Applying Visual Styles to the TabControl in .NET 2-CSDN博客

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Sample Image

Introduction

I had faced a big problem with the TabControl included in Visual Studio 2005. So I applied a "Mnemonic" (hot key) feature to the TabControl, and for this reason I had set the DrawMode property to OwnerDrawFixed. But setting this property removed the XP-look style for the button.

So I tried to implement the DrawItem event for re-drawing the button, but it did not seem to work. I even tried the "Sky Bound component" which is freely available on the net, but it did not match my requirement.

So, finally I decided to build my own control. I browsed the internet for some resources concerning this, but I was not satisfied with what I found.

So here is the control, in which I have applied the XP-look style with the hot key feature.

Background

First of all, we need to set the double buffering technique to improve painting and to allow the control to change its appearance:

Me.SetStyle(ControlStyles.UserPaint, True)
Me.SetStyle(ControlStyles.AllPaintingInWmPaint, True)
Me.SetStyle(ControlStyles.DoubleBuffer, True)
Me.SetStyle(ControlStyles.ResizeRedraw, True)
Me.SetStyle(ControlStyles.SupportsTransparentBackColor, True)

Then, you need to override the OnPaint event and draw your own control. The basic steps involved are:

Collapse

Protected Overrides Function ProcessMnemonic(ByVal charCode As Char) As Boolean
    For Each p As TabPage In Me.TabPages
        If Control.IsMnemonic(charCode, p.Text) Then
            Me.SelectedTab = p
            Me.Focus()
            Return True
        End If
    Next p
    Return False
End Function 'ProcessMnemonic

          
Protected Overrides Sub OnPaint(ByVal e As _
          System.Windows.Forms.PaintEventArgs)
    MyBase.OnPaint(e)
    DrawControl(e.Graphics)
End Sub

Friend Sub DrawControl(ByVal g As Graphics)
    If Not Visible Then
        Return
    End If
    Dim render As New VisualStyleRenderer(VisualStyleElement.Tab.Pane.Normal)
    Dim TabControlArea As Rectangle = Me.ClientRectangle
    Dim TabArea As Rectangle = Me.DisplayRectangle
    TabArea.Y = TabArea.Y + 1
    TabArea.Width = TabArea.Width + 1
    Dim nDelta As Integer = SystemInformation.Border3DSize.Width
    TabArea.Inflate(nDelta, nDelta)
    render.DrawBackground(g, TabArea)
      
    Dim i As Integer = 0
    While i < Me.TabCount
        DrawTab(g, Me.TabPages(i), i)
        i += 1
    End While
      
End Sub
          
Friend Sub DrawTab(ByVal g As Graphics, ByVal tabPage _
           As TabPage, ByVal nIndex As Integer)
    Dim recBounds As Rectangle = Me.GetTabRect(nIndex)
      
    Dim tabTextArea As RectangleF = _
        CType(Me.GetTabRect(nIndex), RectangleF)
    Dim bSelected As Boolean = (Me.SelectedIndex = nIndex)
    Dim render As New VisualStyleRenderer(VisualStyleElement.Tab.Pane.Normal)
    render = New VisualStyleRenderer(VisualStyleElement.Tab.TabItem.Pressed)
    If bSelected Then
        recBounds.Height = recBounds.Height + 10
        render = New VisualStyleRenderer(VisualStyleElement.Tab.TabItem.Pressed)
        render.DrawBackground(g, recBounds)
        render.DrawEdge(g, recBounds, Edges.Diagonal, _
               EdgeStyle.Sunken, EdgeEffects.Flat)
    Else
        recBounds.Y = recBounds.Y + 1
        render = New VisualStyleRenderer(VisualStyleElement.Tab.TabItem.Normal)
        render.DrawBackground(g, recBounds)
        render.DrawEdge(g, recBounds, Edges.Diagonal, _
               EdgeStyle.Sunken, EdgeEffects.Flat)
    End If
    If (tabPage.ImageIndex >= 0) AndAlso _
                (Not (ImageList Is Nothing)) _
                AndAlso (Not (ImageList.Images(tabPage.ImageIndex) _
                Is Nothing)) Then
        Dim nLeftMargin As Integer = 8
        Dim nRightMargin As Integer = 2
        Dim img As Image = ImageList.Images(tabPage.ImageIndex)
        Dim rimage As Rectangle = New Rectangle(recBounds.X + _
                   nLeftMargin, recBounds.Y + 1, img.Width, img.Height)
        Dim nAdj As Single = CType((nLeftMargin + _
                    img.Width + nRightMargin), Single)
        rimage.Y += (recBounds.Height - img.Height) / 2
        tabTextArea.X += nAdj
        tabTextArea.Width -= nAdj
        g.DrawImage(img, rimage)
    End If
    Dim stringFormat As StringFormat = New StringFormat
    stringFormat.Alignment = StringAlignment.Center
    stringFormat.LineAlignment = StringAlignment.Center
    If FlagControl Then
        stringFormat.HotkeyPrefix = Drawing.Text.HotkeyPrefix.Show
    Else
        stringFormat.HotkeyPrefix = Drawing.Text.HotkeyPrefix.Hide
    End If
    Dim br As Brush
    br = New SolidBrush(tabPage.ForeColor)
    g.DrawString(tabPage.Text, Font, br, tabTextArea, stringFormat)
End Sub