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Xceed Toolkit Plus for WPF v5.1 Documentation
Welcome to Xceed Toolkit Plus for WPF v5.1 / DataGrid, ListBox, Chart, AvalonDock, and PropertyGrid / Datagrid control / Fundamentals / Manipulating Data / Grouping Data / Custom Group Configuration Selectors
In This Topic
    Custom Group Configuration Selectors
    In This Topic
    Prerequisite Knowledge
    Appearance: Group Configurations


    In addition to the built-in LevelGroupConfigurationSelector and FieldNameGroupConfigurationSelector, which can be used to select the appropriate configuration for a group based on its level or field name, custom GroupConfigurationSelectors can also be created and used.

    These selectors (with or without the corresponding selector items) can be created by deriving from the GroupConfigurationSelector class and overriding the SelectGroupConfiguration method to return the appropriate configuration based on the desired criteria (see Example 1 at the bottom of the page). If a selector does not have a GroupConfiguration that corresponds to the specified information, it should either call the base implementation or return null (Nothing in VisualBasic).

    When a grid is in a TableView layout, Rows located in a grid's headers, footers, fixed headers, and fixed footers (e.g., ColumnManagerRows) will query the selector in order to retrieve the GroupLevelIndicatorStyle of the appropriate GroupConfiguration. In this case, collectionViewGroup will be a null reference (Nothing in Visual Basic).

    If the selector chooses GroupConfigurations based on the specified collectionViewGroup, a "dummy" GroupConfiguration that provides an identical GroupLevelIndicator style should be returned. For example, if a GroupConfiguration sets the width of its GroupLevelIndicator to 30, the "dummy" GroupConfiguration should also return 30 in its GroupLevelIndicatorStyle so that the items in the headers and footers have the same indentation as the other items to preserve Cell alignment.

    It is recommended that all GroupLevelIndicatorStyles return the same width to preserve the alignment of the Cells throughout the grid.

    Examples

    All examples in this topic assume that the grid is bound to the Orders table of the Northwind database, unless stated otherwise.

    Example 1: Creating a group-configuration selector

    The following example demonstrates how to create a custom group-configuration selector that will return the appropriate group configuration depending on the number of items in a group. The implementation of the ItemCountGroupConfigurationSelector is provided below.

    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="ShipCity" />
      </xcdg:DataGridCollectionViewSource.GroupDescriptions>
    </xcdg:DataGridCollectionViewSource>
  </Grid.Resources>
  <xcdg:DataGridControl x:Name="OrdersGrid"
                        ItemsSource="{Binding Source={StaticResource cvs_orders}}">
    <xcdg:DataGridControl.GroupConfigurationSelector>
      <local:ItemCountGroupConfigurationSelector MinItemCount="10" />
    </xcdg:DataGridControl.GroupConfigurationSelector>
  </xcdg:DataGridControl>
</Grid>
    VB.NET
    Copy Code 
    Dim collectionView As New DataGridCollectionView( Orders )
collectionView.GroupDescriptions.Add( New DataGridGroupDescription( "ShipCity" ) )
dataGridControl.GroupConfigurationSelector = New ItemCountGroupConfigurationSelector( 10 )
dataGridControl.ItemsSource = collectionView
    C#
    Copy Code 
    DataGridCollectionView collectionView = new DataGridCollectionView( Orders );     
collectionView.GroupDescriptions.Add( new DataGridGroupDescription( "ShipCity" ) );
dataGridControl.GroupConfigurationSelector = new ItemCountGroupConfigurationSelector( 10 );
dataGridControl.ItemsSource = collectionView;

    The following code provides the implementation of the ItemCountGroupConfigurationSelector. 

    VB.NET
    Copy Code 
      Public Class ItemCountGroupConfigurationSelector
               Inherits GroupConfigurationSelector
    Public Sub New
    End Sub
    Public Sub New( minItemCount As Integer )
       Me.MinItemCount = minItemCount
    End Sub
    Public Overrides Function SelectGroupConfiguration( ByVal groupLevel As Integer, _
                    ByVal collectionViewGroup As System.Windows.Data.CollectionViewGroup, _
                    ByVal groupDescription As System.ComponentModel.GroupDescription ) As GroupConfiguration
      If collectionViewGroup Is Nothing Then
        Return MyBase.SelectGroupConfiguration( groupLevel, collectionViewGroup, groupDescription )
      End If
      Dim groupConfiguration As New GroupConfiguration()
      Dim style As New Style( GetType( Xceed.Wpf.DataGrid.DataRow ) )
      If collectionViewGroup.ItemCount <= m_minItemCount Then ' red
        style.Setters.Add( New Setter( Xceed.Wpf.DataGrid.DataRow.BackgroundProperty, Brushes.Red ) )
      Else ' green
        style.Setters.Add( New Setter( Xceed.Wpf.DataGrid.DataRow.BackgroundProperty, Brushes.LightGreen ) )
      End If
      groupConfiguration.ItemContainerStyle = style
      Return groupConfiguration
    End Function
    Private m_minItemCount As Integer = 0
    Public Property MinItemCount As Integer
      Get
        Return m_minItemCount
      End Get
      Set
        m_minItemCount = value
    End Property
  End Class
    C#
    Copy Code 
     public class ItemCountGroupConfigurationSelector : GroupConfigurationSelector
  {
    public ItemCountGroupConfigurationSelector()
    {
    }
    public ItemCountGroupConfigurationSelector( int minItemCount )
     :base()
    {
       this.MinItemCount = minItemCount;
    }
   public override GroupConfiguration SelectGroupConfiguration( int groupLevel,
                   System.Windows.Data.CollectionViewGroup collectionViewGroup,
                   System.ComponentModel.GroupDescription groupDescription )
   {
     if( collectionViewGroup == null )
       return base.SelectGroupConfiguration( groupLevel, collectionViewGroup, groupDescription );
     GroupConfiguration groupConfiguration = new GroupConfiguration();
     Style style = new Style( typeof( Xceed.Wpf.DataGrid.DataRow ) );
     if( collectionViewGroup.ItemCount <= m_minItemCount ) // red
     {
       style.Setters.Add( new Setter( Xceed.Wpf.DataGrid.DataRow.BackgroundProperty, Brushes.Red ) );      
     }
     else // green
     {
       style.Setters.Add( new Setter( Xceed.Wpf.DataGrid.DataRow.BackgroundProperty, Brushes.LightGreen ) );      
     }
     groupConfiguration.ItemContainerStyle = style;
     return groupConfiguration;
   }
    private int m_minItemCount = 0;
    public int MinItemCount
    {
      get
      {
        return m_minItemCount;
      }
      set
      {
        if( value != m_minItemCount )
          m_minItemCount = value;
      }
    }
  }

     

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