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[Feature] Add FillRule property for Polyline/Polygon #20159

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[Feature] Add FillRule property for Polyline/Polygon #20159

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d8b5637
Implement FillRuleProperty on Polyline
jsuarezruiz Nov 27, 2025
98bcd5d
Implement FillRule Property on Polygon
jsuarezruiz Nov 27, 2025
fde2e55
Add tests
jsuarezruiz Nov 27, 2025
1eac798
Added comments to new public APIs
jsuarezruiz Nov 27, 2025
471d0fd
Added more comments
jsuarezruiz Nov 27, 2025
ac00710
More tests
jsuarezruiz Nov 27, 2025
eb73efc
More tests
jsuarezruiz Nov 27, 2025
571e74a
Merge branch 'master' into fix-20158
jsuarezruiz Nov 27, 2025
451aed2
Updated API
jsuarezruiz Nov 27, 2025
1814b72
Merge branch 'fix-20158' of https://github.com/jsuarezruiz/Avalonia i…
jsuarezruiz Nov 27, 2025
b54d180
Added render tests
jsuarezruiz Dec 5, 2025
343549b
More render tests
jsuarezruiz Dec 5, 2025
8cc5f37
Reintroducing the original PolylineGeometry constructor
jsuarezruiz Dec 5, 2025
a973fef
Updated API file
jsuarezruiz Dec 5, 2025
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16 changes: 14 additions & 2 deletions src/Avalonia.Base/Media/PolylineGeometry.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ public class PolylineGeometry : Geometry

private IList<Point> _points;
private IDisposable? _pointsObserver;
private readonly FillRule _fillRule;

static PolylineGeometry()
{
Expand All @@ -40,15 +41,17 @@ static PolylineGeometry()
public PolylineGeometry()
{
_points = new Points();
_fillRule = FillRule.EvenOdd;
}

/// <summary>
/// Initializes a new instance of the <see cref="PolylineGeometry"/> class.
/// </summary>
public PolylineGeometry(IEnumerable<Point> points, bool isFilled)
public PolylineGeometry(IEnumerable<Point> points, bool isFilled, FillRule fillRule = FillRule.EvenOdd)
{
_points = new Points(points);
IsFilled = isFilled;
_fillRule = fillRule;
}

/// <summary>
Expand All @@ -70,10 +73,18 @@ public bool IsFilled
set => SetValue(IsFilledProperty, value);
}

/// <summary>
/// Gets how the intersecting areas of the polyline are combined.
/// </summary>
public FillRule FillRule => _fillRule;

/// <inheritdoc/>
public override Geometry Clone()
{
return new PolylineGeometry(Points, IsFilled);
return new PolylineGeometry(Points, IsFilled, _fillRule)
{
Transform = Transform
};
}

private protected sealed override IGeometryImpl? CreateDefiningGeometry()
Expand All @@ -83,6 +94,7 @@ public override Geometry Clone()

using (var context = geometry.Open())
{
context.SetFillRule(_fillRule);
var points = Points;
var isFilled = IsFilled;
if (points.Count > 0)
Expand Down
13 changes: 11 additions & 2 deletions src/Avalonia.Controls/Shapes/Polygon.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,9 +9,12 @@ public class Polygon : Shape
public static readonly StyledProperty<IList<Point>> PointsProperty =
AvaloniaProperty.Register<Polygon, IList<Point>>("Points");

public static readonly StyledProperty<FillRule> FillRuleProperty =
AvaloniaProperty.Register<Polygon, FillRule>(nameof(FillRule));

static Polygon()
{
AffectsGeometry<Polygon>(PointsProperty);
AffectsGeometry<Polygon>(PointsProperty, FillRuleProperty);
}

public Polygon()
Expand All @@ -25,9 +28,15 @@ public IList<Point> Points
set => SetValue(PointsProperty, value);
}

public FillRule FillRule
{
get => GetValue(FillRuleProperty);
set => SetValue(FillRuleProperty, value);
}

protected override Geometry CreateDefiningGeometry()
{
return new PolylineGeometry { Points = Points, IsFilled = true };
return new PolylineGeometry(Points, isFilled: true, fillRule: FillRule);
}
}
}
14 changes: 12 additions & 2 deletions src/Avalonia.Controls/Shapes/Polyline.cs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
using System;
using System.Collections.Generic;
using Avalonia;
using Avalonia.Media;
using Avalonia.Data;

Expand All @@ -10,10 +11,13 @@ public class Polyline : Shape
public static readonly StyledProperty<IList<Point>> PointsProperty =
AvaloniaProperty.Register<Polyline, IList<Point>>("Points");

public static readonly StyledProperty<FillRule> FillRuleProperty =
AvaloniaProperty.Register<Polyline, FillRule>(nameof(FillRule));

static Polyline()
{
StrokeThicknessProperty.OverrideDefaultValue<Polyline>(1);
AffectsGeometry<Polyline>(PointsProperty);
AffectsGeometry<Polyline>(PointsProperty, FillRuleProperty);
}

public Polyline()
Expand All @@ -27,9 +31,15 @@ public IList<Point> Points
set => SetValue(PointsProperty, value);
}

public FillRule FillRule
{
get => GetValue(FillRuleProperty);
set => SetValue(FillRuleProperty, value);
}

protected override Geometry CreateDefiningGeometry()
{
return new PolylineGeometry { Points = Points, IsFilled = false };
return new PolylineGeometry(Points, isFilled: true, fillRule: FillRule);
}
}
}
18 changes: 18 additions & 0 deletions tests/Avalonia.Controls.UnitTests/Shapes/PolygonTests.cs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
using System.Collections.ObjectModel;
using Avalonia.Controls.Shapes;
using Avalonia.Media;
using Avalonia.UnitTests;
using Xunit;

Expand All @@ -25,4 +26,21 @@ public void Polygon_Will_Update_Geometry_On_Shapes_Collection_Content_Change()

root.Child = null;
}

[Fact]
public void FillRule_On_Polygon_Is_Applied_To_DefiningGeometry()
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@jsuarezruiz jsuarezruiz Nov 27, 2025

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Note: Tested in the Gallery already but there is not a specific Shapes Page. Should include it?

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@jsuarezruiz jsuarezruiz Nov 27, 2025

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Tested with:

<TextBlock Classes="h3" Margin="0,12,0,4">Path FillRule</TextBlock>
  <TextBlock Text="EvenOdd creates holes for nested figures; NonZero keeps the interior filled when the contours wind in the same direction." />
  <StackPanel Orientation="Horizontal" Spacing="12">
    <StackPanel Spacing="4">
      <TextBlock Text="EvenOdd" />
      <Border Background="White" BorderBrush="Gainsboro" BorderThickness="1" Padding="8" CornerRadius="4">
        <Path Width="140"
              Height="140"
              Stretch="Fill"
              Fill="Orange"
              Stroke="Black"
              StrokeThickness="1"
              Data="F1 M 10,10 L 130,10 130,130 10,130 Z M 50,50 L 90,50 90,90 50,90 Z"/>
      </Border>
    </StackPanel>
    <StackPanel Spacing="4">
      <TextBlock Text="NonZero" />
      <Border Background="White" BorderBrush="Gainsboro" BorderThickness="1" Padding="8" CornerRadius="4">
        <Path Width="140"
              Height="140"
              Stretch="Fill"
              Fill="Orange"
              Stroke="Black"
              StrokeThickness="1"
              Data="F0 M 10,10 L 130,10 130,130 10,130 Z M 50,50 L 90,50 90,90 50,90 Z"/>
      </Border>
    </StackPanel>
  </StackPanel>
  <TextBlock Classes="h3" Margin="0,12,0,4">Polygon/Polyline FillRule</TextBlock>
  <TextBlock Text="Self-intersecting polygons show different winding behavior for EvenOdd and NonZero." />
  <StackPanel Orientation="Horizontal" Spacing="12">
    <StackPanel Spacing="4">
      <TextBlock Text="EvenOdd" />
      <Border Background="White" BorderBrush="Gainsboro" BorderThickness="1" Padding="8" CornerRadius="4">
        <Polygon Width="160"
                 Height="160"
                 Stretch="Fill"
                 Fill="Gold"
                 Stroke="Black"
                 StrokeThickness="1"
                 FillRule="EvenOdd"
                 Points="50,0  21,90  98,35  2,35  79,90" />
      </Border>
    </StackPanel>
    <StackPanel Spacing="4">
      <TextBlock Text="NonZero" />
      <Border Background="White" BorderBrush="Gainsboro" BorderThickness="1" Padding="8" CornerRadius="4">
        <Polygon Width="160"
                 Height="160"
                 Stretch="Fill"
                 Fill="Gold"
                 Stroke="Black"
                 StrokeThickness="1"
                 FillRule="NonZero"
                 Points="50,0  21,90  98,35  2,35  79,90" />
      </Border>
    </StackPanel>
  </StackPanel>
  <TextBlock Classes="h3" Margin="0,12,0,4">Polyline FillRule</TextBlock>
  <TextBlock Text="A jagged filled polyline using NonZero/EvenOdd winding (adapted from WPF FillRule sample)." />
  <StackPanel Orientation="Horizontal" Spacing="12">
    <StackPanel Spacing="4">
      <TextBlock Text="EvenOdd" />
      <Border Background="White" BorderBrush="Gainsboro" BorderThickness="1" Padding="8" CornerRadius="4">
        <Polyline Width="200"
                  Height="140"
                  Stretch="Fill"
                  Fill="Red"
                  Stroke="Black"
                  StrokeThickness="2"
                  FillRule="EvenOdd"
                  Points="10,140
                  60,20
                  110,140
                  20,60
                  180,60
                  90,140
                  140,20
                  10,140" />
      </Border>
    </StackPanel>
    <StackPanel Spacing="4">
      <TextBlock Text="NonZero" />
      <Border Background="White" BorderBrush="Gainsboro" BorderThickness="1" Padding="8" CornerRadius="4">
        <Polyline Width="200"
                  Height="140"
                  Stretch="Fill"
                  Fill="Red"
                  Stroke="Black"
                  StrokeThickness="2"
                  FillRule="NonZero"
                  Points="10,140
                  60,20
                  110,140
                  20,60
                  180,60
                  90,140
                  140,20
                  10,140" />
      </Border>
    </StackPanel>
  </StackPanel>

{
using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);

var target = new Polygon
{
Points = new Points { new Point(0, 0), new Point(10, 10), new Point(20, 0) },
FillRule = FillRule.NonZero
};

target.Measure(Size.Infinity);

var geometry = Assert.IsType<PolylineGeometry>(target.DefiningGeometry);
Assert.Equal(FillRule.NonZero, geometry.FillRule);
}
}
18 changes: 18 additions & 0 deletions tests/Avalonia.Controls.UnitTests/Shapes/PolylineTests.cs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
using System.Collections.ObjectModel;
using Avalonia.Controls.Shapes;
using Avalonia.Media;
using Avalonia.UnitTests;
using Xunit;

Expand All @@ -25,4 +26,21 @@ public void Polyline_Will_Update_Geometry_On_Shapes_Collection_Content_Change()

root.Child = null;
}

[Fact]
public void FillRule_On_Polyline_Is_Applied_To_DefiningGeometry()
{
using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);

var target = new Polyline
{
Points = new Points { new Point(0, 0), new Point(10, 10), new Point(20, 0) },
FillRule = FillRule.NonZero
};

target.Measure(Size.Infinity);

var geometry = Assert.IsType<PolylineGeometry>(target.DefiningGeometry);
Assert.Equal(FillRule.NonZero, geometry.FillRule);
}
}
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