Invalidate shapes changing any property inside the brushes (Fill, Stroke)

src/Controls/samples/Controls.Sample/Pages/Controls/ShapesGalleries/InvalidateBrushGallery.xaml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    x:Class="Maui.Controls.Sample.Pages.ShapesGalleries.InvalidateBrushGallery"
+    Title="Invalidate Brushes Playground">
+    <VerticalStackLayout
+        Padding="12">
+        <Button 
+            x:Name="MyButton" 
+            Text="Change color" 
+            Margin="4" 
+            HorizontalOptions="Start"/>
+        <Line 
+            x:Name="MyLine" 
+            X1="0" X2="150" 
+            StrokeThickness="4" 
+            HorizontalOptions="Start"/>
+    </VerticalStackLayout>
+</ContentPage>

src/Controls/samples/Controls.Sample/Pages/Controls/ShapesGalleries/InvalidateBrushGallery.xaml.cs

@@ -0,0 +1,49 @@
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Graphics;
+
+namespace Maui.Controls.Sample.Pages.ShapesGalleries
+{
+	public partial class InvalidateBrushGallery : ContentPage
+	{
+		SolidColorBrush _brush;
+		readonly Color[] _colors = { Colors.Green, Colors.Red, Colors.Blue };
+		int _colorIndex = -1;
+
+		public InvalidateBrushGallery()
+		{
+			InitializeComponent();
+
+			_brush = new SolidColorBrush();
+			UpdateBrush();
+
+			MyLine.Stroke = MyButton.Background = _brush;
+		}
+
+		protected override void OnAppearing()
+		{
+			base.OnAppearing();
+
+			MyButton.Clicked += OnButtonClicked;
+		}
+
+		protected override void OnDisappearing()
+		{
+			base.OnDisappearing();
+
+			MyButton.Clicked -= OnButtonClicked;
+		}
+
+		void OnButtonClicked(object sender, System.EventArgs e)
+		{
+			UpdateBrush();
+		}
+
+		void UpdateBrush()
+		{
+			if (++_colorIndex >= _colors.Length)
+				_colorIndex = 0;
+
+			_brush.Color = _colors[_colorIndex];
+		}
+	}
+}

src/Controls/samples/Controls.Sample/Pages/Controls/ShapesGalleries/ShapesGallery.cs

@@ -28,6 +28,7 @@ public ShapesGallery()
 						GalleryBuilder.NavButton("Path Gallery", () => new PathGallery(), Navigation),
 						GalleryBuilder.NavButton("Path Aspect Gallery", () => new PathAspectGallery(), Navigation),
 						GalleryBuilder.NavButton("Path LayoutOptions Gallery", () => new PathLayoutOptionsGallery(), Navigation),
+						GalleryBuilder.NavButton("Invalidate Brushes Gallery", () => new InvalidateBrushGallery(), Navigation),
 						GalleryBuilder.NavButton("Transform Playground", () => new TransformPlaygroundGallery(), Navigation),
 						GalleryBuilder.NavButton("Path Transform using string (TypeConverter) Gallery", () => new PathTransformStringGallery(), Navigation),
 						GalleryBuilder.NavButton("Animate Shape Gallery", () => new AnimateShapeGallery(), Navigation),

src/Controls/src/Core/Internals/WeakEventProxy.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Specialized;
+using System.ComponentModel;
 
 // NOTE: warning disabled for netstandard projects
 #pragma warning disable 0436
@@ -102,4 +103,53 @@ public override void Unsubscribe()
 			base.Unsubscribe();
 		}
 	}
-}
+
+	/// <summary>
+	/// A "proxy" class for subscribing INotifyPropertyChanged via WeakReference.
+	/// General usage is to store this in a member variable and call Subscribe()/Unsubscribe() appropriately.
+	/// Your class should have a finalizer that calls Unsubscribe() to prevent WeakNotifyPropertyChangedProxy objects from leaking.
+	/// </summary>
+	class WeakNotifyPropertyChangedProxy : WeakEventProxy<INotifyPropertyChanged, PropertyChangedEventHandler>
+	{
+		public WeakNotifyPropertyChangedProxy() { }
+
+		public WeakNotifyPropertyChangedProxy(INotifyPropertyChanged source, PropertyChangedEventHandler handler)
+		{
+			Subscribe(source, handler);
+		}
+
+		void OnPropertyChanged(object? sender, PropertyChangedEventArgs e)
+		{
+			if (TryGetHandler(out var handler))
+			{
+				handler(sender, e);
+			}
+			else
+			{
+				Unsubscribe();
+			}
+		}
+
+		public override void Subscribe(INotifyPropertyChanged source, PropertyChangedEventHandler handler)
+		{
+			if (TryGetSource(out var s))
+			{
+				s.PropertyChanged -= OnPropertyChanged;
+			}
+
+			source.PropertyChanged += OnPropertyChanged;
+
+			base.Subscribe(source, handler);
+		}
+
+		public override void Unsubscribe()
+		{
+			if (TryGetSource(out var s))
+			{
+				s.PropertyChanged -= OnPropertyChanged;
+			}
+
+			base.Unsubscribe();
+		}
+	}
+}

src/Controls/src/Core/PublicAPI/net-android/PublicAPI.Unshipped.txt

@@ -5,6 +5,7 @@ Microsoft.Maui.Controls.Handlers.Compatibility.FrameRenderer.FrameRenderer(Andro
 Microsoft.Maui.Controls.LayoutOptions.Equals(Microsoft.Maui.Controls.LayoutOptions other) -> bool
 Microsoft.Maui.Controls.Region.Equals(Microsoft.Maui.Controls.Region other) -> bool
 Microsoft.Maui.Controls.Shapes.Matrix.Equals(Microsoft.Maui.Controls.Shapes.Matrix other) -> bool
+Microsoft.Maui.Controls.Shapes.Shape.~Shape() -> void
 Microsoft.Maui.Controls.VisualElement.~VisualElement() -> void
 override Microsoft.Maui.Controls.LayoutOptions.GetHashCode() -> int
 override Microsoft.Maui.Controls.Region.GetHashCode() -> int

src/Controls/src/Core/PublicAPI/net-ios/PublicAPI.Unshipped.txt

@@ -3,6 +3,7 @@
 Microsoft.Maui.Controls.LayoutOptions.Equals(Microsoft.Maui.Controls.LayoutOptions other) -> bool
 Microsoft.Maui.Controls.Region.Equals(Microsoft.Maui.Controls.Region other) -> bool
 Microsoft.Maui.Controls.Shapes.Matrix.Equals(Microsoft.Maui.Controls.Shapes.Matrix other) -> bool
+Microsoft.Maui.Controls.Shapes.Shape.~Shape() -> void
 Microsoft.Maui.Controls.VisualElement.~VisualElement() -> void
 override Microsoft.Maui.Controls.LayoutOptions.GetHashCode() -> int
 override Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.TitleViewContainer.LayoutSubviews() -> void

src/Controls/src/Core/PublicAPI/net-maccatalyst/PublicAPI.Unshipped.txt

@@ -3,6 +3,7 @@
 Microsoft.Maui.Controls.LayoutOptions.Equals(Microsoft.Maui.Controls.LayoutOptions other) -> bool
 Microsoft.Maui.Controls.Region.Equals(Microsoft.Maui.Controls.Region other) -> bool
 Microsoft.Maui.Controls.Shapes.Matrix.Equals(Microsoft.Maui.Controls.Shapes.Matrix other) -> bool
+Microsoft.Maui.Controls.Shapes.Shape.~Shape() -> void
 Microsoft.Maui.Controls.VisualElement.~VisualElement() -> void
 override Microsoft.Maui.Controls.LayoutOptions.GetHashCode() -> int
 override Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.TitleViewContainer.LayoutSubviews() -> void

src/Controls/src/Core/PublicAPI/net-tizen/PublicAPI.Unshipped.txt

@@ -69,4 +69,5 @@ override Microsoft.Maui.Controls.SearchBar.IsEnabledCore.get -> bool
 Microsoft.Maui.Controls.IValueConverter.Convert(object? value, System.Type! targetType, object? parameter, System.Globalization.CultureInfo! culture) -> object?
 Microsoft.Maui.Controls.IValueConverter.ConvertBack(object? value, System.Type! targetType, object? parameter, System.Globalization.CultureInfo! culture) -> object?
 ~static Microsoft.Maui.Controls.GridExtensions.Add(this Microsoft.Maui.Controls.Grid grid, Microsoft.Maui.IView view, int left, int right, int top, int bottom) -> void
-~static Microsoft.Maui.Controls.GridExtensions.AddWithSpan(this Microsoft.Maui.Controls.Grid grid, Microsoft.Maui.IView view, int row = 0, int column = 0, int rowSpan = 1, int columnSpan = 1) -> void
+~static Microsoft.Maui.Controls.GridExtensions.AddWithSpan(this Microsoft.Maui.Controls.Grid grid, Microsoft.Maui.IView view, int row = 0, int column = 0, int rowSpan = 1, int columnSpan = 1) -> void
+Microsoft.Maui.Controls.Shapes.Shape.~Shape() -> void

src/Controls/src/Core/PublicAPI/net-windows/PublicAPI.Unshipped.txt

@@ -3,6 +3,7 @@
 Microsoft.Maui.Controls.LayoutOptions.Equals(Microsoft.Maui.Controls.LayoutOptions other) -> bool
 Microsoft.Maui.Controls.Region.Equals(Microsoft.Maui.Controls.Region other) -> bool
 Microsoft.Maui.Controls.Shapes.Matrix.Equals(Microsoft.Maui.Controls.Shapes.Matrix other) -> bool
+Microsoft.Maui.Controls.Shapes.Shape.~Shape() -> void
 Microsoft.Maui.Controls.VisualElement.~VisualElement() -> void
 override Microsoft.Maui.Controls.LayoutOptions.GetHashCode() -> int
 override Microsoft.Maui.Controls.Region.GetHashCode() -> int

src/Controls/src/Core/PublicAPI/net/PublicAPI.Unshipped.txt

@@ -3,6 +3,7 @@
 Microsoft.Maui.Controls.LayoutOptions.Equals(Microsoft.Maui.Controls.LayoutOptions other) -> bool
 Microsoft.Maui.Controls.Region.Equals(Microsoft.Maui.Controls.Region other) -> bool
 Microsoft.Maui.Controls.Shapes.Matrix.Equals(Microsoft.Maui.Controls.Shapes.Matrix other) -> bool
+Microsoft.Maui.Controls.Shapes.Shape.~Shape() -> void
 Microsoft.Maui.Controls.VisualElement.~VisualElement() -> void
 override Microsoft.Maui.Controls.LayoutOptions.GetHashCode() -> int
 override Microsoft.Maui.Controls.Region.GetHashCode() -> int

src/Controls/src/Core/PublicAPI/netstandard/PublicAPI.Unshipped.txt

@@ -3,6 +3,7 @@
 Microsoft.Maui.Controls.LayoutOptions.Equals(Microsoft.Maui.Controls.LayoutOptions other) -> bool
 Microsoft.Maui.Controls.Region.Equals(Microsoft.Maui.Controls.Region other) -> bool
 Microsoft.Maui.Controls.Shapes.Matrix.Equals(Microsoft.Maui.Controls.Shapes.Matrix other) -> bool
+Microsoft.Maui.Controls.Shapes.Shape.~Shape() -> void
 Microsoft.Maui.Controls.VisualElement.~VisualElement() -> void
 override Microsoft.Maui.Controls.LayoutOptions.GetHashCode() -> int
 override Microsoft.Maui.Controls.Region.GetHashCode() -> int

src/Controls/src/Core/Shapes/Shape.cs

@@ -1,19 +1,27 @@
 using System;
 using System.Linq;
 using System.Numerics;
-using Microsoft.Extensions.Logging;
 using Microsoft.Maui.Graphics;
 
 namespace Microsoft.Maui.Controls.Shapes
 {
 	/// <include file="../../../docs/Microsoft.Maui.Controls.Shapes/Shape.xml" path="Type[@FullName='Microsoft.Maui.Controls.Shapes.Shape']/Docs/*" />
 	public abstract partial class Shape : View, IShapeView, IShape
 	{
+		WeakNotifyPropertyChangedProxy? _fillProxy = null;
+		WeakNotifyPropertyChangedProxy? _strokeProxy = null;
+
 		/// <include file="../../../docs/Microsoft.Maui.Controls.Shapes/Shape.xml" path="//Member[@MemberName='.ctor']/Docs/*" />
 		public Shape()
 		{
 		}
 
+		~Shape()
+		{
+			_fillProxy?.Unsubscribe();
+			_strokeProxy?.Unsubscribe();
+		}
+
 		public abstract PathF GetPath();
 
 		double _fallbackWidth;
@@ -22,12 +30,30 @@ public Shape()
 		/// <include file="../../../docs/Microsoft.Maui.Controls.Shapes/Shape.xml" path="//Member[@MemberName='FillProperty']/Docs/*" />
 		public static readonly BindableProperty FillProperty =
 			BindableProperty.Create(nameof(Fill), typeof(Brush), typeof(Shape), null,
-				propertyChanged: OnBrushChanged);
+				propertyChanging: (bindable, oldvalue, newvalue) =>
+				{
+					if (oldvalue != null)
+						(bindable as Shape)?.StopNotifyingFillChanges();
+				},
+				propertyChanged: (bindable, oldvalue, newvalue) =>
+				{
+					if (newvalue != null)
+						(bindable as Shape)?.NotifyFillChanges();
+				});
 
 		/// <include file="../../../docs/Microsoft.Maui.Controls.Shapes/Shape.xml" path="//Member[@MemberName='StrokeProperty']/Docs/*" />
 		public static readonly BindableProperty StrokeProperty =
 			BindableProperty.Create(nameof(Stroke), typeof(Brush), typeof(Shape), null,
-				propertyChanged: OnBrushChanged);
+				propertyChanging: (bindable, oldvalue, newvalue) =>
+				{
+					if (oldvalue != null)
+						(bindable as Shape)?.StopNotifyingStrokeChanges();
+				},
+				propertyChanged: (bindable, oldvalue, newvalue) =>
+				{
+					if (newvalue != null)
+						(bindable as Shape)?.NotifyStrokeChanges();
+				});
 
 		/// <include file="../../../docs/Microsoft.Maui.Controls.Shapes/Shape.xml" path="//Member[@MemberName='StrokeThicknessProperty']/Docs/*" />
 		public static readonly BindableProperty StrokeThicknessProperty =
@@ -162,15 +188,62 @@ public float[] StrokeDashPattern
 
 		float IStroke.StrokeMiterLimit => (float)StrokeMiterLimit;
 
-		static void OnBrushChanged(BindableObject bindable, object oldValue, object newValue)
+		void NotifyFillChanges()
+		{
+			var fill = Fill;
+
+			if (fill is ImmutableBrush)
+				return;
+
+			if (fill is not null)
+			{
+				SetInheritedBindingContext(fill, BindingContext);
+				var proxy = _fillProxy ??= new();
+				proxy.Subscribe(fill, (sender, e) => OnPropertyChanged(nameof(Fill)));
+			}
+		}
+
+		void StopNotifyingFillChanges()
 		{
-			((Shape)bindable).UpdateBrushParent((Brush)newValue);
+			var fill = Fill;
+
+			if (fill is ImmutableBrush)
+				return;
+
+			if (fill is not null)
+			{
+				SetInheritedBindingContext(fill, null);
+				_fillProxy?.Unsubscribe();
+			}
 		}
 
-		void UpdateBrushParent(Brush brush)
+		void NotifyStrokeChanges()
 		{
-			if (brush != null && brush is not ImmutableBrush)
-				brush.Parent = this;
+			var stroke = Stroke;
+
+			if (stroke is ImmutableBrush)
+				return;
+
+			if (stroke is not null)
+			{
+				SetInheritedBindingContext(stroke, BindingContext);
+				var proxy = _strokeProxy ??= new();
+				proxy.Subscribe(stroke, (sender, e) => OnPropertyChanged(nameof(Stroke)));
+			}
+		}
+
+		void StopNotifyingStrokeChanges()
+		{
+			var stroke = Stroke;
+
+			if (stroke is ImmutableBrush)
+				return;
+
+			if (stroke is not null)
+			{
+				SetInheritedBindingContext(stroke, null);
+				_strokeProxy?.Unsubscribe();
+			}
 		}
 
 		PathF IShape.PathForBounds(Graphics.Rect viewBounds)
@@ -360,4 +433,4 @@ internal double HeightForPathComputation
 			}
 		}
 	}
-}
+}

src/Controls/tests/DeviceTests/Elements/Shape/ShapeTests.Android.cs

@@ -0,0 +1,20 @@
+using System.Threading.Tasks;
+using AndroidX.AppCompat.Widget;
+using Microsoft.Maui.Handlers;
+
+namespace Microsoft.Maui.DeviceTests
+{
+	public partial class ShapeTests
+	{
+		Task PerformClick(IButton button)
+		{
+			return InvokeOnMainThreadAsync(() =>
+			{
+				GetNativeButton(CreateHandler<ButtonHandler>(button)).PerformClick();
+			});
+		}
+
+		AppCompatButton GetNativeButton(ButtonHandler buttonHandler) =>
+			buttonHandler.PlatformView;
+	}
+}

src/Controls/tests/DeviceTests/Elements/Shape/ShapeTests.Windows.cs

@@ -0,0 +1,24 @@
+using System.Threading.Tasks;
+using Microsoft.Maui.Handlers;
+using Microsoft.UI.Xaml.Automation.Peers;
+using Microsoft.UI.Xaml.Automation.Provider;
+
+namespace Microsoft.Maui.DeviceTests
+{
+	public partial class ShapeTests
+	{
+		Task PerformClick(IButton button)
+		{
+			return InvokeOnMainThreadAsync(() =>
+			{
+				var platformButton = GetNativeButton(CreateHandler<ButtonHandler>(button));
+				var ap = new ButtonAutomationPeer(platformButton);
+				var ip = ap.GetPattern(PatternInterface.Invoke) as IInvokeProvider;
+				ip?.Invoke();
+			});
+
+			UI.Xaml.Controls.Button GetNativeButton(ButtonHandler buttonHandler) =>
+				buttonHandler.PlatformView;
+		}
+	}
+}