Drag and Drop DataGrid Row in WPF (Visual Feedback)

(WPF DataGrid):

To show visual feedback (a red line) at the drop location in a DataGrid, you must draw an adorner during drag-over. WPF does not provide this automatically.

The correct approach is to use a custom Adorner that draws a red line between rows.

How it works (concept)

1. Handle DragOver on the DataGrid

2. Detect the row index under the mouse

3. Show a red horizontal line using an Adorner

4. Remove the adorner on Drop / DragLeave

Step 1: Create a Row Drop Adorner

public class DataGridRowDropAdorner : Adorner
{
    private readonly bool _isAbove;
    private readonly Pen _pen = new Pen(Brushes.Red, 2);

    public DataGridRowDropAdorner(DataGridRow row, bool isAbove)
        : base(row)
    {
        _isAbove = isAbove;
        IsHitTestVisible = false;
    }

    protected override void OnRender(DrawingContext dc)
    {
        var width = AdornedElement.RenderSize.Width;
        var y = _isAbove ? 0 : AdornedElement.RenderSize.Height;
        dc.DrawLine(_pen, new Point(0, y), new Point(width, y));
    }
}

Step 2: Show the red line during DragOver

private AdornerLayer _adornerLayer;
private Adorner _currentAdorner;

private void DataGrid_DragOver(object sender, DragEventArgs e)
{
    var row = GetRowUnderMouse(e);
    if (row == null) return;

    RemoveAdorner();

    bool isAbove = e.GetPosition(row).Y < row.ActualHeight / 2;
    _adornerLayer = AdornerLayer.GetAdornerLayer(row);
    _currentAdorner = new DataGridRowDropAdorner(row, isAbove);
    _adornerLayer.Add(_currentAdorner);
}

Step 3: Remove the visual feedback

private void RemoveAdorner()
{
    if (_adornerLayer != null && _currentAdorner != null)
        _adornerLayer.Remove(_currentAdorner);

    _currentAdorner = null;
}

Call RemoveAdorner() on:

• Drop

• DragLeave

Step 4: Helper to find the row

private DataGridRow GetRowUnderMouse(DragEventArgs e)
{
    var element = e.OriginalSource as DependencyObject;
    return ItemsControl.ContainerFromElement(MyDataGrid, element) as DataGridRow;
}

Result

Red line appears between rows
Mouse cursor stays unchanged
Clear and professional drop indication

Summary

• WPF doesn’t support row drop indicators by default

• Use a custom Adorner

• Draw a red line above/below the row

• Remove it on drop

This is the standard and best-practice solution used in WPF applications.