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KeyboardFocusChangedEventHandler Delegate

Represents the method that will handle the UIElement.LostKeyboardFocus and UIElement.GotKeyboardFocus routed events, as well as related attached and Preview events.

Namespace:  System.Windows.Input
Assembly:  PresentationCore (in PresentationCore.dll)

public delegate void KeyboardFocusChangedEventHandler(
	Object sender,
	KeyboardFocusChangedEventArgs e
)

Parameters

sender
Type: System.Object

The object where the event handler is attached.

e
Type: System.Windows.Input.KeyboardFocusChangedEventArgs

The event data.

This delegate is used with the following attached events:

This delegate is also used with the following routed events on base elements. These routed events forward the previously listed attached events to make them more accessible to the general element model in WPF.

The attached events and the base element routed events share their event data, and the bubbling and tunneling versions of the routed events also share event data. This can affect the handled characteristics of the event as it travels the event route. For details, see Input Overview.

If the PreviewGotKeyboardFocus event or the PreviewLostKeyboardFocus event is handled (Handled is set to true in the event data), keyboard focus will not change.

This example shows how to change the color of an element when it gains and loses focus by using the GotFocus and LostFocus events.

This example consists of a Extensible Application Markup Language (XAML) file and a code-behind file.

The following XAML creates the user interface, which consists of two Button objects, and attaches event handlers for the GotFocus and LostFocus events to the Button objects.

<StackPanel>
  <StackPanel.Resources>
    <Style TargetType="{x:Type Button}">
      <Setter Property="Height" Value="20"/>
      <Setter Property="Width" Value="250"/>
      <Setter Property="HorizontalAlignment" Value="Left"/>
    </Style>
  </StackPanel.Resources>
  <Button
      GotFocus="OnGotFocusHandler"
      LostFocus="OnLostFocusHandler">Click Or Tab To Give Keyboard Focus</Button>
  <Button
      GotFocus="OnGotFocusHandler"
      LostFocus="OnLostFocusHandler">Click Or Tab To Give Keyborad Focus</Button>
</StackPanel>

The following code behind creates the GotFocus and LostFocus event handlers. When the Button gains keyboard focus, the Background of the Button is changed to red. When the Button loses keyboard focus, the Background of the Button is changed back to white.

public partial class Window1 : Window
{
    public Window1()
    {
        InitializeComponent();
    }

    // Raised when Button gains focus. 
    // Changes the color of the Button to Red. 
    private void OnGotFocusHandler(object sender, RoutedEventArgs e)
    {
        Button tb = e.Source as Button;
        tb.Background = Brushes.Red;
    }
    // Raised when Button losses focus.  
    // Changes the color of the Button back to white. 
    private void OnLostFocusHandler(object sender, RoutedEventArgs e)
    {
        Button tb = e.Source as Button;
        tb.Background = Brushes.White;
    }
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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