Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All

Expose the Content of a Table Using UI Automation

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 shows how Microsoft UI Automation can be used to expose the content and intrinsic properties of each cell within a tabular control.

The following code example demonstrates how to obtain a AutomationElement that represents the content of a table cell; cell properties such as row and column indices, row and column spans, and row and column header information are also obtained. This example uses a focus change event handler to simulate keyboard traversal of a tabular control that implements UI Automation. Information for each table item is exposed on a focus change event.

NoteNote

Since focus changes are global desktop events, focus change events outside the table should be filtered. See the TrackFocus Sample for a related implementation.


/// -------------------------------------------------------------------
/// <summary>
/// Starts the target application and returns the AutomationElement 
/// obtained from the targets window handle.
/// </summary>
/// <param name="exe">
/// The target application.
/// </param>
/// <param name="filename">
/// The text file to be opened in the target application
/// </param>
/// <returns>
/// An AutomationElement representing the target application.
/// </returns>
/// -------------------------------------------------------------------
private AutomationElement StartTarget(string exe, string filename)
{
    // Start text editor and load with a text file.
    Process p = Process.Start(exe, filename);

    // targetApp --> the root AutomationElement
    AutomationElement targetApp =
        AutomationElement.FromHandle(p.MainWindowHandle);

    return targetApp;
}


...


/// -------------------------------------------------------------------
/// <summary>
/// Obtain the table control of interest from the target application.
/// </summary>
/// <param name="targetApp">
/// The target application.
/// </param>
/// <returns>
/// An AutomationElement representing a table control.
/// </returns>
/// -------------------------------------------------------------------
private AutomationElement GetTableElement(AutomationElement targetApp)
{
    // The control type we're looking for; in this case 'Document'
    PropertyCondition cond1 =
        new PropertyCondition(
        AutomationElement.ControlTypeProperty,
        ControlType.Table);

    // The control pattern of interest; in this case 'TextPattern'.
    PropertyCondition cond2 =
        new PropertyCondition(
        AutomationElement.IsTablePatternAvailableProperty,
        true);

    AndCondition tableCondition = new AndCondition(cond1, cond2);

    AutomationElement targetTableElement =
        targetApp.FindFirst(TreeScope.Descendants, tableCondition);

    // If targetTableElement is null then a suitable table control 
    // was not found.
    return targetTableElement;
}


...


///--------------------------------------------------------------------
/// <summary>
/// Obtains a TableItemPattern control pattern from an 
/// AutomationElement.
/// </summary>
/// <param name="targetControl">
/// The AutomationElement of interest.
/// </param>
/// <returns>
/// A TableItemPattern object.
/// </returns>
///--------------------------------------------------------------------
private TableItemPattern GetTableItemPattern(
    AutomationElement targetControl)
{
    TableItemPattern tableItemPattern = null;

    try
    {
        tableItemPattern =
            targetControl.GetCurrentPattern(
            TableItemPattern.Pattern)
            as TableItemPattern;
    }
    // Object doesn't support the 
    // TableItemPattern control pattern
    catch (InvalidOperationException)
    {
        return null;
    }

    return tableItemPattern;
}


...


///--------------------------------------------------------------------
/// <summary>
/// Obtains a TablePattern control pattern from an 
/// AutomationElement.
/// </summary>
/// <param name="targetControl">
/// The AutomationElement of interest.
/// </param>
/// <returns>
/// A TablePattern object.
/// </returns>
///--------------------------------------------------------------------
private TablePattern GetTablePattern(
    AutomationElement targetControl)
{
    TablePattern tablePattern = null;

    try
    {
        tablePattern =
            targetControl.GetCurrentPattern(
            TablePattern.Pattern)
            as TablePattern;
    }
    // Object doesn't support the 
    // TablePattern control pattern
    catch (InvalidOperationException)
    {
        return null;
    }

    return tablePattern;
}


...


///--------------------------------------------------------------------
/// <summary>
/// Set up table item event listeners.
/// </summary>
/// <remarks>
/// The event listener is essentially a focus change listener.
/// Since this is a global desktop listener, a filter would be required 
/// to ignore focus change events outside the table.
/// </remarks>
///--------------------------------------------------------------------
private void SetTableItemEventListeners()
{
    AutomationFocusChangedEventHandler tableItemFocusChangedListener =
        new AutomationFocusChangedEventHandler(OnTableItemFocusChange);
    Automation.AddAutomationFocusChangedEventHandler(
        tableItemFocusChangedListener);
}


...


///--------------------------------------------------------------------
/// <summary>
/// Event handler for table item focus change.
/// Can be used to track traversal of individual table items 
/// within a table.
/// </summary>
/// <param name="src">Object that raised the event.</param>
/// <param name="e">Event arguments.</param>
///--------------------------------------------------------------------
private void OnTableItemFocusChange(
    object src, AutomationFocusChangedEventArgs e)
{
    // Make sure the element still exists. Elements such as tooltips
    // can disappear before the event is processed.
    AutomationElement sourceElement;
    try
    {
        sourceElement = src as AutomationElement;
    }
    catch (ElementNotAvailableException)
    {
        return;
    }

    // Get a TableItemPattern from the source of the event.
    TableItemPattern tableItemPattern =
        GetTableItemPattern(sourceElement);

    if (tableItemPattern == null)
    {
        return;
    }

    // Get a TablePattern from the container of the current element.
    TablePattern tablePattern =
        GetTablePattern(tableItemPattern.Current.ContainingGrid);

    if (tablePattern == null)
    {
        return;
    }

    AutomationElement tableItem = null;
    try
    {
        tableItem = tablePattern.GetItem(
        tableItemPattern.Current.Row,
        tableItemPattern.Current.Column);
    }
    catch (ArgumentOutOfRangeException)
    {
        // If the requested row coordinate is larger than the RowCount 
        // or the column coordinate is larger than the ColumnCount.
        // -- OR --
        // If either of the requested row or column coordinates 
        // is less than zero.
        // TO DO: error handling.
    }

    // Further event processing can be done at this point.
    // For the purposes of this sample we can just record item properties.
    string controlType = 
        tableItem.Current.ControlType.LocalizedControlType;
    AutomationElement[] columnHeaders = 
        tableItemPattern.Current.GetColumnHeaderItems();
    AutomationElement[] rowHeaders = 
        tableItemPattern.Current.GetRowHeaderItems();
    int itemRow = tableItemPattern.Current.Row;
    int itemColumn = tableItemPattern.Current.Column;
    int itemRowSpan = tableItemPattern.Current.RowSpan;
    int itemColumnSpan = tableItemPattern.Current.ColumnSpan;
}

///--------------------------------------------------------------------
/// <summary>
/// Handles the application shutdown.
/// </summary>
/// <param name="args">Event arguments.</param>
///--------------------------------------------------------------------
protected override void OnExit(System.Windows.ExitEventArgs args)
{
    Automation.RemoveAllEventHandlers();
    base.OnExit(args);
}


Community Additions

ADD
Show:
© 2015 Microsoft