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CacheRequest.TreeFilter Property

Gets or sets a value specifying the view of the UI Automation element tree to use when caching.

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

public Condition TreeFilter { get; set; }

Property Value

Type: System.Windows.Automation.Condition
The view of the UI Automation element tree. The default view is ControlViewCondition.

For additional information on views of the UI Automation element tree, see UI Automation Tree Overview.

In the following example, TreeFilter is set to RawViewCondition so that caching is done for all elements, regardless of whether they are part of the content view or the control view.

/// <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

Supported in: 4.6, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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