[Android] Fixed Button Shadow Color Transparency Not Applied Correctly (#29371)

* Fixed the shadow transparent issue on android

* Updated the fix.

* Added the test case and updated the fix

* Added the output images.

* Updated the fix.

* Updated the comment.

* Added the output images for mac and Windows

* Updated the test case and added output images.

* Added the output images

Author: NanthiniMahalingam

src/Controls/tests/TestCases.Android.Tests/snapshots/android/ShouldUpdateButtonShadowWithTransparentColor.png

@@ -0,0 +1,80 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 29325, "Button Shadow Color Transparency Not Applied Correctly", PlatformAffected.Android)]
+public class Issue29325 : ContentPage
+{
+	public Issue29325()
+	{
+		var verticalStackLayout = new VerticalStackLayout();
+
+		var withoutAlphaOpacityButton = new Button
+		{
+			AutomationId = "withoutAlphaOpacityButton",
+			HorizontalOptions = LayoutOptions.Center,
+			VerticalOptions = LayoutOptions.Center,
+			Text = "Button shadow color no Alpha nor opacity",
+			Shadow = new Shadow
+			{
+				Brush = Colors.Blue,
+				Offset = new Point(0, 12),
+				Radius = 12,
+			}
+		};
+
+		var alphaButton = new Button
+		{
+			AutomationId = "alphaButton",
+			HorizontalOptions = LayoutOptions.Center,
+			VerticalOptions = LayoutOptions.Center,
+			Text = "Button shadow color with Alpha",
+			Margin = new Thickness(0, 50, 0, 0),
+			Shadow = new Shadow
+			{
+				Brush = Colors.Blue.WithAlpha(0.4f),
+				Offset = new Point(0, 12),
+				Radius = 12,
+			}
+		};
+
+		var opacityButton = new Button
+		{
+			AutomationId = "opacityButton",
+			HorizontalOptions = LayoutOptions.Center,
+			VerticalOptions = LayoutOptions.Center,
+			Text = "Button shadow color with opacity",
+			Margin = new Thickness(0, 50, 0, 0),
+			Shadow = new Shadow
+			{
+				Brush = Colors.Blue,
+				Offset = new Point(0, 12),
+				Radius = 12,
+				Opacity = 0.4f
+			}
+		};
+
+		var alphaOpacityButton = new Button
+		{
+			AutomationId = "alphaOpacityButton",
+			HorizontalOptions = LayoutOptions.Center,
+			VerticalOptions = LayoutOptions.Center,
+			Text = "Button shadow color with alpha and opacity",
+			Margin = new Thickness(0, 50, 0, 0),
+			Shadow = new Shadow
+			{
+				Brush = Colors.Blue.WithAlpha(0.4f),
+				Offset = new Point(0, 12),
+				Radius = 12,
+				Opacity = 0.4f
+			}
+		};
+
+		// Add the Button to the VerticalStackLayout
+		verticalStackLayout.Children.Add(withoutAlphaOpacityButton);
+		verticalStackLayout.Children.Add(alphaButton);
+		verticalStackLayout.Children.Add(opacityButton);
+		verticalStackLayout.Children.Add(alphaOpacityButton);
+
+		// Set the Content of the page
+		Content = verticalStackLayout;
+	}
+}

src/Controls/tests/TestCases.HostApp/Issues/Issue29325.cs

@@ -0,0 +1,23 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue29325 : _IssuesUITest
+{
+	public Issue29325(TestDevice device) : base(device) { }
+
+	public override string Issue => "Button Shadow Color Transparency Not Applied Correctly";
+
+	[Test]
+	[Category(UITestCategories.Button)]
+	public void ShouldUpdateButtonShadowWithTransparentColor()
+	{
+		App.WaitForElement("withoutAlphaOpacityButton");
+		App.WaitForElement("alphaButton");
+		App.WaitForElement("opacityButton");
+		App.WaitForElement("alphaOpacityButton");
+		VerifyScreenshot();
+	}
+}

src/Controls/tests/TestCases.Mac.Tests/snapshots/mac/ShouldUpdateButtonShadowWithTransparentColor.png

@@ -90,7 +90,10 @@ partial void ShadowChanged()
 						break;
 					case SolidPaint solidPaint:
 						paintType = PlatformPaintType.Solid;
-						colors = [solidPaint.Color.WithAlpha(shadowOpacity).ToPlatform().ToArgb()];
+						// If the alpha is set in the color value, the shadow transparency is applied based on that alpha. 
+						// If the Opacity property is set directly, the shadow transparency is applied based on the Opacity. 
+						// If both values are provided, the color alpha is combined with the Opacity to apply a unified transparency effect to the shadow, ensuring consistent behavior across platforms.
+						colors = [solidPaint.Color.WithAlpha(solidPaint.Color.Alpha * shadowOpacity).ToPlatform().ToArgb()];
 						positions = null;
 						bounds = null;
 						break;