Make some of DataGrid cells span multiple columns

Question

OK, I have searched for pretty long time for solution of this problem. I am developing simple printing system for WPF DataGrids and have managed to print tables with uniform cell placement using DataTable and setting it as DataGrid's ItemSource.

However, I needed some rows to contain only one cell (you can think of it like "row group header" inside the table).

So, since I haven't found anything about DataTable's cells spanning multiple columns (if this can be made, it would be a great thing to know how), I figured I would have to add rows to DataGrid manually, and solve it something like this:

• Make new DataGrid with desired columns
• Add rows one by one, setting the DataGridCellPanel that spans or not spans through rows

The second point is where I have the problem (if it's right, that is). I need to add row to a DataGrid that uses simple array of strings as cell data (index in array should mach the cell index). Is there an easy way to do something like that?

Answer 1

So after some more fiddling with all this, I have reached a very nice solution.

The best and easiest thing to do is to apply a data template to particular rows after the DataGrid is loaded. So, I stuck to original idea with DataTables and remembered the indices that needed to have their template changed. I just took the DataGridRows from these indices and applied the template that had custom made ItemsPanelTemplate that spans multiple columns.

EDIT: On Daniel's request, I'm including some code.

First thing we need is a template for spanning row:

<ControlTemplate TargetType='{x:Type DataGridRow}'
                 xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'
                 xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
    <Border>
        <DataGridCellsPresenter Foreground='Black'>
            <DataGridCellsPresenter.ItemsPanel>
                <ItemsPanelTemplate>
                    <local:DataGridSpannedCellPanel />
                </ItemsPanelTemplate>
            </DataGridCellsPresenter.ItemsPanel>
        </DataGridCellsPresenter>
    </Border>
</ControlTemplate>

NOTE: local:DataGridSpannedCellPanel is a custom DataGridCellsPanel with overridden ArrangeOverride method that makes first cell span entire size.

You can make a string in code-behind and load your template from it, for example. The next thing is creating your grid and initializing some of the rows with this new template:

var newGrid = MakeNewDataGrid();
newGrid.ItemsSource = myTable.AsDataView();
var template = XamlReader.Parse(HeaderRowTemplate) as ControlTemplate;

foreach (int index in myHeaderIndices)
{
    var container = newGrid.ItemContainerGenerator.ContainerFromIndex(index);
    var row = container as DataGridRow;
    if (row != null)
    {
        row.Template = template;
    }
}

Also note, rows in your table need to be made as follows:

if (bindableQuote.IsGroup())
{
    table.Rows.Add("Header");
}
else
{
    table.Rows.Add(rowData.ToArray());
}

That's about it, the only thing left is to figure out how to implement DataGridSpannedCellPanel.