WPF horizontal DataGrid

I’ve done this earlier since we wanted to be able to use the same control for a DataGrid and a PropertyGrid. Alot of things have to be changed (like alignment, scrolling, positioning of sort-arrows etc.). There is way to much code to post the whole solution but this should get you started. This is an example with Autogenerated TextColumns but you can easily modify it to use other column types.

<ScrollViewer Name="c_dataGridScrollViewer"
              Loaded="c_dataGridScrollViewer_Loaded"
              VerticalScrollBarVisibility="Auto"
              HorizontalScrollBarVisibility="Auto">
    <DataGrid x:Name="c_dataGrid"
              HorizontalAlignment="Left"
              VerticalAlignment="Top"
              AutoGeneratedColumns="c_dataGrid_AutoGeneratedColumns"
              HorizontalScrollBarVisibility="Hidden"
              VerticalScrollBarVisibility="Hidden">
        <DataGrid.ColumnHeaderStyle>
            <Style TargetType="{x:Type DataGridColumnHeader}">
                <Setter Property="LayoutTransform">
                    <Setter.Value>
                        <TransformGroup>
                            <RotateTransform Angle="90"/>
                        </TransformGroup>
                    </Setter.Value>
                </Setter>
            </Style>
        </DataGrid.ColumnHeaderStyle>
        <DataGrid.LayoutTransform>
            <TransformGroup>
                <RotateTransform Angle="-90"/>
            </TransformGroup>
        </DataGrid.LayoutTransform>
    </DataGrid>
</ScrollViewer>

And when the Columns are generated, we reverse their positions and rotates the TextBlocks and TextBoxes (This is better than rotating the DataGridCell in terms of alignment, blur etc.)

private void c_dataGridScrollViewer_Loaded(object sender, RoutedEventArgs e)
{
    // Add MouseWheel support for the datagrid scrollviewer.
    c_dataGrid.AddHandler(MouseWheelEvent, new RoutedEventHandler(DataGridMouseWheelHorizontal), true);
}

private void DataGridMouseWheelHorizontal(object sender, RoutedEventArgs e)
{
    MouseWheelEventArgs eargs = (MouseWheelEventArgs)e;
    double x = (double)eargs.Delta;
    double y = c_dataGridScrollViewer.VerticalOffset;
    c_dataGridScrollViewer.ScrollToVerticalOffset(y - x);
}

private void c_dataGrid_AutoGeneratedColumns(object sender, EventArgs e)
{
    TransformGroup transformGroup = new TransformGroup();
    transformGroup.Children.Add(new RotateTransform(90));
    foreach (DataGridColumn dataGridColumn in c_dataGrid.Columns)
    {
        if (dataGridColumn is DataGridTextColumn)
        {
            DataGridTextColumn dataGridTextColumn = dataGridColumn as DataGridTextColumn;

            Style style = new Style(dataGridTextColumn.ElementStyle.TargetType, dataGridTextColumn.ElementStyle.BasedOn);
            style.Setters.Add(new Setter(TextBlock.MarginProperty, new Thickness(0, 2, 0, 2)));
            style.Setters.Add(new Setter(TextBlock.LayoutTransformProperty, transformGroup));
            style.Setters.Add(new Setter(TextBlock.HorizontalAlignmentProperty, HorizontalAlignment.Center));

            Style editingStyle = new Style(dataGridTextColumn.EditingElementStyle.TargetType, dataGridTextColumn.EditingElementStyle.BasedOn);
            editingStyle.Setters.Add(new Setter(TextBox.MarginProperty, new Thickness(0, 2, 0, 2)));
            editingStyle.Setters.Add(new Setter(TextBox.LayoutTransformProperty, transformGroup));
            editingStyle.Setters.Add(new Setter(TextBox.HorizontalAlignmentProperty, HorizontalAlignment.Center));

            dataGridTextColumn.ElementStyle = style;
            dataGridTextColumn.EditingElementStyle = editingStyle;
        }
    }
    List<DataGridColumn> dataGridColumns = new List<DataGridColumn>();
    foreach (DataGridColumn dataGridColumn in c_dataGrid.Columns)
    {
        dataGridColumns.Add(dataGridColumn);
    }
    c_dataGrid.Columns.Clear();
    dataGridColumns.Reverse();
    foreach (DataGridColumn dataGridColumn in dataGridColumns)
    {
        c_dataGrid.Columns.Add(dataGridColumn);
    }
}