This example demonstrates how to create a custom group description by deriving from the DataGridGroupDescription class and overriding the GroupNameFromItem method. The custom group description will group items according to the first letter in the value received as a parameter. The implementation for the custom sort comparer assigned to the group description's SortComparer property is provided below.

Visual Basic

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Imports System Imports System.Collections.Generic Imports System.Text Imports Xceed.Wpf.DataGrid Imports System.Collections Imports System.Globalization; Namespace Xceed.Wpf.Documentation   Public Class AlphabeticalGroupDescription          Inherits DataGridGroupDescription     Public Sub New()       MyBase.New()     End Sub     Public Sub New(ByVal propertyName As String)      MyBase.New(propertyName)     End Sub     Public Overrides Function GroupNameFromItem(ByVal item As Object, _                                                 ByVal level As Integer, _                                                 ByVal culture As CultureInfo) As Object       Dim value As Object = MyBase.GroupNameFromItem(item, level, culture)       Try         Dim content As String = Convert.ToString(value)         value = content.ToUpper().Substring(0, 1)       Catch e1 As InvalidCastException       End Try       Return value     End Function   End Class End Namespace

The following code provides the implementation for the custom sort comparer that is used to sort, by vowels then consonants, the group descriptions create above.

Visual Basic

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Imports System Imports System.Collections.Generic Imports System.Text Imports System.Collections Namespace Xceed.Wpf.Documentation   Public Class ConsonantVowelComparer      Implements IComparer     Public Sub New()     End Sub     Public Function Compare(ByVal x As Object, _                             ByVal y As Object) As Integer Implements IComparer.Compare       If (Typeof x Is String) AndAlso (Typeof y Is String) Then         Dim xString As String = x.ToString().ToLowerInvariant()         Dim yString As String = y.ToString().ToLowerInvariant()         Dim isXVowel As Boolean = m_vowels.Contains(xString)         Dim isYVowel As Boolean = m_vowels.Contains(yString)         If isXVowel Xor isYVowel Then           If isXVowel Then             Return -1           Else             Return 1           End If         End If         Return String.Compare(xString, yString)       End If       Throw New ArgumentException()     End Function     Private Const m_vowels As String = "aeiouy"   End Class End Namespace

This example demonstrates how to create a custom group description by deriving from the DataGridGroupDescription class and overriding the GroupNameFromItem method. The custom group description will group items according to the first letter in the value received as a parameter. The implementation for the custom sort comparer assigned to the group description's SortComparer property is provided below.

C#

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using System; using System.Collections.Generic; using System.Text; using Xceed.Wpf.DataGrid; using System.Collections; namespace Xceed.Wpf.Documentation {  public class AlphabeticalGroupDescription : DataGridGroupDescription  {    public AlphabeticalGroupDescription()      : base()    {    }    public AlphabeticalGroupDescription( string propertyName )      : base( propertyName )    {    }       public override object GroupNameFromItem( object item, int level,                                              System.Globalization.CultureInfo culture )    {      object value = base.GroupNameFromItem( item, level, culture );      try      {        string content = Convert.ToString( value );        value = content.ToUpper().Substring( 0, 1 );      }      catch( InvalidCastException )      {      }      return value;    }  } }

The following code provides the implementation for the custom sort comparer that is used to sort, by vowels then consonants, the group descriptions create above.

C#

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using System; using System.Collections.Generic; using System.Text; using System.Collections; namespace Xceed.Wpf.Documentation {  public class ConsonantVowelComparer : IComparer  {    public ConsonantVowelComparer()    {    }    public int Compare( object x, object y )    {      if( ( x is string ) && ( y is string ) )      {        string xString = x.ToString().ToLowerInvariant();        string yString = y.ToString().ToLowerInvariant();        bool isXVowel = m_vowels.Contains( xString );        bool isYVowel = m_vowels.Contains( yString );        if( isXVowel ^ isYVowel )          return isXVowel ? -1 : 1;        return String.Compare( xString, yString );             }      throw new ArgumentException();    }    private const string m_vowels = "aeiouy";  } }

The following code demonstrates how to use the custom group description by adding it to the DataGridCollectionViewSource's GroupDescriptions property.

XAML

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<Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid"       xmlns:local="clr-namespace:Xceed.Wpf.Documentation">    <Grid.Resources>            <local:ConsonantVowelComparer x:Key="consonantVowelComparer"/>        <xcdg:DataGridCollectionViewSource x:Key="cvs_orders"                                         Source="{Binding                                                  Source={x:Static Application.Current},                                                  Path=Orders}">         <xcdg:DataGridCollectionViewSource.GroupDescriptions>         <local:AlphabeticalGroupDescription PropertyName="ShipCountry"                                  SortComparer="{StaticResource consonantVowelComparer}"/>       </xcdg:DataGridCollectionViewSource.GroupDescriptions>      </xcdg:DataGridCollectionViewSource>    </Grid.Resources>    <xcdg:DataGridControl x:Name="OrdersGrid"                          ItemsSource="{Binding Source={StaticResource cvs_orders}}"/>  </Grid>