How do I use WPF bindings with RelativeSource?

If you want to bind to another property on the object:

{Binding Path=PathToProperty, RelativeSource={RelativeSource Self}}

If you want to get a property on an ancestor:

{Binding Path=PathToProperty,
    RelativeSource={RelativeSource AncestorType={x:Type typeOfAncestor}}}

If you want to get a property on the templated parent (so you can do 2 way bindings in a ControlTemplate)

{Binding Path=PathToProperty, RelativeSource={RelativeSource TemplatedParent}}

or, shorter (this only works for OneWay bindings):

{TemplateBinding Path=PathToProperty}

Binding RelativeSource={
    RelativeSource Mode=FindAncestor, AncestorType={x:Type ItemType}
}
...

The default attribute of RelativeSource is the Mode property. A complete set of valid values is given here (from MSDN):

PreviousData Allows you to bind the previous data item (not that control that contains the data item) in the list of data items being displayed.
TemplatedParent Refers to the element to which the template (in which the data-bound element exists) is applied. This is similar to setting a TemplateBindingExtension and is only applicable if the Binding is within a template.
Self 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.
FindAncestor 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 AncestorType and/or AncestorLevel.

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