[Entry/Win] Fixed cursor jumping to the beginning of a PasswordBox

src/Controls/src/Core/Platform/Windows/Extensions/TextBoxExtensions.cs

@@ -1,5 +1,6 @@
 #nullable enable
 using Microsoft.Maui.Controls.Internals;
+using Microsoft.Maui.Platform;
 using Microsoft.UI.Xaml.Controls;
 
 namespace Microsoft.Maui.Controls.Platform
@@ -8,7 +9,10 @@ internal static class TextBoxExtensions
 	{
 		public static void UpdateText(this TextBox platformControl, InputView inputView)
 		{
-			platformControl.Text = TextTransformUtilites.GetTransformedText(inputView.Text, inputView.TextTransform);
+			if (platformControl is MauiPasswordTextBox passwordBox)
+				passwordBox.Password = TextTransformUtilites.GetTransformedText(inputView.Text, passwordBox.IsPassword ? TextTransform.None : inputView.TextTransform);
+			else
+				platformControl.Text = TextTransformUtilites.GetTransformedText(inputView.Text, inputView.TextTransform);
 		}
 	}
 

src/Core/src/Platform/Windows/MauiPasswordTextBox.cs

@@ -53,9 +53,12 @@ static void OnPasswordPropertyChanged(DependencyObject dependencyObject, Depende
 		bool _cachedSpellCheckSetting;
 		CancellationTokenSource? _cts;
 		bool _internalChangeFlag;
+		int _cachedCursorPosition;
+		int _cachedTextLength;
 
 		public MauiPasswordTextBox()
 		{
+			TextChanging += OnNativeTextChanging;
 			TextChanged += OnNativeTextChanged;
 		}
 
@@ -132,6 +135,29 @@ protected override void OnKeyDown(KeyRoutedEventArgs e)
 			base.OnKeyDown(e);
 		}
 
+		private void OnNativeTextChanging(TextBox sender, TextBoxTextChangingEventArgs args)
+		{	
+			// As we are obfuscating the text by ourselves, transforming the text, or a user could be using a custom Converter;
+			// we are setting the Text property directly on code many times.
+			// This causes that we invoke the SelectionChanged event many times with SelectionStart = 0, setting the cursor to
+			// the beginning of the TextBox.
+			// To avoid this behavior let's save the current cursor position of the first time the Text is updated by the user
+			// and keep the same cursor position after each Text update until a new Text update by the user happens.
+			var updatedPassword = DetermineTextFromPassword(Password, SelectionStart, Text);
+
+			if (Password != updatedPassword)
+			{
+				_cachedCursorPosition = SelectionStart;
+				_cachedTextLength = updatedPassword.Length;
+			}
+			else
+			{
+				// Recalculate the cursor position, as the Text could be modified by a user Converter
+				_cachedCursorPosition += (updatedPassword.Length - _cachedTextLength);
+				SelectionStart = _cachedCursorPosition;
+			}
+		}
+
 		void OnNativeTextChanged(object sender, TextChangedEventArgs textChangedEventArgs)
 		{
 			if (IsPassword)
@@ -161,11 +187,7 @@ void UpdateVisibleText()
 			var updatedText = IsPassword ? Obfuscate(Password) : Password;
 
 			if (Text != updatedText)
-			{
-				var savedSelectionStart = SelectionStart;
 				Text = updatedText;
-				SelectionStart = savedSelectionStart;
-			}
 		}
 
 		void UpdateInputScope()
@@ -198,27 +220,14 @@ void UpdateInputScope()
 
 		void ImmediateObfuscation()
 		{
-			var updatedPassword = DetermineTextFromPassword(Password, SelectionStart, Text);
-			var updatedVisibleText = Obfuscate(updatedPassword);
-
-			if (Password != updatedPassword)
-				Password = updatedPassword;
-
-			if (Text != updatedVisibleText)
-			{
-				var savedSelectionStart = SelectionStart;
-				Text = updatedVisibleText;
-				SelectionStart = savedSelectionStart;
-			}
+			UpdatePasswordIfNeeded();
 		}
 
 		void DelayObfuscation()
 		{
 			var lengthDifference = Text.Length - Password.Length;
-			var updatedPassword = DetermineTextFromPassword(Password, SelectionStart, Text);
 
-			if (Password != updatedPassword)
-				Password = updatedPassword;
+			UpdatePasswordIfNeeded();
 
 			// Cancel any pending delayed obfuscation
 			_cts?.Cancel();
@@ -244,11 +253,7 @@ void DelayObfuscation()
 			}
 
 			if (Text != updatedVisibleText)
-			{
-				var savedSelectionStart = SelectionStart;
 				Text = updatedVisibleText;
-				SelectionStart = savedSelectionStart;
-			}
 
 			void StartTimeout(CancellationToken token)
 			{
@@ -260,14 +265,20 @@ void StartTimeout(CancellationToken token)
 
 					DispatcherQueue.TryEnqueue(UI.Dispatching.DispatcherQueuePriority.Normal, () =>
 					{
-						var savedSelectionStart = SelectionStart;
-						Text = Obfuscate(Password);
-						SelectionStart = savedSelectionStart;
+						UpdateVisibleText();
 					});
 				}, token);
 			}
 		}
 
+		void UpdatePasswordIfNeeded()
+		{
+			var updatedPassword = DetermineTextFromPassword(Password, SelectionStart, Text);
+
+			if (Password != updatedPassword)
+				Password = updatedPassword;
+		}
+
 		static string Obfuscate(string text, bool leaveLastVisible = false)
 		{
 			if (string.IsNullOrEmpty(text))