DatePicker.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Controls / DatePicker.cs / 1305600 / DatePicker.cs

                            //---------------------------------------------------------------------------- 
//
// Copyright (C) Microsoft Corporation.  All rights reserved.
//
//--------------------------------------------------------------------------- 

using System; 
using System.Collections.Generic; 
using System.Collections.ObjectModel;
using System.Diagnostics; 
using System.Globalization;
using System.Windows;
using System.Windows.Automation.Peers;
using System.Windows.Controls.Primitives; 
using System.Windows.Data;
using System.Windows.Input; 
using System.Windows.Media; 
using System.Windows.Threading;
using MS.Internal.KnownBoxes; 

namespace System.Windows.Controls
{
    ///  
    /// Represents a control that allows the user to select a date.
    ///  
    [TemplatePart(Name = DatePicker.ElementRoot, Type = typeof(Grid))] 
    [TemplatePart(Name = DatePicker.ElementTextBox, Type = typeof(DatePickerTextBox))]
    [TemplatePart(Name = DatePicker.ElementButton, Type = typeof(Button))] 
    [TemplatePart(Name = DatePicker.ElementPopup, Type = typeof(Popup))]
    public class DatePicker : Control
    {
        #region Constants 

        private const string ElementRoot = "PART_Root"; 
        private const string ElementTextBox = "PART_TextBox"; 
        private const string ElementButton = "PART_Button";
        private const string ElementPopup = "PART_Popup"; 

        #endregion Constants

        #region Data 

        private Calendar _calendar; 
        private string _defaultText; 
        private ButtonBase _dropDownButton;
        private Popup _popUp; 
        private bool _disablePopupReopen;
        private DatePickerTextBox _textBox;
        private IDictionary _isHandlerSuspended;
        private DateTime? _originalSelectedDate; 

        #endregion Data 
 
        #region Public Events
 
        public static readonly RoutedEvent SelectedDateChangedEvent = EventManager.RegisterRoutedEvent("SelectedDateChanged", RoutingStrategy.Direct, typeof(EventHandler), typeof(DatePicker));

        /// 
        /// Occurs when the drop-down Calendar is closed. 
        /// 
        public event RoutedEventHandler CalendarClosed; 
 
        /// 
        /// Occurs when the drop-down Calendar is opened. 
        /// 
        public event RoutedEventHandler CalendarOpened;

        ///  
        /// Occurs when text entered into the DatePicker cannot be parsed or the Date is not valid to be selected.
        ///  
        public event EventHandler DateValidationError; 

        ///  
        /// Occurs when a date is selected.
        /// 
        public event EventHandler SelectedDateChanged
        { 
            add { AddHandler(SelectedDateChangedEvent, value); }
            remove { RemoveHandler(SelectedDateChangedEvent, value); } 
        } 

        #endregion Public Events 

        /// 
        /// Static constructor
        ///  
        static DatePicker()
        { 
            DefaultStyleKeyProperty.OverrideMetadata(typeof(DatePicker), new FrameworkPropertyMetadata(typeof(DatePicker))); 
            EventManager.RegisterClassHandler(typeof(DatePicker), UIElement.GotFocusEvent, new RoutedEventHandler(OnGotFocus));
            KeyboardNavigation.TabNavigationProperty.OverrideMetadata(typeof(DatePicker), new FrameworkPropertyMetadata(KeyboardNavigationMode.Once)); 
            KeyboardNavigation.IsTabStopProperty.OverrideMetadata(typeof(DatePicker), new FrameworkPropertyMetadata(false));
            IsEnabledProperty.OverrideMetadata(typeof(DatePicker), new UIPropertyMetadata(new PropertyChangedCallback(OnIsEnabledChanged)));
        }
 
        /// 
        /// Initializes a new instance of the DatePicker class. 
        ///  
        public DatePicker()
        { 
            InitializeCalendar();
            this._defaultText = string.Empty;

            // Binding to FirstDayOfWeek and DisplayDate wont work 
            this.SetCurrentValueInternal(FirstDayOfWeekProperty, DateTimeHelper.GetCurrentDateFormat().FirstDayOfWeek);
            this.DisplayDate = DateTime.Today; 
        } 

        #region Public properties 

        #region BlackoutDates

        ///  
        /// Gets the days that are not selectable.
        ///  
        public CalendarBlackoutDatesCollection BlackoutDates 
        {
            get { return _calendar.BlackoutDates; } 
        }

        #endregion BlackoutDates
 
        #region CalendarStyle
 
        ///  
        /// Gets or sets the style that is used when rendering the calendar.
        ///  
        public Style CalendarStyle
        {
            get { return (Style)GetValue(CalendarStyleProperty); }
            set { SetValue(CalendarStyleProperty, value); } 
        }
 
        ///  
        /// Identifies the CalendarStyle dependency property.
        ///  
        public static readonly DependencyProperty CalendarStyleProperty =
            DependencyProperty.Register(
            "CalendarStyle",
            typeof(Style), 
            typeof(DatePicker));
 
        #endregion CalendarStyle 

        #region DisplayDate 

        /// 
        /// Gets or sets the date to display.
        ///  
        ///
        public DateTime DisplayDate 
        { 
            get { return (DateTime)GetValue(DisplayDateProperty); }
            set { SetValue(DisplayDateProperty, value); } 
        }

        /// 
        /// Identifies the DisplayDate dependency property. 
        /// 
        public static readonly DependencyProperty DisplayDateProperty = 
            DependencyProperty.Register( 
            "DisplayDate",
            typeof(DateTime), 
            typeof(DatePicker),
            new FrameworkPropertyMetadata(DateTime.Now, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, null, CoerceDisplayDate));

        private static object CoerceDisplayDate(DependencyObject d, object value) 
        {
            DatePicker dp = d as DatePicker; 
 
            // We set _calendar.DisplayDate in order to get _calendar to compute the coerced value
            dp._calendar.DisplayDate = (DateTime)value; 
            return dp._calendar.DisplayDate;
        }

        #endregion DisplayDate 

        #region DisplayDateEnd 
 
        /// 
        /// Gets or sets the last date to be displayed. 
        /// 
        ///
        public DateTime? DisplayDateEnd
        { 
            get { return (DateTime?)GetValue(DisplayDateEndProperty); }
            set { SetValue(DisplayDateEndProperty, value); } 
        } 

        ///  
        /// Identifies the DisplayDateEnd dependency property.
        /// 
        public static readonly DependencyProperty DisplayDateEndProperty =
            DependencyProperty.Register( 
            "DisplayDateEnd",
            typeof(DateTime?), 
            typeof(DatePicker), 
            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnDisplayDateEndChanged, CoerceDisplayDateEnd));
 
        /// 
        /// DisplayDateEndProperty property changed handler.
        /// 
        /// DatePicker that changed its DisplayDateEnd. 
        /// DependencyPropertyChangedEventArgs.
        private static void OnDisplayDateEndChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        { 
            DatePicker dp = d as DatePicker;
            Debug.Assert(dp != null); 

            dp.CoerceValue(DisplayDateProperty);
        }
 
        private static object CoerceDisplayDateEnd(DependencyObject d, object value)
        { 
            DatePicker dp = d as DatePicker; 

            // We set _calendar.DisplayDateEnd in order to get _calendar to compute the coerced value 
            dp._calendar.DisplayDateEnd = (DateTime?)value;
            return dp._calendar.DisplayDateEnd;
        }
 
        #endregion DisplayDateEnd
 
        #region DisplayDateStart 

        ///  
        /// Gets or sets the first date to be displayed.
        /// 
        ///
        public DateTime? DisplayDateStart 
        {
            get { return (DateTime?)GetValue(DisplayDateStartProperty); } 
            set { SetValue(DisplayDateStartProperty, value); } 
        }
 
        /// 
        /// Identifies the DisplayDateStart dependency property.
        /// 
        public static readonly DependencyProperty DisplayDateStartProperty = 
            DependencyProperty.Register(
            "DisplayDateStart", 
            typeof(DateTime?), 
            typeof(DatePicker),
            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnDisplayDateStartChanged, CoerceDisplayDateStart)); 

        /// 
        /// DisplayDateStartProperty property changed handler.
        ///  
        /// DatePicker that changed its DisplayDateStart.
        /// DependencyPropertyChangedEventArgs. 
        private static void OnDisplayDateStartChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker; 
            Debug.Assert(dp != null);

            dp.CoerceValue(DisplayDateEndProperty);
            dp.CoerceValue(DisplayDateProperty); 
        }
 
        private static object CoerceDisplayDateStart(DependencyObject d, object value) 
        {
            DatePicker dp = d as DatePicker; 

            // We set _calendar.DisplayDateStart in order to get _calendar to compute the coerced value
            dp._calendar.DisplayDateStart = (DateTime?)value;
            return dp._calendar.DisplayDateStart; 
        }
 
        #endregion DisplayDateStart 

        #region FirstDayOfWeek 

        /// 
        /// Gets or sets the day that is considered the beginning of the week.
        ///  
        public DayOfWeek FirstDayOfWeek
        { 
            get { return (DayOfWeek)GetValue(FirstDayOfWeekProperty); } 
            set { SetValue(FirstDayOfWeekProperty, value); }
        } 

        /// 
        /// Identifies the FirstDayOfWeek dependency property.
        ///  
        public static readonly DependencyProperty FirstDayOfWeekProperty =
            DependencyProperty.Register( 
            "FirstDayOfWeek", 
            typeof(DayOfWeek),
            typeof(DatePicker), 
            null,
            Calendar.IsValidFirstDayOfWeek);

        #endregion FirstDayOfWeek 

        #region IsDropDownOpen 
 
        /// 
        /// Gets or sets a value that indicates whether the drop-down Calendar is open or closed. 
        /// 
        public bool IsDropDownOpen
        {
            get { return (bool)GetValue(IsDropDownOpenProperty); } 
            set { SetValue(IsDropDownOpenProperty, value); }
        } 
 
        /// 
        /// Identifies the IsDropDownOpen dependency property. 
        /// 
        public static readonly DependencyProperty IsDropDownOpenProperty =
            DependencyProperty.Register(
            "IsDropDownOpen", 
            typeof(bool),
            typeof(DatePicker), 
            new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnIsDropDownOpenChanged, OnCoerceIsDropDownOpen)); 

        private static object OnCoerceIsDropDownOpen(DependencyObject d, object baseValue) 
        {
            DatePicker dp = d as DatePicker;
            Debug.Assert(dp != null);
 
            if (!dp.IsEnabled)
            { 
                return false; 
            }
 
            return baseValue;
        }

        ///  
        /// IsDropDownOpenProperty property changed handler.
        ///  
        /// DatePicker that changed its IsDropDownOpen. 
        /// DependencyPropertyChangedEventArgs.
        private static void OnIsDropDownOpenChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker;
            Debug.Assert(dp != null);
 
            bool newValue = (bool)e.NewValue;
            if (dp._popUp != null && dp._popUp.IsOpen != newValue) 
            { 
                dp._popUp.IsOpen = newValue;
                if (newValue) 
                {
                    dp._originalSelectedDate = dp.SelectedDate;

                    // When the popup is opened set focus to the DisplayDate button. 
                    // Do this asynchronously because the IsDropDownOpen could
                    // have been set even before the template for the DatePicker is 
                    // applied. And this would mean that the visuals wouldn't be available yet. 

                    dp.Dispatcher.BeginInvoke(DispatcherPriority.Input, (Action)delegate() 
                        {
                            // setting the focus to the calendar will focus the correct date.
                            dp._calendar.Focus();
                        }); 
                }
            } 
        } 

        private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker;
            Debug.Assert(dp != null);
 
            dp.CoerceValue(IsDropDownOpenProperty);
 
            OnVisualStatePropertyChanged(d, e); 
        }
 
        #endregion IsDropDownOpen

        #region IsTodayHighlighted
 
        /// 
        /// Gets or sets a value that indicates whether the current date will be highlighted. 
        ///  
        public bool IsTodayHighlighted
        { 
            get { return (bool)GetValue(IsTodayHighlightedProperty); }
            set { SetValue(IsTodayHighlightedProperty, value); }
        }
 
        /// 
        /// Identifies the IsTodayHighlighted dependency property. 
        ///  
        public static readonly DependencyProperty IsTodayHighlightedProperty =
            DependencyProperty.Register( 
            "IsTodayHighlighted",
            typeof(bool),
            typeof(DatePicker));
 
        #endregion IsTodayHighlighted
 
        #region SelectedDate 

        ///  
        /// Gets or sets the currently selected date.
        /// 
        ///
        public DateTime? SelectedDate 
        {
            get { return (DateTime?)GetValue(SelectedDateProperty); } 
            set { SetValue(SelectedDateProperty, value); } 
        }
 
        /// 
        /// Identifies the SelectedDate dependency property.
        /// 
        public static readonly DependencyProperty SelectedDateProperty = 
            DependencyProperty.Register(
            "SelectedDate", 
            typeof(DateTime?), 
            typeof(DatePicker),
            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnSelectedDateChanged, CoerceSelectedDate)); 

        /// 
        /// SelectedDateProperty property changed handler.
        ///  
        /// DatePicker that changed its SelectedDate.
        /// DependencyPropertyChangedEventArgs. 
        private static void OnSelectedDateChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker; 
            Debug.Assert(dp != null);

            Collection addedItems = new Collection();
            Collection removedItems = new Collection(); 
            DateTime? addedDate;
            DateTime? removedDate; 
 
            dp.CoerceValue(DisplayDateStartProperty);
            dp.CoerceValue(DisplayDateEndProperty); 
            dp.CoerceValue(DisplayDateProperty);

            addedDate = (DateTime?)e.NewValue;
            removedDate = (DateTime?)e.OldValue; 

            if (dp.SelectedDate.HasValue) 
            { 
                DateTime day = dp.SelectedDate.Value;
                dp.SetTextInternal(dp.DateTimeToString(day)); 

                // When DatePickerDisplayDateFlag is TRUE, the SelectedDate change is coming from the Calendar UI itself,
                // so, we shouldn't change the DisplayDate since it will automatically be changed by the Calendar
                if ((day.Month != dp.DisplayDate.Month || day.Year != dp.DisplayDate.Year) && !dp._calendar.DatePickerDisplayDateFlag) 
                {
                    dp.SetCurrentValueInternal(DisplayDateProperty, day); 
                } 

                dp._calendar.DatePickerDisplayDateFlag = false; 
            }
            else
            {
                dp.SetWaterMarkText(); 
            }
 
            if (addedDate.HasValue) 
            {
                addedItems.Add(addedDate.Value); 
            }

            if (removedDate.HasValue)
            { 
                removedItems.Add(removedDate.Value);
            } 
 
            dp.OnSelectedDateChanged(new CalendarSelectionChangedEventArgs(DatePicker.SelectedDateChangedEvent, removedItems, addedItems));
 
            DatePickerAutomationPeer peer = UIElementAutomationPeer.FromElement(dp) as DatePickerAutomationPeer;
            // Raise the propetyChangeEvent for Value if Automation Peer exist
            if (peer != null)
            { 
                string addedDateString = addedDate.HasValue ? dp.DateTimeToString(addedDate.Value) : "";
                string removedDateString = removedDate.HasValue ? dp.DateTimeToString(removedDate.Value) : ""; 
                peer.RaiseValuePropertyChangedEvent(removedDateString, addedDateString); 
            }
        } 

        private static object CoerceSelectedDate(DependencyObject d, object value)
        {
            DatePicker dp = d as DatePicker; 

            // We set _calendar.SelectedDate in order to get _calendar to compute the coerced value 
            dp._calendar.SelectedDate = (DateTime?)value; 
            return dp._calendar.SelectedDate;
        } 

        #endregion SelectedDate

        #region SelectedDateFormat 

        ///  
        /// Gets or sets the format that is used to display the selected date. 
        /// 
        public DatePickerFormat SelectedDateFormat 
        {
            get { return (DatePickerFormat)GetValue(SelectedDateFormatProperty); }
            set { SetValue(SelectedDateFormatProperty, value); }
        } 

        ///  
        /// Identifies the SelectedDateFormat dependency property. 
        /// 
        public static readonly DependencyProperty SelectedDateFormatProperty = 
            DependencyProperty.Register(
            "SelectedDateFormat",
            typeof(DatePickerFormat),
            typeof(DatePicker), 
            new FrameworkPropertyMetadata(DatePickerFormat.Long, OnSelectedDateFormatChanged),
            IsValidSelectedDateFormat); 
 
        /// 
        /// SelectedDateFormatProperty property changed handler. 
        /// 
        /// DatePicker that changed its SelectedDateFormat.
        /// DependencyPropertyChangedEventArgs.
        private static void OnSelectedDateFormatChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker; 
            Debug.Assert(dp != null); 

            if (dp._textBox != null) 
            {
                // Update DatePickerTextBox.Text
                if (string.IsNullOrEmpty(dp._textBox.Text))
                { 
                    dp.SetWaterMarkText();
                } 
                else 
                {
                    DateTime? date = dp.ParseText(dp._textBox.Text); 

                    if (date != null)
                    {
                        dp.SetTextInternal(dp.DateTimeToString((DateTime)date)); 
                    }
                } 
            } 
        }
 
        #endregion SelectedDateFormat

        #region Text
 
        /// 
        /// Gets or sets the text that is displayed by the DatePicker. 
        ///  
        public string Text
        { 
            get { return (string)GetValue(TextProperty); }
            set { SetValue(TextProperty, value); }
        }
 
        /// 
        /// Identifies the Text dependency property. 
        ///  
        public static readonly DependencyProperty TextProperty =
            DependencyProperty.Register( 
            "Text",
            typeof(string),
            typeof(DatePicker),
            new FrameworkPropertyMetadata(string.Empty, OnTextChanged)); 

        ///  
        /// TextProperty property changed handler. 
        /// 
        /// DatePicker that changed its Text. 
        /// DependencyPropertyChangedEventArgs.
        private static void OnTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            DatePicker dp = d as DatePicker; 
            Debug.Assert(dp != null);
 
            if (!dp.IsHandlerSuspended(DatePicker.TextProperty)) 
            {
                string newValue = e.NewValue as string; 

                if (newValue != null)
                {
                    if (dp._textBox != null) 
                    {
                        dp._textBox.Text = newValue; 
                    } 
                    else
                    { 
                        dp._defaultText = newValue;
                    }

                    dp.SetSelectedDate(); 
                }
                else 
                { 
                    dp.SetValueNoCallback(DatePicker.SelectedDateProperty, null);
                } 
            }
        }

 
        /// 
        /// Sets the local Text property without breaking bindings 
        ///  
        /// 
        private void SetTextInternal(string value) 
        {
            SetCurrentValueInternal(TextProperty, value);
        }
 
        #endregion Text
 
        #endregion Public Properties 

        #region Protected properties 

        #endregion Protected Properties

        #region Internal Properties 

        internal Calendar Calendar 
        { 
            get
            { 
                return _calendar;
            }
        }
 
        internal TextBox TextBox
        { 
            get 
            {
                return _textBox; 
            }
        }

 
        #endregion Internal Properties
 
        #region Private Properties 
        #endregion Private Properties
 
        #region Public Methods

        /// 
        /// Builds the visual tree for the DatePicker control when a new template is applied. 
        /// 
        public override void OnApplyTemplate() 
        { 
            if (_popUp != null)
            { 
                _popUp.RemoveHandler(PreviewMouseLeftButtonDownEvent, new MouseButtonEventHandler(PopUp_PreviewMouseLeftButtonDown));
                _popUp.Opened -= PopUp_Opened;
                _popUp.Closed -= PopUp_Closed;
                _popUp.Child = null; 
            }
 
            if (_dropDownButton != null) 
            {
                _dropDownButton.Click -= DropDownButton_Click; 
                _dropDownButton.RemoveHandler(MouseLeaveEvent, new MouseEventHandler(DropDownButton_MouseLeave));
            }

            if (_textBox != null) 
            {
                _textBox.RemoveHandler(TextBox.KeyDownEvent, new KeyEventHandler(TextBox_KeyDown)); 
                _textBox.RemoveHandler(TextBox.TextChangedEvent, new TextChangedEventHandler(TextBox_TextChanged)); 
                _textBox.RemoveHandler(TextBox.LostFocusEvent, new RoutedEventHandler(TextBox_LostFocus));
            } 

            base.OnApplyTemplate();

            _popUp = GetTemplateChild(ElementPopup) as Popup; 

            if (_popUp != null) 
            { 
                _popUp.AddHandler(PreviewMouseLeftButtonDownEvent, new MouseButtonEventHandler(PopUp_PreviewMouseLeftButtonDown));
                _popUp.Opened += PopUp_Opened; 
                _popUp.Closed += PopUp_Closed;
                _popUp.Child = this._calendar;

                if (this.IsDropDownOpen) 
                {
                    this._popUp.IsOpen = true; 
                } 
            }
 
            _dropDownButton = GetTemplateChild(ElementButton) as Button;
            if (_dropDownButton != null)
            {
                _dropDownButton.Click += DropDownButton_Click; 
                _dropDownButton.AddHandler(MouseLeaveEvent, new MouseEventHandler(DropDownButton_MouseLeave), true);
 
                // If the user does not provide a Content value in template, we provide a helper text that can be used in Accessibility 
                // this text is not shown on the UI, just used for Accessibility purposes
                if (_dropDownButton.Content == null) 
                {
                    _dropDownButton.Content = SR.Get(SRID.DatePicker_DropDownButtonName);
                }
            } 

            _textBox = GetTemplateChild(ElementTextBox) as DatePickerTextBox; 
 
            if (this.SelectedDate == null)
            { 
                SetWaterMarkText();
            }

            if (_textBox != null) 
            {
                _textBox.AddHandler(TextBox.KeyDownEvent, new KeyEventHandler(TextBox_KeyDown), true); 
                _textBox.AddHandler(TextBox.TextChangedEvent, new TextChangedEventHandler(TextBox_TextChanged), true); 
                _textBox.AddHandler(TextBox.LostFocusEvent, new RoutedEventHandler(TextBox_LostFocus), true);
 
                if (this.SelectedDate == null)
                {
                    if (!string.IsNullOrEmpty(this._defaultText))
                    { 
                        _textBox.Text = this._defaultText;
                        SetSelectedDate(); 
                    } 
                }
                else 
                {
                    _textBox.Text = this.DateTimeToString((DateTime)this.SelectedDate);
                }
            } 
        }
 
        ///  
        /// Provides a text representation of the selected date.
        ///  
        /// A text representation of the selected date, or an empty string if SelectedDate is a null reference.
        public override string ToString()
        {
            if (this.SelectedDate != null) 
            {
                return this.SelectedDate.Value.ToString(DateTimeHelper.GetDateFormat(DateTimeHelper.GetCulture(this))); 
            } 
            else
            { 
                return string.Empty;
            }
        }
 
        #endregion Public Methods
 
        #region Protected Methods 

        internal override void ChangeVisualState(bool useTransitions) 
        {
            if (!IsEnabled)
            {
                VisualStates.GoToState(this, useTransitions, VisualStates.StateDisabled, VisualStates.StateNormal); 
            }
            else 
            { 
                VisualStateManager.GoToState(this, VisualStates.StateNormal, useTransitions);
            } 

            base.ChangeVisualState(useTransitions);
        }
 
        /// 
        /// Creates the automation peer for this DatePicker Control. 
        ///  
        /// 
        protected override AutomationPeer OnCreateAutomationPeer() 
        {
            return new DatePickerAutomationPeer(this);
        }
 
        protected virtual void OnCalendarClosed(RoutedEventArgs e)
        { 
            RoutedEventHandler handler = this.CalendarClosed; 
            if (null != handler)
            { 
                handler(this, e);
            }
        }
 
        protected virtual void OnCalendarOpened(RoutedEventArgs e)
        { 
            RoutedEventHandler handler = this.CalendarOpened; 
            if (null != handler)
            { 
                handler(this, e);
            }
        }
 
        protected virtual void OnSelectedDateChanged(SelectionChangedEventArgs e)
        { 
            RaiseEvent(e); 
        }
 
        /// 
        /// Raises the DateValidationError event.
        /// 
        /// A DatePickerDateValidationErrorEventArgs that contains the event data. 
        protected virtual void OnDateValidationError(DatePickerDateValidationErrorEventArgs e)
        { 
            EventHandler handler = this.DateValidationError; 
            if (handler != null)
            { 
                handler(this, e);
            }
        }
 
        #endregion Protected Methods
 
        #region Private Methods 

        ///  
        ///     Called when this element gets focus.
        /// 
        private static void OnGotFocus(object sender, RoutedEventArgs e)
        { 
            // When Datepicker gets focus move it to the TextBox
            DatePicker picker = (DatePicker)sender; 
            if ((!e.Handled) && (picker._textBox != null)) 
            {
                if (e.OriginalSource == picker) 
                {
                    picker._textBox.Focus();
                    e.Handled = true;
                } 
                else if (e.OriginalSource == picker._textBox)
                { 
                    picker._textBox.SelectAll(); 
                    e.Handled = true;
                } 
            }
        }

        private void SetValueNoCallback(DependencyProperty property, object value) 
        {
            SetIsHandlerSuspended(property, true); 
            try 
            {
                SetCurrentValue(property, value); 
            }
            finally
            {
                SetIsHandlerSuspended(property, false); 
            }
        } 
 
        private bool IsHandlerSuspended(DependencyProperty property)
        { 
            return _isHandlerSuspended != null && _isHandlerSuspended.ContainsKey(property);
        }

        private void SetIsHandlerSuspended(DependencyProperty property, bool value) 
        {
            if (value) 
            { 
                if (_isHandlerSuspended == null)
                { 
                    _isHandlerSuspended = new Dictionary(2);
                }

                _isHandlerSuspended[property] = true; 
            }
            else 
            { 
                if (_isHandlerSuspended != null)
                { 
                    _isHandlerSuspended.Remove(property);
                }
            }
        } 

        private void PopUp_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) 
        { 
            Popup popup = sender as Popup;
            if (popup != null && !popup.StaysOpen) 
            {
                if (this._dropDownButton != null)
                {
                    if (this._dropDownButton.InputHitTest(e.GetPosition(this._dropDownButton)) != null) 
                    {
                        // This popup is being closed by a mouse press on the drop down button 
                        // The following mouse release will cause the closed popup to immediately reopen. 
                        // Raise a flag to block reopeneing the popup
                        this._disablePopupReopen = true; 
                    }
                }
            }
        } 

        private void PopUp_Opened(object sender, EventArgs e) 
        { 
            if (!this.IsDropDownOpen)
            { 
                this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.TrueBox);
            }

            if (this._calendar != null) 
            {
                this._calendar.DisplayMode = CalendarMode.Month; 
                this._calendar.MoveFocus(new TraversalRequest(FocusNavigationDirection.First)); 
            }
 
            this.OnCalendarOpened(new RoutedEventArgs());
        }

        private void PopUp_Closed(object sender, EventArgs e) 
        {
            if (this.IsDropDownOpen) 
            { 
                this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.FalseBox);
            } 

            if (_calendar.IsKeyboardFocusWithin)
            {
                this.MoveFocus(new TraversalRequest(FocusNavigationDirection.First)); 
            }
 
            OnCalendarClosed(new RoutedEventArgs()); 
        }
 
        private void Calendar_DayButtonMouseUp(object sender, MouseButtonEventArgs e)
        {
            this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.FalseBox);
        } 

        private void CalendarDayOrMonthButton_PreviewKeyDown(object sender, RoutedEventArgs e) 
        { 
            Calendar c = sender as Calendar;
            KeyEventArgs args = (KeyEventArgs)e; 

            Debug.Assert(c != null);
            Debug.Assert(args != null);
 
            if (args.Key == Key.Escape || ((args.Key == Key.Enter || args.Key == Key.Space) && c.DisplayMode == CalendarMode.Month))
            { 
                this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.FalseBox); 
                if (args.Key == Key.Escape)
                { 
                    SetCurrentValueInternal(SelectedDateProperty, _originalSelectedDate);
                }
            }
        } 

        private void Calendar_DisplayDateChanged(object sender, CalendarDateChangedEventArgs e) 
        { 
            if (e.AddedDate != this.DisplayDate)
            { 
                SetCurrentValueInternal(DisplayDateProperty, (DateTime)e.AddedDate);
            }
        }
 
        private void Calendar_SelectedDatesChanged(object sender, SelectionChangedEventArgs e)
        { 
            Debug.Assert(e.AddedItems.Count < 2); 

            if (e.AddedItems.Count > 0 && this.SelectedDate.HasValue && DateTime.Compare((DateTime)e.AddedItems[0], this.SelectedDate.Value) != 0) 
            {
                this.SetCurrentValueInternal(SelectedDateProperty, (DateTime?)e.AddedItems[0]);
            }
            else 
            {
                if (e.AddedItems.Count == 0) 
                { 
                    this.SetCurrentValueInternal(SelectedDateProperty, (DateTime?)null);
                    return; 
                }

                if (!this.SelectedDate.HasValue)
                { 
                    if (e.AddedItems.Count > 0)
                    { 
                        this.SetCurrentValueInternal(SelectedDateProperty, (DateTime?)e.AddedItems[0]); 
                    }
                } 
            }
        }

        private string DateTimeToString(DateTime d) 
        {
            DateTimeFormatInfo dtfi = DateTimeHelper.GetDateFormat(DateTimeHelper.GetCulture(this)); 
 
            switch (this.SelectedDateFormat)
            { 
                case DatePickerFormat.Short:
                    {
                        return string.Format(CultureInfo.CurrentCulture, d.ToString(dtfi.ShortDatePattern, dtfi));
                    } 

                case DatePickerFormat.Long: 
                    { 
                        return string.Format(CultureInfo.CurrentCulture, d.ToString(dtfi.LongDatePattern, dtfi));
                    } 
            }

            return null;
        } 

        private static DateTime DiscardDayTime(DateTime d) 
        { 
            int year = d.Year;
            int month = d.Month; 
            DateTime newD = new DateTime(year, month, 1, 0, 0, 0);
            return newD;
        }
 
        private static DateTime? DiscardTime(DateTime? d)
        { 
            if (d == null) 
            {
                return null; 
            }
            else
            {
                DateTime discarded = (DateTime)d; 
                int year = discarded.Year;
                int month = discarded.Month; 
                int day = discarded.Day; 
                DateTime newD = new DateTime(year, month, day, 0, 0, 0);
                return newD; 
            }
        }

        private void DropDownButton_Click(object sender, RoutedEventArgs e) 
        {
            TogglePopUp(); 
        } 

        private void DropDownButton_MouseLeave(object sender, MouseEventArgs e) 
        {
            this._disablePopupReopen = false;
        }
 
        private void TogglePopUp()
        { 
            if (this.IsDropDownOpen) 
            {
                this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.FalseBox); 
            }
            else
            {
                if (this._disablePopupReopen) 
                {
                    this._disablePopupReopen = false; 
                } 
                else
                { 
                    SetSelectedDate();
                    this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.TrueBox);
                }
            } 
        }
 
        private void InitializeCalendar() 
        {
            _calendar = new Calendar(); 
            _calendar.DayButtonMouseUp += new MouseButtonEventHandler(Calendar_DayButtonMouseUp);
            _calendar.DisplayDateChanged += new EventHandler(Calendar_DisplayDateChanged);
            _calendar.SelectedDatesChanged += new EventHandler(Calendar_SelectedDatesChanged);
            _calendar.DayOrMonthPreviewKeyDown += new RoutedEventHandler(CalendarDayOrMonthButton_PreviewKeyDown); 
            _calendar.HorizontalAlignment = HorizontalAlignment.Left;
            _calendar.VerticalAlignment = VerticalAlignment.Top; 
 
            _calendar.SelectionMode = CalendarSelectionMode.SingleDate;
            _calendar.SetBinding(Calendar.ForegroundProperty, GetDatePickerBinding(DatePicker.ForegroundProperty)); 
            _calendar.SetBinding(Calendar.StyleProperty, GetDatePickerBinding(DatePicker.CalendarStyleProperty));
            _calendar.SetBinding(Calendar.IsTodayHighlightedProperty, GetDatePickerBinding(DatePicker.IsTodayHighlightedProperty));
            _calendar.SetBinding(Calendar.FirstDayOfWeekProperty, GetDatePickerBinding(DatePicker.FirstDayOfWeekProperty));
            _calendar.SetBinding(Calendar.FlowDirectionProperty, GetDatePickerBinding(DatePicker.FlowDirectionProperty)); 

            RenderOptions.SetClearTypeHint(_calendar, ClearTypeHint.Enabled); 
        } 

        private BindingBase GetDatePickerBinding(DependencyProperty property) 
        {
            Binding binding = new Binding(property.Name);
            binding.Source = this;
            return binding; 
        }
 
        private static bool IsValidSelectedDateFormat(object value) 
        {
            DatePickerFormat format = (DatePickerFormat)value; 

            return format == DatePickerFormat.Long
                || format == DatePickerFormat.Short;
        } 

        // iT SHOULD RETURN NULL IF THE STRING IS NOT VALID, RETURN THE DATETIME VALUE IF IT IS VALID 
 
        /// 
        /// Input text is parsed in the correct format and changed into a DateTime object. 
        /// If the text can not be parsed TextParseError Event is thrown.
        /// 
        private DateTime? ParseText(string text)
        { 
            DateTime newSelectedDate;
 
            // TryParse is not used in order to be able to pass the exception to the TextParseError event 
            try
            { 
                newSelectedDate = DateTime.Parse(text, DateTimeHelper.GetDateFormat(DateTimeHelper.GetCulture(this)));

                if (Calendar.IsValidDateSelection(this._calendar, newSelectedDate))
                { 
                    return newSelectedDate;
                } 
                else 
                {
                    DatePickerDateValidationErrorEventArgs dateValidationError = new DatePickerDateValidationErrorEventArgs(new ArgumentOutOfRangeException("text", SR.Get(SRID.Calendar_OnSelectedDateChanged_InvalidValue)), text); 
                    OnDateValidationError(dateValidationError);

                    if (dateValidationError.ThrowException)
                    { 
                        throw dateValidationError.Exception;
                    } 
                } 
            }
            catch (FormatException ex) 
            {
                DatePickerDateValidationErrorEventArgs textParseError = new DatePickerDateValidationErrorEventArgs(ex, text);
                OnDateValidationError(textParseError);
 
                if (textParseError.ThrowException && textParseError.Exception != null)
                { 
                    throw textParseError.Exception; 
                }
            } 

            return null;
        }
 
        private bool ProcessDatePickerKey(KeyEventArgs e)
        { 
            switch (e.Key) 
            {
                case Key.System: 
                {
                    switch (e.SystemKey)
                    {
                        case Key.Down: 
                        {
                            if ((Keyboard.Modifiers & ModifierKeys.Alt) == ModifierKeys.Alt) 
                            { 
                                TogglePopUp();
                                return true; 
                            }

                            break;
                        } 
                    }
 
                    break; 
                }
 
                case Key.Enter:
                {
                    SetSelectedDate();
                    return true; 
                }
            } 
 
            return false;
        } 

        private void SetSelectedDate()
        {
            if (this._textBox != null) 
            {
                if (!string.IsNullOrEmpty(this._textBox.Text)) 
                { 
                    string s = this._textBox.Text;
 
                    if (this.SelectedDate != null)
                    {
                        // If the string value of the SelectedDate and the TextBox string value are equal,
                        // we do not parse the string again 
                        // if we do an extra parse, we lose data in M/d/yy format
                        // ex: SelectedDate = DateTime(1008,12,19) but when "12/19/08" is parsed it is interpreted as DateTime(2008,12,19) 
                        string selectedDate = DateTimeToString(this.SelectedDate.Value); 

                        if (string.Compare(selectedDate, s, StringComparison.Ordinal) == 0) 
                        {
                            return;
                        }
                    } 

                    DateTime? d = SetTextBoxValue(s); 
                    if (!this.SelectedDate.Equals(d)) 
                    {
                        this.SetCurrentValueInternal(SelectedDateProperty, d); 
                        this.SetCurrentValueInternal(DisplayDateProperty, d);
                    }
                }
                else 
                {
                    if (this.SelectedDate.HasValue) 
                    { 
                        this.SetCurrentValueInternal(SelectedDateProperty, (DateTime?)null);
                    } 
                }
            }
            else
            { 
                DateTime? d = SetTextBoxValue(_defaultText);
                if (!this.SelectedDate.Equals(d)) 
                { 
                    this.SetCurrentValueInternal(SelectedDateProperty, d);
                } 
            }
        }

        ///  
        ///     Set the Text property if it's not already set to the supplied value.  This avoids making the ValueSource Local.
        ///  
        private void SafeSetText(string s) 
        {
            if (string.Compare(Text, s, StringComparison.Ordinal) != 0) 
            {
                SetCurrentValueInternal(TextProperty, s);
            }
        } 

        private DateTime? SetTextBoxValue(string s) 
        { 
            if (string.IsNullOrEmpty(s))
            { 
                SafeSetText(s);
                return this.SelectedDate;
            }
            else 
            {
                DateTime? d = ParseText(s); 
 
                if (d != null)
                { 
                    SafeSetText(this.DateTimeToString((DateTime)d));
                    return d;
                }
                else 
                {
                    // If parse error: 
                    // TextBox should have the latest valid selecteddate value: 
                    if (this.SelectedDate != null)
                    { 
                        string newtext = this.DateTimeToString((DateTime)this.SelectedDate);
                        SafeSetText(newtext);
                        return this.SelectedDate;
                    } 
                    else
                    { 
                        SetWaterMarkText(); 
                        return null;
                    } 
                }
            }
        }
 
        private void SetWaterMarkText()
        { 
            if (this._textBox != null) 
            {
                DateTimeFormatInfo dtfi = DateTimeHelper.GetDateFormat(DateTimeHelper.GetCulture(this)); 
                this.SetTextInternal(string.Empty);
                this._defaultText = string.Empty;

                switch (this.SelectedDateFormat) 
                {
                    case DatePickerFormat.Long: 
                        { 
                            this._textBox.Watermark = string.Format(CultureInfo.CurrentCulture, SR.Get(SRID.DatePicker_WatermarkText), dtfi.LongDatePattern.ToString());
                            break; 
                        }

                    case DatePickerFormat.Short:
                        { 
                            this._textBox.Watermark = string.Format(CultureInfo.CurrentCulture, SR.Get(SRID.DatePicker_WatermarkText), dtfi.ShortDatePattern.ToString());
                            break; 
                        } 
                }
            } 
        }

        private void TextBox_LostFocus(object sender, RoutedEventArgs e)
        { 
            SetSelectedDate();
        } 
 
        private void TextBox_KeyDown(object sender, KeyEventArgs e)
        { 
            e.Handled = ProcessDatePickerKey(e) || e.Handled;
        }

        private void TextBox_TextChanged(object sender, TextChangedEventArgs e) 
        {
            this.SetValueNoCallback(DatePicker.TextProperty, this._textBox.Text); 
        } 

        #endregion Private Methods 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
//---------------------------------------------------------------------------- 
//
// Copyright (C) Microsoft Corporation.  All rights reserved.
//
//--------------------------------------------------------------------------- 

using System; 
using System.Collections.Generic; 
using System.Collections.ObjectModel;
using System.Diagnostics; 
using System.Globalization;
using System.Windows;
using System.Windows.Automation.Peers;
using System.Windows.Controls.Primitives; 
using System.Windows.Data;
using System.Windows.Input; 
using System.Windows.Media; 
using System.Windows.Threading;
using MS.Internal.KnownBoxes; 

namespace System.Windows.Controls
{
    ///  
    /// Represents a control that allows the user to select a date.
    ///  
    [TemplatePart(Name = DatePicker.ElementRoot, Type = typeof(Grid))] 
    [TemplatePart(Name = DatePicker.ElementTextBox, Type = typeof(DatePickerTextBox))]
    [TemplatePart(Name = DatePicker.ElementButton, Type = typeof(Button))] 
    [TemplatePart(Name = DatePicker.ElementPopup, Type = typeof(Popup))]
    public class DatePicker : Control
    {
        #region Constants 

        private const string ElementRoot = "PART_Root"; 
        private const string ElementTextBox = "PART_TextBox"; 
        private const string ElementButton = "PART_Button";
        private const string ElementPopup = "PART_Popup"; 

        #endregion Constants

        #region Data 

        private Calendar _calendar; 
        private string _defaultText; 
        private ButtonBase _dropDownButton;
        private Popup _popUp; 
        private bool _disablePopupReopen;
        private DatePickerTextBox _textBox;
        private IDictionary _isHandlerSuspended;
        private DateTime? _originalSelectedDate; 

        #endregion Data 
 
        #region Public Events
 
        public static readonly RoutedEvent SelectedDateChangedEvent = EventManager.RegisterRoutedEvent("SelectedDateChanged", RoutingStrategy.Direct, typeof(EventHandler), typeof(DatePicker));

        /// 
        /// Occurs when the drop-down Calendar is closed. 
        /// 
        public event RoutedEventHandler CalendarClosed; 
 
        /// 
        /// Occurs when the drop-down Calendar is opened. 
        /// 
        public event RoutedEventHandler CalendarOpened;

        ///  
        /// Occurs when text entered into the DatePicker cannot be parsed or the Date is not valid to be selected.
        ///  
        public event EventHandler DateValidationError; 

        ///  
        /// Occurs when a date is selected.
        /// 
        public event EventHandler SelectedDateChanged
        { 
            add { AddHandler(SelectedDateChangedEvent, value); }
            remove { RemoveHandler(SelectedDateChangedEvent, value); } 
        } 

        #endregion Public Events 

        /// 
        /// Static constructor
        ///  
        static DatePicker()
        { 
            DefaultStyleKeyProperty.OverrideMetadata(typeof(DatePicker), new FrameworkPropertyMetadata(typeof(DatePicker))); 
            EventManager.RegisterClassHandler(typeof(DatePicker), UIElement.GotFocusEvent, new RoutedEventHandler(OnGotFocus));
            KeyboardNavigation.TabNavigationProperty.OverrideMetadata(typeof(DatePicker), new FrameworkPropertyMetadata(KeyboardNavigationMode.Once)); 
            KeyboardNavigation.IsTabStopProperty.OverrideMetadata(typeof(DatePicker), new FrameworkPropertyMetadata(false));
            IsEnabledProperty.OverrideMetadata(typeof(DatePicker), new UIPropertyMetadata(new PropertyChangedCallback(OnIsEnabledChanged)));
        }
 
        /// 
        /// Initializes a new instance of the DatePicker class. 
        ///  
        public DatePicker()
        { 
            InitializeCalendar();
            this._defaultText = string.Empty;

            // Binding to FirstDayOfWeek and DisplayDate wont work 
            this.SetCurrentValueInternal(FirstDayOfWeekProperty, DateTimeHelper.GetCurrentDateFormat().FirstDayOfWeek);
            this.DisplayDate = DateTime.Today; 
        } 

        #region Public properties 

        #region BlackoutDates

        ///  
        /// Gets the days that are not selectable.
        ///  
        public CalendarBlackoutDatesCollection BlackoutDates 
        {
            get { return _calendar.BlackoutDates; } 
        }

        #endregion BlackoutDates
 
        #region CalendarStyle
 
        ///  
        /// Gets or sets the style that is used when rendering the calendar.
        ///  
        public Style CalendarStyle
        {
            get { return (Style)GetValue(CalendarStyleProperty); }
            set { SetValue(CalendarStyleProperty, value); } 
        }
 
        ///  
        /// Identifies the CalendarStyle dependency property.
        ///  
        public static readonly DependencyProperty CalendarStyleProperty =
            DependencyProperty.Register(
            "CalendarStyle",
            typeof(Style), 
            typeof(DatePicker));
 
        #endregion CalendarStyle 

        #region DisplayDate 

        /// 
        /// Gets or sets the date to display.
        ///  
        ///
        public DateTime DisplayDate 
        { 
            get { return (DateTime)GetValue(DisplayDateProperty); }
            set { SetValue(DisplayDateProperty, value); } 
        }

        /// 
        /// Identifies the DisplayDate dependency property. 
        /// 
        public static readonly DependencyProperty DisplayDateProperty = 
            DependencyProperty.Register( 
            "DisplayDate",
            typeof(DateTime), 
            typeof(DatePicker),
            new FrameworkPropertyMetadata(DateTime.Now, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, null, CoerceDisplayDate));

        private static object CoerceDisplayDate(DependencyObject d, object value) 
        {
            DatePicker dp = d as DatePicker; 
 
            // We set _calendar.DisplayDate in order to get _calendar to compute the coerced value
            dp._calendar.DisplayDate = (DateTime)value; 
            return dp._calendar.DisplayDate;
        }

        #endregion DisplayDate 

        #region DisplayDateEnd 
 
        /// 
        /// Gets or sets the last date to be displayed. 
        /// 
        ///
        public DateTime? DisplayDateEnd
        { 
            get { return (DateTime?)GetValue(DisplayDateEndProperty); }
            set { SetValue(DisplayDateEndProperty, value); } 
        } 

        ///  
        /// Identifies the DisplayDateEnd dependency property.
        /// 
        public static readonly DependencyProperty DisplayDateEndProperty =
            DependencyProperty.Register( 
            "DisplayDateEnd",
            typeof(DateTime?), 
            typeof(DatePicker), 
            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnDisplayDateEndChanged, CoerceDisplayDateEnd));
 
        /// 
        /// DisplayDateEndProperty property changed handler.
        /// 
        /// DatePicker that changed its DisplayDateEnd. 
        /// DependencyPropertyChangedEventArgs.
        private static void OnDisplayDateEndChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        { 
            DatePicker dp = d as DatePicker;
            Debug.Assert(dp != null); 

            dp.CoerceValue(DisplayDateProperty);
        }
 
        private static object CoerceDisplayDateEnd(DependencyObject d, object value)
        { 
            DatePicker dp = d as DatePicker; 

            // We set _calendar.DisplayDateEnd in order to get _calendar to compute the coerced value 
            dp._calendar.DisplayDateEnd = (DateTime?)value;
            return dp._calendar.DisplayDateEnd;
        }
 
        #endregion DisplayDateEnd
 
        #region DisplayDateStart 

        ///  
        /// Gets or sets the first date to be displayed.
        /// 
        ///
        public DateTime? DisplayDateStart 
        {
            get { return (DateTime?)GetValue(DisplayDateStartProperty); } 
            set { SetValue(DisplayDateStartProperty, value); } 
        }
 
        /// 
        /// Identifies the DisplayDateStart dependency property.
        /// 
        public static readonly DependencyProperty DisplayDateStartProperty = 
            DependencyProperty.Register(
            "DisplayDateStart", 
            typeof(DateTime?), 
            typeof(DatePicker),
            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnDisplayDateStartChanged, CoerceDisplayDateStart)); 

        /// 
        /// DisplayDateStartProperty property changed handler.
        ///  
        /// DatePicker that changed its DisplayDateStart.
        /// DependencyPropertyChangedEventArgs. 
        private static void OnDisplayDateStartChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker; 
            Debug.Assert(dp != null);

            dp.CoerceValue(DisplayDateEndProperty);
            dp.CoerceValue(DisplayDateProperty); 
        }
 
        private static object CoerceDisplayDateStart(DependencyObject d, object value) 
        {
            DatePicker dp = d as DatePicker; 

            // We set _calendar.DisplayDateStart in order to get _calendar to compute the coerced value
            dp._calendar.DisplayDateStart = (DateTime?)value;
            return dp._calendar.DisplayDateStart; 
        }
 
        #endregion DisplayDateStart 

        #region FirstDayOfWeek 

        /// 
        /// Gets or sets the day that is considered the beginning of the week.
        ///  
        public DayOfWeek FirstDayOfWeek
        { 
            get { return (DayOfWeek)GetValue(FirstDayOfWeekProperty); } 
            set { SetValue(FirstDayOfWeekProperty, value); }
        } 

        /// 
        /// Identifies the FirstDayOfWeek dependency property.
        ///  
        public static readonly DependencyProperty FirstDayOfWeekProperty =
            DependencyProperty.Register( 
            "FirstDayOfWeek", 
            typeof(DayOfWeek),
            typeof(DatePicker), 
            null,
            Calendar.IsValidFirstDayOfWeek);

        #endregion FirstDayOfWeek 

        #region IsDropDownOpen 
 
        /// 
        /// Gets or sets a value that indicates whether the drop-down Calendar is open or closed. 
        /// 
        public bool IsDropDownOpen
        {
            get { return (bool)GetValue(IsDropDownOpenProperty); } 
            set { SetValue(IsDropDownOpenProperty, value); }
        } 
 
        /// 
        /// Identifies the IsDropDownOpen dependency property. 
        /// 
        public static readonly DependencyProperty IsDropDownOpenProperty =
            DependencyProperty.Register(
            "IsDropDownOpen", 
            typeof(bool),
            typeof(DatePicker), 
            new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnIsDropDownOpenChanged, OnCoerceIsDropDownOpen)); 

        private static object OnCoerceIsDropDownOpen(DependencyObject d, object baseValue) 
        {
            DatePicker dp = d as DatePicker;
            Debug.Assert(dp != null);
 
            if (!dp.IsEnabled)
            { 
                return false; 
            }
 
            return baseValue;
        }

        ///  
        /// IsDropDownOpenProperty property changed handler.
        ///  
        /// DatePicker that changed its IsDropDownOpen. 
        /// DependencyPropertyChangedEventArgs.
        private static void OnIsDropDownOpenChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker;
            Debug.Assert(dp != null);
 
            bool newValue = (bool)e.NewValue;
            if (dp._popUp != null && dp._popUp.IsOpen != newValue) 
            { 
                dp._popUp.IsOpen = newValue;
                if (newValue) 
                {
                    dp._originalSelectedDate = dp.SelectedDate;

                    // When the popup is opened set focus to the DisplayDate button. 
                    // Do this asynchronously because the IsDropDownOpen could
                    // have been set even before the template for the DatePicker is 
                    // applied. And this would mean that the visuals wouldn't be available yet. 

                    dp.Dispatcher.BeginInvoke(DispatcherPriority.Input, (Action)delegate() 
                        {
                            // setting the focus to the calendar will focus the correct date.
                            dp._calendar.Focus();
                        }); 
                }
            } 
        } 

        private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker;
            Debug.Assert(dp != null);
 
            dp.CoerceValue(IsDropDownOpenProperty);
 
            OnVisualStatePropertyChanged(d, e); 
        }
 
        #endregion IsDropDownOpen

        #region IsTodayHighlighted
 
        /// 
        /// Gets or sets a value that indicates whether the current date will be highlighted. 
        ///  
        public bool IsTodayHighlighted
        { 
            get { return (bool)GetValue(IsTodayHighlightedProperty); }
            set { SetValue(IsTodayHighlightedProperty, value); }
        }
 
        /// 
        /// Identifies the IsTodayHighlighted dependency property. 
        ///  
        public static readonly DependencyProperty IsTodayHighlightedProperty =
            DependencyProperty.Register( 
            "IsTodayHighlighted",
            typeof(bool),
            typeof(DatePicker));
 
        #endregion IsTodayHighlighted
 
        #region SelectedDate 

        ///  
        /// Gets or sets the currently selected date.
        /// 
        ///
        public DateTime? SelectedDate 
        {
            get { return (DateTime?)GetValue(SelectedDateProperty); } 
            set { SetValue(SelectedDateProperty, value); } 
        }
 
        /// 
        /// Identifies the SelectedDate dependency property.
        /// 
        public static readonly DependencyProperty SelectedDateProperty = 
            DependencyProperty.Register(
            "SelectedDate", 
            typeof(DateTime?), 
            typeof(DatePicker),
            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnSelectedDateChanged, CoerceSelectedDate)); 

        /// 
        /// SelectedDateProperty property changed handler.
        ///  
        /// DatePicker that changed its SelectedDate.
        /// DependencyPropertyChangedEventArgs. 
        private static void OnSelectedDateChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker; 
            Debug.Assert(dp != null);

            Collection addedItems = new Collection();
            Collection removedItems = new Collection(); 
            DateTime? addedDate;
            DateTime? removedDate; 
 
            dp.CoerceValue(DisplayDateStartProperty);
            dp.CoerceValue(DisplayDateEndProperty); 
            dp.CoerceValue(DisplayDateProperty);

            addedDate = (DateTime?)e.NewValue;
            removedDate = (DateTime?)e.OldValue; 

            if (dp.SelectedDate.HasValue) 
            { 
                DateTime day = dp.SelectedDate.Value;
                dp.SetTextInternal(dp.DateTimeToString(day)); 

                // When DatePickerDisplayDateFlag is TRUE, the SelectedDate change is coming from the Calendar UI itself,
                // so, we shouldn't change the DisplayDate since it will automatically be changed by the Calendar
                if ((day.Month != dp.DisplayDate.Month || day.Year != dp.DisplayDate.Year) && !dp._calendar.DatePickerDisplayDateFlag) 
                {
                    dp.SetCurrentValueInternal(DisplayDateProperty, day); 
                } 

                dp._calendar.DatePickerDisplayDateFlag = false; 
            }
            else
            {
                dp.SetWaterMarkText(); 
            }
 
            if (addedDate.HasValue) 
            {
                addedItems.Add(addedDate.Value); 
            }

            if (removedDate.HasValue)
            { 
                removedItems.Add(removedDate.Value);
            } 
 
            dp.OnSelectedDateChanged(new CalendarSelectionChangedEventArgs(DatePicker.SelectedDateChangedEvent, removedItems, addedItems));
 
            DatePickerAutomationPeer peer = UIElementAutomationPeer.FromElement(dp) as DatePickerAutomationPeer;
            // Raise the propetyChangeEvent for Value if Automation Peer exist
            if (peer != null)
            { 
                string addedDateString = addedDate.HasValue ? dp.DateTimeToString(addedDate.Value) : "";
                string removedDateString = removedDate.HasValue ? dp.DateTimeToString(removedDate.Value) : ""; 
                peer.RaiseValuePropertyChangedEvent(removedDateString, addedDateString); 
            }
        } 

        private static object CoerceSelectedDate(DependencyObject d, object value)
        {
            DatePicker dp = d as DatePicker; 

            // We set _calendar.SelectedDate in order to get _calendar to compute the coerced value 
            dp._calendar.SelectedDate = (DateTime?)value; 
            return dp._calendar.SelectedDate;
        } 

        #endregion SelectedDate

        #region SelectedDateFormat 

        ///  
        /// Gets or sets the format that is used to display the selected date. 
        /// 
        public DatePickerFormat SelectedDateFormat 
        {
            get { return (DatePickerFormat)GetValue(SelectedDateFormatProperty); }
            set { SetValue(SelectedDateFormatProperty, value); }
        } 

        ///  
        /// Identifies the SelectedDateFormat dependency property. 
        /// 
        public static readonly DependencyProperty SelectedDateFormatProperty = 
            DependencyProperty.Register(
            "SelectedDateFormat",
            typeof(DatePickerFormat),
            typeof(DatePicker), 
            new FrameworkPropertyMetadata(DatePickerFormat.Long, OnSelectedDateFormatChanged),
            IsValidSelectedDateFormat); 
 
        /// 
        /// SelectedDateFormatProperty property changed handler. 
        /// 
        /// DatePicker that changed its SelectedDateFormat.
        /// DependencyPropertyChangedEventArgs.
        private static void OnSelectedDateFormatChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            DatePicker dp = d as DatePicker; 
            Debug.Assert(dp != null); 

            if (dp._textBox != null) 
            {
                // Update DatePickerTextBox.Text
                if (string.IsNullOrEmpty(dp._textBox.Text))
                { 
                    dp.SetWaterMarkText();
                } 
                else 
                {
                    DateTime? date = dp.ParseText(dp._textBox.Text); 

                    if (date != null)
                    {
                        dp.SetTextInternal(dp.DateTimeToString((DateTime)date)); 
                    }
                } 
            } 
        }
 
        #endregion SelectedDateFormat

        #region Text
 
        /// 
        /// Gets or sets the text that is displayed by the DatePicker. 
        ///  
        public string Text
        { 
            get { return (string)GetValue(TextProperty); }
            set { SetValue(TextProperty, value); }
        }
 
        /// 
        /// Identifies the Text dependency property. 
        ///  
        public static readonly DependencyProperty TextProperty =
            DependencyProperty.Register( 
            "Text",
            typeof(string),
            typeof(DatePicker),
            new FrameworkPropertyMetadata(string.Empty, OnTextChanged)); 

        ///  
        /// TextProperty property changed handler. 
        /// 
        /// DatePicker that changed its Text. 
        /// DependencyPropertyChangedEventArgs.
        private static void OnTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            DatePicker dp = d as DatePicker; 
            Debug.Assert(dp != null);
 
            if (!dp.IsHandlerSuspended(DatePicker.TextProperty)) 
            {
                string newValue = e.NewValue as string; 

                if (newValue != null)
                {
                    if (dp._textBox != null) 
                    {
                        dp._textBox.Text = newValue; 
                    } 
                    else
                    { 
                        dp._defaultText = newValue;
                    }

                    dp.SetSelectedDate(); 
                }
                else 
                { 
                    dp.SetValueNoCallback(DatePicker.SelectedDateProperty, null);
                } 
            }
        }

 
        /// 
        /// Sets the local Text property without breaking bindings 
        ///  
        /// 
        private void SetTextInternal(string value) 
        {
            SetCurrentValueInternal(TextProperty, value);
        }
 
        #endregion Text
 
        #endregion Public Properties 

        #region Protected properties 

        #endregion Protected Properties

        #region Internal Properties 

        internal Calendar Calendar 
        { 
            get
            { 
                return _calendar;
            }
        }
 
        internal TextBox TextBox
        { 
            get 
            {
                return _textBox; 
            }
        }

 
        #endregion Internal Properties
 
        #region Private Properties 
        #endregion Private Properties
 
        #region Public Methods

        /// 
        /// Builds the visual tree for the DatePicker control when a new template is applied. 
        /// 
        public override void OnApplyTemplate() 
        { 
            if (_popUp != null)
            { 
                _popUp.RemoveHandler(PreviewMouseLeftButtonDownEvent, new MouseButtonEventHandler(PopUp_PreviewMouseLeftButtonDown));
                _popUp.Opened -= PopUp_Opened;
                _popUp.Closed -= PopUp_Closed;
                _popUp.Child = null; 
            }
 
            if (_dropDownButton != null) 
            {
                _dropDownButton.Click -= DropDownButton_Click; 
                _dropDownButton.RemoveHandler(MouseLeaveEvent, new MouseEventHandler(DropDownButton_MouseLeave));
            }

            if (_textBox != null) 
            {
                _textBox.RemoveHandler(TextBox.KeyDownEvent, new KeyEventHandler(TextBox_KeyDown)); 
                _textBox.RemoveHandler(TextBox.TextChangedEvent, new TextChangedEventHandler(TextBox_TextChanged)); 
                _textBox.RemoveHandler(TextBox.LostFocusEvent, new RoutedEventHandler(TextBox_LostFocus));
            } 

            base.OnApplyTemplate();

            _popUp = GetTemplateChild(ElementPopup) as Popup; 

            if (_popUp != null) 
            { 
                _popUp.AddHandler(PreviewMouseLeftButtonDownEvent, new MouseButtonEventHandler(PopUp_PreviewMouseLeftButtonDown));
                _popUp.Opened += PopUp_Opened; 
                _popUp.Closed += PopUp_Closed;
                _popUp.Child = this._calendar;

                if (this.IsDropDownOpen) 
                {
                    this._popUp.IsOpen = true; 
                } 
            }
 
            _dropDownButton = GetTemplateChild(ElementButton) as Button;
            if (_dropDownButton != null)
            {
                _dropDownButton.Click += DropDownButton_Click; 
                _dropDownButton.AddHandler(MouseLeaveEvent, new MouseEventHandler(DropDownButton_MouseLeave), true);
 
                // If the user does not provide a Content value in template, we provide a helper text that can be used in Accessibility 
                // this text is not shown on the UI, just used for Accessibility purposes
                if (_dropDownButton.Content == null) 
                {
                    _dropDownButton.Content = SR.Get(SRID.DatePicker_DropDownButtonName);
                }
            } 

            _textBox = GetTemplateChild(ElementTextBox) as DatePickerTextBox; 
 
            if (this.SelectedDate == null)
            { 
                SetWaterMarkText();
            }

            if (_textBox != null) 
            {
                _textBox.AddHandler(TextBox.KeyDownEvent, new KeyEventHandler(TextBox_KeyDown), true); 
                _textBox.AddHandler(TextBox.TextChangedEvent, new TextChangedEventHandler(TextBox_TextChanged), true); 
                _textBox.AddHandler(TextBox.LostFocusEvent, new RoutedEventHandler(TextBox_LostFocus), true);
 
                if (this.SelectedDate == null)
                {
                    if (!string.IsNullOrEmpty(this._defaultText))
                    { 
                        _textBox.Text = this._defaultText;
                        SetSelectedDate(); 
                    } 
                }
                else 
                {
                    _textBox.Text = this.DateTimeToString((DateTime)this.SelectedDate);
                }
            } 
        }
 
        ///  
        /// Provides a text representation of the selected date.
        ///  
        /// A text representation of the selected date, or an empty string if SelectedDate is a null reference.
        public override string ToString()
        {
            if (this.SelectedDate != null) 
            {
                return this.SelectedDate.Value.ToString(DateTimeHelper.GetDateFormat(DateTimeHelper.GetCulture(this))); 
            } 
            else
            { 
                return string.Empty;
            }
        }
 
        #endregion Public Methods
 
        #region Protected Methods 

        internal override void ChangeVisualState(bool useTransitions) 
        {
            if (!IsEnabled)
            {
                VisualStates.GoToState(this, useTransitions, VisualStates.StateDisabled, VisualStates.StateNormal); 
            }
            else 
            { 
                VisualStateManager.GoToState(this, VisualStates.StateNormal, useTransitions);
            } 

            base.ChangeVisualState(useTransitions);
        }
 
        /// 
        /// Creates the automation peer for this DatePicker Control. 
        ///  
        /// 
        protected override AutomationPeer OnCreateAutomationPeer() 
        {
            return new DatePickerAutomationPeer(this);
        }
 
        protected virtual void OnCalendarClosed(RoutedEventArgs e)
        { 
            RoutedEventHandler handler = this.CalendarClosed; 
            if (null != handler)
            { 
                handler(this, e);
            }
        }
 
        protected virtual void OnCalendarOpened(RoutedEventArgs e)
        { 
            RoutedEventHandler handler = this.CalendarOpened; 
            if (null != handler)
            { 
                handler(this, e);
            }
        }
 
        protected virtual void OnSelectedDateChanged(SelectionChangedEventArgs e)
        { 
            RaiseEvent(e); 
        }
 
        /// 
        /// Raises the DateValidationError event.
        /// 
        /// A DatePickerDateValidationErrorEventArgs that contains the event data. 
        protected virtual void OnDateValidationError(DatePickerDateValidationErrorEventArgs e)
        { 
            EventHandler handler = this.DateValidationError; 
            if (handler != null)
            { 
                handler(this, e);
            }
        }
 
        #endregion Protected Methods
 
        #region Private Methods 

        ///  
        ///     Called when this element gets focus.
        /// 
        private static void OnGotFocus(object sender, RoutedEventArgs e)
        { 
            // When Datepicker gets focus move it to the TextBox
            DatePicker picker = (DatePicker)sender; 
            if ((!e.Handled) && (picker._textBox != null)) 
            {
                if (e.OriginalSource == picker) 
                {
                    picker._textBox.Focus();
                    e.Handled = true;
                } 
                else if (e.OriginalSource == picker._textBox)
                { 
                    picker._textBox.SelectAll(); 
                    e.Handled = true;
                } 
            }
        }

        private void SetValueNoCallback(DependencyProperty property, object value) 
        {
            SetIsHandlerSuspended(property, true); 
            try 
            {
                SetCurrentValue(property, value); 
            }
            finally
            {
                SetIsHandlerSuspended(property, false); 
            }
        } 
 
        private bool IsHandlerSuspended(DependencyProperty property)
        { 
            return _isHandlerSuspended != null && _isHandlerSuspended.ContainsKey(property);
        }

        private void SetIsHandlerSuspended(DependencyProperty property, bool value) 
        {
            if (value) 
            { 
                if (_isHandlerSuspended == null)
                { 
                    _isHandlerSuspended = new Dictionary(2);
                }

                _isHandlerSuspended[property] = true; 
            }
            else 
            { 
                if (_isHandlerSuspended != null)
                { 
                    _isHandlerSuspended.Remove(property);
                }
            }
        } 

        private void PopUp_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) 
        { 
            Popup popup = sender as Popup;
            if (popup != null && !popup.StaysOpen) 
            {
                if (this._dropDownButton != null)
                {
                    if (this._dropDownButton.InputHitTest(e.GetPosition(this._dropDownButton)) != null) 
                    {
                        // This popup is being closed by a mouse press on the drop down button 
                        // The following mouse release will cause the closed popup to immediately reopen. 
                        // Raise a flag to block reopeneing the popup
                        this._disablePopupReopen = true; 
                    }
                }
            }
        } 

        private void PopUp_Opened(object sender, EventArgs e) 
        { 
            if (!this.IsDropDownOpen)
            { 
                this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.TrueBox);
            }

            if (this._calendar != null) 
            {
                this._calendar.DisplayMode = CalendarMode.Month; 
                this._calendar.MoveFocus(new TraversalRequest(FocusNavigationDirection.First)); 
            }
 
            this.OnCalendarOpened(new RoutedEventArgs());
        }

        private void PopUp_Closed(object sender, EventArgs e) 
        {
            if (this.IsDropDownOpen) 
            { 
                this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.FalseBox);
            } 

            if (_calendar.IsKeyboardFocusWithin)
            {
                this.MoveFocus(new TraversalRequest(FocusNavigationDirection.First)); 
            }
 
            OnCalendarClosed(new RoutedEventArgs()); 
        }
 
        private void Calendar_DayButtonMouseUp(object sender, MouseButtonEventArgs e)
        {
            this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.FalseBox);
        } 

        private void CalendarDayOrMonthButton_PreviewKeyDown(object sender, RoutedEventArgs e) 
        { 
            Calendar c = sender as Calendar;
            KeyEventArgs args = (KeyEventArgs)e; 

            Debug.Assert(c != null);
            Debug.Assert(args != null);
 
            if (args.Key == Key.Escape || ((args.Key == Key.Enter || args.Key == Key.Space) && c.DisplayMode == CalendarMode.Month))
            { 
                this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.FalseBox); 
                if (args.Key == Key.Escape)
                { 
                    SetCurrentValueInternal(SelectedDateProperty, _originalSelectedDate);
                }
            }
        } 

        private void Calendar_DisplayDateChanged(object sender, CalendarDateChangedEventArgs e) 
        { 
            if (e.AddedDate != this.DisplayDate)
            { 
                SetCurrentValueInternal(DisplayDateProperty, (DateTime)e.AddedDate);
            }
        }
 
        private void Calendar_SelectedDatesChanged(object sender, SelectionChangedEventArgs e)
        { 
            Debug.Assert(e.AddedItems.Count < 2); 

            if (e.AddedItems.Count > 0 && this.SelectedDate.HasValue && DateTime.Compare((DateTime)e.AddedItems[0], this.SelectedDate.Value) != 0) 
            {
                this.SetCurrentValueInternal(SelectedDateProperty, (DateTime?)e.AddedItems[0]);
            }
            else 
            {
                if (e.AddedItems.Count == 0) 
                { 
                    this.SetCurrentValueInternal(SelectedDateProperty, (DateTime?)null);
                    return; 
                }

                if (!this.SelectedDate.HasValue)
                { 
                    if (e.AddedItems.Count > 0)
                    { 
                        this.SetCurrentValueInternal(SelectedDateProperty, (DateTime?)e.AddedItems[0]); 
                    }
                } 
            }
        }

        private string DateTimeToString(DateTime d) 
        {
            DateTimeFormatInfo dtfi = DateTimeHelper.GetDateFormat(DateTimeHelper.GetCulture(this)); 
 
            switch (this.SelectedDateFormat)
            { 
                case DatePickerFormat.Short:
                    {
                        return string.Format(CultureInfo.CurrentCulture, d.ToString(dtfi.ShortDatePattern, dtfi));
                    } 

                case DatePickerFormat.Long: 
                    { 
                        return string.Format(CultureInfo.CurrentCulture, d.ToString(dtfi.LongDatePattern, dtfi));
                    } 
            }

            return null;
        } 

        private static DateTime DiscardDayTime(DateTime d) 
        { 
            int year = d.Year;
            int month = d.Month; 
            DateTime newD = new DateTime(year, month, 1, 0, 0, 0);
            return newD;
        }
 
        private static DateTime? DiscardTime(DateTime? d)
        { 
            if (d == null) 
            {
                return null; 
            }
            else
            {
                DateTime discarded = (DateTime)d; 
                int year = discarded.Year;
                int month = discarded.Month; 
                int day = discarded.Day; 
                DateTime newD = new DateTime(year, month, day, 0, 0, 0);
                return newD; 
            }
        }

        private void DropDownButton_Click(object sender, RoutedEventArgs e) 
        {
            TogglePopUp(); 
        } 

        private void DropDownButton_MouseLeave(object sender, MouseEventArgs e) 
        {
            this._disablePopupReopen = false;
        }
 
        private void TogglePopUp()
        { 
            if (this.IsDropDownOpen) 
            {
                this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.FalseBox); 
            }
            else
            {
                if (this._disablePopupReopen) 
                {
                    this._disablePopupReopen = false; 
                } 
                else
                { 
                    SetSelectedDate();
                    this.SetCurrentValueInternal(IsDropDownOpenProperty, BooleanBoxes.TrueBox);
                }
            } 
        }
 
        private void InitializeCalendar() 
        {
            _calendar = new Calendar(); 
            _calendar.DayButtonMouseUp += new MouseButtonEventHandler(Calendar_DayButtonMouseUp);
            _calendar.DisplayDateChanged += new EventHandler(Calendar_DisplayDateChanged);
            _calendar.SelectedDatesChanged += new EventHandler(Calendar_SelectedDatesChanged);
            _calendar.DayOrMonthPreviewKeyDown += new RoutedEventHandler(CalendarDayOrMonthButton_PreviewKeyDown); 
            _calendar.HorizontalAlignment = HorizontalAlignment.Left;
            _calendar.VerticalAlignment = VerticalAlignment.Top; 
 
            _calendar.SelectionMode = CalendarSelectionMode.SingleDate;
            _calendar.SetBinding(Calendar.ForegroundProperty, GetDatePickerBinding(DatePicker.ForegroundProperty)); 
            _calendar.SetBinding(Calendar.StyleProperty, GetDatePickerBinding(DatePicker.CalendarStyleProperty));
            _calendar.SetBinding(Calendar.IsTodayHighlightedProperty, GetDatePickerBinding(DatePicker.IsTodayHighlightedProperty));
            _calendar.SetBinding(Calendar.FirstDayOfWeekProperty, GetDatePickerBinding(DatePicker.FirstDayOfWeekProperty));
            _calendar.SetBinding(Calendar.FlowDirectionProperty, GetDatePickerBinding(DatePicker.FlowDirectionProperty)); 

            RenderOptions.SetClearTypeHint(_calendar, ClearTypeHint.Enabled); 
        } 

        private BindingBase GetDatePickerBinding(DependencyProperty property) 
        {
            Binding binding = new Binding(property.Name);
            binding.Source = this;
            return binding; 
        }
 
        private static bool IsValidSelectedDateFormat(object value) 
        {
            DatePickerFormat format = (DatePickerFormat)value; 

            return format == DatePickerFormat.Long
                || format == DatePickerFormat.Short;
        } 

        // iT SHOULD RETURN NULL IF THE STRING IS NOT VALID, RETURN THE DATETIME VALUE IF IT IS VALID 
 
        /// 
        /// Input text is parsed in the correct format and changed into a DateTime object. 
        /// If the text can not be parsed TextParseError Event is thrown.
        /// 
        private DateTime? ParseText(string text)
        { 
            DateTime newSelectedDate;
 
            // TryParse is not used in order to be able to pass the exception to the TextParseError event 
            try
            { 
                newSelectedDate = DateTime.Parse(text, DateTimeHelper.GetDateFormat(DateTimeHelper.GetCulture(this)));

                if (Calendar.IsValidDateSelection(this._calendar, newSelectedDate))
                { 
                    return newSelectedDate;
                } 
                else 
                {
                    DatePickerDateValidationErrorEventArgs dateValidationError = new DatePickerDateValidationErrorEventArgs(new ArgumentOutOfRangeException("text", SR.Get(SRID.Calendar_OnSelectedDateChanged_InvalidValue)), text); 
                    OnDateValidationError(dateValidationError);

                    if (dateValidationError.ThrowException)
                    { 
                        throw dateValidationError.Exception;
                    } 
                } 
            }
            catch (FormatException ex) 
            {
                DatePickerDateValidationErrorEventArgs textParseError = new DatePickerDateValidationErrorEventArgs(ex, text);
                OnDateValidationError(textParseError);
 
                if (textParseError.ThrowException && textParseError.Exception != null)
                { 
                    throw textParseError.Exception; 
                }
            } 

            return null;
        }
 
        private bool ProcessDatePickerKey(KeyEventArgs e)
        { 
            switch (e.Key) 
            {
                case Key.System: 
                {
                    switch (e.SystemKey)
                    {
                        case Key.Down: 
                        {
                            if ((Keyboard.Modifiers & ModifierKeys.Alt) == ModifierKeys.Alt) 
                            { 
                                TogglePopUp();
                                return true; 
                            }

                            break;
                        } 
                    }
 
                    break; 
                }
 
                case Key.Enter:
                {
                    SetSelectedDate();
                    return true; 
                }
            } 
 
            return false;
        } 

        private void SetSelectedDate()
        {
            if (this._textBox != null) 
            {
                if (!string.IsNullOrEmpty(this._textBox.Text)) 
                { 
                    string s = this._textBox.Text;
 
                    if (this.SelectedDate != null)
                    {
                        // If the string value of the SelectedDate and the TextBox string value are equal,
                        // we do not parse the string again 
                        // if we do an extra parse, we lose data in M/d/yy format
                        // ex: SelectedDate = DateTime(1008,12,19) but when "12/19/08" is parsed it is interpreted as DateTime(2008,12,19) 
                        string selectedDate = DateTimeToString(this.SelectedDate.Value); 

                        if (string.Compare(selectedDate, s, StringComparison.Ordinal) == 0) 
                        {
                            return;
                        }
                    } 

                    DateTime? d = SetTextBoxValue(s); 
                    if (!this.SelectedDate.Equals(d)) 
                    {
                        this.SetCurrentValueInternal(SelectedDateProperty, d); 
                        this.SetCurrentValueInternal(DisplayDateProperty, d);
                    }
                }
                else 
                {
                    if (this.SelectedDate.HasValue) 
                    { 
                        this.SetCurrentValueInternal(SelectedDateProperty, (DateTime?)null);
                    } 
                }
            }
            else
            { 
                DateTime? d = SetTextBoxValue(_defaultText);
                if (!this.SelectedDate.Equals(d)) 
                { 
                    this.SetCurrentValueInternal(SelectedDateProperty, d);
                } 
            }
        }

        ///  
        ///     Set the Text property if it's not already set to the supplied value.  This avoids making the ValueSource Local.
        ///  
        private void SafeSetText(string s) 
        {
            if (string.Compare(Text, s, StringComparison.Ordinal) != 0) 
            {
                SetCurrentValueInternal(TextProperty, s);
            }
        } 

        private DateTime? SetTextBoxValue(string s) 
        { 
            if (string.IsNullOrEmpty(s))
            { 
                SafeSetText(s);
                return this.SelectedDate;
            }
            else 
            {
                DateTime? d = ParseText(s); 
 
                if (d != null)
                { 
                    SafeSetText(this.DateTimeToString((DateTime)d));
                    return d;
                }
                else 
                {
                    // If parse error: 
                    // TextBox should have the latest valid selecteddate value: 
                    if (this.SelectedDate != null)
                    { 
                        string newtext = this.DateTimeToString((DateTime)this.SelectedDate);
                        SafeSetText(newtext);
                        return this.SelectedDate;
                    } 
                    else
                    { 
                        SetWaterMarkText(); 
                        return null;
                    } 
                }
            }
        }
 
        private void SetWaterMarkText()
        { 
            if (this._textBox != null) 
            {
                DateTimeFormatInfo dtfi = DateTimeHelper.GetDateFormat(DateTimeHelper.GetCulture(this)); 
                this.SetTextInternal(string.Empty);
                this._defaultText = string.Empty;

                switch (this.SelectedDateFormat) 
                {
                    case DatePickerFormat.Long: 
                        { 
                            this._textBox.Watermark = string.Format(CultureInfo.CurrentCulture, SR.Get(SRID.DatePicker_WatermarkText), dtfi.LongDatePattern.ToString());
                            break; 
                        }

                    case DatePickerFormat.Short:
                        { 
                            this._textBox.Watermark = string.Format(CultureInfo.CurrentCulture, SR.Get(SRID.DatePicker_WatermarkText), dtfi.ShortDatePattern.ToString());
                            break; 
                        } 
                }
            } 
        }

        private void TextBox_LostFocus(object sender, RoutedEventArgs e)
        { 
            SetSelectedDate();
        } 
 
        private void TextBox_KeyDown(object sender, KeyEventArgs e)
        { 
            e.Handled = ProcessDatePickerKey(e) || e.Handled;
        }

        private void TextBox_TextChanged(object sender, TextChangedEventArgs e) 
        {
            this.SetValueNoCallback(DatePicker.TextProperty, this._textBox.Text); 
        } 

        #endregion Private Methods 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
                        

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