CacheRequest.Pop メソッド

定義

名前空間:

System.Windows.Automation

アセンブリ:

UIAutomationClient.dll

現在のスレッドの内部スタックから、アクティブな CacheRequest を削除します。

public:
 void Pop();

public void Pop ();

member this.Pop : unit -> unit

Public Sub Pop ()

例外

InvalidOperationException

スタックに最後にプッシュされたものではないキャッシュ要求を削除しようとしました。

例

次の例は、a を使用Popして非アクティブ化する方法をCacheRequest示しています。

/// <summary>
/// Caches and retrieves properties for a list item by using CacheRequest.Push.
/// </summary>
/// <param name="autoElement">Element from which to retrieve a child element.</param>
/// <remarks>
/// This code demonstrates various aspects of caching. It is not intended to be 
/// an example of a useful method.
/// </remarks>
private void CachePropertiesByPush(AutomationElement elementList)
{
    // Set up the request.
    CacheRequest cacheRequest = new CacheRequest();

    // Do not get a full reference to the cached objects, only to their cached properties and patterns.
    cacheRequest.AutomationElementMode = AutomationElementMode.None;

    // Cache all elements, regardless of whether they are control or content elements.
    cacheRequest.TreeFilter = Automation.RawViewCondition;

    // Property and pattern to cache.
    cacheRequest.Add(AutomationElement.NameProperty);
    cacheRequest.Add(SelectionItemPattern.Pattern);

    // Activate the request.
    cacheRequest.Push();

    // Obtain an element and cache the requested items.
    Condition cond = new PropertyCondition(AutomationElement.IsSelectionItemPatternAvailableProperty, true);
    AutomationElement elementListItem = elementList.FindFirst(TreeScope.Children, cond);

    // At this point, you could call another method that creates a CacheRequest and calls Push/Pop.
    // While that method was retrieving automation elements, the CacheRequest set in this method 
    // would not be active. 

    // Deactivate the request.
    cacheRequest.Pop();

    // Retrieve the cached property and pattern.
    String itemName = elementListItem.Cached.Name;
    SelectionItemPattern pattern = elementListItem.GetCachedPattern(SelectionItemPattern.Pattern) as SelectionItemPattern;

    // The following is an alternative way of retrieving the Name property.
    itemName = elementListItem.GetCachedPropertyValue(AutomationElement.NameProperty) as String;

    // This is yet another way, which returns AutomationElement.NotSupported if the element does
    // not supply a value. If the second parameter is false, a default name is returned.
    object objName = elementListItem.GetCachedPropertyValue(AutomationElement.NameProperty, true);
    if (objName == AutomationElement.NotSupported)
    {
        itemName = "Unknown";
    }
    else
    {
        itemName = objName as String;
    }

    // The following call raises an exception, because only the cached properties are available, 
    //  as specified by cacheRequest.AutomationElementMode. If AutomationElementMode had its
    //  default value (Full), this call would be valid.
    /*** bool enabled = elementListItem.Current.IsEnabled; ***/
}

''' <summary>
''' Caches and retrieves properties for a list item by using CacheRequest.Push.
''' </summary>
''' <param name="elementList">Element from which to retrieve a child element.</param>
''' <remarks>
''' This code demonstrates various aspects of caching. It is not intended to be 
''' an example of a useful method.
''' </remarks>
Private Sub CachePropertiesByPush(ByVal elementList As AutomationElement)
    ' Set up the request.
    Dim cacheRequest As New CacheRequest()

    ' Do not get a full reference to the cached objects, only to their cached properties and patterns.
    cacheRequest.AutomationElementMode = AutomationElementMode.None

    ' Cache all elements, regardless of whether they are control or content elements.
    cacheRequest.TreeFilter = Automation.RawViewCondition

    ' Property and pattern to cache.
    cacheRequest.Add(AutomationElement.NameProperty)
    cacheRequest.Add(SelectionItemPattern.Pattern)

    ' Activate the request.
    cacheRequest.Push()

    ' Obtain an element and cache the requested items.
    Dim myCondition As New PropertyCondition(AutomationElement.IsSelectionItemPatternAvailableProperty, _
        True)
    Dim elementListItem As AutomationElement = elementList.FindFirst(TreeScope.Children, myCondition)

    ' At this point, you could call another method that creates a CacheRequest and calls Push/Pop.
    ' While that method was retrieving automation elements, the CacheRequest set in this method 
    ' would not be active. 
    ' Deactivate the request.
    cacheRequest.Pop()

    ' Retrieve the cached property and pattern.
    Dim itemName As String = elementListItem.Cached.Name
    Dim pattern As SelectionItemPattern = _
        DirectCast(elementListItem.GetCachedPattern(SelectionItemPattern.Pattern), SelectionItemPattern)

    ' The following is an alternative way of retrieving the Name property.
    itemName = CStr(elementListItem.GetCachedPropertyValue(AutomationElement.NameProperty))

    ' This is yet another way, which returns AutomationElement.NotSupported if the element does
    ' not supply a value. If the second parameter is false, a default name is returned.
    Dim objName As Object = elementListItem.GetCachedPropertyValue(AutomationElement.NameProperty, True)
    If objName Is AutomationElement.NotSupported Then
        itemName = "Unknown"
    Else
        itemName = CStr(objName)
    End If
    ' The following call raises an exception, because only the cached properties are available, 
    '  as specified by cacheRequest.AutomationElementMode. If AutomationElementMode had its
    '  default value (Full), this call would be valid.
    '** bool enabled = elementListItem.Current.IsEnabled; **

End Sub

注釈

メソッドを使用して Pop 削除できるのは、現在アクティブな要求のみです。 現在の要求ではない要求を削除しようとすると、例外が発生します。

キャッシュ要求を入れ子にしない限り、要求をスタックに配置するために使用 Activate することをお勧めします。 その理由は、ブロック内 (UsingVisual Basic) 内usingで使用Activateできるため、例外が発生した場合でも要求がスタックからポップされます。

こちらもご覧ください

• Push()
• UI オートメーション クライアントにおけるキャッシュ
• UI オートメーションにおけるキャッシュの使用