Automation.AddAutomationPropertyChangedEventHandler Metod

Definition

Namnområde:
System.Windows.Automation
Sammansättning:
UIAutomationClient.dll

Registrerar en metod som hanterar egenskapsändringshändelser.

public:
 static void AddAutomationPropertyChangedEventHandler(System::Windows::Automation::AutomationElement ^ element, System::Windows::Automation::TreeScope scope, System::Windows::Automation::AutomationPropertyChangedEventHandler ^ eventHandler, ... cli::array <System::Windows::Automation::AutomationProperty ^> ^ properties);
public static void AddAutomationPropertyChangedEventHandler(System.Windows.Automation.AutomationElement element, System.Windows.Automation.TreeScope scope, System.Windows.Automation.AutomationPropertyChangedEventHandler eventHandler, params System.Windows.Automation.AutomationProperty[] properties);
static member AddAutomationPropertyChangedEventHandler : System.Windows.Automation.AutomationElement * System.Windows.Automation.TreeScope * System.Windows.Automation.AutomationPropertyChangedEventHandler * System.Windows.Automation.AutomationProperty[] -> unit
Public Shared Sub AddAutomationPropertyChangedEventHandler (element As AutomationElement, scope As TreeScope, eventHandler As AutomationPropertyChangedEventHandler, ParamArray properties As AutomationProperty())

Parametrar

element
AutomationElement

Det UI Automation element som händelsehanteraren ska associeras med.

scope
TreeScope

Omfattningen av händelser som ska hanteras. det vill: om de är på själva elementet, eller på dess förfäder och barn.

eventHandler
AutomationPropertyChangedEventHandler

Den metod som ska anropas när händelsen inträffar.

properties
AutomationProperty[]

De UI Automation egenskaperna av intresse.

Exempel

Följande exempelkod lägger till en händelsehanterare som lyssnar efter en ändring i det aktiverade tillståndet för ett angivet element.


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

Kommentarer

Användargränssnittsobjektet (UI) som anges av det angivna UI Automation-elementet kanske inte stöder de egenskaper som anges av parametern properties.

eventHandler kan vara en instans av metoden eller en referens till metoden (AddressOf i Visual Basic).

Gäller för

Se även