Invoke a Control Using UI Automation

Note Note

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 demonstrates how to perform the following tasks:

  • Find a control that matches specific property conditions by walking the control view of the UI Automation tree for the target application.

  • Create an AutomationElement for each control.

  • Obtain an InvokePattern object from any UI Automation element found that supports the InvokePattern control pattern.

  • Use Invoke to invoke the control from a client event handler.

This example uses the TryGetCurrentPattern method of the AutomationElement class to generate an InvokePattern object and invoke a control by using the Invoke method.

///-------------------------------------------------------------------- 
/// <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);
    }
}


...


///-------------------------------------------------------------------- 
/// <summary> 
/// Handles the Invoke click event on the client control.  
/// The client click handler calls Invoke() on the equivalent target control. 
/// </summary> 
/// <param name="sender">The object that raised the event.</param>
/// <param name="e">Event arguments.</param>
/// <remarks> 
/// The Tag property of the FrameworkElement, the client button in this  
/// case, is used to store the InvokePattern object previously obtained  
/// from the associated target control. 
/// </remarks> 
///-------------------------------------------------------------------- 
void Invoke_Click(object sender, RoutedEventArgs e)
{
    Button clientButton = sender as Button;
    InvokePattern targetInvokePattern = clientButton.Tag as InvokePattern;
    if (targetInvokePattern == null)
        return;
    targetInvokePattern.Invoke();
    statusText.Text = "Button invoked.";
}
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