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Invoke a Control Using 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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