public static class DragDropRowBehavior
{
    private static DataGrid dataGrid;
    private static Popup popup;
    private static bool enable;
    private static object draggedItem;

    public static object DraggedItem
    {
        get { return DragDropRowBehavior.draggedItem; }
        set { DragDropRowBehavior.draggedItem = value; }
    }

    // 定義PopupControl附加屬性
    public static readonly DependencyProperty PopupControlProperty =
        DependencyProperty.RegisterAttached("PopupControl", typeof(Popup), 
            typeof(DragDropRowBehavior), new UIPropertyMetadata(null, OnPopupControlChanged));

    public static Popup GetPopupControl(DependencyObject obj)
    {
        return (Popup)obj.GetValue(PopupControlProperty);
    }

    public static void SetPopupControl(DependencyObject obj, Popup value)
    {
        obj.SetValue(PopupControlProperty, value);
    }

    private static void OnPopupControlChanged(DependencyObject depObject, DependencyPropertyChangedEventArgs e)
    {
        if (e.NewValue == null || !(e.NewValue is Popup))
        {
            throw new ArgumentException("Popup Control should be set", "PopupControl");
        }
        popup = e.NewValue as Popup;

        dataGrid = depObject as DataGrid;
        if (dataGrid == null) return;

        if (enable && popup != null)
        {
            dataGrid.BeginningEdit += OnBeginEdit;
            dataGrid.CellEditEnding += OnEndEdit;
            dataGrid.MouseLeftButtonUp += OnMouseLeftButtonUp;
            dataGrid.PreviewMouseLeftButtonDown += OnMouseLeftButtonDown;
            dataGrid.MouseMove += OnMouseMove;
        }
        else
        {
            dataGrid.BeginningEdit -= OnBeginEdit;
            dataGrid.CellEditEnding -= OnEndEdit;
            dataGrid.MouseLeftButtonUp -= OnMouseLeftButtonUp;
            dataGrid.MouseLeftButtonDown -= OnMouseLeftButtonDown;
            dataGrid.MouseMove -= OnMouseMove;

            dataGrid = null;
            popup = null;
            draggedItem = null;
            IsEditing = false;
            IsDragging = false;
        }
    }

    // 定義Enabled附加屬性
    public static readonly DependencyProperty EnabledProperty =
        DependencyProperty.RegisterAttached("Enabled", typeof(bool), 
            typeof(DragDropRowBehavior), new UIPropertyMetadata(false, OnEnabledChanged));

    public static bool GetEnabled(DependencyObject obj)
    {
        return (bool)obj.GetValue(EnabledProperty);
    }

    public static void SetEnabled(DependencyObject obj, bool value)
    {
        obj.SetValue(EnabledProperty, value);
    }

    private static void OnEnabledChanged(DependencyObject depObject, DependencyPropertyChangedEventArgs e)
    {
        if (e.NewValue is bool == false)
            throw new ArgumentException("Value should be of bool type", "Enabled");

        enable = (bool)e.NewValue;
    }

    public static bool IsEditing { get; set; }
    public static bool IsDragging { get; set; }

    private static void OnBeginEdit(object sender, DataGridBeginningEditEventArgs e)
    {
        IsEditing = true;
        if (IsDragging) ResetDragDrop();
    }

    private static void OnEndEdit(object sender, DataGridCellEditEndingEventArgs e)
    {
        IsEditing = false;
    }

    private static void OnMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (IsEditing) return;
        
        var row = UIHelpers.TryFindFromPoint<DataGridRow>((UIElement)sender, e.GetPosition(dataGrid));
        if (row == null || row.IsEditing) return;

        IsDragging = true;
        DraggedItem = row.Item;
    }

    private static void OnMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        if (!IsDragging || IsEditing) return;
        
        dataGrid.Cursor = Cursors.Arrow;
        var targetItem = dataGrid.SelectedItem;

        if (targetItem == null || !ReferenceEquals(DraggedItem, targetItem))
        {
            var targetIndex = ((dataGrid).ItemsSource as IList).IndexOf(targetItem);
            ((dataGrid).ItemsSource as IList).Remove(DraggedItem);
            ((dataGrid).ItemsSource as IList).Insert(targetIndex, DraggedItem);
            dataGrid.SelectedItem = DraggedItem;
        }

        ResetDragDrop();
    }

    private static void ResetDragDrop()
    {
        IsDragging = false;
        popup.IsOpen = false;
        dataGrid.IsReadOnly = false;
    }

    private static void OnMouseMove(object sender, MouseEventArgs e)
    {
        if (!IsDragging || e.LeftButton != MouseButtonState.Pressed) return;
        
        if (dataGrid.Cursor != Cursors.SizeAll) dataGrid.Cursor = Cursors.SizeAll;
        
        popup.DataContext = DraggedItem;
        
        if (!popup.IsOpen)
        {
            dataGrid.IsReadOnly = true;
            popup.IsOpen = true;
        }

        Size popupSize = new Size(popup.ActualWidth, popup.ActualHeight);
        popup.PlacementRectangle = new Rect(e.GetPosition(dataGrid), popupSize);

        Point position = e.GetPosition(dataGrid);
        var row = UIHelpers.TryFindFromPoint<DataGridRow>(dataGrid, position);
        if (row != null) dataGrid.SelectedItem = row.Item;
    }
}

public static class UIHelpers
{
    // 查找父元素
    public static T TryFindParent<T>(DependencyObject child) where T : DependencyObject
    {
        DependencyObject parentObject = GetParentObject(child);
        if (parentObject == null) return null;
        
        T parent = parentObject as T;
        if (parent != null) return parent;
        else return TryFindParent<T>(parentObject);
    }

    public static DependencyObject GetParentObject(DependencyObject child)
    {
        if (child == null) return null;
        
        if (child is ContentElement contentElement)
        {
            DependencyObject parent = ContentOperations.GetParent(contentElement);
            if (parent != null) return parent;

            if (contentElement is FrameworkContentElement fce) 
                return fce.Parent;
        }
        
        return VisualTreeHelper.GetParent(child);
    }

    // 更新綁定源
    public static void UpdateBindingSources(DependencyObject obj, params DependencyProperty[] properties)
    {
        foreach (DependencyProperty depProperty in properties)
        {
            BindingExpression be = BindingOperations.GetBindingExpression(obj, depProperty);
            if (be != null) be.UpdateSource();
        }

        int count = VisualTreeHelper.GetChildrenCount(obj);
        for (int i = 0; i < count; i++)
        {
            DependencyObject childObject = VisualTreeHelper.GetChild(obj, i);
            UpdateBindingSources(childObject, properties);
        }
    }

    // 從指定點(diǎn)查找元素
    public static T TryFindFromPoint<T>(UIElement reference, Point point) where T : DependencyObject
    {
        DependencyObject element = reference.InputHitTest(point) as DependencyObject;
        if (element == null) return null;
        else if (element is T) return (T)element;
        else return TryFindParent<T>(element);
    }
}

<Grid Grid.Row="1" Margin="5">
    <!-- 拖拽提示Popup -->
    <Popup x:Name="popup1" AllowsTransparency="True" 
           IsHitTestVisible="False" Placement="RelativePoint" 
           PlacementTarget="{Binding ElementName=dataGrid1}">
        <TextBlock Margin="8,0,0,0" VerticalAlignment="Center" 
                   FontSize="14" FontWeight="Bold" Text="Dragging..." />
    </Popup>
    
    <!-- 啟用拖拽行為的DataGrid -->
    <DataGrid x:Name="dataGrid1" 
              controlEx:DragDropRowBehavior.Enabled="True"
              controlEx:DragDropRowBehavior.PopupControl="{Binding ElementName=popup1}"
              AutoGenerateColumns="False" 
              ItemsSource="{Binding ListItem}" 
              RowHeaderWidth="60">
        <DataGrid.Columns>
            <DataGridTextColumn Binding="{Binding Column1}" Header="column1" />
            <DataGridTextColumn Binding="{Binding Column2}" Header="column2" />
            <DataGridTextColumn Binding="{Binding Column3}" Header="column3" />
        </DataGrid.Columns>
    </DataGrid>
</Grid>