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Cara: Menerapkan Pemberitahuan Perubahan Properti

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Untuk mendukung OneWay atau TwoWay mengikat untuk mengaktifkan properti target pengikatan Anda untuk secara otomatis mencerminkan perubahan dinamis sumber pengikatan (misalnya, agar panel pratinjau diperbarui secara otomatis saat pengguna mengedit formulir), kelas Anda perlu memberikan pemberitahuan perubahan properti yang tepat. Contoh ini menunjukkan cara membuat kelas yang mengimplementasikan INotifyPropertyChanged.

Contoh

Untuk mengimplementasikan INotifyPropertyChanged , Anda perlu mendeklarasikan PropertyChanged peristiwa dan membuat OnPropertyChanged metode . Kemudian untuk setiap properti yang ingin Anda ubah pemberitahuannya, Anda memanggil OnPropertyChanged setiap kali properti diperbarui.

using System.ComponentModel;
using System.Runtime.CompilerServices;

namespace SDKSample
{
  // This class implements INotifyPropertyChanged
  // to support one-way and two-way bindings
  // (such that the UI element updates when the source
  // has been changed dynamically)
  public class Person : INotifyPropertyChanged
  {
      private string name;
      // Declare the event
      public event PropertyChangedEventHandler PropertyChanged;

      public Person()
      {
      }

      public Person(string value)
      {
          this.name = value;
      }

      public string PersonName
      {
          get { return name; }
          set
          {
              name = value;
              // Call OnPropertyChanged whenever the property is updated
              OnPropertyChanged();
          }
      }

      // Create the OnPropertyChanged method to raise the event
      // The calling member's name will be used as the parameter.
      protected void OnPropertyChanged([CallerMemberName] string name = null)
      {
          PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
      }
  }
}

Imports System.ComponentModel
Imports System.Runtime.CompilerServices

' This class implements INotifyPropertyChanged
' to support one-way and two-way bindings
' (such that the UI element updates when the source
' has been changed dynamically)
Public Class Person
    Implements INotifyPropertyChanged

    Private personName As String

    Sub New()
    End Sub

    Sub New(ByVal Name As String)
        Me.personName = Name
    End Sub

    ' Declare the event
    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged

    Public Property Name() As String
        Get
            Return personName
        End Get
        Set(ByVal value As String)
            personName = value
            ' Call OnPropertyChanged whenever the property is updated
            OnPropertyChanged()
        End Set
    End Property

    ' Create the OnPropertyChanged method to raise the event
    ' Use the name of the member that called this method in place of name
    Protected Sub OnPropertyChanged(<CallerMemberName> Optional name As String = Nothing)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(name))
    End Sub

End Class

Untuk melihat contoh bagaimana Person kelas dapat digunakan untuk mendukung TwoWay pengikatan, lihat Kontrol Saat Teks Kotak Teks Memperbarui Sumber.

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