This documentation is archived and is not being maintained.

TableLayoutSettings.ColumnCount Property

Gets or sets the maximum number of columns allowed in the table layout.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public int ColumnCount { get; set; }

Property Value

Type: System.Int32
The maximum number of columns allowed in the table layout. The default is 0.


The property value is less than 0.

Setting the ColumnCount property does not allocate the columns or any backing memory. This allocation occurs when the columns are created.

Setting this property causes the table to undergo another layout operation.

The following example shows how to initialize a TableLayoutSettings object for a TableLayoutPanel control. For a full code listing, see How to: Implement a Custom ToolStripRenderer.

// The following class implements a sliding-tile puzzle.
// The GridStrip control is a custom ToolStrip that arranges
// its ToolStripButton controls in a grid layout. There is 
// one empty cell, into which the user can slide an adjacent
// tile with a drag-and-drop operation. Tiles that are eligible 
// for moving are highlighted.
public class GridStrip : ToolStrip
    // The button that is the drag source.
    private ToolStripButton dragButton = null;

    // Settings for the ToolStrip control's TableLayoutPanel.
    // This provides access to the cell position of each
    // ToolStripButton.
    private TableLayoutSettings tableSettings = null;

    // The empty cell. ToolStripButton controls that are
    // adjacent to this button can be moved to this button's
    // cell position.
    private ToolStripButton emptyCellButton = null;

    // The dimensions of each tile. A tile is represented
    // by a ToolStripButton controls.
    private Size tileSize = new Size(128, 128);

    // The number of rows in the GridStrip control.
    private readonly int rows = 5;

    // The number of columns in the GridStrip control.
    private readonly int columns = 5;

    // The one-time initialzation behavior is enforced
    // with this field. For more information, see the 
    // OnPaint method.
    private bool firstTime = false;

    // This is a required by the Windows Forms designer.
    private System.ComponentModel.IContainer components;

    // The default constructor.  
    public GridStrip()


    // This property exposes the empty cell to the 
    // GridStripRenderer class.
    internal ToolStripButton EmptyCell
            return this.emptyCellButton;

    // This utility method initializes the TableLayoutPanel 
    // which contains the ToolStripButton controls.
    private void InitializeTableLayoutSettings()
        // Specify the numbers of rows and columns in the GridStrip control.
        this.tableSettings = base.LayoutSettings as TableLayoutSettings;
        this.tableSettings.ColumnCount = this.rows;
        this.tableSettings.RowCount = this.columns;

        // Create a dummy bitmap with the dimensions of each tile.
        // The GridStrip control sizes itself based on these dimensions.
        Bitmap b = new Bitmap(tileSize.Width, tileSize.Height);

        // Populate the GridStrip control with ToolStripButton controls.
        for (int i = 0; i < this.tableSettings.ColumnCount; i++)
            for (int j = 0; j < this.tableSettings.RowCount; j++)
                // Create a new ToolStripButton control.
                ToolStripButton btn = new ToolStripButton();
                btn.DisplayStyle = ToolStripItemDisplayStyle.Image;
                btn.Image = b;
                btn.ImageAlign = ContentAlignment.MiddleCenter;
                btn.ImageScaling = ToolStripItemImageScaling.None;
                btn.Margin = Padding.Empty;
                btn.Padding = Padding.Empty;

                // Add the new ToolStripButton control to the GridStrip.

                // Set the cell position of the ToolStripButton control.
                TableLayoutPanelCellPosition cellPos = new TableLayoutPanelCellPosition(i, j);
                this.tableSettings.SetCellPosition(btn, cellPos);

                // If this is the ToolStripButton control at cell (0,0),
                // assign it as the empty cell button.
                if( i == 0 && j == 0 )
                    btn.Text = "Empty Cell";
                    btn.Image = b;
                    this.emptyCellButton = btn;

    // This method defines the Paint event behavior.
    // The GridStripRenderer requires that the GridStrip
    // be fully layed out when it is renders, so this
    // initialization code cannot be placed in the
    // GridStrip constructor. By the time the Paint
    // event is raised, the control layout has been 
    // completed, so the GridStripRenderer can paint
    // correctly. This one-time initialization is
    // implemented with the firstTime field.
    protected override void OnPaint(PaintEventArgs e)

        if (!this.firstTime)
            this.Renderer = new GridStripRenderer();

            // Comment this line to see the unscrambled image.
            this.firstTime = true;

    // This utility method changes the ToolStripButton control 
    // positions in the TableLayoutPanel. This scrambles the 
    // buttons to initialize the puzzle.
    private void ScrambleButtons()
        int i = 0;
        int lastElement = this.Items.Count - 1;

        while ( (i != lastElement ) &&
                (lastElement - i > 1) )
            TableLayoutPanelCellPosition pos1 = 

            TableLayoutPanelCellPosition pos2 = 



    // This method defines the MouseDown event behavior. 
    // If the user has clicked on a valid drag source, 
    // the drag operation starts.
    protected override void OnMouseDown(MouseEventArgs mea)

        ToolStripButton btn = this.GetItemAt(mea.Location) as ToolStripButton;

        if (btn != null)
            if (this.IsValidDragSource(btn))
                this.dragButton = btn;

    // This method defines the MouseMove event behavior. 
    protected override void OnMouseMove(MouseEventArgs mea)

        // Is a drag operation pending?
        if (this.dragButton != null)
            // A drag operation is pending. Call DoDragDrop to 
            // determine the disposition of the operation.
            DragDropEffects dropEffect = this.DoDragDrop(
                new DataObject(this.dragButton), 

    // This method defines the DragOver event behavior. 
    protected override void OnDragOver(DragEventArgs dea)

        // Get the ToolStripButton control 
        // at the given mouse position.
        Point p = new Point(dea.X, dea.Y);
        ToolStripButton item = this.GetItemAt(
            this.PointToClient(p)) as ToolStripButton;

        // If the ToolStripButton control is the empty cell,
        // indicate that the move operation is valid.
        if( item == this.emptyCellButton )
            // Set the drag operation to indicate a valid move.
            dea.Effect = DragDropEffects.Move;

    // This method defines the DragDrop event behavior. 
    protected override void OnDragDrop(DragEventArgs dea)

        // Did a valid move operation occur?
        if (dea.Effect == DragDropEffects.Move)
            // The move operation is valid. Adjust the state
            // of the GridStrip control's TableLayoutPanel,
            // by swapping the positions of the source button
            // and the empty cell button.

            // Get the cell of the control to move.
            TableLayoutPanelCellPosition sourcePos = 

            // Get the cell of the emptyCellButton.
            TableLayoutPanelCellPosition dropPos = 

            // Move the control to the empty cell.
            tableSettings.SetCellPosition(this.dragButton, dropPos);

            // Set the position of the empty cell to 
            // that of the previously occupied cell.
            tableSettings.SetCellPosition(this.emptyCellButton, sourcePos);

            // Reset the drag operation.
            this.dragButton = null;

    // This method defines the DragLeave event behavior. 
    // If the mouse leaves the client area of the GridStrip
    // control, the drag operation is canceled.
    protected override void OnDragLeave(EventArgs e)

        // Reset the drag operation.
        this.dragButton = null;

    // This method defines the ueryContinueDrag event behavior. 
    // If the mouse leaves the client area of the GridStrip
    // control, the drag operation is canceled.
    protected override void OnQueryContinueDrag(QueryContinueDragEventArgs qcdevent)

        // Get the current mouse position, in screen coordinates.
        Point mousePos = this.PointToClient(Control.MousePosition);

        // If the mouse position is outside the GridStrip control's
        // client area, cancel the drag operation. Be sure to
        // transform the mouse's screen coordinates to client coordinates. 
        if (!this.ClientRectangle.Contains(mousePos))
            qcdevent.Action = DragAction.Cancel;

    // This utility method determines if a button
    // is positioned relative to the empty cell 
    // such that it can be dragged into the empty cell.
    private bool IsValidDragSource(ToolStripButton b)
        TableLayoutPanelCellPosition sourcePos = 

        TableLayoutPanelCellPosition emptyPos = 

        return (IsValidDragSource(sourcePos, emptyPos));

    // This utility method determines if a cell position
    // is adjacent to the empty cell.
    internal static bool IsValidDragSource(
        TableLayoutPanelCellPosition sourcePos, 
        TableLayoutPanelCellPosition emptyPos)
        bool returnValue = false;

        // A cell is considered to be a valid drag source if it
        // is adjacent to the empty cell. Cells that are positioned
        // on a diagonal are not valid.
        if (((sourcePos.Column == emptyPos.Column - 1) && (sourcePos.Row == emptyPos.Row)) ||
            ((sourcePos.Column == emptyPos.Column + 1) && (sourcePos.Row == emptyPos.Row)) ||
            ((sourcePos.Column == emptyPos.Column) && (sourcePos.Row == emptyPos.Row - 1)) ||
            ((sourcePos.Column == emptyPos.Column) && (sourcePos.Row == emptyPos.Row + 1)))
            returnValue = true;

        return returnValue;

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.