SelectionChangedEventArgs.InvokeEventHandler Method (Delegate, Object)

 

Performs the proper type casting to call the type-safe SelectionChangedEventHandler delegate for the SelectionChanged event.

Namespace:   System.Windows.Controls
Assembly:  PresentationFramework (in PresentationFramework.dll)

Protected Overrides Sub InvokeEventHandler (
	genericHandler As Delegate,
	genericTarget As Object
)

Parameters

genericHandler
Type: System.Delegate

The handler to invoke.

genericTarget
Type: System.Object

The current object along the event's route.

The following example creates a ListBox and subscribes to the SelectionChanged event. It uses the SelectionChangedEventArgs to find the selected item in the ListBox.

<WrapPanel Width="500" Orientation="Horizontal" Name="rectanglesPanel">
  <WrapPanel.Resources>
    <Style TargetType="Rectangle">
      <Setter Property="Height" Value="20"/>
      <Setter Property="Width" Value="20"/>
      <Setter Property="Margin" Value="5"/>
    </Style>
  </WrapPanel.Resources>
</WrapPanel>

<ListBox Name="myListBox" HorizontalAlignment="Left" SelectionMode="Extended" 
      Width="265" Height="55" Background="HoneyDew" SelectionChanged="myListBox_SelectionChanged"
      ItemsSource="{Binding Source={StaticResource Colors}}" IsSynchronizedWithCurrentItem="true">
</ListBox>

Private Sub myListBox_SelectionChanged(ByVal sender As Object, ByVal args As SelectionChangedEventArgs)

    Dim converter As BrushConverter = New BrushConverter()
    Dim color As String

    ' Show Rectangles that are the selected colors.
    For Each color In args.AddedItems

        If GetRectangle(color) Is Nothing Then
            Dim aRect As Rectangle = New Rectangle()
            aRect.Fill = CType(converter.ConvertFrom(color), Brush)
            aRect.Tag = color
            rectanglesPanel.Children.Add(aRect)
        End If

    Next

    ' Remove the Rectangles that are the unselected colors.
    For Each color In args.RemovedItems

        Dim removedItem As FrameworkElement = GetRectangle(color)
        If Not removedItem Is Nothing Then
            rectanglesPanel.Children.Remove(removedItem)
        End If

    Next

End Sub

Private Function GetRectangle(ByVal color As String) As FrameworkElement
    Dim rect As FrameworkElement
    For Each rect In rectanglesPanel.Children
        If rect.Tag.ToString() = color Then
            Return rect
        End If
    Next

    Return Nothing
End Function

.NET Framework
Available since 3.0
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