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ToolStripRenderer Class

Handles the painting functionality for ToolStrip objects.

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

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

Use the ToolStripRenderer class to apply a particular style or theme to a ToolStrip. Rather than custom painting a ToolStrip and the ToolStripItem objects it contains, you set the ToolStrip.Renderer property to an object that inherits from ToolStripRenderer. The painting specified by the ToolStripRenderer is applied to the ToolStrip, as well as the items it contains.

You can do custom painting in ToolStrip controls in several ways. As with other Windows Forms controls, the ToolStrip and ToolStripItem both have overridable OnPaint methods and Paint events. As with regular painting, the coordinate system is relative to the client area of the control; that is, the upper left-hand corner of the control is 0, 0. The Paint event and OnPaint method for a ToolStripItem behave like other control paint events.

The ToolStripRenderer class has overridable methods for painting the background, item background, item image, item arrow, item text, and border of the ToolStrip. The event arguments for these methods expose several properties such as rectangles, colors, and text formats that you can adjust as desired.

To adjust just a few aspects of how an item is painted, you typically override the ToolStripRenderer.

If you are writing a new item and want to control all aspects of the painting, override the OnPaint method. From within OnPaint, you can use methods from the ToolStripRenderer.

By default, the ToolStrip is double buffered, taking advantage of the OptimizedDoubleBuffer setting.

The following code example demonstrates how to implement a custom ToolStripRenderer class. The GridStripRenderer class customizes three aspects of the GridStrip control's appearance: GridStrip border, ToolStripButton border, and ToolStripButton image. For a full code listing, see How to: Implement a Custom ToolStripRenderer.

' This class implements a custom ToolStripRenderer for the  
' GridStrip control. It customizes three aspects of the  
' GridStrip control's appearance: GridStrip border,  
' ToolStripButton border, and ToolStripButton image. 
Friend Class GridStripRenderer
     Inherits ToolStripRenderer

   ' The style of the empty cell's text. 
   Private Shared style As New StringFormat()

   ' The thickness (width or height) of a  
   ' ToolStripButton control's border. 
   Private Shared borderThickness As Integer = 2

   ' The main bitmap that is the source for the  
   ' subimagesthat are assigned to individual  
   ' ToolStripButton controls. 
   Private bmp As Bitmap = Nothing 

   ' The brush that paints the background of  
   ' the GridStrip control. 
   Private backgroundBrush As Brush = Nothing 


   ' This is the static constructor. It initializes the 
   ' StringFormat for drawing the text in the empty cell. 
   Shared Sub New()
      style.Alignment = StringAlignment.Center
      style.LineAlignment = StringAlignment.Center
   End Sub  

   ' This method initializes the GridStripRenderer by 
   ' creating the image that is used as the source for 
   ' the individual button images. 
   Protected Overrides Sub Initialize(ts As ToolStrip)
      MyBase.Initialize(ts)

      Me.InitializeBitmap(ts)
     End Sub 

   ' This method initializes an individual ToolStripButton 
   ' control. It copies a subimage from the GridStripRenderer's 
   ' main image, according to the position and size of  
   ' the ToolStripButton. 
   Protected Overrides Sub InitializeItem(item As ToolStripItem)
      MyBase.InitializeItem(item)

         Dim gs As GridStrip = item.Owner

      ' The empty cell does not receive a subimage. 
         If ((TypeOf (item) Is ToolStripButton) And _
              (item IsNot gs.EmptyCell)) Then 
             ' Copy the subimage from the appropriate  
             ' part of the main image. 
             Dim subImage As Bitmap = bmp.Clone(item.Bounds, PixelFormat.Undefined)

             ' Assign the subimage to the ToolStripButton 
             ' control's Image property.
             item.Image = subImage
         End If 
   End Sub  

   ' This utility method creates the main image that 
   ' is the source for the subimages of the individual  
   ' ToolStripButton controls. 
   Private Sub InitializeBitmap(toolStrip As ToolStrip)
      ' Create the main bitmap, into which the image is drawn. 
      Me.bmp = New Bitmap(toolStrip.Size.Width, toolStrip.Size.Height)

      ' Draw a fancy pattern. This could be any image or drawing. 
      Dim g As Graphics = Graphics.FromImage(bmp)
      Try 
         ' Draw smoothed lines.
         g.SmoothingMode = SmoothingMode.AntiAlias

         ' Draw the image. In this case, it is  
         ' a number of concentric ellipses.  
         Dim i As Integer 
         For i = 0 To toolStrip.Size.Width - 8 Step 8
            g.DrawEllipse(Pens.Blue, 0, 0, i, i)
         Next i
      Finally
         g.Dispose()
      End Try 
   End Sub  

   ' This method draws a border around the GridStrip control. 
   Protected Overrides Sub OnRenderToolStripBorder(e As ToolStripRenderEventArgs)
      MyBase.OnRenderToolStripBorder(e)

      ControlPaint.DrawFocusRectangle(e.Graphics, e.AffectedBounds, SystemColors.ControlDarkDark, SystemColors.ControlDarkDark)
   End Sub  

   ' This method renders the GridStrip control's background. 
   Protected Overrides Sub OnRenderToolStripBackground(e As ToolStripRenderEventArgs)
      MyBase.OnRenderToolStripBackground(e)

      ' This late initialization is a workaround. The gradient 
      ' depends on the bounds of the GridStrip control. The bounds  
      ' are dependent on the layout engine, which hasn't fully 
      ' performed layout by the time the Initialize method runs. 
      If Me.backgroundBrush Is Nothing Then 
         Me.backgroundBrush = New LinearGradientBrush(e.ToolStrip.ClientRectangle, SystemColors.ControlLightLight, SystemColors.ControlDark, 90, True)
      End If 

      ' Paint the GridStrip control's background.
      e.Graphics.FillRectangle(Me.backgroundBrush, e.AffectedBounds)
     End Sub 

   ' This method draws a border around the button's image. If the background 
   ' to be rendered belongs to the empty cell, a string is drawn. Otherwise, 
   ' a border is drawn at the edges of the button. 
   Protected Overrides Sub OnRenderButtonBackground(e As ToolStripItemRenderEventArgs)
      MyBase.OnRenderButtonBackground(e)

      ' Define some local variables for convenience. 
      Dim g As Graphics = e.Graphics
      Dim gs As GridStrip = e.ToolStrip 
      Dim gsb As ToolStripButton = e.Item 

      ' Calculate the rectangle around which the border is painted. 
      Dim imageRectangle As New Rectangle(borderThickness, borderThickness, e.Item.Width - 2 * borderThickness, e.Item.Height - 2 * borderThickness)

      ' If rendering the empty cell background, draw an  
      ' explanatory string, centered in the ToolStripButton. 
         If gsb Is gs.EmptyCell Then
             e.Graphics.DrawString("Drag to here", gsb.Font, SystemBrushes.ControlDarkDark, imageRectangle, style)
         Else 
             ' If the button can be a drag source, paint its border red. 
             ' otherwise, paint its border a dark color. 
             Dim b As Brush = IIf(gs.IsValidDragSource(gsb), Brushes.Red, SystemBrushes.ControlDarkDark)

             ' Draw the top segment of the border. 
             Dim borderSegment As New Rectangle(0, 0, e.Item.Width, imageRectangle.Top)
             g.FillRectangle(b, borderSegment)

             ' Draw the right segment.
             borderSegment = New Rectangle(imageRectangle.Right, 0, e.Item.Bounds.Right - imageRectangle.Right, imageRectangle.Bottom)
             g.FillRectangle(b, borderSegment)

             ' Draw the left segment.
             borderSegment = New Rectangle(0, 0, imageRectangle.Left, e.Item.Height)
             g.FillRectangle(b, borderSegment)

             ' Draw the bottom segment.
             borderSegment = New Rectangle(0, imageRectangle.Bottom, e.Item.Width, e.Item.Bounds.Bottom - imageRectangle.Bottom)
             g.FillRectangle(b, borderSegment)
         End If 
     End Sub 
 End Class

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 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0
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