Apply Custom Grouping to a Collection : CollectionViewSource « Windows Presentation Foundation « VB.Net Tutorial

1. VB.Net Tutorial
2. Windows Presentation Foundation
3. CollectionViewSource

<Window 
    x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:WpfApplication1="clr-namespace:WpfApplication1"
    Title="WPF" Height="300" Width="160">

    <Window.Resources>
        <WpfApplication1:Countries x:Key="countries"/>
        <WpfApplication1:GroupByContinentConverter x:Key="GroupByContinentConverter"/>
        <CollectionViewSource 
            x:Key="cvs" 
            Source="{Binding Source={StaticResource countries}}">
            <CollectionViewSource.GroupDescriptions>
                <PropertyGroupDescription Converter="{StaticResource GroupByContinentConverter}" />
            </CollectionViewSource.GroupDescriptions>
        </CollectionViewSource>
    </Window.Resources>
    <Grid>
        <ItemsControl ItemsSource="{Binding Source={StaticResource cvs}}" DisplayMemberPath="Name" >
            <ItemsControl.GroupStyle>
                <x:Static Member="GroupStyle.Default"/>
            </ItemsControl.GroupStyle>
        </ItemsControl>

    </Grid>
</Window>
//File:Window.xaml.vb

Imports System
Imports System.Globalization
Imports System.Windows.Data
Imports System.Collections.ObjectModel

Namespace WpfApplication1
  Public Class GroupByContinentConverter
    Implements IValueConverter
    Public Function Convert(value As Object, targetType As Type, parameter As Object, culture As CultureInfo) As Object Implements IValueConverter.Convert
      Dim country As Country = DirectCast(value, Country)
      ' Decide which group the country belongs in
      Select Case country.Continent
        Case Continent.NorthAmerica
          Return "Americas"
        Case Else
          Return "Others"
      End Select
    End Function

    Public Function ConvertBack(value As Object, targetType As Type, parameter As Object, culture As CultureInfo) As Object Implements IValueConverter.ConvertBack
      Throw New NotImplementedException()
    End Function
  End Class

  Public Class Country
    Private m_name As String
    Private m_continent As Continent

    Public Sub New(name As String, continent As Continent)
      Me.m_name = name
      Me.m_continent = continent
    End Sub

    Public Property Name() As String
      Get
        Return m_name
      End Get
      Set
        m_name = value
      End Set
    End Property

    Public Property Continent() As Continent
      Get
        Return m_continent
      End Get
      Set
        m_continent = value
      End Set
    End Property
  End Class

  Public Enum Continent
    Europe
    NorthAmerica
  End Enum

  Public Class Countries
    Inherits Collection(Of Country)
    Public Sub New()
      Me.Add(New Country("Great Britan", Continent.Europe))
      Me.Add(New Country("USA", Continent.NorthAmerica))
      Me.Add(New Country("Canada", Continent.NorthAmerica))
    End Sub
  End Class
End Namespace

16.105.CollectionViewSource
	16.105.1.	Use CollectionViewSource to sort and group data in XAML.
	16.105.2.	Apply Custom Grouping to a Collection
	16.105.3.	Filter Data in a Collection, Set the Filter property to a FilterEventHandler
	16.105.4.	Set DisplayMemberPath for ItemsControl
	16.105.5.	Wrap collection based resource in a CollectionViewSource