Programmatically toggling group expansion

The following example demonstrates how to handle the PreviewMouseLeftButtonDown event on the GroupHeaderControl objects contained in the headers of the child groups to toggle the expansion state of child groups using the ToggleGroupExpansion method. The group whose state is to be toggled will be retrieved using the GetParentGroupFromItem method.

XAML	Copy Code
<Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid"> <Grid.Resources> <xcdg:DataGridCollectionViewSource x:Key="cvs_orders" Source="{Binding Source={x:Static Application.Current}, Path=Orders}"> <xcdg:DataGridCollectionViewSource.GroupDescriptions> <xcdg:DataGridGroupDescription PropertyName="ShipCountry"/> <xcdg:DataGridGroupDescription PropertyName="ShipCity"/> </xcdg:DataGridCollectionViewSource.GroupDescriptions> </xcdg:DataGridCollectionViewSource> <Style TargetType="{x:Type xcdg:GroupHeaderControl}"> <EventSetter Event="PreviewMouseLeftButtonDown" Handler="HeaderDown"/> </Style> </Grid.Resources> <xcdg:DataGridControl x:Name="OrdersGrid" ItemsSource="{Binding Source={StaticResource cvs_orders}}"/> </Grid>

XAML

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<Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid">

  <Grid.Resources>

    <xcdg:DataGridCollectionViewSource x:Key="cvs_orders"

                                       Source="{Binding Source={x:Static Application.Current},

                                                        Path=Orders}">

      <xcdg:DataGridCollectionViewSource.GroupDescriptions>

        <xcdg:DataGridGroupDescription PropertyName="ShipCountry"/>

        <xcdg:DataGridGroupDescription PropertyName="ShipCity"/>

      </xcdg:DataGridCollectionViewSource.GroupDescriptions>

    </xcdg:DataGridCollectionViewSource>

    <Style TargetType="{x:Type xcdg:GroupHeaderControl}">

      <EventSetter Event="PreviewMouseLeftButtonDown"

                   Handler="HeaderDown"/>

    </Style>  

</Grid.Resources>

  <xcdg:DataGridControl x:Name="OrdersGrid"

                        ItemsSource="{Binding Source={StaticResource cvs_orders}}"/>

</Grid>

The following code provides the implementation of the PreviewMouseLeftButtonDown event in which we will retrieve the item represented by the GroupHeaderControl (GroupHeaderFooterItem) using the GetItemFromContainer method, which will then be used to retrieve the parent group (GetParentGroupFromItem) whose state is to be toggled.

VB.NET	Copy Code
Private Sub HeaderDown( ByVal sender As Object, ByVal e As MouseButtonEventArgs ) Dim headerControl As GroupHeaderControl = TryCast( sender, GroupHeaderControl ); If headerControl Is Nothing Then Return End If Dim context As DataGridContext = DataGridControl.GetDataGridContext( headerControl ) Dim item As Object = context.GetItemFromContainer( headerControl ) ) If Not item Is Nothing Then Dim group As CollectionViewGroup = context.GetParentGroupFromItem( item ) If Not group Is Nothing context.ToggleGroupExpansion( group ) End If End If End Sub

VB.NET

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Private Sub HeaderDown( ByVal sender As Object, ByVal e As MouseButtonEventArgs )

  Dim headerControl As GroupHeaderControl = TryCast( sender, GroupHeaderControl );

  If headerControl Is Nothing Then

    Return

  End If

  Dim context As DataGridContext = DataGridControl.GetDataGridContext( headerControl )

  Dim item As Object = context.GetItemFromContainer( headerControl ) )

  If Not item Is Nothing Then

    Dim group As CollectionViewGroup = context.GetParentGroupFromItem( item )

    If Not group Is Nothing

      context.ToggleGroupExpansion( group )

    End If

  End If

End Sub

C#	Copy Code
private void HeaderDown( object sender, MouseEventArgs e ) { GroupHeaderControl headerControl = sender as GroupHeaderControl; if( headerControl == null ) return; DataGridContext context = DataGridControl.GetDataGridContext( headerControl ); object item = context.GetItemFromContainer( headerControl ); if( item != null ) { CollectionViewGroup group = context.GetParentGroupFromItem( item ); if( group != null ) { context.ToggleGroupExpansion( group ); } } }

Copy Code

private void HeaderDown( object sender, MouseEventArgs e )

{

  GroupHeaderControl headerControl = sender as GroupHeaderControl;

  if( headerControl == null )

    return;

  DataGridContext context = DataGridControl.GetDataGridContext( headerControl );

  object item = context.GetItemFromContainer( headerControl );

  if( item != null )

  {

    CollectionViewGroup group = context.GetParentGroupFromItem( item );

    if( group != null )

    {

      context.ToggleGroupExpansion( group );

    }

  }

}