Get Row from Index in Silverlight DataGrid

Question

I am trying to implement reordering rows in a Silverlight DataGrid. For this I am extending the default DataGridDragDropTarget, and I need to override and implement the following method:

protected override DataGridRow ContainerFromIndex(DataGrid itemsControl, int index)
{

}

How can I get the DataGridRow from the DataGrid and the Index?

Answer 1

I haven't looked at the DataGridDragDropTarget yet, but couldn't you do just

protected override DataGridRow ContainerFromIndex(DataGrid itemsControl, int index)
{
    var row = base.ContainerFromIndex(itemsControl, index);
    if (row != null)
    {
        // do something with row
    }
}

?

If that is not implemented for whatever reason, you can try this:

// requires Assembly System.Windows.Controls.Toolkit.dll

using System.Windows.Controls.Primitives;
// ...

protected override DataGridRow ContainerFromIndex(DataGrid itemsControl, int index)
{
    var rowsPresenter =
        itemsControl.GetVisualDescendants()
            .OfType<DataGridRowsPresenter>().FirstOrDefault();
    if (rowsPresenter != null)
    {
        var row = rowsPresenter.Children[index];
        // do something with row
    }
}

I don't know however how you want to implement the reordering of rows. Chances are you must keep track of your indexes by yourself and return one of your own stored index values in that method.

Answer 2

A slight improvement on Herzmeister's answer, see comments:

protected override DataGridRow ContainerFromIndex(DataGrid itemsControl, int index)
{
    var rowsPresenter = itemsControl.GetVisualDescendants().OfType<DataGridRowsPresenter>().FirstOrDefault();
    if (rowsPresenter != null)
    {
        return rowsPresenter.Children.OfType<DataGridRow>()
                .Where(row => row.GetIndex() == index).SingleOrDefault();
    }
    return null;
}