AutomationEventHandler Delegate

Definition

public delegate void AutomationEventHandler(System::Object ^ sender, AutomationEventArgs ^ e);

public delegate void AutomationEventHandler(object sender, AutomationEventArgs e);

type AutomationEventHandler = delegate of obj * AutomationEventArgs -> unit

Public Delegate Sub AutomationEventHandler(sender As Object, e As AutomationEventArgs)

Parameters

Examples

The following example shows how to subscribe to and handle an event.

// Member variables.
AutomationElement ElementSubscribeButton;
AutomationEventHandler UIAeventHandler;

/// <summary>
/// Register an event handler for InvokedEvent on the specified element.
/// </summary>
/// <param name="elementButton">The automation element.</param>
public void SubscribeToInvoke(AutomationElement elementButton)
{
 if (elementButton != null)
 {
 Automation.AddAutomationEventHandler(InvokePattern.InvokedEvent,
 elementButton, TreeScope.Element,
 UIAeventHandler = new AutomationEventHandler(OnUIAutomationEvent));
 ElementSubscribeButton = elementButton;
 }
}

/// <summary>
/// AutomationEventHandler delegate.
/// </summary>
/// <param name="src">Object that raised the event.</param>
/// <param name="e">Event arguments.</param>
private void OnUIAutomationEvent(object src, AutomationEventArgs e)
{
 // Make sure the element still exists. Elements such as tooltips
 // can disappear before the event is processed.
 AutomationElement sourceElement;
 try
 {
 sourceElement = src as AutomationElement;
 }
 catch (ElementNotAvailableException)
 {
 return;
 }
 if (e.EventId == InvokePattern.InvokedEvent)
 {
 // TODO Add handling code.
 }
 else
 {
 // TODO Handle any other events that have been subscribed to.
 }
}

private void ShutdownUIA()
{
 if (UIAeventHandler != null)
 {
 Automation.RemoveAutomationEventHandler(InvokePattern.InvokedEvent,
 ElementSubscribeButton, UIAeventHandler);
 }
}

' Member variables.
Private ElementSubscribeButton As AutomationElement
Private UIAeventHandler As AutomationEventHandler


''' <summary>
''' Register an event handler for InvokedEvent on the specified element.
''' </summary>
''' <param name="elementButton">The automation element.</param>
Public Sub SubscribeToInvoke(ByVal elementButton As AutomationElement)
 If (elementButton IsNot Nothing) Then
 UIAeventHandler = New AutomationEventHandler(AddressOf OnUIAutomationEvent)
 Automation.AddAutomationEventHandler(InvokePattern.InvokedEvent, elementButton, _
 TreeScope.Element, UIAeventHandler)
 ElementSubscribeButton = elementButton
 End If

End Sub


''' <summary>
''' AutomationEventHandler delegate.
''' </summary>
''' <param name="src">Object that raised the event.</param>
''' <param name="e">Event arguments.</param>
Private Sub OnUIAutomationEvent(ByVal src As Object, ByVal e As AutomationEventArgs)
 ' Make sure the element still exists. Elements such as tooltips can disappear
 ' before the event is processed.
 Dim sourceElement As AutomationElement
 Try
 sourceElement = DirectCast(src, AutomationElement)
 Catch ex As ElementNotAvailableException
 Exit Sub
 End Try
 If e.EventId Is InvokePattern.InvokedEvent Then
 ' TODO Add handling code.
 Else
 End If
 ' TODO Handle any other events that have been subscribed to.
 Console.WriteLine("Event: " & e.EventId.ProgrammaticName)
End Sub

Private Sub ShutdownUIA()
 If (UIAeventHandler IsNot Nothing) Then
 Automation.RemoveAutomationEventHandler(InvokePattern.InvokedEvent, ElementSubscribeButton, UIAeventHandler)
 End If

End Sub

Remarks

Use an AutomationEventHandler delegate to specify the method that is called by a client to handle UI Automation events.

The AutomationElement represented by sender might not have any cached properties or patterns, depending on whether the application subscribed to this event while a CacheRequest was active.

See also

• AddAutomationEventHandler(AutomationEvent, AutomationElement, TreeScope, AutomationEventHandler)
• RemoveAutomationEventHandler(AutomationEvent, AutomationElement, AutomationEventHandler)
• AutomationEventArgs
• Subscribe to UI Automation Events
• UI Automation Events Overview