什么是正确的DatePicker SelectedDateChangedEvent处理程序类型FrameworkElementFactory？

Question

我正在DataGrid控件中创建绑定DataGrid控件的列。对于每个DatePicker控件，我都想附加一个SelectedDateChangedEvent处理程序，但是我很难做到这一点。

考虑WPF的下列代码：

private void dg_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
    if (e.PropertyName == "Event Date")
    {
        var f = new FrameworkElementFactory(typeof(DatePicker));

         ...

        // I tried this:
        //f.AddHandler(DatePicker.SelectedDateChangedEvent, new RoutedEventHandler(aRoutedEventHandler));
        // and I tried this:
        //f.AddHandler(DatePicker.SelectedDateChangedEvent, new SelectionChangedEventHandler(aSelectionChangedEventHandler));

        e.Column = new DataGridTemplateColumn()
        {
            Header = e.Column.Header,
            CellTemplate = new DataTemplate() { VisualTree = f },
        };
    }
}

private void aRoutedEventHandler(object sender, RoutedEventArgs e)   { ... }

private void aSelectionChangedEventHandler(object sender, SelectionChangedEventArgs e) {...}

尝试任何一个事件处理程序都会导致“参数异常”：

System.ArgumentException类型的第一次异常发生在PresentationFramework.dll附加信息中:处理程序类型无效。

正确的处理程序是什么？

Answer 1

您需要为DatePicker SelectedDateChangedEvent添加处理程序如下所示

f.AddHandler(DatePicker.SelectedDateChangedEvent, new EventHandler<SelectionChangedEventArgs>(aSelectionChangedEventHandler));

通过查看声明的公共事件中的DatePicker类，可以找到处理程序类型。

public event RoutedEventHandler CalendarOpened;
public event RoutedEventHandler CalendarOpened;
public event EventHandler<DatePickerDateValidationErrorEventArgs> 
public event EventHandler<SelectionChangedEventArgs> SelectedDateChanged;