Initial import

1 files changed, 236 insertions, 0 deletions

diff --git a/Xamarin.Forms.Platform.WP8/FormsPhoneTextBox.cs b/Xamarin.Forms.Platform.WP8/FormsPhoneTextBox.cs
new file mode 100644
index 00000000..342646cd
--- /dev/null
+++ b/Xamarin.Forms.Platform.WP8/FormsPhoneTextBox.cs
@@ -0,0 +1,236 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Input;
+using System.Windows.Media;
+using Microsoft.Phone.Controls;
+
+namespace Xamarin.Forms.Platform.WinPhone
+{
+	/// <summary>
+	///     An intermediate class for injecting bindings for things the default
+	///     textbox doesn't allow us to bind/modify
+	/// </summary>
+	public class FormsPhoneTextBox : PhoneTextBox
+	{
+		const char ObfuscationCharacter = '●';
+
+		public static readonly DependencyProperty PlaceholderForegroundBrushProperty = DependencyProperty.Register("PlaceholderForegroundBrush", typeof(Brush), typeof(FormsPhoneTextBox),
+			new PropertyMetadata(default(Brush)));
+
+		public static readonly DependencyProperty IsPasswordProperty = DependencyProperty.Register("IsPassword", typeof(bool), typeof(FormsPhoneTextBox),
+			new PropertyMetadata(default(bool), OnIsPasswordChanged));
+
+		public new static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof(string), typeof(FormsPhoneTextBox), new PropertyMetadata("", TextPropertyChanged));
+
+		protected internal static readonly DependencyProperty DisabledTextProperty = DependencyProperty.Register("DisabledText", typeof(string), typeof(FormsPhoneTextBox), new PropertyMetadata(""));
+
+		static InputScope s_passwordInputScope;
+		InputScope _cachedInputScope;
+		CancellationTokenSource _cts;
+		bool _internalChangeFlag;
+
+		public FormsPhoneTextBox()
+		{
+			TextChanged += OnTextChanged;
+			SelectionChanged += OnSelectionChanged;
+		}
+
+		public bool IsPassword
+		{
+			get { return (bool)GetValue(IsPasswordProperty); }
+			set { SetValue(IsPasswordProperty, value); }
+		}
+
+		public Brush PlaceholderForegroundBrush
+		{
+			get { return (Brush)GetValue(PlaceholderForegroundBrushProperty); }
+			set { SetValue(PlaceholderForegroundBrushProperty, value); }
+		}
+
+		public new string Text
+		{
+			get { return (string)GetValue(TextProperty); }
+			set { SetValue(TextProperty, value); }
+		}
+
+		protected internal string DisabledText
+		{
+			get { return (string)GetValue(DisabledTextProperty); }
+			set { SetValue(DisabledTextProperty, value); }
+		}
+
+		static InputScope PasswordInputScope
+		{
+			get
+			{
+				if (s_passwordInputScope != null)
+					return s_passwordInputScope;
+
+				s_passwordInputScope = new InputScope();
+				var name = new InputScopeName { NameValue = InputScopeNameValue.Default };
+				s_passwordInputScope.Names.Add(name);
+
+				return s_passwordInputScope;
+			}
+		}
+
+		void DelayObfuscation()
+		{
+			int lengthDifference = base.Text.Length - Text.Length;
+
+			string updatedRealText = DetermineTextFromPassword(Text, base.Text);
+
+			if (Text == updatedRealText)
+			{
+				// Nothing to do
+				return;
+			}
+
+			Text = updatedRealText;
+
+			// Cancel any pending delayed obfuscation
+			_cts?.Cancel();
+			_cts = null;
+
+			string newText;
+
+			if (lengthDifference != 1)
+			{
+				// Either More than one character got added in this text change (e.g., a paste operation)
+				// Or characters were removed. Either way, we don't need to do the delayed obfuscation dance
+				newText = Obfuscate();
+			}
+			else
+			{
+				// Only one character was added; we need to leave it visible for a brief time period
+				// Obfuscate all but the last character for now
+				newText = Obfuscate(true);
+
+				// Leave the last character visible until a new character is added
+				// or sufficient time has passed
+				if (_cts == null)
+					_cts = new CancellationTokenSource();
+
+				Task.Run(async () =>
+				{
+					await Task.Delay(TimeSpan.FromSeconds(0.5), _cts.Token);
+					_cts.Token.ThrowIfCancellationRequested();
+					Dispatcher.BeginInvoke(() =>
+					{
+						base.Text = Obfuscate();
+						SelectionStart = base.Text.Length;
+					});
+				}, _cts.Token);
+			}
+
+			if (base.Text == newText)
+				return;
+
+			base.Text = newText;
+			SelectionStart = base.Text.Length;
+		}
+
+		static string DetermineTextFromPassword(string realText, string passwordText)
+		{
+			int firstObfuscationChar = passwordText.IndexOf(ObfuscationCharacter);
+
+			if (firstObfuscationChar > 0)
+			{
+				// The user is typing faster than we can process, and the text is coming in at the beginning
+				// of the textbox instead of the end
+				passwordText = passwordText.Substring(firstObfuscationChar, passwordText.Length - firstObfuscationChar) + passwordText.Substring(0, firstObfuscationChar);
+			}
+
+			if (realText.Length == passwordText.Length)
+				return realText;
+
+			if (passwordText.Length == 0)
+				return "";
+
+			if (passwordText.Length < realText.Length)
+				return realText.Substring(0, passwordText.Length);
+
+			int lengthDifference = passwordText.Length - realText.Length;
+
+			return realText + passwordText.Substring(passwordText.Length - lengthDifference, lengthDifference);
+		}
+
+		string Obfuscate(bool leaveLastVisible = false)
+		{
+			if (leaveLastVisible && Text.Length == 1)
+				return Text;
+
+			if (leaveLastVisible && Text.Length > 1)
+				return new string(ObfuscationCharacter, Text.Length - 1) + Text.Substring(Text.Length - 1, 1);
+
+			return new string(ObfuscationCharacter, Text.Length);
+		}
+
+		static void OnIsPasswordChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
+		{
+			var textBox = (FormsPhoneTextBox)dependencyObject;
+			textBox.UpdateInputScope();
+			textBox.SyncBaseText();
+		}
+
+		void OnSelectionChanged(object sender, RoutedEventArgs routedEventArgs)
+		{
+			if (!IsPassword)
+				return;
+
+			// Prevent the user from selecting any text in the password box by forcing all selection
+			// to zero-length at the end of the text
+			// This simulates the "do not allow clipboard copy" behavior the PasswordBox control has
+			if (SelectionLength > 0 || SelectionStart < Text.Length)
+			{
+				SelectionLength = 0;
+				SelectionStart = Text.Length;
+			}
+		}
+
+		void OnTextChanged(object sender, System.Windows.Controls.TextChangedEventArgs textChangedEventArgs)
+		{
+			if (IsPassword)
+				DelayObfuscation();
+			else if (base.Text != Text)
+			{
+				// Not in password mode, so we just need to make the "real" Text match
+				// what's in the textbox; the internalChange flag keeps the TextProperty
+				// synchronization from happening 
+				_internalChangeFlag = true;
+				Text = base.Text;
+				_internalChangeFlag = false;
+			}
+		}
+
+		void SyncBaseText()
+		{
+			if (_internalChangeFlag)
+				return;
+
+			base.Text = IsPassword ? Obfuscate() : Text;
+			DisabledText = base.Text;
+
+			SelectionStart = base.Text.Length;
+		}
+
+		static void TextPropertyChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
+		{
+			var textBox = (FormsPhoneTextBox)dependencyObject;
+			textBox.SyncBaseText();
+		}
+
+		void UpdateInputScope()
+		{
+			if (IsPassword)
+			{
+				_cachedInputScope = InputScope;
+				InputScope = PasswordInputScope; // We don't want suggestions turned on if we're in password mode
+			}
+			else
+				InputScope = _cachedInputScope;
+		}
+	}
+}
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