PM-3349 Fix Picker selection style by doing a custom PickerHandler for Android which uses SetSingleChoiceItems(...) to provide with the appropriate UI

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

@@ -0,0 +1,299 @@
+#if ANDROID
+using System;
+using System.Collections.Specialized;
+using Android.App;
+using Android.Content.PM;
+using Android.Content.Res;
+using Android.Graphics.Drawables;
+using Android.Text;
+using Android.Text.Style;
+using Android.Widget;
+using Microsoft.Maui;
+using Microsoft.Maui.Handlers;
+using Microsoft.Maui.Platform;
+using AGravityFlags = Android.Views.GravityFlags;
+using ALayoutDirection = Android.Views.LayoutDirection;
+using AppCompatAlertDialog = AndroidX.AppCompat.App.AlertDialog;
+using AResource = Android.Resource;
+using ATextAlignment = Android.Views.TextAlignment;
+using ATextDirection = Android.Views.TextDirection;
+
+namespace Bit.Core.Controls.Picker
+{
+    // HACK: Due to https://github.com/dotnet/maui/issues/19681 and not willing to use reflection to access
+    // the alert dialog, we need to redefine the PickerHandler implementation for a custom one of ours
+    // which handles showing the current selected item. Remove this workaround when MAUI releases a fix for this.
+    // This is an adapted copy from https://github.com/dotnet/maui/blob/main/src/Core/src/Handlers/Picker/PickerHandler.Android.cs
+    public partial class PickerHandler : ViewHandler<IPicker, MauiPicker>
+	{
+		AppCompatAlertDialog? _dialog;
+
+		protected override MauiPicker CreatePlatformView() =>
+			new MauiPicker(Context);
+
+		protected override void ConnectHandler(MauiPicker platformView)
+		{
+			platformView.FocusChange += OnFocusChange;
+			platformView.Click += OnClick;
+
+			base.ConnectHandler(platformView);
+		}
+
+		protected override void DisconnectHandler(MauiPicker platformView)
+		{
+			platformView.FocusChange -= OnFocusChange;
+			platformView.Click -= OnClick;
+
+			base.DisconnectHandler(platformView);
+		}
+
+		// This is a Android-specific mapping
+		public static void MapBackground(IPickerHandler handler, IPicker picker)
+		{
+			handler.PlatformView?.UpdateBackground(picker);
+		}
+
+		// TODO Uncomment me on NET8 [Obsolete]
+		public static void MapReload(IPickerHandler handler, IPicker picker, object? args) => Reload(handler);
+
+		internal static void MapItems(IPickerHandler handler, IPicker picker) => Reload(handler);
+
+		public static void MapTitle(IPickerHandler handler, IPicker picker)
+		{
+			handler.PlatformView?.UpdateTitle(picker);
+		}
+
+		public static void MapTitleColor(IPickerHandler handler, IPicker picker)
+		{
+			handler.PlatformView?.UpdateTitleColor(picker);
+		}
+
+		public static void MapSelectedIndex(IPickerHandler handler, IPicker picker)
+		{
+			handler.PlatformView?.UpdateSelectedIndex(picker);
+		}
+
+		public static void MapCharacterSpacing(IPickerHandler handler, IPicker picker)
+		{
+			handler.PlatformView?.UpdateCharacterSpacing(picker);
+		}
+
+		public static void MapFont(IPickerHandler handler, IPicker picker)
+		{
+			var fontManager = handler.GetRequiredService<IFontManager>();
+
+			handler.PlatformView?.UpdateFont(picker, fontManager);
+		}
+
+		public static void MapHorizontalTextAlignment(IPickerHandler handler, IPicker picker)
+		{
+			handler.PlatformView?.UpdateHorizontalAlignment(picker.HorizontalTextAlignment);
+		}
+
+		public static void MapTextColor(IPickerHandler handler, IPicker picker)
+		{
+			handler.PlatformView.UpdateTextColor(picker);
+		}
+
+		public static void MapVerticalTextAlignment(IPickerHandler handler, IPicker picker)
+		{
+			handler.PlatformView?.UpdateVerticalAlignment(picker.VerticalTextAlignment);
+		}
+
+		void OnFocusChange(object? sender, global::Android.Views.View.FocusChangeEventArgs e)
+		{
+			if (PlatformView == null)
+				return;
+
+			if (e.HasFocus)
+			{
+				if (PlatformView.Clickable)
+					PlatformView.CallOnClick();
+				else
+					OnClick(PlatformView, EventArgs.Empty);
+			}
+			else if (_dialog != null)
+			{
+				_dialog.Hide();
+				_dialog = null;
+			}
+		}
+
+		void OnClick(object? sender, EventArgs e)
+		{
+			if (_dialog == null && VirtualView != null)
+			{
+				using (var builder = new AppCompatAlertDialog.Builder(Context))
+				{
+					if (VirtualView.TitleColor == null)
+					{
+						builder.SetTitle(VirtualView.Title ?? string.Empty);
+					}
+					else
+					{
+						var title = new SpannableString(VirtualView.Title ?? string.Empty);
+#pragma warning disable CA1416 // https://github.com/xamarin/xamarin-android/issues/6962
+						title.SetSpan(new ForegroundColorSpan(VirtualView.TitleColor.ToPlatform()), 0, title.Length(), SpanTypes.ExclusiveExclusive);
+#pragma warning restore CA1416
+						builder.SetTitle(title);
+					}
+
+					string[] items = VirtualView.GetItemsAsArray();
+
+					for (var i = 0; i < items.Length; i++)
+					{
+						var item = items[i];
+						if (item == null)
+							items[i] = String.Empty;
+					}
+
+					builder.SetSingleChoiceItems(items, VirtualView.SelectedIndex, (s, e) =>
+					{
+						var selectedIndex = e.Which;
+						VirtualView.SelectedIndex = selectedIndex;
+						base.PlatformView?.UpdatePicker(VirtualView);
+						_dialog.Dismiss();
+					});
+
+					builder.SetNegativeButton(AResource.String.Cancel, (o, args) => { });
+
+					_dialog = builder.Create();
+				}
+
+				if (_dialog == null)
+					return;
+
+				_dialog.UpdateFlowDirection(PlatformView);
+
+				_dialog.SetCanceledOnTouchOutside(true);
+
+				_dialog.DismissEvent += (sender, args) =>
+				{
+					_dialog = null;
+				};
+
+				_dialog.Show();
+			}
+		}
+
+		static void Reload(IPickerHandler handler)
+		{
+			handler.PlatformView.UpdatePicker(handler.VirtualView);
+		}
+	}
+
+	public static class PickerExtensions
+	{
+        const AGravityFlags HorizontalGravityMask = AGravityFlags.CenterHorizontal | AGravityFlags.End | AGravityFlags.Start;
+
+        internal static void UpdatePicker(this MauiPicker platformPicker, IPicker picker)
+		{
+			platformPicker.Hint = picker.Title;
+
+			if (picker.SelectedIndex == -1 || picker.SelectedIndex >= picker.GetCount())
+				platformPicker.Text = null;
+			else
+				platformPicker.Text = picker.GetItem(picker.SelectedIndex);
+		}
+
+        internal static void UpdateHorizontalAlignment(this EditText view, TextAlignment alignment, AGravityFlags orMask = AGravityFlags.NoGravity)
+        {
+            if (!Rtl.IsSupported)
+            {
+                view.Gravity = (view.Gravity & ~HorizontalGravityMask) | alignment.ToHorizontalGravityFlags() | orMask;
+            }
+            else
+                view.TextAlignment = alignment.ToTextAlignment();
+        }
+
+        internal static AGravityFlags ToHorizontalGravityFlags(this TextAlignment alignment)
+        {
+            switch (alignment)
+            {
+                case TextAlignment.Center:
+                    return AGravityFlags.CenterHorizontal;
+                case TextAlignment.End:
+                    return AGravityFlags.End;
+                default:
+                    return AGravityFlags.Start;
+            }
+        }
+
+        internal static ATextAlignment ToTextAlignment(this TextAlignment alignment)
+        {
+            switch (alignment)
+            {
+                case TextAlignment.Center:
+                    return ATextAlignment.Center;
+                case TextAlignment.End:
+                    return ATextAlignment.ViewEnd;
+                default:
+                    return ATextAlignment.ViewStart;
+            }
+        }
+
+        internal static void UpdateFlowDirection(this AndroidX.AppCompat.App.AlertDialog alertDialog, MauiPicker platformPicker)
+        {
+            var platformLayoutDirection = platformPicker.LayoutDirection;
+
+            // Propagate the MauiPicker LayoutDirection to the AlertDialog
+            var dv = alertDialog.Window?.DecorView;
+
+            if (dv is not null)
+                dv.LayoutDirection = platformLayoutDirection;
+
+            var lv = alertDialog?.ListView;
+
+            if (lv is not null)
+            {
+                lv.LayoutDirection = platformLayoutDirection;
+                lv.TextDirection = platformLayoutDirection.ToTextDirection();
+            }
+        }
+
+        internal static ATextDirection ToTextDirection(this ALayoutDirection direction)
+        {
+            switch (direction)
+            {
+                case ALayoutDirection.Ltr:
+                    return ATextDirection.Ltr;
+                case ALayoutDirection.Rtl:
+                    return ATextDirection.Rtl;
+                default:
+                    return ATextDirection.Inherit;
+            }
+        }
+
+        public static T GetRequiredService<T>(this IElementHandler handler)
+            where T : notnull
+        {
+            var services = handler.GetServiceProvider();
+
+            var service = services.GetRequiredService<T>();
+
+            return service;
+        }
+
+        public static IServiceProvider GetServiceProvider(this IElementHandler handler)
+        {
+            var context = handler.MauiContext ??
+                throw new InvalidOperationException($"Unable to find the context. The {nameof(ElementHandler.MauiContext)} property should have been set by the host.");
+
+            var services = context?.Services ??
+                throw new InvalidOperationException($"Unable to find the service provider. The {nameof(ElementHandler.MauiContext)} property should have been set by the host.");
+
+            return services;
+        }
+    }
+
+    static class Rtl
+    {
+        /// <summary>
+        /// True if /manifest/application@android:supportsRtl="true"
+        /// </summary>
+        public static readonly bool IsSupported =
+            (Android.App.Application.Context?.ApplicationInfo?.Flags & ApplicationInfoFlags.SupportsRtl) != 0;
+    }
+
+}
+#endif

src/Core/Controls/Picker/PickerHandler.cs

@@ -0,0 +1,53 @@
+#if ANDROID
+using Microsoft.Maui.Handlers;
+using Microsoft.Maui.Platform;
+
+namespace Bit.Core.Controls.Picker
+{
+    // HACK: Due to https://github.com/dotnet/maui/issues/19681 and not willing to use reflection to access
+    // the alert dialog, we need to redefine the PickerHandler implementation for a custom one of ours
+    // which handles showing the current selected item. Remove this workaround when MAUI releases a fix for this.
+    // This is a copy from https://github.com/dotnet/maui/blob/main/src/Core/src/Handlers/Picker/PickerHandler.cs
+    public partial class PickerHandler : ViewHandler<IPicker, MauiPicker>, IPickerHandler
+    {
+        public static IPropertyMapper<IPicker, IPickerHandler> Mapper = new PropertyMapper<IPicker, PickerHandler>(ViewMapper)
+        {
+#if __ANDROID__ || WINDOWS
+            [nameof(IPicker.Background)] = MapBackground,
+#endif
+            [nameof(IPicker.CharacterSpacing)] = MapCharacterSpacing,
+            [nameof(IPicker.Font)] = MapFont,
+            [nameof(IPicker.SelectedIndex)] = MapSelectedIndex,
+            [nameof(IPicker.TextColor)] = MapTextColor,
+            [nameof(IPicker.Title)] = MapTitle,
+            [nameof(IPicker.TitleColor)] = MapTitleColor,
+            [nameof(ITextAlignment.HorizontalTextAlignment)] = MapHorizontalTextAlignment,
+            [nameof(ITextAlignment.VerticalTextAlignment)] = MapVerticalTextAlignment,
+            [nameof(IPicker.Items)] = MapItems,
+        };
+
+        public static CommandMapper<IPicker, IPickerHandler> CommandMapper = new(ViewCommandMapper)
+        {
+        };
+
+        public PickerHandler() : base(Mapper, CommandMapper)
+        {
+        }
+
+        public PickerHandler(IPropertyMapper? mapper)
+            : base(mapper ?? Mapper, CommandMapper)
+        {
+        }
+
+        public PickerHandler(IPropertyMapper? mapper, CommandMapper? commandMapper)
+            : base(mapper ?? Mapper, commandMapper ?? CommandMapper)
+        {
+        }
+
+        IPicker IPickerHandler.VirtualView => VirtualView;
+
+        Microsoft.Maui.Platform.MauiPicker IPickerHandler.PlatformView => PlatformView;
+    }
+}
+
+#endif

src/Core/Core.csproj

@@ -72,6 +72,7 @@
     <Folder Include="Utilities\Automation\" />
     <Folder Include="Utilities\Prompts\" />
     <Folder Include="Resources\Localization\" />
+    <Folder Include="Controls\Picker\" />
   </ItemGroup>
 	<ItemGroup>
 	  <MauiImage Include="Resources\Images\dotnet_bot.svg">
@@ -99,4 +100,7 @@
 	    <Generator>MSBuild:Compile</Generator>
 	  </MauiXaml>
 	</ItemGroup>
+	<ItemGroup>
+	  <None Remove="Controls\Picker\" />
+	</ItemGroup>
 </Project>

src/Core/MauiProgram.cs

@@ -3,6 +3,7 @@ using CommunityToolkit.Maui;
 using FFImageLoading.Maui;
 using Microsoft.Extensions.Logging;
 using Microsoft.Maui.Controls.Compatibility.Hosting;
+using Microsoft.Maui.Handlers;
 using SkiaSharp.Views.Maui.Controls.Hosting;
 using AppEffects = Bit.App.Effects;
 
@@ -40,6 +41,16 @@ public static class MauiProgram
             })
             .ConfigureMauiHandlers(handlers =>
             {
+#if ANDROID
+                // HACK: Due to https://github.com/dotnet/maui/issues/19681 and not willing to use reflection to access
+                // the alert dialog, we need to redefine the PickerHandler implementation for a custom one of ours
+                // which handles showing the current selected item. Remove this workaround when MAUI releases a fix for this.
+                if (handlers.FirstOrDefault(h => h.ServiceType == typeof(Picker)) is ServiceDescriptor sd)
+                {
+                    handlers.Remove(sd);
+                    handlers.AddHandler(typeof(IPicker), typeof(Controls.Picker.PickerHandler));
+                }
+#endif
                 customHandlers?.Invoke(handlers);
             });