VB.NET ToolStripRenderer类代码示例

' 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