avalonia.Base/Media/TextDecoration.cs b/src/Avalonia.Base/Media/TextDecoration.cs
index 0ed73e7786..d6b2841214 100644
--- a/src/Avalonia.Base/Media/TextDecoration.cs
+++ b/src/Avalonia.Base/Media/TextDecoration.cs
@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using Avalonia.Collections;
 using Avalonia.Collections.Pooled;
 using Avalonia.Media.TextFormatting;
@@ -200,26 +201,24 @@ namespace Avalonia.Media
                     break;
             }
 
-            var strokeOffset = 0.0;
-
             switch (StrokeOffsetUnit)
             {
                 case TextDecorationUnit.FontRenderingEmSize:
-                    strokeOffset = StrokeOffset * textMetrics.FontRenderingEmSize;
+                    origin += new Point(0, StrokeOffset * textMetrics.FontRenderingEmSize);
                     break;
                 case TextDecorationUnit.Pixel:
-                    strokeOffset = StrokeOffset;
+                    origin += new Point(0, StrokeOffset);
                     break;
             }
 
-            origin += new Point(0, strokeOffset);
-
             var pen = new Pen(Stroke ?? defaultBrush, thickness,
                 new DashStyle(StrokeDashArray, StrokeDashOffset), StrokeLineCap);
 
-            if (Location == TextDecorationLocation.Underline && MathUtilities.IsZero(strokeOffset))
+            if (Location != TextDecorationLocation.Strikethrough)
             {
-                var intersections = glyphRun.GlyphRunImpl.GetIntersections((float)(thickness * 0.5d + strokeOffset), (float)(thickness * 1.5d + strokeOffset));
+                var offsetY = glyphRun.BaselineOrigin.Y - origin.Y;
+
+                var intersections = glyphRun.GlyphRunImpl.GetIntersections((float)(thickness * 0.5d - offsetY), (float)(thickness * 1.5d - offsetY));
 
                 if (intersections != null && intersections.Count > 0)
                 {
@@ -257,7 +256,7 @@ namespace Avalonia.Media
                     }
 
                     return;
-                }              
+                }
             }
 
             drawingContext.DrawLine(pen, origin, origin + new Point(glyphRun.Metrics.Width, 0));
diff --git a/tests/Avalonia.Benchmarks/NullGlyphRun.cs b/tests/Avalonia.Benchmarks/NullGlyphRun.cs
index 5ba0822649..1c2c7c0d7d 100644
--- a/tests/Avalonia.Benchmarks/NullGlyphRun.cs
+++ b/tests/Avalonia.Benchmarks/NullGlyphRun.cs
@@ -1,4 +1,5 @@
-using Avalonia.Platform;
+using System.Collections.Generic;
+using Avalonia.Platform;
 
 namespace Avalonia.Benchmarks
 {
@@ -7,5 +8,10 @@ namespace Avalonia.Benchmarks
         public void Dispose()
         {
         }
+
+        public IReadOnlyList<float> GetIntersections(float lowerBound, float upperBound)
+        {
+            return null;
+        }
     }
 }