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Find a UI Automation Element Based on a Property Condition

NoteNote

This documentation is intended for .NET Framework developers who want to use the managed UI Automation classes defined in the System.Windows.Automation namespace. For the latest information about UI Automation, see Windows Automation API: UI Automation.

This topic contains example code that shows how to locate an element within the UI Automation tree based on a specific property or properties.

In the following example, a set of property conditions are specified that identify a certain element (or elements) of interest in the AutomationElement tree. A search for all matching elements is then performed with the FindAll method that incorporates a series of AndCondition boolean operations to limit the number of matching elements.

NoteNote

When searching from the RootElement, you should try to obtain only direct children. A search for descendants might iterate through hundreds or even thousands of elements, possibly resulting in a stack overflow. If you are attempting to obtain a specific element at a lower level, you should start your search from the application window or from a container at a lower level.


///--------------------------------------------------------------------
/// <summary>
/// Walks the UI Automation tree of the target and reports the control 
/// type of each element it finds in the control view to the client.
/// </summary>
/// <param name="targetTreeViewElement">
/// The root of the search on this iteration.
/// </param>
/// <param name="elementIndex">
/// The TreeView index for this iteration.
/// </param>
/// <remarks>
/// This is a recursive function that maps out the structure of the 
/// subtree of the target beginning at the AutomationElement passed in 
/// as the rootElement on the first call. This could be, for example,
/// an application window.
/// CAUTION: Do not pass in AutomationElement.RootElement. Attempting 
/// to map out the entire subtree of the desktop could take a very 
/// long time and even lead to a stack overflow.
/// </remarks>
///--------------------------------------------------------------------
private void FindTreeViewDescendants(
    AutomationElement targetTreeViewElement, int treeviewIndex)
{
    if (targetTreeViewElement == null)
        return;

    AutomationElement elementNode =
        TreeWalker.ControlViewWalker.GetFirstChild(targetTreeViewElement);

    while (elementNode != null)
    {
        Label elementInfo = new Label();
        elementInfo.Margin = new Thickness(0);
        clientTreeViews[treeviewIndex].Children.Add(elementInfo);

        // Compile information about the control.
        elementInfoCompile = new StringBuilder();
        string controlName =
            (elementNode.Current.Name == "") ?
            "Unnamed control" : elementNode.Current.Name;
        string autoIdName =
            (elementNode.Current.AutomationId == "") ?
            "No AutomationID" : elementNode.Current.AutomationId;

        elementInfoCompile.Append(controlName)
            .Append(" (")
            .Append(elementNode.Current.ControlType.LocalizedControlType)
            .Append(" - ")
            .Append(autoIdName)
            .Append(")");

        // Test for the control patterns of interest for this sample.
        object objPattern;
        ExpandCollapsePattern expcolPattern;
        if (true == elementNode.TryGetCurrentPattern(ExpandCollapsePattern.Pattern, out objPattern))
        {
            expcolPattern = objPattern as ExpandCollapsePattern;
            if (expcolPattern.Current.ExpandCollapseState != ExpandCollapseState.LeafNode)
            {
                Button expcolButton = new Button();
                expcolButton.Margin = new Thickness(0, 0, 0, 5);
                expcolButton.Height = 20;
                expcolButton.Width = 100;
                expcolButton.Content = "ExpandCollapse";
                expcolButton.Tag = expcolPattern;
                expcolButton.Click +=
                    new RoutedEventHandler(ExpandCollapse_Click);
                clientTreeViews[treeviewIndex].Children.Add(expcolButton);
            }
        }
        TogglePattern togPattern;
        if (true == elementNode.TryGetCurrentPattern(TogglePattern.Pattern, out objPattern))
        {
            togPattern = objPattern as TogglePattern;
            Button togButton = new Button();
            togButton.Margin = new Thickness(0, 0, 0, 5);
            togButton.Height = 20;
            togButton.Width = 100;
            togButton.Content = "Toggle";
            togButton.Tag = togPattern;
            togButton.Click += new RoutedEventHandler(Toggle_Click);
            clientTreeViews[treeviewIndex].Children.Add(togButton);
        }
        InvokePattern invPattern;
        if (true == elementNode.TryGetCurrentPattern(InvokePattern.Pattern, out objPattern))
        {
            invPattern = objPattern as InvokePattern;
            Button invButton = new Button();
            invButton.Margin = new Thickness(0);
            invButton.Height = 20;
            invButton.Width = 100;
            invButton.Content = "Invoke";
            invButton.Tag = invPattern;
            invButton.Click += new RoutedEventHandler(Invoke_Click);
            clientTreeViews[treeviewIndex].Children.Add(invButton);
        }
        // Display compiled information about the control.
        elementInfo.Content = elementInfoCompile;
        Separator sep = new Separator();
        clientTreeViews[treeviewIndex].Children.Add(sep);

        // Iterate to next element.
        // elementNode - Current element.
        // treeviewIndex - Index of parent TreeView.
        FindTreeViewDescendants(elementNode, treeviewIndex);
        elementNode = 
            TreeWalker.ControlViewWalker.GetNextSibling(elementNode);
    }
}


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