Bagikan melalui

AutomationPropertyChangedEventHandler Delegasikan

Definisi

Ruang nama:
System.Windows.Automation
Rakitan:
UIAutomationTypes.dll

Mewakili metode yang diterapkan oleh aplikasi klien Automation UI untuk menangani peristiwa yang dinaikkan oleh penyedia Automation UI ketika properti telah berubah.

public delegate void AutomationPropertyChangedEventHandler(System::Object ^ sender, AutomationPropertyChangedEventArgs ^ e);
public delegate void AutomationPropertyChangedEventHandler(object sender, AutomationPropertyChangedEventArgs e);
type AutomationPropertyChangedEventHandler = delegate of obj * AutomationPropertyChangedEventArgs -> unit
Public Delegate Sub AutomationPropertyChangedEventHandler(sender As Object, e As AutomationPropertyChangedEventArgs)

Parameter

sender
Object

Objek yang menaikkan peristiwa.

e
AutomationPropertyChangedEventArgs

Informasi tentang peristiwa tersebut.

Contoh

Dalam contoh berikut, perubahan properti elemen berlangganan ditangani IsEnabled .


AutomationPropertyChangedEventHandler propChangeHandler;
/// <summary>
/// Adds a handler for property-changed event; in particular, a change in the enabled state.
/// </summary>
/// <param name="element">The UI Automation element whose state is being monitored.</param>
public void SubscribePropertyChange(AutomationElement element)
{
    Automation.AddAutomationPropertyChangedEventHandler(element, 
        TreeScope.Element, 
        propChangeHandler = new AutomationPropertyChangedEventHandler(OnPropertyChange),
        AutomationElement.IsEnabledProperty);
}

/// <summary>
/// Handler for property changes.
/// </summary>
/// <param name="src">The source whose properties changed.</param>
/// <param name="e">Event arguments.</param>
private void OnPropertyChange(object src, AutomationPropertyChangedEventArgs e)
{
    AutomationElement sourceElement = src as AutomationElement;
    if (e.Property == AutomationElement.IsEnabledProperty)
    {
        bool enabled = (bool)e.NewValue;
        // TODO: Do something with the new value. 
        // The element that raised the event can be identified by its runtime ID property.
    }
    else
    { 
        // TODO: Handle other property-changed events.
    }
}

public void UnsubscribePropertyChange(AutomationElement element)
{
    if (propChangeHandler != null)
    {
        Automation.RemoveAutomationPropertyChangedEventHandler(element, propChangeHandler);
    }
}


Dim propChangeHandler As AutomationPropertyChangedEventHandler

''' <summary>
''' Adds a handler for property-changed event; in particular, a change in the enabled state.
''' </summary>
''' <param name="element">The UI Automation element whose state is being monitored.</param>
Public Sub SubscribePropertyChange(ByVal element As AutomationElement)
    propChangeHandler = _
        New AutomationPropertyChangedEventHandler(AddressOf OnPropertyChange)
    Automation.AddAutomationPropertyChangedEventHandler(element, TreeScope.Element, _
        propChangeHandler, AutomationElement.IsEnabledProperty)

End Sub



''' <summary>
''' Handler for property changes.
''' </summary>
''' <param name="src">The source whose properties changed.</param>
''' <param name="e">Event arguments.</param>
Private Sub OnPropertyChange(ByVal src As Object, ByVal e As AutomationPropertyChangedEventArgs) 
    Dim sourceElement As AutomationElement = DirectCast(src, AutomationElement)
    If e.Property Is AutomationElement.IsEnabledProperty Then
        Dim enabled As Boolean = CBool(e.NewValue)
        ' TODO: Do something with the new value. 
        ' The element that raised the event can be identified by its runtime ID property.
    Else
    End If
 ' TODO: Handle other property-changed events.
End Sub


Public Sub UnsubscribePropertyChange(ByVal element As AutomationElement)
    If (propChangeHandler IsNot Nothing) Then
        Automation.RemoveAutomationPropertyChangedEventHandler(element, propChangeHandler)
    End If

End Sub

Keterangan

Yang AutomationElement diwakili oleh sender mungkin tidak memiliki properti atau pola yang di-cache, tergantung pada apakah aplikasi berlangganan peristiwa ini saat CacheRequest aktif.

Tergantung pada implementasi penyedia, peristiwa yang diubah properti tidak selalu menandakan bahwa nilai properti berbeda; mungkin hanya berarti bahwa properti telah diatur, bahkan ke nilai yang sama. Jika aplikasi Anda hanya perlu merespons perubahan aktual, Anda bertanggung jawab untuk melacak status properti.

Metode Ekstensi

Nama Deskripsi
GetMethodInfo(Delegate)

Mendapatkan objek yang mewakili metode yang diwakili oleh delegasi yang ditentukan.

Berlaku untuk

Lihat juga