WPF Toolkit DatePicker Month/Year Only

Question

Estoy usando el Datepicker del Toolkit como se indicó anteriormente, pero me gustaría restringirlo solo a las selecciones de mes y año, ya que en esta situación los usuarios no conocen ni se preocupan por la fecha exacta . Obviamente, con los datos almacenados en formato Datetime, habrá un día almacenado, pero eso no me concierne. ¿Hay alguna manera fácil de atar esto?

Gracias

Answer 1

Si puede utilizar el control Calendar lugar que podría hacer

<toolkit:Calendar x:Name="_calendar" DisplayModeChanged="_calendar_DisplayModeChanged" DisplayMode="Year" /> 

con este código subyacente

Private Sub _calendar_DisplayModeChanged(ByVal sender As System.Object, ByVal e As Microsoft.Windows.Controls.CalendarModeChangedEventArgs) 

    If _calendar.DisplayMode = Microsoft.Windows.Controls.CalendarMode.Month Then 
     _calendar.DisplayMode = Microsoft.Windows.Controls.CalendarMode.Year 
    End If 

End Sub 

Answer 2

Recientemente tuve un requisito específico para el calendario con la opción de elegir solo mes y año. Así que tengo una publicación anterior sobre el formato personalizado para wpf datepicker, pero en este caso tenemos que hacer una pequeña respuesta difícil. Primero necesita crear un control específico como este:

public class DatePickerCo : DatePicker 

Una vez que ya ha hecho esto. Existe otro post cuando otra persona, yo no lo Recuerda la url para ese puesto, pero de todos modos, el pensar es lo que necesita para sobrescribir el método OnCalendarOpened como este:

protected override void OnCalendarOpened(RoutedEventArgs e) 
     { 
      var popup = this.Template.FindName(
       "PART_Popup", this) as Popup; 
      if (popup != null && popup.Child is System.Windows.Controls.Calendar) 
      { 
       ((System.Windows.Controls.Calendar)popup.Child).DisplayMode = CalendarMode.Year; 
      } 

      ((System.Windows.Controls.Calendar)popup.Child).DisplayModeChanged += new EventHandler(DatePickerCo_DisplayModeChanged); 
     } 

en cuenta que añadimos una última línea con el controlador para el evento DisplayModeChanged. Esto es realmente importante para los siguientes pasos. Ok por lo que el siguiente paso es definir el DisplayModeChanged

private void DatePickerCo_DisplayModeChanged(object sender, CalendarModeChangedEventArgs e) 
     { 
      var popup = this.Template.FindName(
       "PART_Popup", this) as Popup; 
      if (popup != null && popup.Child is System.Windows.Controls.Calendar) 
      { 
       var _calendar = popup.Child as System.Windows.Controls.Calendar; 
       if (_calendar.DisplayMode == CalendarMode.Month) 
       { 
        _calendar.DisplayMode = CalendarMode.Year; 

        if (IsDropDownOpen) 
        { 
         this.SelectedDate = GetSelectedMonth(_calendar.DisplayDate); 
         this.IsDropDownOpen = false; 
         ((System.Windows.Controls.Calendar)popup.Child).DisplayModeChanged -= new EventHandler(DatePickerCo_DisplayModeChanged); 
        } 
       } 

      } 
     } 

private DateTime? GetSelectedMonth(DateTime? selectedDate) 
     { 
      if (selectedDate == null) 
      { 
       selectedDate = DateTime.Now; 
      } 

      int monthDifferenceStart = DateTimeHelper.CompareYearMonth(selectedDate.Value, DisplayDateRangeStart); 
      int monthDifferenceEnd = DateTimeHelper.CompareYearMonth(selectedDate.Value, DisplayDateRangeEnd); 

      if (monthDifferenceStart >= 0 && monthDifferenceEnd 0, "monthDifferenceEnd should be greater than 0!"); 
        _selectedMonth = DateTimeHelper.DiscardDayTime(DisplayDateRangeEnd); 
       } 
      } 

      return _selectedMonth; 
     } 

Aquí hay un par de cosas, primero que hay que escoger un mes, por lo que esa es la razón para crear el GetSelectedMonth función. La segunda cosa es que el método use una clase de WPFToolkit llamada DateTimeHelper.cs. Ok Hasta ahora solo creamos la funcionalidad para recoger el mes. Pero una vez que haya hecho clic en el calendario mensual, procederemos a mostrar la fecha seleccionada en el formato mes/año. Para lograr eso sólo tenemos que crear un estilo específico a nuestro control personalizado como esto:

En mi primera defensa How to change format (e.g. dd/MMM/yyyy) of DateTimePicker in WPF application

todo lo explicado acerca con el formato personalizado del selector de fecha. Espero que esto te ayude. por favor, cualquier comentario o sugerencia, solo házmelo saber, ¡saludos !!

Answer 3

Gracias a @Fernando García por la base de esto.

He escrito las propiedades adjuntas DateFormat e IsMonthYear para DatePicker para habilitar la selección Mes/Año.

La propiedad adjunta IsMonthYear restringe el Calendar.DisplayMode de DatePicker a Year y Decade para evitar la selección de CalendarMode.Month. También establece la porción de día de DatePicker.SelectedDate en 1.

La propiedad adjunta de DateFormat no se limita a este escenario, sino que también se puede usar de forma separada de IsMonthYear para proporcionar una cadena de formato para la visualización y entrada de DatePicker.

Ejemplo de uso de las propiedades adjuntas:

<DatePicker my:DatePickerCalendar.IsMonthYear="True" 
      my:DatePickerDateFormat.DateFormat="MM/yyyy"/> 

El IsMonthYear unido propiedad es:

public class DatePickerCalendar 
{ 
    public static readonly DependencyProperty IsMonthYearProperty = 
     DependencyProperty.RegisterAttached("IsMonthYear", typeof(bool), typeof(DatePickerCalendar), 
              new PropertyMetadata(OnIsMonthYearChanged)); 

    public static bool GetIsMonthYear(DependencyObject dobj) 
    { 
     return (bool)dobj.GetValue(IsMonthYearProperty); 
    } 

    public static void SetIsMonthYear(DependencyObject dobj, bool value) 
    { 
     dobj.SetValue(IsMonthYearProperty, value); 
    } 

    private static void OnIsMonthYearChanged(DependencyObject dobj, DependencyPropertyChangedEventArgs e) 
    { 
     var datePicker = (DatePicker) dobj; 

     Application.Current.Dispatcher 
      .BeginInvoke(DispatcherPriority.Loaded, 
         new Action<DatePicker, DependencyPropertyChangedEventArgs>(SetCalendarEventHandlers), 
         datePicker, e); 
    } 

    private static void SetCalendarEventHandlers(DatePicker datePicker, DependencyPropertyChangedEventArgs e) 
    { 
     if (e.NewValue == e.OldValue) 
      return; 

     if ((bool)e.NewValue) 
     { 
      datePicker.CalendarOpened += DatePickerOnCalendarOpened; 
      datePicker.CalendarClosed += DatePickerOnCalendarClosed; 
     } 
     else 
     { 
      datePicker.CalendarOpened -= DatePickerOnCalendarOpened; 
      datePicker.CalendarClosed -= DatePickerOnCalendarClosed; 
     } 
    } 

    private static void DatePickerOnCalendarOpened(object sender, RoutedEventArgs routedEventArgs) 
    { 
     var calendar = GetDatePickerCalendar(sender); 
     calendar.DisplayMode = CalendarMode.Year; 

     calendar.DisplayModeChanged += CalendarOnDisplayModeChanged; 
    } 

    private static void DatePickerOnCalendarClosed(object sender, RoutedEventArgs routedEventArgs) 
    { 
     var datePicker = (DatePicker) sender; 
     var calendar = GetDatePickerCalendar(sender); 
     datePicker.SelectedDate = calendar.SelectedDate; 

     calendar.DisplayModeChanged -= CalendarOnDisplayModeChanged; 
    } 

    private static void CalendarOnDisplayModeChanged(object sender, CalendarModeChangedEventArgs e) 
    { 
     var calendar = (Calendar) sender; 
     if (calendar.DisplayMode != CalendarMode.Month) 
      return; 

     calendar.SelectedDate = GetSelectedCalendarDate(calendar.DisplayDate); 

     var datePicker = GetCalendarsDatePicker(calendar); 
     datePicker.IsDropDownOpen = false; 
    } 

    private static Calendar GetDatePickerCalendar(object sender) 
    { 
     var datePicker = (DatePicker) sender; 
     var popup = (Popup) datePicker.Template.FindName("PART_Popup", datePicker); 
     return ((Calendar) popup.Child); 
    } 

    private static DatePicker GetCalendarsDatePicker(FrameworkElement child) 
    { 
     var parent = (FrameworkElement) child.Parent; 
     if (parent.Name == "PART_Root") 
      return (DatePicker) parent.TemplatedParent; 
     return GetCalendarsDatePicker(parent); 
    } 

    private static DateTime? GetSelectedCalendarDate(DateTime? selectedDate) 
    { 
     if (!selectedDate.HasValue) 
      return null; 
     return new DateTime(selectedDate.Value.Year, selectedDate.Value.Month, 1); 
    } 
} 

y la propiedad DateFormat adjunto es:

public class DatePickerDateFormat 
{ 
    public static readonly DependencyProperty DateFormatProperty = 
     DependencyProperty.RegisterAttached("DateFormat", typeof (string), typeof (DatePickerDateFormat), 
              new PropertyMetadata(OnDateFormatChanged)); 

    public static string GetDateFormat(DependencyObject dobj) 
    { 
     return (string) dobj.GetValue(DateFormatProperty); 
    } 

    public static void SetDateFormat(DependencyObject dobj, string value) 
    { 
     dobj.SetValue(DateFormatProperty, value); 
    } 

    private static void OnDateFormatChanged(DependencyObject dobj, DependencyPropertyChangedEventArgs e) 
    { 
     var datePicker = (DatePicker) dobj; 

     Application.Current.Dispatcher.BeginInvoke(
      DispatcherPriority.Loaded, new Action<DatePicker>(ApplyDateFormat), datePicker); 
    } 

    private static void ApplyDateFormat(DatePicker datePicker) 
    { 
     var binding = new Binding("SelectedDate") 
      { 
       RelativeSource = new RelativeSource {AncestorType = typeof (DatePicker)}, 
       Converter = new DatePickerDateTimeConverter(), 
       ConverterParameter = new Tuple<DatePicker, string>(datePicker, GetDateFormat(datePicker)) 
      }; 
     var textBox = GetTemplateTextBox(datePicker); 
     textBox.SetBinding(TextBox.TextProperty, binding); 

     textBox.PreviewKeyDown -= TextBoxOnPreviewKeyDown; 
     textBox.PreviewKeyDown += TextBoxOnPreviewKeyDown; 

     datePicker.CalendarOpened -= DatePickerOnCalendarOpened; 
     datePicker.CalendarOpened += DatePickerOnCalendarOpened; 
    } 

    private static TextBox GetTemplateTextBox(Control control) 
    { 
     control.ApplyTemplate(); 
     return (TextBox) control.Template.FindName("PART_TextBox", control); 
    } 

    private static void TextBoxOnPreviewKeyDown(object sender, KeyEventArgs e) 
    { 
     if (e.Key != Key.Return) 
      return; 

     /* DatePicker subscribes to its TextBox's KeyDown event to set its SelectedDate if Key.Return was 
     * pressed. When this happens its text will be the result of its internal date parsing until it 
     * loses focus or another date is selected. A workaround is to stop the KeyDown event bubbling up 
     * and handling setting the DatePicker.SelectedDate. */ 

     e.Handled = true; 

     var textBox = (TextBox) sender; 
     var datePicker = (DatePicker) textBox.TemplatedParent; 
     var dateStr = textBox.Text; 
     var formatStr = GetDateFormat(datePicker); 
     datePicker.SelectedDate = DatePickerDateTimeConverter.StringToDateTime(datePicker, formatStr, dateStr); 
    } 

    private static void DatePickerOnCalendarOpened(object sender, RoutedEventArgs e) 
    { 
     /* When DatePicker's TextBox is not focused and its Calendar is opened by clicking its calendar button 
     * its text will be the result of its internal date parsing until its TextBox is focused and another 
     * date is selected. A workaround is to set this string when it is opened. */ 

     var datePicker = (DatePicker) sender; 
     var textBox = GetTemplateTextBox(datePicker); 
     var formatStr = GetDateFormat(datePicker); 
     textBox.Text = DatePickerDateTimeConverter.DateTimeToString(formatStr, datePicker.SelectedDate); 
    } 

    private class DatePickerDateTimeConverter : IValueConverter 
    { 
     public object Convert(object value, Type targetType, object parameter, CultureInfo culture) 
     { 
      var formatStr = ((Tuple<DatePicker, string>) parameter).Item2; 
      var selectedDate = (DateTime?) value; 
      return DateTimeToString(formatStr, selectedDate); 
     } 

     public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) 
     { 
      var tupleParam = ((Tuple<DatePicker, string>) parameter); 
      var dateStr = (string) value; 
      return StringToDateTime(tupleParam.Item1, tupleParam.Item2, dateStr); 
     } 

     public static string DateTimeToString(string formatStr, DateTime? selectedDate) 
     { 
      return selectedDate.HasValue ? selectedDate.Value.ToString(formatStr) : null; 
     } 

     public static DateTime? StringToDateTime(DatePicker datePicker, string formatStr, string dateStr) 
     { 
      DateTime date; 
      var canParse = DateTime.TryParseExact(dateStr, formatStr, CultureInfo.CurrentCulture, 
                DateTimeStyles.None, out date); 

      if (!canParse) 
       canParse = DateTime.TryParse(dateStr, CultureInfo.CurrentCulture, DateTimeStyles.None, out date); 

      return canParse ? date : datePicker.SelectedDate; 
     } 
    } 
} 

Answer 4

i traducidos Simon La respuesta a VB, publico aquí el re sults (déle créditos)

Imports System.Windows.Threading 
Imports System.Windows.Controls.Primitives 
Imports System.Windows.Controls 

''' <summary>  Allows the Date Picker Calendar to select month. 
'''      Use with the attached property IsMonthYear Property. 
''' </summary> 
''' <remarks> Source : https://stackoverflow.com/questions/1798513/wpf-toolkit-datepicker-month-year-only 
'''   Author : </remarks> 
Public Class DatePickerCalendar 

Public Shared IsMonthYearProperty As DependencyProperty = DependencyProperty.RegisterAttached("IsMonthYear", GetType(System.Boolean), GetType(DatePickerCalendar), New PropertyMetadata(AddressOf OnIsMonthYearChanged)) 

Public Shared Function GetIsMonthYear(ByVal dobj As DependencyObject) As Boolean 
    Return CType(dobj.GetValue(IsMonthYearProperty), Boolean) 
End Function 

Public Shared Sub SetIsMonthYear(ByVal dobj As DependencyObject, ByVal value As Boolean) 
    dobj.SetValue(IsMonthYearProperty, value) 
End Sub 

Private Shared Sub OnIsMonthYearChanged(ByVal dobj As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs) 
    Dim MyDatePicker = CType(dobj, DatePicker) 
    Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, _ 
        New Action(Of DatePicker, DependencyPropertyChangedEventArgs)(AddressOf SetCalendarEventHandlers), MyDatePicker, e) 
End Sub 

Private Shared Sub SetCalendarEventHandlers(ByVal datePicker As DatePicker, ByVal e As DependencyPropertyChangedEventArgs) 
    If (e.NewValue = e.OldValue) Then 
     Return 
    End If 
    If CType(e.NewValue, Boolean) Then 
     AddHandler datePicker.CalendarOpened, AddressOf DatePickerOnCalendarOpened 
     AddHandler datePicker.CalendarClosed, AddressOf DatePickerOnCalendarClosed 
    Else 
     RemoveHandler datePicker.CalendarOpened, AddressOf DatePickerOnCalendarOpened 
     RemoveHandler datePicker.CalendarClosed, AddressOf DatePickerOnCalendarClosed 
    End If 
End Sub 

Private Shared Sub DatePickerOnCalendarOpened(ByVal sender As Object, ByVal routedEventArgs As RoutedEventArgs) 
    Dim MyCalendar = GetDatePickerCalendar(sender) 
    MyCalendar.DisplayMode = CalendarMode.Year 
    AddHandler MyCalendar.DisplayModeChanged, AddressOf CalendarOnDisplayModeChanged 
End Sub 

Private Shared Sub DatePickerOnCalendarClosed(ByVal sender As Object, ByVal routedEventArgs As RoutedEventArgs) 
    Dim MyDatePicker = CType(sender, DatePicker) 
    Dim MyCalendar = GetDatePickerCalendar(sender) 
    MyDatePicker.SelectedDate = MyCalendar.SelectedDate 
    RemoveHandler MyCalendar.DisplayModeChanged, AddressOf CalendarOnDisplayModeChanged 
End Sub 

Private Shared Sub CalendarOnDisplayModeChanged(ByVal sender As Object, ByVal e As CalendarModeChangedEventArgs) 
    Dim MyCalendar = CType(sender, Calendar) 
    If (MyCalendar.DisplayMode <> CalendarMode.Month) Then 
     Return 
    End If 
    MyCalendar.SelectedDate = GetSelectedCalendarDate(MyCalendar.DisplayDate) 
    Dim MyDatePicker = GetCalendarsDatePicker(MyCalendar) 
    MyDatePicker.IsDropDownOpen = False 
End Sub 

Private Shared Function GetDatePickerCalendar(ByVal sender As Object) As Calendar 
    Dim MyDatePicker = CType(sender, DatePicker) 
    Dim MyPopup = CType(MyDatePicker.Template.FindName("PART_Popup", MyDatePicker), Popup) 
    Return CType(MyPopup.Child, Calendar) 
End Function 

Private Shared Function GetCalendarsDatePicker(ByVal child As FrameworkElement) As DatePicker 
    Dim MyParent = CType(child.Parent, FrameworkElement) 
    If (MyParent.Name = "PART_Root") Then 
     Return CType(MyParent.TemplatedParent, DatePicker) 
    End If 
    Return GetCalendarsDatePicker(MyParent) 
End Function 

Private Shared Function GetSelectedCalendarDate(ByVal selectedDate As DateTime?) As DateTime? 
    If Not selectedDate.HasValue Then 
     Return Nothing 
    End If 
    Return New DateTime(selectedDate.Value.Year, selectedDate.Value.Month, 1) 
End Function 
End Class 

Pero para la clase de formato, no pude hacer que funcionara.
Utilicé y modifiqué levemente la respuesta (más simple) de petrycol para la visualización de mes/año. Fuente:
Changing the string format of the WPF DatePicker

<DatePicker SelectedDate="{Binding FromDate}" 
        l:DatePickerCalendar.IsMonthYear="True" 
        x:Name="MonthCalendar" HorizontalAlignment="Center"     
       > 
     <DatePicker.Resources> 
      <!--Source : https://stackoverflow.com/questions/3819832/changing-the-string-format-of-the-wpf-datepicker 
       Author : petrycol --> 
      <Style TargetType="{x:Type DatePickerTextBox}"> 
       <Setter Property="Control.Template"> 
        <Setter.Value> 
         <ControlTemplate> 
          <TextBox Width="60" TextAlignment="Center" x:Name="PART_TextBox" 
            Text="{Binding Path=SelectedDate, StringFormat='MM yy', 
            RelativeSource={RelativeSource AncestorType={x:Type DatePicker}},FallbackValue='-- --'}" /> 
         </ControlTemplate> 
        </Setter.Value> 
       </Setter> 
      </Style> 
     </DatePicker.Resources> 
     <!--CalendarOpened="DatePicker_CalendarOpened"--> 
    </DatePicker> 

Answer 5

Para añadir a Simon's brilliant answer, he hecho algunos cambios en DatePickerDateFormat.cs para evitar un error en el cuadro de texto parpadea momentáneamente entre dd/mm/aaaa (formato de cadena original) y MM/aaaa (formato de cadena anulada).

Esto ocurre debido a que DatePicker establece el texto de cuadro de texto PART_ internamente inmediatamente antes de que se abra el menú desplegable. Lo establece en el texto con formato de cadena y hay algo que puede hacer al respecto: anulará su encuadernación.

Para evitar este comportamiento, agregué este código al DatePickerDateFormat class from above.

1. en ApplyDateFormat, obtener el botón desplegable y manejar PreviewMouseUp

   private static void ApplyDateFormat(DatePicker datePicker) 
   { 
       var binding = new Binding("SelectedDate") 
           { 
            RelativeSource = new RelativeSource { AncestorType = typeof(DatePicker) }, 
            Converter = new DatePickerDateTimeConverter(), 
            ConverterParameter = new Tuple<DatePicker, string>(datePicker, GetDateFormat(datePicker)), 
            StringFormat = GetDateFormat(datePicker) // This is also new but didnt seem to help 
           }; 
   
       var textBox = GetTemplateTextBox(datePicker); 
       textBox.SetBinding(TextBox.TextProperty, binding); 
   
       textBox.PreviewKeyDown -= TextBoxOnPreviewKeyDown; 
       textBox.PreviewKeyDown += TextBoxOnPreviewKeyDown; 
   
       var dropDownButton = GetTemplateButton(datePicker); 
   
       datePicker.CalendarOpened -= DatePickerOnCalendarOpened; 
       datePicker.CalendarOpened += DatePickerOnCalendarOpened; 
   
       // Handle Dropdownbutton PreviewMouseUp to prevent issue of flickering textboxes 
       dropDownButton.PreviewMouseUp -= DropDownButtonPreviewMouseUp; 
       dropDownButton.PreviewMouseUp += DropDownButtonPreviewMouseUp; 
   } 
   
   private static ButtonBase GetTemplateButton(DatePicker datePicker) 
   { 
       return (ButtonBase)datePicker.Template.FindName("PART_Button", datePicker); 
   } 
   

Cuando los incendios PreviewMouseUp, si hay una fecha seleccionada, anulan el menú desplegable se muestra el comportamiento de encendido (que imitan todo lo que el Datepicker sí, pero no establecemos el texto de PART_TextBox)

/// <summary> 
    ///  Prevents a bug in the DatePicker, where clicking the Dropdown open button results in Text being set to default formatting regardless of StringFormat or binding overrides 
    /// </summary> 
    private static void DropDownButtonPreviewMouseUp(object sender, MouseButtonEventArgs e) 
    { 
     var fe = sender as FrameworkElement; 
     if (fe == null) return; 

     var datePicker = fe.TryFindAncestorOrSelf<DatePicker>(); 
     if (datePicker == null || datePicker.SelectedDate == null) return;    

     var dropDownButton = GetTemplateButton(datePicker); 

     // Dropdown button was clicked 
     if (e.OriginalSource == dropDownButton && datePicker.IsDropDownOpen == false) 
     {         
      // Open dropdown 
      datePicker.SetCurrentValue(DatePicker.IsDropDownOpenProperty, true); 

      // Mimic everything else in the standard DatePicker dropdown opening *except* setting textbox value 
      datePicker.SetCurrentValue(DatePicker.DisplayDateProperty, datePicker.SelectedDate.Value); 

      // Important otherwise calendar does not work 
      dropDownButton.ReleaseMouseCapture(); 

      // Prevent datePicker.cs from handling this event 
      e.Handled = true;     
     } 
    } 

donde la extensión método iónico TryFindAncestorOrSelf camina por el árbol visual para encontrar un objeto de tipo T. Puede encontrar una implementación de esto aquí: http://www.hardcodet.net/2008/02/find-wpf-parent

Espero que esto ayude a alguien!

Answer 6

Esta es una combinación de Simon's y Dr. ABT's respuestas, incluyendo todo el código requerido extra y con los conflictos de referencia entre Windows y Microsoft controles fijos.

Es bastante ridículo que esto requiera una clase de 345 líneas para lograr, pero debería funcionar si incluye DatePickerCalendar.cs (con su espacio de nombre), construya su proyecto y utilice el siguiente XAML.

<DatePicker local:DatePickerCalendar.IsMonthYear="True" 
      local:DatePickerDateFormat.DateFormat="MMM-yyyy" 
      Text="MMM-yyyy"></DatePicker> 

DatePickerCalendar.cs

using System; 
using System.Globalization; 
using System.Windows; 
using System.Windows.Controls; 
using System.Windows.Controls.Primitives; 
using System.Windows.Data; 
using System.Windows.Input; 
using System.Windows.Media; 
using System.Windows.Threading; 
using Calendar = System.Windows.Controls.Calendar; 
using CalendarMode = System.Windows.Controls.CalendarMode; 
using CalendarModeChangedEventArgs = System.Windows.Controls.CalendarModeChangedEventArgs; 
using DatePicker = System.Windows.Controls.DatePicker; 

namespace <YourProject> 
{ 
    public class DatePickerCalendar 
    { 
     public static readonly DependencyProperty IsMonthYearProperty = 
      DependencyProperty.RegisterAttached("IsMonthYear", typeof(bool), typeof(DatePickerCalendar), 
               new PropertyMetadata(OnIsMonthYearChanged)); 

     public static bool GetIsMonthYear(DependencyObject dobj) 
     { 
      return (bool)dobj.GetValue(IsMonthYearProperty); 
     } 

     public static void SetIsMonthYear(DependencyObject dobj, bool value) 
     { 
      dobj.SetValue(IsMonthYearProperty, value); 
     } 

     private static void OnIsMonthYearChanged(DependencyObject dobj, DependencyPropertyChangedEventArgs e) 
     { 
      var datePicker = (DatePicker)dobj; 

      Application.Current.Dispatcher 
       .BeginInvoke(DispatcherPriority.Loaded, 
          new Action<DatePicker, DependencyPropertyChangedEventArgs>(SetCalendarEventHandlers), 
          datePicker, e); 
     } 

     private static void SetCalendarEventHandlers(DatePicker datePicker, DependencyPropertyChangedEventArgs e) 
     { 
      if (e.NewValue == e.OldValue) 
       return; 

      if ((bool)e.NewValue) 
      { 
       datePicker.CalendarOpened += DatePickerOnCalendarOpened; 
       datePicker.CalendarClosed += DatePickerOnCalendarClosed; 
      } 
      else 
      { 
       datePicker.CalendarOpened -= DatePickerOnCalendarOpened; 
       datePicker.CalendarClosed -= DatePickerOnCalendarClosed; 
      } 
     } 

     private static void DatePickerOnCalendarOpened(object sender, RoutedEventArgs routedEventArgs) 
     { 
      var calendar = GetDatePickerCalendar(sender); 
      calendar.DisplayMode = CalendarMode.Year; 

      calendar.DisplayModeChanged += CalendarOnDisplayModeChanged; 
     } 

     private static void DatePickerOnCalendarClosed(object sender, RoutedEventArgs routedEventArgs) 
     { 
      var datePicker = (DatePicker)sender; 
      var calendar = GetDatePickerCalendar(sender); 
      datePicker.SelectedDate = calendar.SelectedDate; 

      calendar.DisplayModeChanged -= CalendarOnDisplayModeChanged; 
     } 

     private static void CalendarOnDisplayModeChanged(object sender, CalendarModeChangedEventArgs e) 
     { 
      var calendar = (Calendar)sender; 
      if (calendar.DisplayMode != CalendarMode.Month) 
       return; 

      calendar.SelectedDate = GetSelectedCalendarDate(calendar.DisplayDate); 

      var datePicker = GetCalendarsDatePicker(calendar); 
      datePicker.IsDropDownOpen = false; 
     } 

     private static Calendar GetDatePickerCalendar(object sender) 
     { 
      var datePicker = (DatePicker)sender; 
      var popup = (Popup)datePicker.Template.FindName("PART_Popup", datePicker); 
      return ((Calendar)popup.Child); 
     } 

     private static DatePicker GetCalendarsDatePicker(FrameworkElement child) 
     { 
      var parent = (FrameworkElement)child.Parent; 
      if (parent.Name == "PART_Root") 
       return (DatePicker)parent.TemplatedParent; 
      return GetCalendarsDatePicker(parent); 
     } 

     private static DateTime? GetSelectedCalendarDate(DateTime? selectedDate) 
     { 
      if (!selectedDate.HasValue) 
       return null; 
      return new DateTime(selectedDate.Value.Year, selectedDate.Value.Month, 1); 
     } 
    } 

    public class DatePickerDateFormat 
    { 
     public static readonly DependencyProperty DateFormatProperty = 
      DependencyProperty.RegisterAttached("DateFormat", typeof(string), typeof(DatePickerDateFormat), 
               new PropertyMetadata(OnDateFormatChanged)); 

     public static string GetDateFormat(DependencyObject dobj) 
     { 
      return (string)dobj.GetValue(DateFormatProperty); 
     } 

     public static void SetDateFormat(DependencyObject dobj, string value) 
     { 
      dobj.SetValue(DateFormatProperty, value); 
     } 

     private static void OnDateFormatChanged(DependencyObject dobj, DependencyPropertyChangedEventArgs e) 
     { 
      var datePicker = (DatePicker)dobj; 

      Application.Current.Dispatcher.BeginInvoke(
       DispatcherPriority.Loaded, new Action<DatePicker>(ApplyDateFormat), datePicker); 
     } 
     private static void ApplyDateFormat(DatePicker datePicker) 
     { 
      var binding = new Binding("SelectedDate") 
      { 
       RelativeSource = new RelativeSource { AncestorType = typeof(DatePicker) }, 
       Converter = new DatePickerDateTimeConverter(), 
       ConverterParameter = new Tuple<DatePicker, string>(datePicker, GetDateFormat(datePicker)), 
       StringFormat = GetDateFormat(datePicker) // This is also new but didnt seem to help 
      }; 

      var textBox = GetTemplateTextBox(datePicker); 
      textBox.SetBinding(TextBox.TextProperty, binding); 

      textBox.PreviewKeyDown -= TextBoxOnPreviewKeyDown; 
      textBox.PreviewKeyDown += TextBoxOnPreviewKeyDown; 

      var dropDownButton = GetTemplateButton(datePicker); 

      datePicker.CalendarOpened -= DatePickerOnCalendarOpened; 
      datePicker.CalendarOpened += DatePickerOnCalendarOpened; 

      // Handle Dropdownbutton PreviewMouseUp to prevent issue of flickering textboxes 
      dropDownButton.PreviewMouseUp -= DropDownButtonPreviewMouseUp; 
      dropDownButton.PreviewMouseUp += DropDownButtonPreviewMouseUp; 
     } 

     private static ButtonBase GetTemplateButton(DatePicker datePicker) 
     { 
      return (ButtonBase)datePicker.Template.FindName("PART_Button", datePicker); 
     } 


     /// <summary> 
     ///  Prevents a bug in the DatePicker, where clicking the Dropdown open button results in Text being set to default formatting regardless of StringFormat or binding overrides 
     /// </summary> 
     private static void DropDownButtonPreviewMouseUp(object sender, MouseButtonEventArgs e) 
     { 
      var fe = sender as FrameworkElement; 
      if (fe == null) return; 

      var datePicker = fe.TryFindParent<DatePicker>(); 
      if (datePicker == null || datePicker.SelectedDate == null) return; 

      var dropDownButton = GetTemplateButton(datePicker); 

      // Dropdown button was clicked 
      if (e.OriginalSource == dropDownButton && datePicker.IsDropDownOpen == false) 
      { 
       // Open dropdown 
       datePicker.SetCurrentValue(DatePicker.IsDropDownOpenProperty, true); 

       // Mimic everything else in the standard DatePicker dropdown opening *except* setting textbox value 
       datePicker.SetCurrentValue(DatePicker.DisplayDateProperty, datePicker.SelectedDate.Value); 

       // Important otherwise calendar does not work 
       dropDownButton.ReleaseMouseCapture(); 

       // Prevent datePicker.cs from handling this event 
       e.Handled = true; 
      } 
     } 



     private static TextBox GetTemplateTextBox(Control control) 
     { 
      control.ApplyTemplate(); 
      return (TextBox)control?.Template?.FindName("PART_TextBox", control); 
     } 

     private static void TextBoxOnPreviewKeyDown(object sender, KeyEventArgs e) 
     { 
      if (e.Key != Key.Return) 
       return; 

      /* DatePicker subscribes to its TextBox's KeyDown event to set its SelectedDate if Key.Return was 
      * pressed. When this happens its text will be the result of its internal date parsing until it 
      * loses focus or another date is selected. A workaround is to stop the KeyDown event bubbling up 
      * and handling setting the DatePicker.SelectedDate. */ 

      e.Handled = true; 

      var textBox = (TextBox)sender; 
      var datePicker = (DatePicker)textBox.TemplatedParent; 
      var dateStr = textBox.Text; 
      var formatStr = GetDateFormat(datePicker); 
      datePicker.SelectedDate = DatePickerDateTimeConverter.StringToDateTime(datePicker, formatStr, dateStr); 
     } 

     private static void DatePickerOnCalendarOpened(object sender, RoutedEventArgs e) 
     { 
      /* When DatePicker's TextBox is not focused and its Calendar is opened by clicking its calendar button 
      * its text will be the result of its internal date parsing until its TextBox is focused and another 
      * date is selected. A workaround is to set this string when it is opened. */ 

      var datePicker = (DatePicker)sender; 
      var textBox = GetTemplateTextBox(datePicker); 
      var formatStr = GetDateFormat(datePicker); 
      textBox.Text = DatePickerDateTimeConverter.DateTimeToString(formatStr, datePicker.SelectedDate); 
     } 

     private class DatePickerDateTimeConverter : IValueConverter 
     { 
      public object Convert(object value, Type targetType, object parameter, CultureInfo culture) 
      { 
       var formatStr = ((Tuple<DatePicker, string>)parameter).Item2; 
       var selectedDate = (DateTime?)value; 
       return DateTimeToString(formatStr, selectedDate); 
      } 

      public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) 
      { 
       var tupleParam = ((Tuple<DatePicker, string>)parameter); 
       var dateStr = (string)value; 
       return StringToDateTime(tupleParam.Item1, tupleParam.Item2, dateStr); 
      } 

      public static string DateTimeToString(string formatStr, DateTime? selectedDate) 
      { 
       return selectedDate.HasValue ? selectedDate.Value.ToString(formatStr) : null; 
      } 

      public static DateTime? StringToDateTime(DatePicker datePicker, string formatStr, string dateStr) 
      { 
       DateTime date; 
       var canParse = DateTime.TryParseExact(dateStr, formatStr, CultureInfo.CurrentCulture, 
                 DateTimeStyles.None, out date); 

       if (!canParse) 
        canParse = DateTime.TryParse(dateStr, CultureInfo.CurrentCulture, DateTimeStyles.None, out date); 

       return canParse ? date : datePicker.SelectedDate; 
      } 


     } 

    } 



    public static class FEExten 
    { 
     /// <summary> 
     /// Finds a parent of a given item on the visual tree. 
     /// </summary> 
     /// <typeparam name="T">The type of the queried item.</typeparam> 
     /// <param name="child">A direct or indirect child of the 
     /// queried item.</param> 
     /// <returns>The first parent item that matches the submitted 
     /// type parameter. If not matching item can be found, a null 
     /// reference is being returned.</returns> 
     public static T TryFindParent<T>(this DependencyObject child) 
      where T : DependencyObject 
     { 
      //get parent item 
      DependencyObject parentObject = GetParentObject(child); 

      //we've reached the end of the tree 
      if (parentObject == null) return null; 

      //check if the parent matches the type we're looking for 
      T parent = parentObject as T; 
      if (parent != null) 
      { 
       return parent; 
      } 
      else 
      { 
       //use recursion to proceed with next level 
       return TryFindParent<T>(parentObject); 
      } 
     } 

     /// <summary> 
     /// This method is an alternative to WPF's 
     /// <see cref="VisualTreeHelper.GetParent"/> method, which also 
     /// supports content elements. Keep in mind that for content element, 
     /// this method falls back to the logical tree of the element! 
     /// </summary> 
     /// <param name="child">The item to be processed.</param> 
     /// <returns>The submitted item's parent, if available. Otherwise 
     /// null.</returns> 
     public static DependencyObject GetParentObject(this DependencyObject child) 
     { 
      if (child == null) return null; 

      //handle content elements separately 
      ContentElement contentElement = child as ContentElement; 
      if (contentElement != null) 
      { 
       DependencyObject parent = ContentOperations.GetParent(contentElement); 
       if (parent != null) return parent; 

       FrameworkContentElement fce = contentElement as FrameworkContentElement; 
       return fce != null ? fce.Parent : null; 
      } 

      //also try searching for parent in framework elements (such as DockPanel, etc) 
      FrameworkElement frameworkElement = child as FrameworkElement; 
      if (frameworkElement != null) 
      { 
       DependencyObject parent = frameworkElement.Parent; 
       if (parent != null) return parent; 
      } 

      //if it's not a ContentElement/FrameworkElement, rely on VisualTreeHelper 
      return VisualTreeHelper.GetParent(child); 
     } 
    } 
} 

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