[Silverlight] How to make a simple PivotTable extended from Silverlight DataGrid

Recently, I have recieved a few questions about Silverlight DataGrid. It's about how to change one row to be columns just like we see in an Excel book sheet. Actually, we call this kind of table as a PivotTable or PivotGrid.
As this is another control which has not been included as a build-in control, so the best way is to create this kind of controls by ourselves, but it need a lot of labor time. By the way, there are many third-part Silverlight control manufactures have already create it, if you need good support, good built-in styles for your control and also you have the budget, then buy one and you don't need to read the later part of this blog.
This is a simple sample which talked about how to extend the build-in DataGrid to be a PivotTable for those people who has no spare money or a Silverlight-lover.
So let's start the topic and show the preview image.

The left part of the preview image is the PivotDataGrid, the right part is a common datagrid with the same ItemsSource.
Step 1, please open the Visual Studio, and create a Silverlight Application project, and also you need to install the Silverlight toolkit(http://silverlight.codeplex.com/)
Step 2, please create a Silverlight Class Library for the PivotDataGrid class, name it and change the namespace.
Step 3, let me post all the codes and please read the comments in the codes.

namespace System.Windows.Controls.Extend
{
public class PivotDataGrid : DataGrid
{
// tempdata used to make a new pivoted collection and bind it
// to the datagrid.
private ObservableCollection<PivotDataGridItem> tempdata;
// columnHeaderValues used temporarily to store the all the data
// which used to be the new headers.
private List<object> columnHeaderValues;
// rowdata used temporarily to store the other data which used
// to be the left rows.
private Dictionary<object, List<object>> rowdata;

private IEnumerable _workSource;
// we hide the base ItemsSource because we need to make them two
// available at the same time.
public new IEnumerable ItemsSource
{
get
{
return _workSource;
}
set
{
_workSource = value;
// we pivot the collection here and
// create the new collection to bind.
ApplyWorkDataSource(value);
}
}

// we should know which property will be changed to column header.
public string HeaderProperty { get; set; }

public PivotDataGrid()
: base()
{

this.HeadersVisibility = DataGridHeadersVisibility.All;
this.LoadingRow += new EventHandler<DataGridRowEventArgs>(PivotGrid_LoadingRow);
}


private void ApplyWorkDataSource(IEnumerable source)
{
// generate the new source
this.convertItemsSourceForPivotGrid(source);
this.AutoGenerateColumns = false;
int i = 0;
// generate the new columns according to the new source
foreach (object obj in columnHeaderValues)
{

this.Columns.Add(new DataGridTextColumn()
{
Header = obj.ToString(),
Binding = new Binding("Cells[" + i.ToString() + "]")
});

i++;
}
// generate the new collection
tempdata = new ObservableCollection<PivotDataGridItem>();
foreach (object objkey in rowdata.Keys)
{
PivotDataGridItem item = new PivotDataGridItem();
foreach (object obj2 in rowdata[objkey])
{
item.Cells.Add(obj2);
}
item.RowHeader = objkey;
tempdata.Add(item);
}
// bind the source to the base datagrid
base.ItemsSource = tempdata;
}

private void convertItemsSourceForPivotGrid(IEnumerable original)
{
this.columnHeaderValues = new List<object>();
this.rowdata = new Dictionary<object, List<object>>();
// the principle is to use Reflection to get all the public
// properties which need to be show in the columns.
// we can extend this part to meet different requirements.
foreach (object obj in original)
{
if (obj == null)
continue;

foreach (PropertyInfo pinfo in obj.GetType().GetProperties())
{
if (pinfo != null)
{
if (pinfo.Name == this.HeaderProperty)
{
this.columnHeaderValues.Add(pinfo.GetValue(obj, null));
}
else
{
if (!rowdata.ContainsKey(pinfo.Name))
{
this.rowdata.Add(pinfo.Name, new List<object>());
}
this.rowdata[pinfo.Name].Add(pinfo.GetValue(obj, null));
}
}
}
}
}

private void PivotGrid_LoadingRow(object sender, DataGridRowEventArgs e)
{
// set the new row header.
if (tempdata != null && tempdata.Count >= e.Row.GetIndex() + 1)
e.Row.Header = tempdata[e.Row.GetIndex()].RowHeader;
}
}
}

namespace System.Windows.Controls.Extend
{
public class PivotDataGridItem
{
private ObservableCollection<object> _items = new ObservableCollection<object>();
public ObservableCollection<object> Cells { get { return _items; } }
public object RowHeader { get; set; }
}
}

Step 4, then we can test the control.

<Grid x:Name="LayoutRoot" Background="White">
<Grid.ColumnDefinitions>
<ColumnDefinition></ColumnDefinition>
<ColumnDefinition></ColumnDefinition>
</Grid.ColumnDefinitions>
</Grid>

public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
// generate a sample data
ObservableCollection<PivotGridSampleItem> source = new ObservableCollection<PivotGridSampleItem>();
DateTime nextMonday = DateTime.Now.AddDays((double)((8 - (int)DateTime.Now.DayOfWeek) % 7));
for (int i = 0; i < 10; i++)
{
source.Add(new PivotGridSampleItem()
{
Date = nextMonday.AddDays(28 * i),
RowA = "RowA_" + i,
RowB = new Random(i).Next(100, 9999),
RowC = Convert.ToBoolean(i % 2)
});
}

// create a PivotDataGrid
PivotDataGrid pGrid = new PivotDataGrid();
pGrid.HeaderProperty = "Date";
pGrid.ItemsSource = source;
pGrid.Loaded += (se, ev) =>
{
foreach (DataGridColumn dgc in pGrid.Columns)
{
dgc.Header = DateTime.Parse(dgc.Header.ToString()).ToString("yyyy-MM-dd");
}
};
Grid.SetColumn(pGrid, 0);
this.LayoutRoot.Children.Add(pGrid);

// create a common DataGrid
DataGrid dg = new DataGrid();
dg.ItemsSource = source;
Grid.SetColumn(dg, 1);
this.LayoutRoot.Children.Add(dg);
}
}

public class PivotGridSampleItem
{
public DateTime Date { get; set; }
public string RowA { get; set; }
public int RowB { get; set; }
public bool RowC { get; set; }
}

That's all, hope this is helpful.
Attach the sample project: