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RelativeSource Class

Implements a markup extension that describes the location of the binding source relative to the position of the binding target.

Namespace:  System.Windows.Data
Assembly:  PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation

[MarkupExtensionReturnTypeAttribute(typeof(RelativeSource))]
public ref class RelativeSource : public MarkupExtension, 
	ISupportInitialize
For XAML information, see RelativeSource MarkupExtension.

One of the ways to specify a binding source is to use the Binding::RelativeSource property. This is the property type of that property. RelativeSource is simultaneously a markup extension implementation and a data object. When the extension returns itself (see ProvideValue), the relevant information is contained in the data. The main purpose of the markup extension is to allow a variable-argument constructor syntax in attribute form, so that the FindAncestor mode can be defined inline with the two extra arguments for ancestor type and level that the other modes do not require.

The following example shows a style trigger that creates a ToolTip that reports a validation error message. Using the RelativeSource property, the value of the setter binds to the error content of the current TextBox (the TextBox using the style). For more information on this example, see How to: Implement Binding Validation.

<Style x:Key="textBoxInError" TargetType="{x:Type TextBox}">
  <Style.Triggers>
    <Trigger Property="Validation.HasError" Value="true">
      <Setter Property="ToolTip"
        Value="{Binding RelativeSource={x:Static RelativeSource.Self},
                        Path=(Validation.Errors)[0].ErrorContent}"/>
    </Trigger>
  </Style.Triggers>
</Style>

The following example shows the Style definition of a custom control called NumericUpDown. The Text property of the TextBlock is bound to the Value of the object that is the TemplatedParent, which is the NumericUpDown control that this Style is applied to in this case.

<!--ControlTemplate for NumericUpDown that inherits from
    Control.-->
<Style TargetType="{x:Type local:NumericUpDown}">
  <Setter Property="HorizontalAlignment" Value="Center"/>
  <Setter Property="VerticalAlignment" Value="Center"/>
  <Setter Property="Template">
    <Setter.Value>
      <ControlTemplate TargetType="{x:Type local:NumericUpDown}">
        <Grid Margin="3">
          <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
          </Grid.RowDefinitions>
          <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition/>
          </Grid.ColumnDefinitions>

          <Border BorderThickness="1" BorderBrush="Gray" 
                  Margin="2" Grid.RowSpan="2" 
                  VerticalAlignment="Center" HorizontalAlignment="Stretch">

            <TextBlock Text="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Value}" 
                       Width="60" TextAlignment="Right" Padding="5"/>
          </Border>

          <RepeatButton Command="{x:Static local:NumericUpDown.IncreaseCommand}"  
                        Grid.Column="1" Grid.Row="0">Up</RepeatButton>

          <RepeatButton Command="{x:Static local:NumericUpDown.DecreaseCommand}"
                        Grid.Column="1" Grid.Row="1">Down</RepeatButton>

        </Grid>

      </ControlTemplate>
    </Setter.Value>
  </Setter>
</Style>

For the complete sample, see NumericUpDown Custom Control with Theme and UI Automation Support Sample.

The following returns the second ItemsControl encountered on the upward path starting at the target element of the binding.

Binding myBinding = new Binding();
// Returns the second ItemsControl encountered on the upward path 
// starting at the target element of the binding
myBinding.RelativeSource = new RelativeSource(
    RelativeSourceMode.FindAncestor, typeof(ItemsControl), 2);

More Code

How to: Create ListViewItems with a CheckBox This example shows how to display a column of CheckBox controls in a ListView control that uses a GridView.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

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

.NET Framework

Supported in: 3.5, 3.0

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