Android: fix dialog button colors in dark mode (#15091)

* Core(Android): fix dialog button colors in dark mode

Fix alert dialog button colors in dark mode.
Use ?attr/colorOnSurface for text color in dialogs.
This ensures contrasting color for both dark and light modes.

* Core(Android): use AppCompat alert dialog in picker

Use AppCompat version of AlertDialog in picker.
This ensures consistent styling between picker dialog and
alert dialog.

* Controls.DeviceTests: add AlertDialogTests

Add tests for checking brightness of AlertDialog button text.

Co-authored-by: webwarrior <reg@webwarrior.ws>

---------

Co-authored-by: Parham Saremi <parhaamsaremi@gmail.com>

src/Controls/tests/DeviceTests/Elements/AlertDialog/AlertDialogTests.Android.cs

@@ -0,0 +1,54 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Maui.DeviceTests.Stubs;
+using Microsoft.Maui.Platform;
+using Xunit;
+using AndroidX.AppCompat.App;
+using Android.Graphics;
+
+namespace Microsoft.Maui.DeviceTests
+{
+	public partial class AlertDialogTests: ControlsHandlerTestBase
+	{
+
+		async Task<Color> GetDialogButtonTextColor(int nightMode)
+		{
+			var mauiContextStub1 = new ContextStub(ApplicationServices);
+			var activity = mauiContextStub1.GetActivity();
+			mauiContextStub1.Context = new Android.Views.ContextThemeWrapper(activity, Resource.Style.Maui_MainTheme_NoActionBar);
+			Color color = Color.Transparent;
+			await InvokeOnMainThreadAsync(() =>
+			{
+				var initialNightMode = activity.Delegate.LocalNightMode;
+				activity.Delegate.SetLocalNightMode(nightMode);
+				var builder = new AlertDialog.Builder(activity);
+				var alertDialog = builder.Create();
+				alertDialog.Show();
+				var button = alertDialog.GetButton((int)Android.Content.DialogButtonType.Negative);
+				var textColor = button.CurrentTextColor;
+				color = new Color(textColor);
+				activity.Delegate.SetLocalNightMode(initialNightMode);
+				alertDialog.Hide();
+			});
+
+			return color;
+		}
+
+		[Fact]
+		public void AlertDialogButtonColorLightTheme()
+		{
+			var textColor = GetDialogButtonTextColor(AppCompatDelegate.ModeNightNo).Result;
+			Assert.True(textColor.GetBrightness() < 0.5);
+		}
+
+		[Fact]
+		public void AlertDialogButtonColorDarkTheme()
+		{
+			var textColor = GetDialogButtonTextColor(AppCompatDelegate.ModeNightYes).Result;
+			Assert.True(textColor.GetBrightness() > 0.5);
+		}
+	}
+}

src/Core/src/Handlers/Picker/PickerHandler.Android.cs

@@ -6,12 +6,13 @@
 using Android.Text;
 using Android.Text.Style;
 using AResource = Android.Resource;
+using AppCompatAlertDialog = AndroidX.AppCompat.App.AlertDialog;
 
 namespace Microsoft.Maui.Handlers
 {
 	public partial class PickerHandler : ViewHandler<IPicker, MauiPicker>
 	{
-		AlertDialog? _dialog;
+		AppCompatAlertDialog? _dialog;
 
 		protected override MauiPicker CreatePlatformView() =>
 			new MauiPicker(Context);
@@ -108,7 +109,7 @@ void OnClick(object? sender, EventArgs e)
 		{
 			if (_dialog == null && VirtualView != null)
 			{
-				using (var builder = new AlertDialog.Builder(Context))
+				using (var builder = new AppCompatAlertDialog.Builder(Context))
 				{
 					if (VirtualView.TitleColor == null)
 					{

src/Core/src/Platform/Android/PickerExtensions.cs

@@ -47,7 +47,7 @@ internal static void UpdatePicker(this MauiPicker platformPicker, IPicker picker
 				platformPicker.Text = picker.GetItem(picker.SelectedIndex);
 		}
 
-		internal static void UpdateFlowDirection(this AlertDialog alertDialog, MauiPicker platformPicker)
+		internal static void UpdateFlowDirection(this AndroidX.AppCompat.App.AlertDialog alertDialog, MauiPicker platformPicker)
 		{
 			var platformLayoutDirection = platformPicker.LayoutDirection;
 

src/Core/src/Platform/Android/Resources/values/styles.xml

@@ -11,6 +11,7 @@
         <item name="materialButtonStyle">@style/MauiMaterialButton</item>
         <item name="checkboxStyle">@style/MauiCheckBox</item>
         <item name="android:textAllCaps">false</item>
+        <item name="alertDialogTheme">@style/MauiAlertDialogTheme</item>
     </style>
     <style name="Maui.MainTheme.NoActionBar" parent="Maui.MainTheme">
         <item name="windowActionBar">false</item>
@@ -66,6 +67,10 @@
       <item name="android:minHeight">0dp</item>
     </style>
 
+    <style name="MauiAlertDialogTheme" parent="ThemeOverlay.MaterialComponents.MaterialAlertDialog">
+      <item name="colorPrimary">?attr/colorOnSurface</item>
+    </style>
+
   <!-- 
     The collectionViewScrollBars style will be used as the default style for ItemsViewRenderer (the base renderer
     for CollectionView and CarouselView. We have to use a style to set up the scrollbars because there is currently