这似乎是因为 2.5 中的事件是从以下位置触发的：
at Xceed.Wpf.Toolkit.DateTimePicker.OnValueChanged(Nullable`1 oldValue, Nullable`1 newValue) in C:\Users\Mark Vinten\Downloads\wpftoolkit-114314\Main\Source\ExtendedWPFToolkitSolution\Src\Xceed.Wpf.Toolkit\DateTimePicker\Implementation\DateTimePicker.cs:line 264
然后从基类开始：
at Xceed.Wpf.Toolkit.TimePicker.OnValueChanged(Nullable`1 oldValue, Nullable`1 newValue) in C:\Users\Mark Vinten\Downloads\wpftoolkit-114314\Main\Source\ExtendedWPFToolkitSolution\Src\Xceed.Wpf.Toolkit\TimePicker\Implementation\TimePicker.cs:line 264
现在基类，似乎也经历了CLR绑定过程，提示这是绑定值。我仍在研究为什么会这样，但一种解决方法是像这样使用 Binding：
MainWindow.cs
public DateTime? DateTimeValue
{
get { return (DateTime?)GetValue(DateTimeValueProperty); }
set { SetValue(DateTimeValueProperty, value); }
}
// Using a DependencyProperty as the backing store for DateTimeValue. This enables animation, styling, binding, etc...
public static readonly DependencyProperty DateTimeValueProperty =
DependencyProperty.Register("DateTimeValue", typeof(DateTime?), typeof(MainWindow), new PropertyMetadata(null, new PropertyChangedCallback(DateTimeValueProperty_Changed)));
private static void DateTimeValueProperty_Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
MainWindow mw = d as MainWindow;
System.Diagnostics.Debug.WriteLine("d is " + d == null ? "null" : d.GetType().FullName);
if (mw != null && e.Property == DateTimeValueProperty)
{
var value = e.NewValue as DateTime?;
var listbox = FindChild<ListBox>(mw, "listbox");
if (value == null)
listbox.Items.Add("[NULL]");
else
listbox.Items.Add(value.Value.ToString(System.Globalization.CultureInfo.InvariantCulture));
}
}
/// <summary>
/// Finds a Child of a given item in the visual tree.
/// </summary>
/// <param name="parent">A direct parent of the queried item.</param>
/// <typeparam name="T">The type of the queried item.</typeparam>
/// <param name="childName">x:Name or Name of child. </param>
/// <returns>The first parent item that matches the submitted type parameter.
/// If not matching item can be found,
/// a null parent is being returned.</returns>
public static T FindChild<T>(DependencyObject parent, string childName)
where T : DependencyObject
{
// Confirm parent and childName are valid.
if (parent == null) return null;
T foundChild = null;
int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < childrenCount; i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
// If the child is not of the request child type child
T childType = child as T;
if (childType == null)
{
// recursively drill down the tree
foundChild = FindChild<T>(child, childName);
// If the child is found, break so we do not overwrite the found child.
if (foundChild != null) break;
}
else if (!string.IsNullOrEmpty(childName))
{
var frameworkElement = child as FrameworkElement;
// If the child's name is set for search
if (frameworkElement != null && frameworkElement.Name == childName)
{
// if the child's name is of the request name
foundChild = (T)child;
break;
}
}
else
{
// child element found.
foundChild = (T)child;
break;
}
}
return foundChild;
}
MainWindow.xaml
<StackPanel DataContext="{Binding RelativeSource={RelativeSource AncestorType={x:Type local:MainWindow}}}">
<xctk:DateTimePicker AutoCloseCalendar="True" Name="picker" Width="400" Height="40" Value="{Binding DateTimeValue}" />
<ListBox Height="300" Name="listbox"></ListBox>
</StackPanel>
这使用绑定系统自动检查值是否已更改，如果已更改则仅引发事件。
注意：FindChild 是我在 How can I find WPF controls by name or type? 帖子中找到的一个函数
更新最终摘要
原因似乎是因为在 DateTimePicker 中嵌入了一个 TimePicker 以提供该功能。不幸的是，DateTimePicker 和 TimePicker 都派生自同一个基数，因此在 UpDownBase 中引发相同的路由事件，其中 T 是 DateTime?。
如果您检查事件参数，则 e.RoutedEVent 始终为 UpDownBase.OnValueChanged，因为这是引发事件的类。 e.Source 或 e.OriginalSource 始终是 DateTimePicker 本身，这意味着您没有有用的方法来过滤掉一个或另一个事件。
DateTimeUpDown.RaiseValueChangedEvent() 中有代码来检查 TemplatedParent 是否是 TimePicker 以防止重新引发，但无论是从 DateTimePicker 还是 TimePicker 引发事件，TemplatedParent 似乎总是是 DateTimePicker 所以失败因此你获得两次事件。
我在 WPFToolkit 项目站点上的发现中提出了一个错误：
https://wpftoolkit.codeplex.com/workitem/22014