RelativeSource Class (System.Windows.Data)

Examples

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)/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>
    
     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);
     
      Dim myBinding As 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, GetType(ItemsControl), 2)
      
       Remarks
      
      
       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.
      
      
       For XAML information, see
       
        RelativeSource MarkupExtension
       
       .
      
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