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CacheRequest.TreeScope Свойство

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Определение

Пространство имен:
System.Windows.Automation
Сборка:
UIAutomationClient.dll

Возвращает или задает значение, которое показывает, выполняется ли кэширование только для корня вложенного дерева или также для дочерних элементов и потомков.

public:
 property System::Windows::Automation::TreeScope TreeScope { System::Windows::Automation::TreeScope get(); void set(System::Windows::Automation::TreeScope value); };
public System.Windows.Automation.TreeScope TreeScope { get; set; }
member this.TreeScope : System.Windows.Automation.TreeScope with get, set
Public Property TreeScope As TreeScope

Значение свойства

TreeScope

Одно или несколько полей Element, Children, Descendants или Subtree. Значение по умолчанию — Element.

Исключения

ArgumentException

Была предпринята попытка задать свойству значение Parent или Ancestors.

Примеры

В следующем примере элемент list box получается из родительского элемента окна, в то время как CacheRequest активен и TreeScope имеет значение Children. Указанные свойства дочерних элементов (т. е. элементов списка) хранятся в кэше и могут быть получены из CachedChildren списка.

/// <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

Комментарии

Область кэширования относится к извлекаемому объекту или объектам, а не к объекту, для которого FindFirst вызывается или FindAll . См. пример.

Применяется к

См. также раздел