还有的时候，会遇到DataGrid里面嵌套DataGrid（重叠嵌套），然后里面的鼠标滚轮无法响应外面的滚动，为此记录下解决方案

与上一篇区别在于，详情里面的模板通常是通用的，被定义在样式文件中，被重复使用，因此无法为其添加后台代码，如果能添加后台代码，请翻阅第一篇；所以需要用到命令的方式来辅助事件的抛出，当然还可以利用第三方库Prism，他可以把事件当命令传递，且能传递事件的默认参数，详情请参阅这篇文章；好了，下面开始介绍，扩展DataGrid类，通过自定义命令抛出事件，并传递事件参数...

先请大致看下运行效果：

下面是详情代码，尾部有完整demo，下载

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:local="clr-namespace:CustomCommand">

    <Style TargetType="DataGrid">
        <Setter Property="IsReadOnly" Value="True" />
        <Setter Property="CanUserAddRows" Value="False" />
        <Setter Property="CanUserDeleteRows" Value="False" />
        <Setter Property="VirtualizingPanel.ScrollUnit" Value="Pixel" />
    </Style>
    
    <!--为了不影响已设置的最基础样式，所以下面这个集成样式很重要-->
    <Style TargetType="local:CustomDataGrid" BasedOn="{StaticResource {x:Type DataGrid}}" />

    <DataTemplate x:Key="RowDetails">
        <local:CustomDataGrid ItemsSource="{Binding Infos}" 
                              MouseWheelCommand="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Window},Path=MouseWheelCommand}" />
    </DataTemplate>
</ResourceDictionary>

特别标注下，需要继承默认样式，否则应用到项目中，会区别出异样的
<!--为了不影响已设置的最基础样式，所以下面这个集成样式很重要-->
<Style TargetType="local:CustomDataGrid" BasedOn="{StaticResource {x:Type DataGrid}}" />

using Prism.Commands;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace CustomCommand
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        /// <summary>
        /// 鼠标滚动时发送
        /// </summary>
        public ICommand MouseWheelCommand { get; private set; }

        public ObservableCollection<Info> Datas = new ObservableCollection<Info>();

        public MainWindow()
        {
            MouseWheelCommand = new DelegateCommand<object>(CustomMouseWheel);

            InitializeComponent();
            datagrid.ItemsSource = Datas;

            for (int i = 0; i < 50; i++)
            {
                var info = new Info();
                info.name = "第一级" + i;
                Datas.Add(info);

                if (i % 2 == 0)
                {
                    for (int j = 0; j < 20; j++)
                    {
                        info.Infos.Add(new Info()
                        {
                            name = "第二级" + j
                        });
                    }
                }
            }
        }


        /// <summary>
        /// 当DataGrid的详情行里的DataGrid滚动时发生
        /// </summary>
        /// <param name="obj"></param>
        void CustomMouseWheel(object p)
        {
            if (p is MouseWheelEventArgs e)
            {
                var sc = GetVisualChild<ScrollViewer>(datagrid);
                if (sc != null)
                {
                    sc.ScrollToVerticalOffset(sc.VerticalOffset - e.Delta);
                }
            }
        }

        T GetVisualChild<T>(Visual parent) where T : Visual
        {
            T child = default(T);
            int numVisuals = VisualTreeHelper.GetChildrenCount(parent);
            for (int i = 0; i < numVisuals; i++)
            {
                var v = (Visual)VisualTreeHelper.GetChild(parent, i);
                child = v as T ?? GetVisualChild<T>(v);
                if (child != null)
                    break;
            }
            return child;
        }
    }

    public class Info
    {
        public string name { get; set; }

        public ObservableCollection<Info> Infos { get; set; } = new ObservableCollection<Info>();
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace CustomCommand
{
    /// <summary>
    /// 自定义扩展DataGrid  主要是用于响应滚轮事件
    /// </summary>
    public class CustomDataGrid : DataGrid
    {
        public CustomDataGrid()
        {
            PreviewMouseWheel += CustomDataGrid_PreviewMouseWheel;
        }

        /// <summary>
        /// 鼠标滚动滚动时
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CustomDataGrid_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
        {
            MouseWheelCommand?.Execute(e);//触发命令，并把MouseWheelEventArgs传递
        }

        /// <summary>
        /// 声明一个用于滚动通知的命令
        /// </summary>
        public ICommand MouseWheelCommand
        {
            get { return (ICommand)GetValue(MouseWheelCommandProperty); }
            set { SetValue(MouseWheelCommandProperty, value); }
        }

        public static readonly DependencyProperty MouseWheelCommandProperty =
            DependencyProperty.Register("MouseWheelCommand", typeof(ICommand), typeof(CustomDataGrid), new PropertyMetadata(default(ICommand)));

    }
}

下面是完整demo，有需要的可以下载