Provides data for various property changed events. Typically these events report effective value changes in the value of a read-only dependency property. Another usage is as part of a PropertyChangedCallback implementation.
Assembly: WindowsBase (in WindowsBase.dll)
Thetype exposes the following members.
|Equals(DependencyPropertyChangedEventArgs)||Determines whether the provided is equivalent to the current .|
|Equals(Object)||Determines whether the provided object is equivalent to the current . (Overrides ValueType::Equals(Object).)|
|GetHashCode||Gets a hash code for this . (Overrides ValueType::GetHashCode().)|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|ToString||Returns the fully qualified type name of this instance. (Inherited from ValueType.)|
The events that use the class for event data, and the DependencyPropertyChangedEventHandler method implementations for handlers, generally follow the naming pattern Is*Changed, and are generally implemented as common language runtime (CLR) events without RoutedEvent backing (they are not routed events). Some class handling methods that "handle" otherwise unexposed events that report a state change through a property change, such as ButtonBase::OnIsPressedChanged, also use the class for event data.
The scenario for PropertyChangedCallback is to use the arguments to report old and new values that come from the property system evaluation of the property. A callback that processes old and new values might choose special handling depending on these values, such as choosing to not respond to value changes that are deemed insignificant.
The following example uses the class in the context of a PropertyChangedCallback for a particular property of a custom class that also defines events. The callback takes the results of old and new values from the property system as communicated by , and repackages these into a different events arguments class RoutedPropertyChangedEventArgs<T>. The new arguments are then used as the data for a "ValueChanged" event defined by and raised by the custom class.