DependencyPropertyChangedEventArgs 構造体

定義

さまざまなプロパティ変更イベントにデータを提供します。Provides data for various property changed events. 通常、これらのイベントは、読み取り専用の依存関係プロパティの有効値の変更を報告します。Typically these events report effective value changes in the value of a read-only dependency property. もう 1 つの用途は、PropertyChangedCallback 実装の一部として使用することです。Another usage is as part of a PropertyChangedCallback implementation.

public value class DependencyPropertyChangedEventArgs
public struct DependencyPropertyChangedEventArgs
type DependencyPropertyChangedEventArgs = struct
Public Structure DependencyPropertyChangedEventArgs
継承
DependencyPropertyChangedEventArgs

次の例ではDependencyPropertyChangedEventArgs 、イベントも定義するカスタムPropertyChangedCallbackクラスの特定のプロパティについて、のコンテキストでクラスを使用します。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. コールバックは、によってDependencyPropertyChangedEventArgs伝達されるプロパティシステムから、古い値と新しい値の結果を受け取り、それらを別の events arguments クラスRoutedPropertyChangedEventArgs<T>に再パッケージ化します。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>. 新しい引数は、カスタムクラスによって定義および発生した "ValueChanged" イベントのデータとして使用されます。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

注釈

イベントデータDependencyPropertyChangedEventArgsにクラスを使用するイベントIs*Changed DependencyPropertyChangedEventHandlerと、ハンドラーのメソッド実装は通常、名前付けパターンに従い、通常共通言語ランタイム (CLR)common language runtime (CLR)RoutedEventバッキング (ルーティングイベントではありません)。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 共通言語ランタイム (CLR)common language runtime (CLR) events without RoutedEvent backing (they are not routed events). クラス処理メソッドの中には、プロパティの変更によって状態の変更を報告する非公開イベント ( ButtonBase.OnIsPressedChangedなど) を " DependencyPropertyChangedEventArgs処理" しているものがあります。たとえば、イベントデータにはクラスも使用されます。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.

PropertyChangedCallbackシナリオでは、引数を使用して、プロパティのプロパティシステムの評価から取得された古い値と新しい値を報告します。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. 古い値と新しい値を処理するコールバックでは、これらの値に応じて特別な処理が選択される場合があります。たとえば、重要でないと思われる値の変化に対応しないようにする場合などです。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.

コンストラクター

DependencyPropertyChangedEventArgs(DependencyProperty, Object, Object)

DependencyPropertyChangedEventArgs クラスの新しいインスタンスを初期化します。Initializes a new instance of the DependencyPropertyChangedEventArgs class.

プロパティ

NewValue

変更後のプロパティの値を取得します。Gets the value of the property after the change.

OldValue

変更前のプロパティの値を取得します。Gets the value of the property before the change.

Property

値が変更された依存関係プロパティの識別子を取得します。Gets the identifier for the dependency property where the value change occurred.

メソッド

Equals(DependencyPropertyChangedEventArgs)

提供された DependencyPropertyChangedEventArgs が現在の DependencyPropertyChangedEventArgs と等価であるかどうかを判断します。Determines whether the provided DependencyPropertyChangedEventArgs is equivalent to the current DependencyPropertyChangedEventArgs.

Equals(Object)

提供されたオブジェクトが現在の DependencyPropertyChangedEventArgs と等価であるかどうかを判断します。Determines whether the provided object is equivalent to the current DependencyPropertyChangedEventArgs.

GetHashCode()

この DependencyPropertyChangedEventArgs のハッシュ コードを取得します。Gets a hash code for this DependencyPropertyChangedEventArgs.

演算子

Equality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs)

指定した 2 つの DependencyPropertyChangedEventArgs オブジェクトの値が同一かどうかを判断します。Determines whether two specified DependencyPropertyChangedEventArgs objects have the same value.

Inequality(DependencyPropertyChangedEventArgs, DependencyPropertyChangedEventArgs)

指定した 2 つの DependencyPropertyChangedEventArgs オブジェクトが異なっているどうかを判断します。Determines whether two specified DependencyPropertyChangedEventArgs objects are different.

適用対象

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