Fix culture change detection to work automatically without manual triggers

Co-authored-by: SuthiYuvaraj <92777079+SuthiYuvaraj@users.noreply.github.com>

Author: Copilot

src/Core/src/CultureTracker.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Globalization;
+using System.Threading;
 
 namespace Microsoft.Maui
 {
@@ -11,6 +12,8 @@ internal static class CultureTracker
 	{
 		static CultureInfo? s_currentCulture;
 		static readonly ConcurrentDictionary<WeakReference, Action> s_subscribers = new();
+		static Timer? s_cultureCheckTimer;
+		static readonly object s_lockObject = new();
 
 		/// <summary>
 		/// Checks if the culture has changed since the last call and notifies subscribers if it has.
@@ -35,6 +38,19 @@ public static void Subscribe(object subscriber, Action action)
 		{
 			var weakRef = new WeakReference(subscriber);
 			s_subscribers.TryAdd(weakRef, action);
+			
+			// Start monitoring when first subscriber is added
+			lock (s_lockObject)
+			{
+				if (s_cultureCheckTimer == null && s_subscribers.Count > 0)
+				{
+					// Initialize current culture if not set
+					s_currentCulture = CultureInfo.CurrentCulture;
+					
+					// Check for culture changes every 100ms when there are subscribers
+					s_cultureCheckTimer = new Timer(OnTimerTick, null, TimeSpan.FromMilliseconds(100), TimeSpan.FromMilliseconds(100));
+				}
+			}
 		}
 
 		/// <summary>
@@ -52,6 +68,21 @@ public static void Unsubscribe(object subscriber)
 					break;
 				}
 			}
+
+			// Stop monitoring when no subscribers remain
+			lock (s_lockObject)
+			{
+				if (s_subscribers.Count == 0 && s_cultureCheckTimer != null)
+				{
+					s_cultureCheckTimer.Dispose();
+					s_cultureCheckTimer = null;
+				}
+			}
+		}
+
+		static void OnTimerTick(object? state)
+		{
+			CheckForCultureChanges();
 		}
 
 		static void NotifyCultureChanged()
@@ -83,6 +114,16 @@ static void NotifyCultureChanged()
 			{
 				s_subscribers.TryRemove(deadRef, out _);
 			}
+
+			// Stop monitoring if all references are dead
+			lock (s_lockObject)
+			{
+				if (s_subscribers.Count == 0 && s_cultureCheckTimer != null)
+				{
+					s_cultureCheckTimer.Dispose();
+					s_cultureCheckTimer = null;
+				}
+			}
 		}
 	}
 }

src/Core/src/Platform/Android/DatePickerExtensions.cs

@@ -55,9 +55,6 @@ public static void UpdateMaximumDate(this MauiDatePicker platformDatePicker, IDa
 
 		internal static void SetText(this MauiDatePicker platformDatePicker, IDatePicker datePicker)
 		{
-			// Check for culture changes before updating
-			CultureTracker.CheckForCultureChanges();
-
 			platformDatePicker.Text = datePicker.Date.ToString(datePicker.Format);
 		}
 	}

src/Core/src/Platform/Windows/DatePickerExtensions.cs

@@ -9,9 +9,6 @@ public static class DatePickerExtensions
 	{
 		public static void UpdateDate(this CalendarDatePicker platformDatePicker, IDatePicker datePicker)
 		{
-			// Check for culture changes before updating
-			CultureTracker.CheckForCultureChanges();
-
 			var date = datePicker.Date;
 			platformDatePicker.UpdateDate(date);
 

src/Core/src/Platform/iOS/DatePickerExtensions.cs

@@ -56,9 +56,6 @@ public static void UpdateDate(this UIDatePicker picker, IDatePicker datePicker)
 
 		public static void UpdateDate(this MauiDatePicker platformDatePicker, IDatePicker datePicker, UIDatePicker? picker)
 		{
-			// Check for culture changes before updating
-			CultureTracker.CheckForCultureChanges();
-
 			if (picker != null && picker.Date.ToDateTime().Date != datePicker.Date.Date)
 				picker.SetDate(datePicker.Date.ToNSDate(), false);
 

src/Core/tests/UnitTests/Views/DatePickerCultureTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Globalization;
+using System.Threading;
 using Microsoft.Maui.Controls;
 using Xunit;
 
@@ -31,7 +32,9 @@ public void DatePickerCultureTrackerSubscription()
 			try
 			{
 				CultureInfo.CurrentCulture = new CultureInfo("de-DE");
-				CultureTracker.CheckForCultureChanges();
+				
+				// Wait a bit for the timer to detect the change (max 200ms)
+				Thread.Sleep(250);
 
 				Assert.True(called);
 			}
@@ -42,6 +45,37 @@ public void DatePickerCultureTrackerSubscription()
 			}
 		}
 
+		[Fact]
+		public void DatePickerCultureTrackerAutoDetection()
+		{
+			var callCount = 0;
+			var subscriber = new object();
+			
+			CultureTracker.Subscribe(subscriber, () => callCount++);
+			
+			var originalCulture = CultureInfo.CurrentCulture;
+			try
+			{
+				// Change culture multiple times
+				CultureInfo.CurrentCulture = new CultureInfo("de-DE");
+				Thread.Sleep(150); // Allow detection
+				
+				CultureInfo.CurrentCulture = new CultureInfo("fr-FR");
+				Thread.Sleep(150); // Allow detection
+				
+				CultureInfo.CurrentCulture = new CultureInfo("ja-JP");
+				Thread.Sleep(150); // Allow detection
+				
+				// Should have detected at least 3 culture changes
+				Assert.True(callCount >= 3, $"Expected at least 3 culture changes, but got {callCount}");
+			}
+			finally
+			{
+				CultureInfo.CurrentCulture = originalCulture;
+				CultureTracker.Unsubscribe(subscriber);
+			}
+		}
+
 		[Theory]
 		[InlineData("en-US", "d")]
 		[InlineData("de-DE", "d")]