通过

Automation.RemoveAutomationPropertyChangedEventHandler 方法

  • 参考

定义

命名空间:
System.Windows.Automation
程序集:
UIAutomationClient.dll

移除指定的 property-changed 事件处理程序。

public:
 static void RemoveAutomationPropertyChangedEventHandler(System::Windows::Automation::AutomationElement ^ element, System::Windows::Automation::AutomationPropertyChangedEventHandler ^ eventHandler);
public static void RemoveAutomationPropertyChangedEventHandler (System.Windows.Automation.AutomationElement element, System.Windows.Automation.AutomationPropertyChangedEventHandler eventHandler);
static member RemoveAutomationPropertyChangedEventHandler : System.Windows.Automation.AutomationElement * System.Windows.Automation.AutomationPropertyChangedEventHandler -> unit
Public Shared Sub RemoveAutomationPropertyChangedEventHandler (element As AutomationElement, eventHandler As AutomationPropertyChangedEventHandler)

参数

element
AutomationElement

要从中删除事件处理程序的UI 自动化元素。

eventHandler
AutomationPropertyChangedEventHandler

传递给AddAutomationPropertyChangedEventHandler(AutomationElement, TreeScope, AutomationPropertyChangedEventHandler, AutomationProperty[])指定UI 自动化元素的处理程序方法。

注解

以下示例代码显示正在添加和删除的属性更改事件处理程序。


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

适用于

另请参阅