public class DataGridBehavior

{

    #region DisplayRowNumber

​

    public static DependencyProperty DisplayRowNumberProperty =

        DependencyProperty.RegisterAttached("DisplayRowNumber",

                                            typeof(bool),

                                            typeof(DataGridBehavior),

                                            new FrameworkPropertyMetadata(false, OnDisplayRowNumberChanged));

    public static bool GetDisplayRowNumber(DependencyObject target)

    {

        return (bool)target.GetValue(DisplayRowNumberProperty);

    }

    public static void SetDisplayRowNumber(DependencyObject target, bool value)

    {

        target.SetValue(DisplayRowNumberProperty, value);

    }

​

    private static void OnDisplayRowNumberChanged(DependencyObject target, DependencyPropertyChangedEventArgs e)

    {

        DataGrid dataGrid = target as DataGrid;

        if ((bool)e.NewValue == true)

        {

            EventHandler<DataGridRowEventArgs> loadedRowHandler = null;

            loadedRowHandler = (object sender, DataGridRowEventArgs ea) =>

            {

                if (GetDisplayRowNumber(dataGrid) == false)

                {

                    dataGrid.LoadingRow -= loadedRowHandler;

                    return;

                }

                ea.Row.Header = ea.Row.GetIndex();

            };

            dataGrid.LoadingRow += loadedRowHandler;

​

            ItemsChangedEventHandler itemsChangedHandler = null;

            itemsChangedHandler = (object sender, ItemsChangedEventArgs ea) =>

            {

                if (GetDisplayRowNumber(dataGrid) == false)

                {

                    dataGrid.ItemContainerGenerator.ItemsChanged -= itemsChangedHandler;

                    return;

                }

                GetVisualChildCollection<DataGridRow>(dataGrid).

                    ForEach(d => d.Header = d.GetIndex());

            };

            dataGrid.ItemContainerGenerator.ItemsChanged += itemsChangedHandler;

        }

    }

​

    #endregion // DisplayRowNumber

​

    #region Get Visuals

​

    private static List<T> GetVisualChildCollection<T>(object parent) where T : Visual

    {

        List<T> visualCollection = new List<T>();

        GetVisualChildCollection(parent as DependencyObject, visualCollection);

        return visualCollection;

    }

​

    private static void GetVisualChildCollection<T>(DependencyObject parent, List<T> visualCollection) where T : Visual

    {

        int count = VisualTreeHelper.GetChildrenCount(parent);

        for (int i = 0; i < count; i++)

        {

            DependencyObject child = VisualTreeHelper.GetChild(parent, i);

            if (child is T)

            {

                visualCollection.Add(child as T);

            }

            if (child != null)

            {

                GetVisualChildCollection(child, visualCollection);

            }

        }

    }

​

    #endregion // Get Visuals

}