LayoutSettings Class

Note: This class is new in the .NET Framework version 2.0.

Provides a base class for collecting layout scheme characteristics.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

'Declaration
Public MustInherit Class LayoutSettings
'Usage
Dim instance As LayoutSettings

public abstract class LayoutSettings
public abstract class LayoutSettings

The LayoutSettings class is the base class for types that collect the various characteristics common to a specific user interface (UI) layout scheme, such as TableLayoutSettings and FlowLayoutSettings.

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
    Inherits ToolStrip

   ' The button that is the drag source.
   Private dragButton As ToolStripButton = Nothing
   
   ' Settings for the ToolStrip control's TableLayoutPanel.
   ' This provides access to the cell position of each
   ' ToolStripButton.
   Private tableSettings As TableLayoutSettings = Nothing
   
   ' The empty cell. ToolStripButton controls that are
   ' adjacent to this button can be moved to this button's
   ' cell position.
   Private emptyCellButton As ToolStripButton = Nothing
   
   ' The dimensions of each tile. A tile is represented
   ' by a ToolStripButton controls.
   Private tileSize As New Size(128, 128)
   
   ' The number of rows in the GridStrip control.
   Private rows As Integer = 5
   
   ' The number of columns in the GridStrip control.
   Private columns As Integer = 5
   
   ' The one-time initialzation behavior is enforced
   ' with this field. For more information, see the 
   ' OnPaint method.
   Private firstTime As Boolean = False
   
   ' This is a required by the Windows Forms designer.
   Private components As System.ComponentModel.IContainer
   
   
   ' The default constructor.  
    Public Sub New()
        MyBase.New()

        Me.InitializeComponent()

        Me.InitializeTableLayoutSettings()
    End Sub
   
   ' This property exposes the empty cell to the 
   ' GridStripRenderer class.
   Friend ReadOnly Property EmptyCell() As ToolStripButton
      Get
         Return Me.emptyCellButton
      End Get
   End Property
   
   
   ' This utility method initializes the TableLayoutPanel 
   ' which contains the ToolStripButton controls.
    Private Sub InitializeTableLayoutSettings()

        ' Specify the numbers of rows and columns in the GridStrip control.
        Me.tableSettings = CType(MyBase.LayoutSettings, TableLayoutSettings)
        Me.tableSettings.ColumnCount = Me.rows
        Me.tableSettings.RowCount = Me.columns

        ' Create a dummy bitmap with the dimensions of each tile.
        ' The GridStrip control sizes itself based on these dimensions.
        Dim b As New Bitmap(tileSize.Width, tileSize.Height)

        ' Populate the GridStrip control with ToolStripButton controls.
        Dim i As Integer
        For i = 0 To (Me.tableSettings.ColumnCount) - 1
            Dim j As Integer
            For j = 0 To (Me.tableSettings.RowCount) - 1
                ' Create a new ToolStripButton control.
                Dim btn As New ToolStripButton()
                btn.DisplayStyle = ToolStripItemDisplayStyle.Image
                btn.Image = b
                btn.ImageAlign = ContentAlignment.MiddleCenter
                btn.ImageScaling = ToolStripItemImageScaling.None
                btn.Margin = System.Windows.Forms.Padding.Empty
                btn.Padding = System.Windows.Forms.Padding.Empty

                ' Add the new ToolStripButton control to the GridStrip.
                Me.Items.Add(btn)

                ' Set the cell position of the ToolStripButton control.
                Dim cellPos As New TableLayoutPanelCellPosition(i, j)
                Me.tableSettings.SetCellPosition(btn, cellPos)

                ' If this is the ToolStripButton control at cell (0,0),
                ' assign it as the empty cell button.
                If i = 0 AndAlso j = 0 Then
                    btn.Text = "Empty Cell"
                    btn.Image = b
                    Me.emptyCellButton = btn
                End If
            Next j
        Next i
    End Sub
   
   
   ' 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 Overrides Sub OnPaint(e As PaintEventArgs)
      MyBase.OnPaint(e)
      
      If Not Me.firstTime Then
         Me.Renderer = New GridStripRenderer()
         
         ' Comment this line to see the unscrambled image.
         Me.ScrambleButtons()
         Me.firstTime = True
      End If
    End Sub
   
   
   ' This utility method changes the ToolStripButton control 
   ' positions in the TableLayoutPanel. This scrambles the 
   ' buttons to initialize the puzzle.
   Private Sub ScrambleButtons()
      Dim i As Integer = 0
      Dim lastElement As Integer = Me.Items.Count - 1
      
      While i <> lastElement AndAlso lastElement - i > 1
            Dim pos1 As TableLayoutPanelCellPosition = _
            Me.tableSettings.GetCellPosition(Me.Items(i))
         
            Dim pos2 As TableLayoutPanelCellPosition = _
            Me.tableSettings.GetCellPosition(Me.Items(lastElement))
         
            Me.tableSettings.SetCellPosition(Me.Items(i), pos2)
            i += 1
         
            Me.tableSettings.SetCellPosition(Me.Items(lastElement), pos1)
            lastElement -= 1
      End While
    End Sub
   
   
   ' This method defines the MouseDown event behavior. 
   ' If the user has clicked on a valid drag source, 
   ' the drag operation starts.
   Protected Overrides Sub OnMouseDown(mea As MouseEventArgs)
      MyBase.OnMouseDown(mea)
      
        Dim btn As ToolStripButton = CType(Me.GetItemAt(mea.Location), ToolStripButton)
      
      If Not (btn Is Nothing) Then
         If Me.IsValidDragSource(btn) Then
            Me.dragButton = btn
         End If
      End If
    End Sub
   
   
   ' This method defines the MouseMove event behavior. 
   Protected Overrides Sub OnMouseMove(mea As MouseEventArgs)
      MyBase.OnMouseMove(mea)
      
      ' Is a drag operation pending?
      If Not (Me.dragButton Is Nothing) Then
         ' A drag operation is pending. Call DoDragDrop to 
         ' determine the disposition of the operation.
         Dim dropEffect As DragDropEffects = Me.DoDragDrop(New DataObject(Me.dragButton), DragDropEffects.Move)
      End If
    End Sub
   
   ' This method defines the DragOver event behavior. 
   Protected Overrides Sub OnDragOver(dea As DragEventArgs)
      MyBase.OnDragOver(dea)
      
      ' Get the ToolStripButton control 
      ' at the given mouse position.
      Dim p As New Point(dea.X, dea.Y)
      Dim item As ToolStripButton = CType(Me.GetItemAt(Me.PointToClient(p)), ToolStripButton)
      
      
      ' If the ToolStripButton control is the empty cell,
      ' indicate that the move operation is valid.
        If item Is Me.emptyCellButton Then
            ' Set the drag operation to indicate a valid move.
            dea.Effect = DragDropEffects.Move
        End If
    End Sub
   
   
   ' This method defines the DragDrop event behavior. 
   Protected Overrides Sub OnDragDrop(dea As DragEventArgs)
      MyBase.OnDragDrop(dea)
      
      ' Did a valid move operation occur?
      If dea.Effect = DragDropEffects.Move Then
         ' 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.
         Dim sourcePos As TableLayoutPanelCellPosition = tableSettings.GetCellPosition(Me.dragButton)
         
         ' Get the cell of the emptyCellButton.
         Dim dropPos As TableLayoutPanelCellPosition = tableSettings.GetCellPosition(Me.emptyCellButton)
         
         ' Move the control to the empty cell.
         tableSettings.SetCellPosition(Me.dragButton, dropPos)
         
         ' Set the position of the empty cell to 
         ' that of the previously occupied cell.
         tableSettings.SetCellPosition(Me.emptyCellButton, sourcePos)
         
         ' Reset the drag operation.
         Me.dragButton = Nothing
      End If
    End Sub
   
   
   ' This method defines the DragLeave event behavior. 
   ' If the mouse leaves the client area of the GridStrip
   ' control, the drag operation is canceled.
   Protected Overrides Sub OnDragLeave(e As EventArgs)
      MyBase.OnDragLeave(e)
      
      ' Reset the drag operation.
      Me.dragButton = Nothing
    End Sub
   
   
   ' This method defines the ueryContinueDrag event behavior. 
   ' If the mouse leaves the client area of the GridStrip
   ' control, the drag operation is canceled.
   Protected Overrides Sub OnQueryContinueDrag(qcdevent As QueryContinueDragEventArgs)
      MyBase.OnQueryContinueDrag(qcdevent)
      
      ' Get the current mouse position, in screen coordinates.
      Dim mousePos As Point = Me.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 Not Me.ClientRectangle.Contains(mousePos) Then
         qcdevent.Action = DragAction.Cancel
      End If
    End Sub
   
   
   ' This utility method determines if a button
   ' is positioned relative to the empty cell 
   ' such that it can be dragged into the empty cell.
   Overloads Private Function IsValidDragSource(b As ToolStripButton) As Boolean
      Dim sourcePos As TableLayoutPanelCellPosition = tableSettings.GetCellPosition(b)
      
      Dim emptyPos As TableLayoutPanelCellPosition = tableSettings.GetCellPosition(Me.emptyCellButton)
      
        Return IsValidDragSource(sourcePos, emptyPos)

    End Function
   
   
   ' This utility method determines if a cell position
   ' is adjacent to the empty cell.
    Friend Overloads Shared Function IsValidDragSource( _
    ByVal sourcePos As TableLayoutPanelCellPosition, _
    ByVal emptyPos As TableLayoutPanelCellPosition) As Boolean
        Dim returnValue As Boolean = 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 AndAlso sourcePos.Row = emptyPos.Row OrElse _
        (sourcePos.Column = emptyPos.Column + 1 AndAlso sourcePos.Row = emptyPos.Row) OrElse _
        (sourcePos.Column = emptyPos.Column AndAlso sourcePos.Row = emptyPos.Row - 1) OrElse _
        (sourcePos.Column = emptyPos.Column AndAlso sourcePos.Row = emptyPos.Row + 1) Then
            returnValue = True
        End If

        Return returnValue
    End Function

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0

Community Additions

ADD
Show: