Použití mezipaměti při automatizaci uživatelského rozhraní
Poznámka:
Tato dokumentace je určená pro vývojáře rozhraní .NET Framework, kteří chtějí používat spravované třídy model UI Automation definované v System.Windows.Automation oboru názvů. Nejnovější informace o model UI Automation najdete v tématu Rozhraní API služby Windows Automation: model UI Automation.
Tato část ukazuje, jak implementovat ukládání vlastností do mezipaměti AutomationElement a vzorů ovládacích prvků.
Aktivace žádosti o mezipaměť
Vytvoření souboru CacheRequest.
Zadejte vlastnosti a vzory, které se mají ukládat do mezipaměti pomocí .Add
Zadejte obor ukládání do mezipaměti nastavením TreeScope vlastnosti.
Určete zobrazení podstromu nastavením TreeFilter vlastnosti.
AutomationElementMode Vlastnost nastavte, None pokud chcete zvýšit efektivitu načtením úplného odkazu na objekty. (To znemožní načtení aktuálních hodnot z těchto objektů.)
Aktivujte požadavek pomocí Activate bloku
using(Usingv jazyce Microsoft Visual Basic .NET).
Po získání AutomationElement objektů nebo přihlášení k odběru událostí deaktivujte žádost pomocí Pop (pokud Push byl použit) nebo odstraněním objektu vytvořeného Activate. (Používá Activate se using v bloku (Using v jazyce Microsoft Visual Basic .NET).
Vlastnosti AutomationElement mezipaměti
CacheRequest Zatímco je aktivní, získejte AutomationElement objekty pomocí FindFirst nebo FindAll; nebo získejte AutomationElement jako zdroj události, pro kterou jste zaregistrovali, když CacheRequest byl aktivní. (Mezipaměť můžete vytvořit také předáním CacheRequest do GetUpdatedCache nebo jedné z TreeWalker metod.)
Použijte GetCachedPropertyValue nebo načtěte vlastnost z Cached vlastnosti objektu AutomationElement.
Získání vzorů uložených v mezipaměti a jejich vlastností
CacheRequest Zatímco je aktivní, získejte AutomationElement objekty pomocí FindFirst nebo FindAll; nebo získejte AutomationElement jako zdroj události, pro kterou jste zaregistrovali, když CacheRequest byl aktivní. (Mezipaměť můžete vytvořit také předáním CacheRequest do GetUpdatedCache nebo jedné z TreeWalker metod.)
Použijte GetCachedPattern nebo TryGetCachedPattern načtěte vzor uložený v mezipaměti.
Načtěte hodnoty vlastností z
Cachedvlastnosti vzoru ovládacího prvku.
Příklad 1
Následující příklad kódu ukazuje různé aspekty ukládání do mezipaměti pomocí Activate aktivace CacheRequest.
/// <summary>
/// Caches and retrieves properties for a list item by using CacheRequest.Activate.
/// </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 void CachePropertiesByActivate(AutomationElement elementList)
{
AutomationElement elementListItem;
// Set up the request.
CacheRequest cacheRequest = new CacheRequest();
cacheRequest.Add(AutomationElement.NameProperty);
cacheRequest.Add(AutomationElement.IsEnabledProperty);
cacheRequest.Add(SelectionItemPattern.Pattern);
cacheRequest.Add(SelectionItemPattern.SelectionContainerProperty);
// Obtain an element and cache the requested items.
using (cacheRequest.Activate())
{
Condition cond = new PropertyCondition(AutomationElement.IsSelectionItemPatternAvailableProperty, true);
elementListItem = elementList.FindFirst(TreeScope.Children, cond);
}
// The CacheRequest is now inactive.
// Retrieve the cached property and pattern.
SelectionItemPattern pattern;
String itemName;
try
{
itemName = elementListItem.Cached.Name;
pattern = elementListItem.GetCachedPattern(SelectionItemPattern.Pattern) as SelectionItemPattern;
}
catch (InvalidOperationException)
{
Console.WriteLine("Object was not in cache.");
return;
}
// Alternatively, you can use TryGetCachedPattern to retrieve the cached pattern.
object cachedPattern;
if (true == elementListItem.TryGetCachedPattern(SelectionItemPattern.Pattern, out cachedPattern))
{
pattern = cachedPattern as SelectionItemPattern;
}
// Specified pattern properties are also in the cache.
AutomationElement parentList = pattern.Cached.SelectionContainer;
// The following line will raise an exception, because the HelpText property was not cached.
/*** String itemHelp = elementListItem.Cached.HelpText; ***/
// Similarly, pattern properties that were not specified in the CacheRequest cannot be
// retrieved from the cache. This would raise an exception.
/*** bool selected = pattern.Cached.IsSelected; ***/
// This is still a valid call, even though the property is in the cache.
// Of course, the cached value and the current value are not guaranteed to be the same.
itemName = elementListItem.Current.Name;
}
''' <summary>
''' Caches and retrieves properties for a list item by using CacheRequest.Activate.
''' </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 CachePropertiesByActivate(ByVal elementList As AutomationElement)
' Set up the request.
Dim myCacheRequest As New CacheRequest()
myCacheRequest.Add(AutomationElement.NameProperty)
myCacheRequest.Add(AutomationElement.IsEnabledProperty)
myCacheRequest.Add(SelectionItemPattern.Pattern)
myCacheRequest.Add(SelectionItemPattern.SelectionContainerProperty)
Dim elementListItem As AutomationElement
' Obtain an element and cache the requested items.
Using myCacheRequest.Activate()
Dim myCondition As New PropertyCondition( _
AutomationElement.IsSelectionItemPatternAvailableProperty, True)
elementListItem = elementList.FindFirst(TreeScope.Children, myCondition)
End Using
' The CacheRequest is now inactive.
' Retrieve the cached property and pattern.
Dim pattern As SelectionItemPattern
Dim itemName As String
Try
itemName = elementListItem.Cached.Name
pattern = DirectCast(elementListItem.GetCachedPattern(SelectionItemPattern.Pattern), _
SelectionItemPattern)
Catch ex As InvalidOperationException
Console.WriteLine("Object was not in cache.")
Return
End Try
' Alternatively, you can use TryGetCachedPattern to retrieve the cached pattern.
Dim cachedPattern As Object = Nothing
If True = elementListItem.TryGetCachedPattern(SelectionItemPattern.Pattern, cachedPattern) Then
pattern = DirectCast(cachedPattern, SelectionItemPattern)
End If
' Specified pattern properties are also in the cache.
Dim parentList As AutomationElement = pattern.Cached.SelectionContainer
' The following line will raise an exception, because the HelpText property was not cached.
'** String itemHelp = elementListItem.Cached.HelpText; **
' Similarly, pattern properties that were not specified in the CacheRequest cannot be
' retrieved from the cache. This would raise an exception.
'** bool selected = pattern.Cached.IsSelected; **
' This is still a valid call, even though the property is in the cache.
' Of course, the cached value and the current value are not guaranteed to be the same.
itemName = elementListItem.Current.Name
End Sub
Příklad 2
Následující příklad kódu ukazuje různé aspekty ukládání do mezipaměti pomocí Push aktivace CacheRequest. S výjimkou případů, kdy chcete vnořit požadavky mezipaměti, je vhodnější použít Activate.
/// <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