Sunday, May 2, 2010

Get WPF DataGrid row and cell

There are no simple built-in methods for accessing individual rows or columns in WPF DataGrid. The following code samples will provide simple methods for accessing these items.

First of all we need a helper function for selecting a visual child:

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

There is a simple method for getting the current (selected) row of the DataGrid:

public static DataGridRow GetSelectedRow(this DataGrid grid)
{
    return (DataGridRow)grid.ItemContainerGenerator.ContainerFromItem(grid.SelectedItem);
}

We can also get a row by its indices:

public static DataGridRow GetRow(this DataGrid grid, int index)
{
    DataGridRow row = (DataGridRow)grid.ItemContainerGenerator.ContainerFromIndex(index);
    if (row == null)
    {
        // May be virtualized, bring into view and try again.
        grid.UpdateLayout();
        grid.ScrollIntoView(grid.Items[index]);
        row = (DataGridRow)grid.ItemContainerGenerator.ContainerFromIndex(index);
    }
    return row;
}

Now we can get a cell of a DataGrid by an existing row:

public static DataGridCell GetCell(this DataGrid grid, DataGridRow row, int column)
{
    if (row != null)
    {
        DataGridCellsPresenter presenter = GetVisualChild<DataGridCellsPresenter>(row);

        if (presenter == null)
        {
            grid.ScrollIntoView(row, grid.Columns[column]);
            presenter = GetVisualChild<DataGridCellsPresenter>(row);
        }

        DataGridCell cell = (DataGridCell)presenter.ItemContainerGenerator.ContainerFromIndex(column);
        return cell;
    }
    return null;
}

Or we can simply select a row by its indices:

public static DataGridCell GetCell(this DataGrid grid, int row, int column)
{
    DataGridRow rowContainer = grid.GetRow(row);
    return grid.GetCell(rowContainer, column);
}

The functions above are extension methods. Their use is simple:

var selectedRow = grid.GetSelectedRow();
var columnCell = grid.GetCell(selectedRow, 0);

View source on Google Code (unformatted selection possible)