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This article describes how to implement a dependency property by using a
DependencyProperty
field to back a common language runtime (CLR) property. Dependency properties support several advanced Windows Presentation Foundation (WPF) property system features. These features include styles, data binding, inheritance, animation, and default values. If you want properties that you define to support those features, then implement your properties as a dependency property.
Important
The Desktop Guide documentation for .NET 7 and .NET 6 is under construction.
Example
The following example shows how to register a dependency property, by calling the
Register
method. The
Register
method returns a
DependencyProperty
instance called a
dependency property identifier
. The identifier is stored in a
static readonly
field, and holds the name and characteristics of a dependency property.
The identifier field must follow the naming convention
<property name>Property
. For instance, if you register a dependency property with the name
Location
, then the identifier field should be named
LocationProperty
. If you fail to follow this naming pattern, then WPF designers might not report your property correctly, and aspects of the property system style application might not behave as expected.
In the following example, the
name
of the dependency property and its CLR accessor is
HasFish
, so the identifier field is named
HasFishProperty
. The dependency property type is
Boolean
and the owner type that registers the dependency property is
Aquarium
.
You can specify default
metadata
for a dependency property. This example sets a default value of
false
for the
HasFish
dependency property.
public class Aquarium : DependencyObject
public static readonly DependencyProperty HasFishProperty =
DependencyProperty.Register(
name: "HasFish",
propertyType: typeof(bool),
ownerType: typeof(Aquarium),
typeMetadata: new FrameworkPropertyMetadata(defaultValue: false));
public bool HasFish
get => (bool)GetValue(HasFishProperty);
set => SetValue(HasFishProperty, value);
Public Class Aquarium
Inherits DependencyObject
Public Shared ReadOnly HasFishProperty As DependencyProperty =
DependencyProperty.Register(
name:="HasFish",
propertyType:=GetType(Boolean),
ownerType:=GetType(Aquarium),
typeMetadata:=New FrameworkPropertyMetadata(defaultValue:=False))
Public Property HasFish As Boolean
Return GetValue(HasFishProperty)
End Get
Set(value As Boolean)
SetValue(HasFishProperty, value)
End Set
End Property
End Class
For more information about how and why to implement a dependency property, rather than just backing a CLR property with a private field, see
Dependency properties overview
.
See also
Dependency properties overview
How-to topics
