[Android] Fix Ripple effect with custom background (alternative to #17821)

src/Controls/samples/Controls.Sample.UITests/Issues/Issue17642.xaml

@@ -0,0 +1,132 @@
+<?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.Issues.Issue17642"
+    Title="Issue 17642">
+    <ContentPage.Resources>
+        <ResourceDictionary>
+
+            <Style TargetType="Button">
+                <Setter Property="Margin" Value="12" />
+            </Style>
+
+        </ResourceDictionary>
+    </ContentPage.Resources>
+    <ScrollView>
+        <StackLayout
+            Padding="12">
+            <Button
+                Text="No Background"/>
+            <Button
+                BorderColor="Red"
+                BorderWidth="4"
+                Text="No Background with Border"/>
+            <Button
+                Text="BackgroundColor"
+                TextColor="White"
+                BackgroundColor="Red"/>
+            <Button
+                Text="Background"
+                TextColor="White"
+                Background="Red"/>
+            <Button
+                Text="Gradient Background"
+                TextColor="White">
+                <Button.Background>
+                    <LinearGradientBrush
+                        StartPoint="0, 0"
+                        EndPoint="1, 0">
+                        <LinearGradientBrush.GradientStops>
+                            <GradientStop Color="GreenYellow" Offset="0" />
+                            <GradientStop Color="LawnGreen" Offset="0.25" />
+                            <GradientStop Color="Green" Offset="0.5" />
+                            <GradientStop Color="DarkGreen" Offset="0.75" />
+                        </LinearGradientBrush.GradientStops>
+                    </LinearGradientBrush>
+                </Button.Background>
+            </Button>
+            <Button
+                CornerRadius="{Binding Value, Source={x:Reference CornerSlider}}"
+                Text="Corner Radius Background"
+                TextColor="White">
+                <Button.Background>
+                    <LinearGradientBrush
+                        StartPoint="0, 0"
+                        EndPoint="1, 0">
+                        <LinearGradientBrush.GradientStops>
+                            <GradientStop Color="GreenYellow" Offset="0" />
+                            <GradientStop Color="LawnGreen" Offset="0.25" />
+                            <GradientStop Color="Green" Offset="0.5" />
+                            <GradientStop Color="DarkGreen" Offset="0.75" />
+                        </LinearGradientBrush.GradientStops>
+                    </LinearGradientBrush>
+                </Button.Background>
+            </Button>
+            <Label 
+                FontSize="9"
+                Text="Corner Radius:"/>
+            <Slider 
+                x:Name="CornerSlider"
+                Minimum="0"               
+                Maximum="60"
+                Value="24"/>
+            <Button
+                BorderColor="Red"
+                BorderWidth="{Binding Value, Source={x:Reference BorderWidthSlider}}"
+                Text="BorderColor"
+                TextColor="White">
+                <Button.Background>
+                    <LinearGradientBrush
+                        StartPoint="0, 0"
+                        EndPoint="1, 0">
+                        <LinearGradientBrush.GradientStops>
+                            <GradientStop Color="GreenYellow" Offset="0" />
+                            <GradientStop Color="LawnGreen" Offset="0.25" />
+                            <GradientStop Color="Green" Offset="0.5" />
+                            <GradientStop Color="DarkGreen" Offset="0.75" />
+                        </LinearGradientBrush.GradientStops>
+                    </LinearGradientBrush>
+                </Button.Background>
+            </Button>
+            <Label 
+                FontSize="9"
+                Text="BorderWidth:"/>
+            <Slider 
+                x:Name="BorderWidthSlider"
+                Minimum="0"               
+                Maximum="12"
+                Value="4"/>
+            <Button
+                x:Name="DynamicBackground"
+                BorderColor="Red"
+                BorderWidth="4"
+                CornerRadius="12"
+                Text="BorderColor"
+                TextColor="White">
+                <Button.Background>
+                    <LinearGradientBrush
+                        StartPoint="0, 0"
+                        EndPoint="1, 0">
+                        <LinearGradientBrush.GradientStops>
+                            <GradientStop Color="GreenYellow" Offset="0" />
+                            <GradientStop Color="LawnGreen" Offset="0.25" />
+                            <GradientStop Color="Green" Offset="0.5" />
+                            <GradientStop Color="DarkGreen" Offset="0.75" />
+                        </LinearGradientBrush.GradientStops>
+                    </LinearGradientBrush>
+                </Button.Background>
+            </Button>
+            <StackLayout
+                HorizontalOptions="Center"
+                Orientation="Horizontal">
+                <Button 
+                    Text="Add"
+                    Clicked="OnAddClicked" />
+                <Button 
+                    Text="Remove"
+                    Clicked="OnRemoveClicked" />
+            </StackLayout>
+        </StackLayout>
+    </ScrollView>
+</ContentPage>

src/Controls/samples/Controls.Sample.UITests/Issues/Issue17642.xaml.cs

@@ -0,0 +1,52 @@
+using System;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+using Microsoft.Maui.Graphics;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Issue(IssueTracker.Github, 17642, "Button Click Ripple Effect Not Working In Android", PlatformAffected.Android)]
+	public partial class Issue17642 : ContentPage
+	{
+		readonly Random _random;
+
+		public Issue17642()
+		{
+			InitializeComponent();
+
+			_random = new Random();
+		}
+
+		void OnAddClicked(object sender, EventArgs args)
+		{
+			var linearGradientBrush = new LinearGradientBrush
+			{
+				StartPoint = new Point(GetRandomInt(), GetRandomInt()),
+				EndPoint = new Point(GetRandomInt(), GetRandomInt()),
+				GradientStops = new GradientStopCollection
+				{
+					new GradientStop { Color = GetRandomColor() },
+					new GradientStop { Color = GetRandomColor() }
+				}
+			};
+
+			DynamicBackground.Background = linearGradientBrush;
+		}
+
+		void OnRemoveClicked(object sender, EventArgs args)
+		{
+			DynamicBackground.Background = null;
+		}
+
+		double GetRandomInt()
+		{
+			return _random.NextDouble() * 1;
+		}
+
+		Color GetRandomColor()
+		{
+			return Color.FromRgb(_random.Next(256), _random.Next(256), _random.Next(256));
+		}
+	}
+}

src/Controls/src/Core/GradientBrush.cs

@@ -29,6 +29,9 @@ public GradientStopCollection GradientStops
 			set => SetValue(GradientStopsProperty, value);
 		}
 
+		public override bool IsEmpty =>
+			GradientStops is null || GradientStops.Count == 0;
+
 		static void OnGradientStopsChanged(BindableObject bindable, object oldValue, object newValue)
 		{
 			(bindable as GradientBrush)?.UpdateGradientStops(oldValue as GradientStopCollection, newValue as GradientStopCollection);

src/Controls/src/Core/LinearGradientBrush.cs

@@ -26,15 +26,7 @@ public LinearGradientBrush(GradientStopCollection gradientStops, Point startPoin
 			EndPoint = endPoint;
 		}
 
-		/// <include file="../../docs/Microsoft.Maui.Controls/LinearGradientBrush.xml" path="//Member[@MemberName='IsEmpty']/Docs/*" />
-		public override bool IsEmpty
-		{
-			get
-			{
-				var linearGradientBrush = this;
-				return linearGradientBrush == null || linearGradientBrush.GradientStops.Count == 0;
-			}
-		}
+		public override bool IsEmpty => base.IsEmpty;
 
 		/// <summary>Bindable property for <see cref="StartPoint"/>.</summary>
 		public static readonly BindableProperty StartPointProperty = BindableProperty.Create(