DependencyPropertyChangedEventArgs DependencyPropertyChangedEventArgs DependencyPropertyChangedEventArgs DependencyPropertyChangedEventArgs Struct

Definición

Proporciona datos de los distintos eventos de cambio de propiedades.Provides data for various property changed events. Normalmente, estos eventos notifican cambios de valor efectivos en el valor de una propiedad de dependencia de solo lectura.Typically these events report effective value changes in the value of a read-only dependency property. Otro uso es como parte de una implementación de PropertyChangedCallback.Another usage is as part of a PropertyChangedCallback implementation.

public value class DependencyPropertyChangedEventArgs
public struct DependencyPropertyChangedEventArgs
type DependencyPropertyChangedEventArgs = struct
Public Structure DependencyPropertyChangedEventArgs
Herencia
DependencyPropertyChangedEventArgsDependencyPropertyChangedEventArgsDependencyPropertyChangedEventArgsDependencyPropertyChangedEventArgs

Ejemplos

En el ejemplo siguiente se usa el DependencyPropertyChangedEventArgs clase en el contexto de un PropertyChangedCallback para una propiedad determinada de una clase personalizada que también define los eventos.The following example uses the DependencyPropertyChangedEventArgs class in the context of a PropertyChangedCallback for a particular property of a custom class that also defines events. La devolución de llamada toma los resultados antiguos y nuevos valores desde el sistema de propiedades comunicado por DependencyPropertyChangedEventArgsy vuelve a empaquetar estos elementos en una clase de argumentos de eventos diferentes RoutedPropertyChangedEventArgs<T>.The callback takes the results of old and new values from the property system as communicated by DependencyPropertyChangedEventArgs, and repackages these into a different events arguments class RoutedPropertyChangedEventArgs<T>. A continuación, se usan los argumentos nuevos como los datos para un evento "ValueChanged" definido por y generados por la clase personalizada.The new arguments are then used as the data for a "ValueChanged" event defined by and raised by the custom class.

public static readonly DependencyProperty ValueProperty =
    DependencyProperty.Register(
        "Value", typeof(decimal), typeof(NumericUpDown),
        new FrameworkPropertyMetadata(MinValue, new PropertyChangedCallback(OnValueChanged),
                                      new CoerceValueCallback(CoerceValue)));

private static object CoerceValue(DependencyObject element, object value)
{
    decimal newValue = (decimal)value;

    newValue = Math.Max(MinValue, Math.Min(MaxValue, newValue));

    return newValue;
}

private static void OnValueChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
{
    NumericUpDown control = (NumericUpDown)obj;

    RoutedPropertyChangedEventArgs<decimal> e = new RoutedPropertyChangedEventArgs<decimal>(
        (decimal)args.OldValue, (decimal)args.NewValue, ValueChangedEvent);
    control.OnValueChanged(e);
}
/// <summary>
/// Identifies the ValueChanged routed event.
/// </summary>
public static readonly RoutedEvent ValueChangedEvent = EventManager.RegisterRoutedEvent(
    "ValueChanged", RoutingStrategy.Bubble,
    typeof(RoutedPropertyChangedEventHandler<decimal>), typeof(NumericUpDown));

/// <summary>
/// Occurs when the Value property changes.
/// </summary>
public event RoutedPropertyChangedEventHandler<decimal> ValueChanged
{
    add { AddHandler(ValueChangedEvent, value); }
    remove { RemoveHandler(ValueChangedEvent, value); }
}
/// <summary>
/// Raises the ValueChanged event.
/// </summary>
/// <param name="args">Arguments associated with the ValueChanged event.</param>
protected virtual void OnValueChanged(RoutedPropertyChangedEventArgs<decimal> args)
{
    RaiseEvent(args);
}
Public Shared ReadOnly ValueProperty As DependencyProperty = DependencyProperty.Register("Value", GetType(Decimal), GetType(NumericUpDown), New FrameworkPropertyMetadata(MinValue, New PropertyChangedCallback(AddressOf OnValueChanged), New CoerceValueCallback(AddressOf CoerceValue)))

Private Shared Overloads Function CoerceValue(ByVal element As DependencyObject, ByVal value As Object) As Object
	Dim newValue As Decimal = CDec(value)

	newValue = Math.Max(MinValue, Math.Min(MaxValue, newValue))

	Return newValue
End Function

Private Shared Sub OnValueChanged(ByVal obj As DependencyObject, ByVal args As DependencyPropertyChangedEventArgs)
	Dim control As NumericUpDown = CType(obj, NumericUpDown)

	Dim e As New RoutedPropertyChangedEventArgs(Of Decimal)(CDec(args.OldValue), CDec(args.NewValue), ValueChangedEvent)
	control.OnValueChanged(e)
End Sub
''' <summary>
''' Identifies the ValueChanged routed event.
''' </summary>
Public Shared ReadOnly ValueChangedEvent As RoutedEvent = EventManager.RegisterRoutedEvent("ValueChanged", RoutingStrategy.Bubble, GetType(RoutedPropertyChangedEventHandler(Of Decimal)), GetType(NumericUpDown))

''' <summary>
''' Occurs when the Value property changes.
''' </summary>
Public Custom Event ValueChanged As RoutedPropertyChangedEventHandler(Of Decimal)
	AddHandler(ByVal value As RoutedPropertyChangedEventHandler(Of Decimal))
		MyBase.AddHandler(ValueChangedEvent, value)
	End AddHandler
	RemoveHandler(ByVal value As RoutedPropertyChangedEventHandler(Of Decimal))
		MyBase.RemoveHandler(ValueChangedEvent, value)
	End RemoveHandler
	RaiseEvent(ByVal sender As System.Object, ByVal e As RoutedPropertyChangedEventArgs(Of Decimal))
	End RaiseEvent
End Event
''' <summary>
''' Raises the ValueChanged event.
''' </summary>
''' <param name="args">Arguments associated with the ValueChanged event.</param>
Protected Overridable Sub OnValueChanged(ByVal args As RoutedPropertyChangedEventArgs(Of Decimal))
	MyBase.RaiseEvent(args)
End Sub

Comentarios

Los eventos que usan el DependencyPropertyChangedEventArgs clase para los datos de evento y el DependencyPropertyChangedEventHandler implementaciones de método para los controladores, suelen seguir el patrón de nomenclatura Is*Changedy generalmente se implementan como Common Language Runtime (CLR)common language runtime (CLR) eventos sin RoutedEvent copia de seguridad (no son eventos enrutados).The events that use the DependencyPropertyChangedEventArgs 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)common language runtime (CLR) events without RoutedEvent backing (they are not routed events). Alguna clase controlar métodos "handle" en caso contrario, expone eventos que notifican un cambio de estado a través de un cambio de propiedad, como ButtonBase.OnIsPressedChanged, utilice también el DependencyPropertyChangedEventArgs clase para los datos de evento.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 DependencyPropertyChangedEventArgs class for event data.

El escenario de PropertyChangedCallback consiste en usar los argumentos para los valores antiguos y nuevos informes que proceden de la evaluación del sistema de propiedades de la propiedad.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. Una devolución de llamada que procesa los valores antiguos y nuevos puede elegir un tratamiento especial según estos valores, como decidir no responder a cambios de valor que se consideran no significativos.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.

Constructores

DependencyPropertyChangedEventArgs(DependencyProperty, Object, Object) DependencyPropertyChangedEventArgs(DependencyProperty, Object, Object) DependencyPropertyChangedEventArgs(DependencyProperty, Object, Object) DependencyPropertyChangedEventArgs(DependencyProperty, Object, Object)

Inicializa una nueva instancia de la clase DependencyPropertyChangedEventArgs.Initializes a new instance of the DependencyPropertyChangedEventArgs class.

Propiedades

NewValue NewValue NewValue NewValue

Obtiene el valor de la propiedad después del cambio.Gets the value of the property after the change.

OldValue OldValue OldValue OldValue

Obtiene el valor de la propiedad antes del cambio.Gets the value of the property before the change.

Property Property Property Property

Obtiene el identificador para la propiedad de dependencia en la que se produjo el cambio de valor.Gets the identifier for the dependency property where the value change occurred.

Métodos

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Determina si el objeto proporcionado es equivalente al DependencyPropertyChangedEventArgs actual.Determines whether the provided object is equivalent to the current DependencyPropertyChangedEventArgs.

Equals(DependencyPropertyChangedEventArgs) Equals(DependencyPropertyChangedEventArgs) Equals(DependencyPropertyChangedEventArgs) Equals(DependencyPropertyChangedEventArgs)

Determina si el DependencyPropertyChangedEventArgs proporcionado es equivalente al DependencyPropertyChangedEventArgs actual.Determines whether the provided DependencyPropertyChangedEventArgs is equivalent to the current DependencyPropertyChangedEventArgs.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Obtiene un código hash de este DependencyPropertyChangedEventArgs.Gets a hash code for this DependencyPropertyChangedEventArgs.

Operadores

Equality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs) Equality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs) Equality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs) Equality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs)

Determina si dos objetos DependencyPropertyChangedEventArgs especificados tienen el mismo valor.Determines whether two specified DependencyPropertyChangedEventArgs objects have the same value.

Inequality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs) Inequality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs) Inequality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs) Inequality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs)

Determina si dos objetos DependencyPropertyChangedEventArgs especificados son diferentes.Determines whether two specified DependencyPropertyChangedEventArgs objects are different.

Se aplica a

Consulte también: