WPF DatePicker日期控件只显示年月

1.需要引用2个类，第一个类DatePickerCalendar

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_Popup”)//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);
}
}

2.第二个类

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;
}
}
}

3.第三步页面引用类库调用

xmlns:local=”clr-namespace:【命名控件】;assembly=【类库名称】”

4.效果图