如何从样式中为 WPF DataGrid 应用自定义排序？

Question

我想将一种样式应用于DataGrid。 DataGrid 需要运行我的自定义排序代码，而不是默认的 DataGrid 排序。我尝试的解决方案如下：

<Style TargetType="{x:Type DataGrid}" x:Key="FilteredDataGrid">
    <EventSetter Event="Sorting" Handler="DataGrid_Sorting"/>
</Style>

在代码隐藏中：

private void DataGrid_Sorting(object sender, DataGridSortingEventArgs e) {

    e.Handled = true;

    //Here is where I put the code for my custom sort.

}//DataGrid_Sorting

但是，此代码无法构建。在我看来，因为DataGrid.Sorting 事件不是RoutedEvent，所以它不能在EventSetter 中使用。

如何为应用了我的样式的任何 DataGrid 自定义排序？

Answer 1

当您只有“正常”事件时，有一种解决方法可以提供路由事件：

创建一个控制事件转发的附加属性和一个替换原始事件的附加事件。为此，请创建一个类 DataGridEx（您喜欢的任何类名称）作为附加属性 (DataGridEx.EnableSortingEvent) 和事件 (DataGridEx.Sorting) 的容器。

另外，创建一个自定义RoutedEventArgs 类，用于转发原始排序事件参数

public class DataGridExSortingEventArgs : RoutedEventArgs
{
    public DataGridExSortingEventArgs(RoutedEvent routedEvent, DataGridSortingEventArgs sourceEventArgs) : base(routedEvent)
    {
        SourceEventArgs = sourceEventArgs;
    }

    public DataGridSortingEventArgs SourceEventArgs { get; set; }
}

public static class DataGridEx
{
    public static bool GetEnableSortingEvent(DependencyObject obj)
    {
        return (bool)obj.GetValue(EnableSortingEventProperty);
    }

    public static void SetEnableSortingEvent(DependencyObject obj, bool value)
    {
        obj.SetValue(EnableSortingEventProperty, value);
    }

    // Setting this property to true enables the event forwarding from the DataGrid.Sorting event to the DataGridEx.Sorting RoutedEvent
    public static readonly DependencyProperty EnableSortingEventProperty = DependencyProperty.RegisterAttached(
        "EnableSortingEvent",
        typeof(bool),
        typeof(DataGridEx),
        new FrameworkPropertyMetadata(false, new PropertyChangedCallback(OnEnableSortingChanged)));

    private static void OnEnableSortingChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is DataGrid dg)
        {
            if ((bool)e.NewValue)
                dg.Sorting += Dg_Sorting;
            else
                dg.Sorting -= Dg_Sorting;
        }
    }

    // When DataGrid.Sorting is called and DataGridEx.EnableSortingEvent is true, raise the DataGridEx.Sorting event
    private static void Dg_Sorting(object sender, DataGridSortingEventArgs e)
    {
        if (sender is DataGrid dg && GetEnableSortingEvent(dg))
        {
            dg.RaiseEvent(new DataGridExSortingEventArgs(SortingEvent, e));
        }
    }

    // When DataGridEx.EnableSortingEvent is true, the DataGrid.Sorting event will be forwarded to this routed event
    public static readonly RoutedEvent SortingEvent = EventManager.RegisterRoutedEvent(
        "Sorting",
        // only effective on the DataGrid itself
        RoutingStrategy.Direct,
        typeof(RoutedEventHandler),
        typeof(DataGridEx));

    public static void AddSortingHandler(DependencyObject d, RoutedEventHandler handler)
    {
        if (d is DataGrid dg)
            dg.AddHandler(SortingEvent, handler);
    }

    public static void RemoveSortingHandler(DependencyObject d, RoutedEventHandler handler)
    {
        if (d is DataGrid dg)
            dg.RemoveHandler(SortingEvent, handler);
    }
}

现在使用您的风格（local 是定义 DataGridEx 的命名空间的 xmlns）：

<Style TargetType="DataGrid">
    <Setter Property="local:DataGridEx.EnableSortingEvent" Value="True"/>
    <EventSetter Event="local:DataGridEx.Sorting" Handler="DataGrid_Sorting"/>
</Style>

处理程序

private void DataGrid_Sorting(object sender, RoutedEventArgs e)
{
    if (e is DataGridExSortingEventArgs args)
    {
        // will prevent datagrid default sorting
        args.SourceEventArgs.Handled = true;
    }

    // More stuff
}

我希望这是您所需要的。不得不刷新我对附加内容的记忆:)