GridPattern.GridPatternInformation.ColumnCount Property

Definition

Namespace:

System.Windows.Automation

Assembly:

UIAutomationClient.dll

Gets the number of columns in a grid.

public:
 property int ColumnCount { int get(); };

public int ColumnCount { get; }

member this.ColumnCount : int

Public ReadOnly Property ColumnCount As Integer

Property Value

Int32

The total number of columns in a grid.

Examples

In the following example, an event listener is set up for a grid structure change such as a row or column grid item being added or removed from the grid.

///--------------------------------------------------------------------
/// <summary>
/// Set up grid event listeners.
/// </summary>
/// <param name="targetControl">
/// The automation element of interest.
/// </param>
///--------------------------------------------------------------------
private void SetGridEventListeners(AutomationElement targetControl)
{
    StructureChangedEventHandler gridStructureChangedListener = 
        new StructureChangedEventHandler(OnGridStructureChange);
    Automation.AddStructureChangedEventHandler(
        targetControl, 
        TreeScope.Element, 
        gridStructureChangedListener);
}

'''--------------------------------------------------------------------
''' <summary>
''' Set up grid event listeners.
''' </summary>
''' <param name="targetControl">
''' The automation element of interest.
''' </param>
'''--------------------------------------------------------------------
Private Sub SetGridEventListeners( _
ByVal targetControl As AutomationElement)
    Dim gridStructureChangedListener As StructureChangedEventHandler = _
    AddressOf OnGridStructureChange
    Automation.AddStructureChangedEventHandler( _
    targetControl, TreeScope.Element, gridStructureChangedListener)
End Sub

///--------------------------------------------------------------------
/// <summary>
/// Event handler for grid structure change.
/// </summary>
/// <param name="src">Object that raised the event.</param>
/// <param name="e">Event arguments.</param>
///--------------------------------------------------------------------
private void OnGridStructureChange(
    object src, StructureChangedEventArgs 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;
    }

    GridPattern gridPattern = GetGridPattern(sourceElement);

    if (gridPattern == null)
    {
        return;
    }

    if (gridPattern.Current.ColumnCount != columnCount)
    {
        // Column item added.
    }
    else if (gridPattern.Current.RowCount != rowCount)
    {
        // Row item added.
    }
}
// Member variables to track current row and column counts.
private int columnCount = 0;
private int rowCount = 0;

///--------------------------------------------------------------------
/// <summary>
/// Handles our 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 grid structure change.
''' </summary>
''' <param name="src">Object that raised the event.</param>
''' <param name="e">Event arguments.</param>
'''--------------------------------------------------------------------
Private Sub OnGridStructureChange( _
ByVal src As Object, ByVal e As StructureChangedEventArgs)
    ' 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

    Dim gridPattern As GridPattern = GetGridPattern(sourceElement)

    If gridPattern Is Nothing Then
        Return
    End If

    If gridPattern.Current.ColumnCount <> columnCount Then
        ' Column item added.
    ElseIf gridPattern.Current.RowCount <> rowCount Then
        ' Row item added.
    End If

End Sub
' Member variables to track current row and column counts.
Private columnCount As Integer = 0
Private rowCount As Integer = 0

'''--------------------------------------------------------------------
''' <summary>
''' Handles our 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

///--------------------------------------------------------------------
/// <summary>
/// Obtains a GridPattern control pattern from an 
/// automation element.
/// </summary>
/// <param name="targetControl">
/// The automation element of interest.
/// </param>
/// <returns>
/// A GridPattern object.
/// </returns>
///--------------------------------------------------------------------
private GridPattern GetGridPattern(
    AutomationElement targetControl)
{
    GridPattern gridPattern = null;

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

    return gridPattern;
}

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

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

    Return gridPattern
End Function 'GetGridPattern

Remarks

Hidden rows and columns, depending on the provider implementation, may be loaded in the UI Automation tree and will therefore be reflected in the RowCount and ColumnCount properties. If the hidden rows and columns have not yet been loaded they are not counted.

The default value is 0.