WPF DatePicker只显示年和月 修改：可以只显示年

public class DatePickerCalendar
{ public static bool GetIsYear(DependencyObject obj)
{
return (bool)obj.GetValue(IsYearProperty);
} public static void SetIsYear(DependencyObject obj, bool value)
{
obj.SetValue(IsYearProperty, value);
} // Using a DependencyProperty as the backing store for IsYear. This enables animation, styling, binding, etc...
public static readonly DependencyProperty IsYearProperty =
DependencyProperty.RegisterAttached("IsYear", typeof(bool), typeof(DatePickerCalendar), new PropertyMetadata(false, new PropertyChangedCallback(OnIsMonthYearChanged))); 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);
if (GetIsYear(sender as DatePicker))
{
calendar.DisplayMode = CalendarMode.Decade;
}
else
{
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;
var datePicker = GetCalendarsDatePicker(calendar); bool mode = (GetIsYear(datePicker) && calendar.DisplayMode != CalendarMode.Year) || (GetIsMonthYear(datePicker) && calendar.DisplayMode != CalendarMode.Month); if (mode)
return; calendar.SelectedDate = GetSelectedCalendarDate(calendar.DisplayDate); 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, );
}
}

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;
}
}
}