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AutomationElement.GetCachedPropertyValue Metoda

  • Reference

Definice

Obor názvů:
System.Windows.Automation
Sestavení:
UIAutomationClient.dll

Načte hodnotu zadanou vlastnost uloženou v mezipaměti z objektu AutomationElement.

Přetížení

GetCachedPropertyValue(AutomationProperty)

Načte hodnotu zadané vlastnosti z mezipaměti tohoto AutomationElementobjektu . Pro vlastnosti, které nejsou explicitně podporovány elementem cílového uživatelského rozhraní (UI) je vrácena odpovídající výchozí hodnota pro typ vlastnosti.
GetCachedPropertyValue(AutomationProperty, Boolean)

Načte hodnotu zadané vlastnosti z mezipaměti tohoto AutomationElementobjektu , volitelně bez ohledu na výchozí vlastnost.

Poznámky

GetCachedPropertyValue Načte zadanou vlastnost z mezipaměti objektu AutomationElement. Pokud chcete načíst aktuální vlastnost, zavolejte GetCurrentPropertyValue.

GetCachedPropertyValue(AutomationProperty)

Načte hodnotu zadané vlastnosti z mezipaměti tohoto AutomationElementobjektu . Pro vlastnosti, které nejsou explicitně podporovány elementem cílového uživatelského rozhraní (UI) je vrácena odpovídající výchozí hodnota pro typ vlastnosti.

public:
 System::Object ^ GetCachedPropertyValue(System::Windows::Automation::AutomationProperty ^ property);
public object GetCachedPropertyValue (System.Windows.Automation.AutomationProperty property);
member this.GetCachedPropertyValue : System.Windows.Automation.AutomationProperty -> obj
Public Function GetCachedPropertyValue (property As AutomationProperty) As Object

Parametry

property
AutomationProperty

Identifikátor vlastnosti, která se má načíst.

Návraty

Object

Objekt obsahující hodnotu zadané vlastnosti.

Výjimky

InvalidOperationException

Požadovaná vlastnost není v mezipaměti.

ElementNotAvailableException

Uživatelské rozhraní pro AutomationElement objekt už neexistuje.

Příklady

Následující příklad ukazuje, jak lze tuto metodu použít k načtení vlastnosti v mezipaměti.

/// <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

Poznámky

Pokud zprostředkovatel automatizace uživatelského rozhraní pro samotný prvek podporuje vlastnost , vrátí se hodnota vlastnosti . V opačném případě se vrátí výchozí vlastnost určená automatizací uživatelského rozhraní. Informace o výchozích vlastnostech najdete v polích identifikátorů vlastností , AutomationElementnapříklad AcceleratorKeyProperty.

GetCachedPropertyValue načte zadanou vlastnost z AutomationElementmezipaměti . K načtení aktuálního objektu pro zadanou vlastnost zavolejte GetCurrentPropertyValue.

Tato metoda vyvolá výjimku, pokud požadovaná vlastnost nebyla dříve uložena v mezipaměti.

Platí pro

GetCachedPropertyValue(AutomationProperty, Boolean)

Načte hodnotu zadané vlastnosti z mezipaměti tohoto AutomationElementobjektu , volitelně bez ohledu na výchozí vlastnost.

public:
 System::Object ^ GetCachedPropertyValue(System::Windows::Automation::AutomationProperty ^ property, bool ignoreDefaultValue);
public object GetCachedPropertyValue (System.Windows.Automation.AutomationProperty property, bool ignoreDefaultValue);
member this.GetCachedPropertyValue : System.Windows.Automation.AutomationProperty * bool -> obj
Public Function GetCachedPropertyValue (property As AutomationProperty, ignoreDefaultValue As Boolean) As Object

Parametry

property
AutomationProperty

Identifikátor vlastnosti, která se má načíst.

ignoreDefaultValue
Boolean

Hodnota, která určuje, zda má být výchozí hodnota ignorována, pokud zadaná vlastnost není podporována.

Návraty

Object

Objekt obsahující hodnotu zadané vlastnosti nebo NotSupported pokud prvek neposkytuje hodnotu a ignoreDefaultValue je true.

Výjimky

InvalidOperationException

Požadovaná vlastnost není v mezipaměti.

ElementNotAvailableException

Uživatelské rozhraní pro objekt AutomationElement už neexistuje.

Příklady

Následující příklad ukazuje, jak lze tuto metodu použít k načtení vlastnosti v mezipaměti.

/// <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

Poznámky

GetCachedPropertyValue Načte zadanou vlastnost z mezipaměti pro AutomationElement. Pokud chcete načíst aktuální vlastnost, zavolejte GetCurrentPropertyValue.

ignoreDefaultValue Předání false je ekvivalentem volání AutomationElement.GetCachedPropertyValue(AutomationProperty)metody .

Pokud zprostředkovatel automatizace uživatelského rozhraní pro samotný prvek podporuje vlastnost , vrátí se hodnota vlastnosti . V opačném případě se ignoreDefaultValuefalsevrátí výchozí vlastnost určená automatizací uživatelského rozhraní. Informace o výchozích vlastnostech najdete v polích identifikátorů vlastností , AutomationElementnapříklad AcceleratorKeyProperty.

Tato metoda vyvolá výjimku, pokud požadovaná vlastnost nebyla dříve uložena v mezipaměti.

Platí pro