AutomationElement.CachedChildren Propiedad

Definición

Espacio de nombres:

System.Windows.Automation

Ensamblado:

UIAutomationClient.dll

Obtiene los elementos secundarios almacenados en memoria caché de AutomationElement.

public:
 property System::Windows::Automation::AutomationElementCollection ^ CachedChildren { System::Windows::Automation::AutomationElementCollection ^ get(); };

public System.Windows.Automation.AutomationElementCollection CachedChildren { get; }

member this.CachedChildren : System.Windows.Automation.AutomationElementCollection

Public ReadOnly Property CachedChildren As AutomationElementCollection

Valor de propiedad

AutomationElementCollection

Colección de elementos secundarios. Esta colección puede estar vacía si el elemento no tiene ningún elemento secundario.

Excepciones

ElementNotAvailableException

La interfaz de usuario para el AutomationElement ya no existe.

InvalidOperationException

No se realizó ninguna solicitud de almacenar los elementos secundarios de este elemento en memoria caché.

Ejemplos

En el ejemplo siguiente, se obtiene un elemento de cuadro de lista del elemento primario de la ventana mientras un CacheRequest elemento está activo y TreeScope es Children. Las propiedades especificadas de los elementos secundarios (es decir, los elementos de lista) se almacenan en la memoria caché y se pueden recuperar del CachedChildren cuadro de lista.

/// <summary>
/// Gets a list box element and caches the Name property of its children (the list items).
/// </summary>
/// <param name="elementMain">The UI Automation element for the parent window.</param>
void CachePropertiesWithScope(AutomationElement elementMain)
{
    AutomationElement elementList;

    // Set up the CacheRequest.
    CacheRequest cacheRequest = new CacheRequest();
    cacheRequest.Add(AutomationElement.NameProperty);
    cacheRequest.TreeScope = TreeScope.Element | TreeScope.Children;

    // Activate the CacheRequest and get the element. Note that the scope of the CacheRequest
    // is in relation to the object being retrieved: the list box and its children are 
    // cached, not the main window and its children.
    using (cacheRequest.Activate())
    {
        // Load the list element and cache the specified properties for its descendants.
        Condition cond = new PropertyCondition(AutomationElement.ControlTypeProperty, ControlType.List);
        elementList = elementMain.FindFirst(TreeScope.Children, cond);
    }
    if (elementList == null) return;

    // The following illustrates that the children of the list are in the cache.
    foreach (AutomationElement listItem in elementList.CachedChildren)
    {
        Console.WriteLine(listItem.Cached.Name);
    }

    // The following call raises an exception, because the IsEnabled property was not cached.
    /*** Console.WriteLine(listItem.Cached.IsEnabled); ***/

    // The following illustrates that because the list box itself was cached, it is now
    // available as the CachedParent of each list item.
    AutomationElement child = elementList.CachedChildren[0];
    Console.WriteLine(child.CachedParent.Cached.Name);
}

''' <summary>
''' Gets a list box element and caches the Name property of its children (the list items).
''' </summary>
''' <param name="elementMain">The UI Automation element for the parent window.</param>
Sub CachePropertiesWithScope(ByVal elementMain As AutomationElement)
    Dim elementList As AutomationElement

    ' Set up the CacheRequest.
    Dim cacheRequest As New CacheRequest()
    cacheRequest.Add(AutomationElement.NameProperty)
    cacheRequest.TreeScope = TreeScope.Element Or TreeScope.Children

    ' Activate the CacheRequest and get the element. Note that the scope of the CacheRequest
    ' is in relation to the object being retrieved: the list box and its children are 
    ' cached, not the main window and its children.
    Using cacheRequest.Activate()
        ' Load the list element and cache the specified properties for its descendants.
        Dim myCondition As New PropertyCondition(AutomationElement.ControlTypeProperty, ControlType.List)
        elementList = elementMain.FindFirst(TreeScope.Children, myCondition)

        If elementList Is Nothing Then
            Return
        End If

        ' The following illustrates that the children of the list are in the cache.
        Dim listItem As AutomationElement
        For Each listItem In elementList.CachedChildren
            Console.WriteLine(listItem.Cached.Name)
        Next listItem

        ' The following call raises an exception, because the IsEnabled property was not cached.
        '** Console.WriteLine(listItem.Cached.IsEnabled) **

        ' The following illustrates that because the list box itself was cached, it is now
        ' available as the CachedParent of each list item.
        Dim child As AutomationElement = elementList.CachedChildren(0)
        Console.WriteLine(child.CachedParent.Cached.Name)
    End Using
End Sub

Comentarios

La vista de la colección devuelta viene determinada por la TreeFilter condición de que CacheRequest estaba activo cuando se obtuvo este AutomationElement objeto.

Los elementos secundarios solo se almacenan en caché si el ámbito de la CacheRequest clase incluida Subtree, Childreno Descendants.

Si se CacheRequest especificó que los elementos secundarios se almacenaron en caché en este nivel, pero no hay elementos secundarios, el valor de esta propiedad es 0. Sin embargo, si no se realizó ninguna solicitud para almacenar en caché los elementos secundarios en este nivel, un intento de recuperar la propiedad genera una excepción.

Consulte también

• Almacenar en caché en los clientes de automatización de la interfaz de usuario