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Expose the Content of a Table Using UI Automation

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

Example

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.

Note

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>
''' 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 Function StartTarget(ByVal exe As String, ByVal filename As String) As AutomationElement
    ' Start text editor and load with a text file.
    Dim p As Process = Process.Start(exe, filename)

    ' targetApp --> the root AutomationElement
    Dim targetApp As AutomationElement = _
    AutomationElement.FromHandle(p.MainWindowHandle)

    Return targetApp
End Function

/// -------------------------------------------------------------------
/// <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>
''' 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 Function GetTableElement(ByVal targetApp As AutomationElement) As AutomationElement
    ' The control type we're looking for; in this case 'Document'
    Dim cond1 As PropertyCondition = _
        New PropertyCondition( _
        AutomationElement.ControlTypeProperty, _
        ControlType.Table)

    ' The control pattern of interest; in this case 'TextPattern'.
    Dim cond2 As PropertyCondition = _
        New PropertyCondition( _
        AutomationElement.IsTablePatternAvailableProperty, _
        True)

    Dim tableCondition As AndCondition = New AndCondition(cond1, cond2)

    Dim targetTableElement As AutomationElement = _
    targetApp.FindFirst(TreeScope.Descendants, tableCondition)

    ' If targetTableElement is null then a suitable table control 
    ' was not found.
    Return targetTableElement
End Function

///--------------------------------------------------------------------
/// <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 TableItemPattern control pattern from an 
''' AutomationElement.
''' </summary>
''' <param name="targetControl">
''' The AutomationElement of interest.
''' </param>
''' <returns>
''' A TableItemPattern object.
''' </returns>
'''--------------------------------------------------------------------
Private Function GetTableItemPattern( _
ByVal targetControl As AutomationElement) As TableItemPattern
    Dim tableItemPattern As TableItemPattern = Nothing

    Try
        tableItemPattern = DirectCast( _
        targetControl.GetCurrentPattern(tableItemPattern.Pattern), TableItemPattern)
    Catch exc As InvalidOperationException
        ' Object doesn't support the 
        ' GridPattern control pattern
        Return Nothing
    End Try

    Return tableItemPattern

End Function 'GetTableItemPattern    

///--------------------------------------------------------------------
/// <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>
''' Obtains a TablePattern control pattern from an 
''' AutomationElement.
''' </summary>
''' <param name="targetControl">
''' The AutomationElement of interest.
''' </param>
''' <returns>
''' A TablePattern object.
''' </returns>
'''--------------------------------------------------------------------
Private Function GetTablePattern( _
ByVal targetControl As AutomationElement) As TablePattern
    Dim tablePattern As TablePattern = Nothing

    Try
        tablePattern = DirectCast( _
        targetControl.GetCurrentPattern(tablePattern.Pattern), _
        TablePattern)
    Catch exc As InvalidOperationException
        ' Object doesn't support the 
        ' TablePattern control pattern
        Return Nothing
    End Try

    Return tablePattern

End Function 'GetTablePattern    

///--------------------------------------------------------------------
/// <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>
''' 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 Sub SetTableItemEventListeners( _
ByVal targetControl As AutomationElement)
    Dim tableItemFocusChangedListener As AutomationFocusChangedEventHandler = _
    AddressOf OnTableItemFocusChange
    Automation.AddAutomationFocusChangedEventHandler( _
    tableItemFocusChangedListener)

End Sub

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

'''--------------------------------------------------------------------
''' <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 Sub OnTableItemFocusChange( _
ByVal src As Object, ByVal e As AutomationFocusChangedEventArgs)
    ' Make sure the element still exists. Elements such as tooltips
    ' can disappear before the event is processed.
    Dim sourceElement As AutomationElement
    Try
        sourceElement = DirectCast(src, AutomationElement)
    Catch exc As ElementNotAvailableException
        Return
    End Try

    ' Get a TableItemPattern from the source of the event.
    Dim tableItemPattern As TableItemPattern = _
    GetTableItemPattern(sourceElement)

    If tableItemPattern Is Nothing Then
        Return
    End If

    ' Get a TablePattern from the container of the current element.
    Dim tablePattern As TablePattern = _
    GetTablePattern(tableItemPattern.Current.ContainingGrid)

    If tablePattern Is Nothing Then
        Return
    End If

    Dim tableItem As AutomationElement = Nothing
    Try
        tableItem = tablePattern.GetItem( _
        tableItemPattern.Current.Row, tableItemPattern.Current.Column)

    Catch exc As 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.
    End Try

    ' Further event processing can be done at this point.
    ' For the purposes of this sample we can just record item properties.
    Dim controlType As String = _
        tableItem.Current.ControlType.LocalizedControlType
    Dim columnHeaders As AutomationElement() = _
    tableItemPattern.Current.GetColumnHeaderItems()
    Dim rowHeaders As AutomationElement() = _
    tableItemPattern.Current.GetRowHeaderItems()
    Dim itemRow As Integer = tableItemPattern.Current.Row
    Dim itemColumn As Integer = tableItemPattern.Current.Column
    Dim itemRowSpan As Integer = tableItemPattern.Current.RowSpan
    Dim itemColumnSpan As Integer = tableItemPattern.Current.ColumnSpan

End Sub


'''--------------------------------------------------------------------
''' <summary>
''' Handles the application shutdown.
''' </summary>
''' <param name="args">Event arguments.</param>
'''--------------------------------------------------------------------
Protected Overrides Sub OnExit(ByVal args As System.Windows.ExitEventArgs)
    Automation.RemoveAllEventHandlers()
    MyBase.OnExit(args)

End Sub

See also