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DependencyProperty.RegisterReadOnly Method (String, Type, Type, PropertyMetadata)

Registers a read-only dependency property, with the specified property type, owner type, and property metadata.

Namespace:  System.Windows
Assembly:  WindowsBase (in WindowsBase.dll)

public static DependencyPropertyKey RegisterReadOnly(
	string name,
	Type propertyType,
	Type ownerType,
	PropertyMetadata typeMetadata


Type: System.String
The name of the dependency property to register.
Type: System.Type
The type of the property.
Type: System.Type
The owner type that is registering the dependency property.
Type: System.Windows.PropertyMetadata
Property metadata for the dependency property.

Return Value

Type: System.Windows.DependencyPropertyKey
A dependency property key that should be used to set the value of a static read-only field in your class, which is then used to reference the dependency property.

This method returns the type DependencyPropertyKey, whereas RegisterAttached returns the type DependencyProperty. Typically, the keys that represent read-only properties are not made public, because the keys can be used to set the dependency property value by calling SetValue(DependencyPropertyKey, Object). Your class design will affect your requirements, but it is generally recommended to limit the access and visibility of any DependencyPropertyKey to only those parts of your code that are necessary to set that dependency property as part of class or application logic. It is also recommended that you expose a dependency property identifier for the read-only dependency property, by exposing the value of DependencyPropertyKey.DependencyProperty as a public static readonly field on your class.

Read-only dependency properties are a fairly typical scenario both in the existing API and for customization scenarios, because other WPF features might require a dependency property even if that property is not intended to be settable by callers. You can use the value of a read-only dependency property as the basis for other property system operations that take a dependency property, such as basing a Trigger on the dependency property in a style.

For more information on dependency property registration, see DependencyProperty.

The following example registers an AquariumSize dependency property as read-only. The example defines AquariumSizeKey as an internal key (so that other classes in the assembly could override metadata) and exposes the dependency property identifier based on that key as AquariumSizeProperty. Also, a wrapper is created for AquariumSize, with only a get accessor.

internal static readonly DependencyPropertyKey AquariumSizeKey = DependencyProperty.RegisterReadOnly(
  new PropertyMetadata(double.NaN)
public static readonly DependencyProperty AquariumSizeProperty =
public double AquariumSize
  get { return (double)GetValue(AquariumSizeProperty); }

.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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