<Binding><Binding.RelativeSource><RelativeSource Mode="modeEnumValue"/></Binding.RelativeSource>
</Binding>
- or
<Binding><Binding.RelativeSource><RelativeSourceMode="FindAncestor"AncestorType="{x:Type typeName}"AncestorLevel="intLevel"/></Binding.RelativeSource>
</Binding>

    // Summary://     Describes the location of the binding source relative to the position of//     the binding target.public enum RelativeSourceMode{// Summary://     Allows you to bind the previous data item (not that control that contains//     the data item) in the list of data items being displayed.PreviousData = 0,//// Summary://     Refers to the element to which the template (in which the data-bound element//     exists) is applied. This is similar to setting a System.Windows.TemplateBindingExtension//     and is only applicable if the System.Windows.Data.Binding is within a template.TemplatedParent = 1,//// Summary://     Refers to the element on which you are setting the binding and allows you//     to bind one property of that element to another property on the same element.Self = 2,//// Summary://     Refers to the ancestor in the parent chain of the data-bound element. You//     can use this to bind to an ancestor of a specific type or its subclasses.//     This is the mode you use if you want to specify System.Windows.Data.RelativeSource.AncestorType//     and/or System.Windows.Data.RelativeSource.AncestorLevel.FindAncestor = 3,}

     <Window.Resources><ControlTemplate x:Key="template"><Canvas><Canvas.RenderTransform><RotateTransform Angle="20"/></Canvas.RenderTransform><Ellipse Height="100" Width="150" Fill="{Binding RelativeSource={RelativeSource TemplatedParent},Path=Background}"></Ellipse><ContentPresenter Margin="35" Content="{Binding RelativeSource={RelativeSource TemplatedParent},Path=Content}"/></Canvas></ControlTemplate></Window.Resources><StackPanel><TextBlock><TextBlock.Text><Binding Path="Title"><Binding.RelativeSource><RelativeSource Mode="FindAncestor" AncestorType="{x:Type Window}" /></Binding.RelativeSource></Binding></TextBlock.Text></TextBlock><TextBlock Text="{Binding Path=Title,RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}} }"></TextBlock>

<Button Template="{StaticResource template}" Background="AliceBlue"><TextBlock FontSize="22">Click me</TextBlock></Button></StackPanel>

using System;
using System.ComponentModel;
using System.Windows.Markup;namespace System.Windows.Data
{
    public class RelativeSource : MarkupExtension, ISupportInitialize{
        public RelativeSource();public RelativeSource(RelativeSourceMode mode);public RelativeSource(RelativeSourceMode mode, Type ancestorType, int ancestorLevel);public Type AncestorType { get; set; }        public RelativeSourceMode Mode { get; set; }public static RelativeSource PreviousData { get; }public static RelativeSource Self { get; }public static RelativeSource TemplatedParent { get; }public override object ProvideValue(IServiceProvider serviceProvider);...}
}

using System;
using System.ComponentModel;
using System.Windows.Markup;namespace System.Windows.Data
{/// <summary>Implements a markup extension that describes the location of the binding source relative to the position of the binding target.</summary>[MarkupExtensionReturnType(typeof(RelativeSource))]public class RelativeSource : MarkupExtension, ISupportInitialize{private RelativeSourceMode _mode;private Type _ancestorType;private int _ancestorLevel = -1;private static RelativeSource s_previousData;private static RelativeSource s_templatedParent;private static RelativeSource s_self;/// <summary>Gets a static value that is used to return a <see cref="T:System.Windows.Data.RelativeSource" /> constructed for the <see cref="F:System.Windows.Data.RelativeSourceMode.PreviousData" /> mode.</summary>/// <returns>A static <see cref="T:System.Windows.Data.RelativeSource" />.</returns>public static RelativeSource PreviousData{get{if (RelativeSource.s_previousData == null){RelativeSource.s_previousData = new RelativeSource(RelativeSourceMode.PreviousData);}return RelativeSource.s_previousData;}}/// <summary>Gets a static value that is used to return a <see cref="T:System.Windows.Data.RelativeSource" /> constructed for the <see cref="F:System.Windows.Data.RelativeSourceMode.TemplatedParent" /> mode.</summary>/// <returns>A static <see cref="T:System.Windows.Data.RelativeSource" />.</returns>public static RelativeSource TemplatedParent{get{if (RelativeSource.s_templatedParent == null){RelativeSource.s_templatedParent = new RelativeSource(RelativeSourceMode.TemplatedParent);}return RelativeSource.s_templatedParent;}}/// <summary>Gets a static value that is used to return a <see cref="T:System.Windows.Data.RelativeSource" /> constructed for the <see cref="F:System.Windows.Data.RelativeSourceMode.Self" /> mode.</summary>/// <returns>A static <see cref="T:System.Windows.Data.RelativeSource" />.</returns>public static RelativeSource Self{get{if (RelativeSource.s_self == null){RelativeSource.s_self = new RelativeSource(RelativeSourceMode.Self);}return RelativeSource.s_self;}}/// <summary>Gets or sets a <see cref="T:System.Windows.Data.RelativeSourceMode" /> value that describes the location of the binding source relative to the position of the binding target.</summary>/// <returns>One of the <see cref="T:System.Windows.Data.RelativeSourceMode" /> values. The default value is null.</returns>/// <exception cref="T:System.InvalidOperationException">This property is immutable after initialization. Instead of changing the <see cref="P:System.Windows.Data.RelativeSource.Mode" /> on this instance, create a new <see cref="T:System.Windows.Data.RelativeSource" /> or use a different static instance.</exception>[ConstructorArgument("mode")]public RelativeSourceMode Mode{
get{return this._mode;}set{if (this.IsUninitialized){this.InitializeMode(value);return;}if (value != this._mode){throw new InvalidOperationException(SR.Get("RelativeSourceModeIsImmutable"));}}}/// <summary>Gets or sets the type of ancestor to look for.</summary>/// <returns>The type of ancestor. The default value is null.</returns>/// <exception cref="T:System.InvalidOperationException">The <see cref="T:System.Windows.Data.RelativeSource" /> is not in the <see cref="F:System.Windows.Data.RelativeSourceMode.FindAncestor" /> mode.</exception>public Type AncestorType{
get{return this._ancestorType;}set{if (this.IsUninitialized){this.AncestorLevel = 1;}if (this._mode != RelativeSourceMode.FindAncestor){if (value != null){throw new InvalidOperationException(SR.Get("RelativeSourceNotInFindAncestorMode"));}}else{this._ancestorType = value;}}}/// <summary>Gets or sets the level of ancestor to look for, in <see cref="F:System.Windows.Data.RelativeSourceMode.FindAncestor" /> mode. Use 1 to indicate the one nearest to the binding target element.</summary>/// <returns>The ancestor level. Use 1 to indicate the one nearest to the binding target element.</returns>public int AncestorLevel{
get{return this._ancestorLevel;}set{if (this._mode != RelativeSourceMode.FindAncestor){if (value != 0){throw new InvalidOperationException(SR.Get("RelativeSourceNotInFindAncestorMode"));}}else{if (value < 1){throw new ArgumentOutOfRangeException(SR.Get("RelativeSourceInvalidAncestorLevel"));}this._ancestorLevel = value;}}}private bool IsUninitialized{get{return this._ancestorLevel == -1;}}/// <summary>Initializes a new instance of the <see cref="T:System.Windows.Data.RelativeSource" /> class.</summary>public RelativeSource(){this._mode = RelativeSourceMode.FindAncestor;}/// <summary>Initializes a new instance of the <see cref="T:System.Windows.Data.RelativeSource" /> class with an initial mode.</summary>/// <param name="mode">One of the <see cref="T:System.Windows.Data.RelativeSourceMode" /> values.</param>public RelativeSource(RelativeSourceMode mode){this.InitializeMode(mode);}/// <summary>Initializes a new instance of the <see cref="T:System.Windows.Data.RelativeSource" /> class with an initial mode and additional tree-walking qualifiers for finding the desired relative source.</summary>/// <param name="mode">One of the <see cref="T:System.Windows.Data.RelativeSourceMode" /> values. For this signature to be relevant, this should be <see cref="F:System.Windows.Data.RelativeSourceMode.FindAncestor" />.</param>/// <param name="ancestorType">The <see cref="T:System.Type" /> of ancestor to look for.</param>/// <param name="ancestorLevel">The ordinal position of the desired ancestor among all ancestors of the given type. </param>public RelativeSource(RelativeSourceMode mode, Type ancestorType, int ancestorLevel){this.InitializeMode(mode);this.AncestorType = ancestorType;this.AncestorLevel = ancestorLevel;}/// <summary>This member supports the Windows Presentation Foundation (WPF) infrastructure and is not intended to be used directly from your code.</summary>void ISupportInitialize.BeginInit(){}///<summary>This member supports the Windows Presentation Foundation (WPF) infrastructure and is not intended to be used directly from your code.</summary>void ISupportInitialize.EndInit(){if (this.IsUninitialized){throw new InvalidOperationException(SR.Get("RelativeSourceNeedsMode"));}if (this._mode == RelativeSourceMode.FindAncestor && this.AncestorType == null){throw new InvalidOperationException(SR.Get("RelativeSourceNeedsAncestorType"));}}/// <summary>Indicates whether the <see cref="P:System.Windows.Data.RelativeSource.AncestorType" /> property should be persisted.</summary>/// <returns>true if the property value has changed from its default; otherwise, false.</returns>
public bool ShouldSerializeAncestorType(){return this._mode == RelativeSourceMode.FindAncestor;}/// <summary>Indicates whether the <see cref="P:System.Windows.Data.RelativeSource.AncestorLevel" /> property should be persisted.</summary>/// <returns>true if the property value has changed from its default; otherwise, false.</returns>
public bool ShouldSerializeAncestorLevel(){return this._mode == RelativeSourceMode.FindAncestor;}/// <summary>Returns an object that should be set as the value on the target object's property for this markup extension. For <see cref="T:System.Windows.Data.RelativeSource" />, this is another <see cref="T:System.Windows.Data.RelativeSource" />, using the appropriate source for the specified mode. </summary>/// <returns>Another <see cref="T:System.Windows.Data.RelativeSource" />.</returns>/// <param name="serviceProvider">An object that can provide services for the markup extension. In this implementation, this parameter can be null.</param>public override object ProvideValue(IServiceProvider serviceProvider){if (this._mode == RelativeSourceMode.PreviousData){return RelativeSource.PreviousData;}if (this._mode == RelativeSourceMode.Self){return RelativeSource.Self;}if (this._mode == RelativeSourceMode.TemplatedParent){return RelativeSource.TemplatedParent;}return this;}private void InitializeMode(RelativeSourceMode mode){if (mode == RelativeSourceMode.FindAncestor){this._ancestorLevel = 1;this._mode = mode;return;}if (mode == RelativeSourceMode.PreviousData || mode == RelativeSourceMode.Self || mode == RelativeSourceMode.TemplatedParent){this._ancestorLevel = 0;this._mode = mode;return;}throw new ArgumentException(SR.Get("RelativeSourceModeInvalid"), "mode");}}
}