AutomationElementMode Property
Collapse the table of content
Expand the table of content

CacheRequest.AutomationElementMode Property

 

Gets or sets a value that specifies whether returned elements should contain full references to the underlying user interface (UI), or only cached information.

Namespace:   System.Windows.Automation
Assembly:  UIAutomationClient (in UIAutomationClient.dll)

public AutomationElementMode AutomationElementMode { get; set; }

Property Value

Type: System.Windows.Automation.AutomationElementMode

Full if the returned elements have a full reference to the underlying user interface (UI); otherwise None.

Full is the default value, and specifies that returned elements contain a full reference to the underlying UI. None specifies that the returned elements have no reference to the underlying UI, and contain only cached information.

Certain operations on elements, including GetCurrentPropertyValue, GetCurrentPattern, and SetFocus, require a full reference; attempting to perform these on an element that has none results in an InvalidOperationException.

Using None can be more efficient when only properties are needed, as it avoids the overhead involved in setting up full references.

In the following example, AutomationElementMode is set to None, with the result that only cached properties and patterns are available for the retrieved object.

/// <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; ***/
}

.NET Framework
Available since 3.0
Return to top
Show:
© 2016 Microsoft