Custom Group-configuration Selectors

Prerequisite Knowledge
Appearance: Group Configurations

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

Custom group-configuration selectors (with or without corresponding selector items) can be created by deriving from the GroupConfigurationSelector class and overriding the SelectGroupConfiguration method to return the appropriate group configuration based on the desired criteria (see Example 1). If a selector does not have a group configuration 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 table-view layout, rows located in the headers, footers, fixed headers, and fixed footers of a grid (e.g., ColumnManagerRows) will query the selector in order to retrieve the GroupLevelIndicatorStyle of the appropriate group configuration. In this case, collectionViewGroup will be a null reference (Nothing in Visual Basic).

If the selector chooses group configurations based on the specified collectionViewGroup, a "dummy" group configuration that provides an identical group-level-indicator style should be returned. For example, if a group configuration sets the width of its group-level indicator to 30, the "dummy" group configuration should also return 30 in its group-level-indicator style 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 group-level-indicator styles 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.

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>

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="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

VB.NET

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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;

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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

VB.NET

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  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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 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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