[Feature] Add StrokeMiterLimit property to Shape (#20156)

* Added StrokeMiterLimitProperty

* Added tests

src/Avalonia.Controls/Shapes/Shape.cs

@@ -60,6 +60,12 @@ namespace Avalonia.Controls.Shapes
         public static readonly StyledProperty<PenLineJoin> StrokeJoinProperty =
             AvaloniaProperty.Register<Shape, PenLineJoin>(nameof(StrokeJoin), PenLineJoin.Miter);
 
+        /// <summary>
+        /// Defines the <see cref="StrokeMiterLimit"/> property.
+        /// </summary>
+        public static readonly StyledProperty<double> StrokeMiterLimitProperty =
+            AvaloniaProperty.Register<Shape, double>(nameof(StrokeMiterLimit), 10.0);
+
         private Matrix _transform = Matrix.Identity;
         private Geometry? _definingGeometry;
         private Geometry? _renderedGeometry;
@@ -191,6 +197,15 @@ namespace Avalonia.Controls.Shapes
             get => GetValue(StrokeJoinProperty);
             set => SetValue(StrokeJoinProperty, value);
         }
+
+        /// <summary>
+        /// Gets or sets the limit on the ratio of the miter length to half the <see cref="StrokeThickness"/> of the pen.
+        /// </summary>
+        public double StrokeMiterLimit
+        {
+            get => GetValue(StrokeMiterLimitProperty);
+            set => SetValue(StrokeMiterLimitProperty, value);
+        }
         
         private EventHandler GeometryChangedHandler => _geometryChangedHandler ??= OnGeometryChanged;
 
@@ -270,7 +285,8 @@ namespace Avalonia.Controls.Shapes
                 || change.Property == StrokeDashArrayProperty
                 || change.Property == StrokeDashOffsetProperty
                 || change.Property == StrokeLineCapProperty
-                || change.Property == StrokeJoinProperty)
+                || change.Property == StrokeJoinProperty
+                || change.Property == StrokeMiterLimitProperty)
             {
                 if (change.Property == StrokeProperty
                     || change.Property == StrokeThicknessProperty)
@@ -278,7 +294,7 @@ namespace Avalonia.Controls.Shapes
                     InvalidateMeasure();
                 }
                 
-                if (Pen.TryModifyOrCreate(ref _strokePen, Stroke, StrokeThickness, StrokeDashArray, StrokeDashOffset, StrokeLineCap, StrokeJoin))
+                if (Pen.TryModifyOrCreate(ref _strokePen, Stroke, StrokeThickness, StrokeDashArray, StrokeDashOffset, StrokeLineCap, StrokeJoin, StrokeMiterLimit))
                 {
                     InvalidateVisual();
                 }

tests/Avalonia.Controls.UnitTests/Shapes/ShapeTests.cs

@@ -0,0 +1,215 @@
+using Avalonia.Collections;
+using Avalonia.Controls.Shapes;
+using Avalonia.Media;
+using Avalonia.Platform;
+using Avalonia.Rendering.SceneGraph;
+using Avalonia.UnitTests;
+using Avalonia.Utilities;
+using Xunit;
+
+namespace Avalonia.Controls.UnitTests.Shapes;
+
+public class ShapeTests : ScopedTestBase
+{
+    [Fact]
+    public void StrokeMiterLimit_Default_Is_Applied_To_Pen()
+    {
+        using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+        var pen = RenderAndGetPen(new TestShape
+        {
+            StrokeThickness = 4,
+            Stroke = Brushes.Black
+        });
+
+        Assert.NotNull(pen);
+        Assert.Equal(10, pen!.MiterLimit);
+    }
+
+    [Fact]
+    public void StrokeMiterLimit_Update_Refreshes_Pen()
+    {
+        using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+        var shape = new TestShape
+        {
+            StrokeThickness = 4,
+            Stroke = Brushes.Black
+        };
+
+        RenderAndGetPen(shape);
+        shape.StrokeMiterLimit = 2;
+        var pen = RenderAndGetPen(shape);
+
+        Assert.NotNull(pen);
+        Assert.Equal(2, pen!.MiterLimit);
+    }
+
+    [Fact]
+    public void StrokeThickness_Is_Applied_To_Pen()
+    {
+        using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+        var pen = RenderAndGetPen(new TestShape
+        {
+            StrokeThickness = 6,
+            Stroke = Brushes.Black
+        });
+
+        Assert.NotNull(pen);
+        Assert.Equal(6, pen!.Thickness);
+    }
+
+    [Fact]
+    public void StrokeLineCap_And_Join_Are_Applied_To_Pen()
+    {
+        using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+        var pen = RenderAndGetPen(new TestShape
+        {
+            Stroke = Brushes.Black,
+            StrokeThickness = 4,
+            StrokeLineCap = PenLineCap.Round,
+            StrokeJoin = PenLineJoin.Bevel
+        });
+
+        Assert.NotNull(pen);
+        Assert.Equal(PenLineCap.Round, pen!.LineCap);
+        Assert.Equal(PenLineJoin.Bevel, pen.LineJoin);
+    }
+
+    [Fact]
+    public void StrokeDashArray_And_Offset_Are_Applied_To_Pen()
+    {
+        using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+        var pen = RenderAndGetPen(new TestShape
+        {
+            Stroke = Brushes.Black,
+            StrokeThickness = 4,
+            StrokeDashArray = new AvaloniaList<double>(1, 2, 3),
+            StrokeDashOffset = 1.5
+        });
+
+        Assert.NotNull(pen);
+        Assert.NotNull(pen!.DashStyle);
+        Assert.Equal(3, pen.DashStyle!.Dashes.Count);
+        Assert.Equal(1, pen.DashStyle.Dashes[0]);
+        Assert.Equal(2, pen.DashStyle.Dashes[1]);
+        Assert.Equal(3, pen.DashStyle.Dashes[2]);
+        Assert.Equal(1.5, pen.DashStyle.Offset);
+    }
+
+    [Fact]
+    public void No_Stroke_Produces_No_Pen()
+    {
+        using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+        var pen = RenderAndGetPen(new TestShape
+        {
+            Stroke = null,
+            StrokeThickness = 4
+        });
+
+        Assert.Null(pen);
+    }
+
+    private static IPen? RenderAndGetPen(Shape shape)
+    {
+        using var context = new RecordingDrawingContext();
+        shape.Render(context);
+        return context.LastPen;
+    }
+
+    private class TestShape : Shape
+    {
+        protected override Geometry? CreateDefiningGeometry() =>
+            new RectangleGeometry(new Rect(0, 0, 20, 20));
+    }
+
+    private class RecordingDrawingContext : DrawingContext
+    {
+        public IPen? LastPen { get; private set; }
+
+        public void Reset() => LastPen = null;
+
+        internal override void DrawBitmap(IRef<IBitmapImpl> source, double opacity, Rect sourceRect, Rect destRect)
+        {
+        }
+
+        protected override void DrawLineCore(IPen pen, Point p1, Point p2)
+        {
+        }
+
+        protected override void DrawGeometryCore(IBrush? brush, IPen? pen, IGeometryImpl geometry)
+        {
+            LastPen = pen;
+        }
+
+        protected override void DrawRectangleCore(IBrush? brush, IPen? pen, RoundedRect rrect, BoxShadows boxShadows = default)
+        {
+        }
+
+        protected override void DrawEllipseCore(IBrush? brush, IPen? pen, Rect rect)
+        {
+        }
+
+        public override void Custom(ICustomDrawOperation custom)
+        {
+        }
+
+        public override void DrawGlyphRun(IBrush? foreground, GlyphRun glyphRun)
+        {
+        }
+
+        protected override void PushClipCore(RoundedRect rect)
+        {
+        }
+
+        protected override void PushClipCore(Rect rect)
+        {
+        }
+
+        protected override void PushGeometryClipCore(Geometry clip)
+        {
+        }
+
+        protected override void PushOpacityCore(double opacity)
+        {
+        }
+
+        protected override void PushOpacityMaskCore(IBrush mask, Rect bounds)
+        {
+        }
+
+        protected override void PushRenderOptionsCore(RenderOptions renderOptions)
+        {
+        }
+
+        protected override void PushTransformCore(Matrix matrix)
+        {
+        }
+
+        protected override void PopClipCore()
+        {
+        }
+
+        protected override void PopGeometryClipCore()
+        {
+        }
+
+        protected override void PopOpacityCore()
+        {
+        }
+
+        protected override void PopOpacityMaskCore()
+        {
+        }
+
+        protected override void PopTransformCore()
+        {
+        }
+
+        protected override void PopRenderOptionsCore()
+        {
+        }
+
+        protected override void DisposeCore()
+        {
+        }
+    }
+}