How to create partially client area in UserControl?

Question

In my previous question I have sorted out how to create container dependent control. Now, I am getting problem in that control. the design of control is little bit confusing

Answer 1

The easy way

The easiest way is to recalculate the bounds of the XWizardPage whenever the size of its parent changes.

Public Class XWizardPage
    Inherits DevExpress.XtraEditors.XtraPanel
    Implements IComparable(Of XWizardPage)

    Protected Overrides Sub OnResize(e As System.EventArgs)
        MyBase.OnResize(e)
        If (Not Me.positioningInternal) Then Me.Position()
    End Sub

    Protected Overrides Sub SetBoundsCore(x As Integer, y As Integer, width As Integer, height As Integer, specified As System.Windows.Forms.BoundsSpecified)
        MyBase.SetBoundsCore(x, y, width, height, specified)
        If (Not Me.positioningInternal) Then Me.Position()
    End Sub

    Protected Overrides Sub OnParentChanged(e As System.EventArgs)
        MyBase.OnParentChanged(e)
        If (Not Me.cachedParent Is Nothing) Then
            RemoveHandler Me.cachedParent.SizeChanged, AddressOf Me.OnParentSizeChanged
        End If
        Me.cachedParent = If(((Not Me.Parent Is Nothing) AndAlso (TypeOf Me.Parent Is XWizardControl)), Me.Parent, Nothing)
        If (Not Me.cachedParent Is Nothing) Then
            AddHandler Me.cachedParent.SizeChanged, AddressOf Me.OnParentSizeChanged
        End If
    End Sub

    Private Sub OnParentSizeChanged(sender As Object, e As EventArgs)
        Me.Position()
    End Sub

    Private Sub Position()
        If (Not Me.cachedParent Is Nothing) Then
            Dim r As Rectangle = Me.cachedParent.ClientRectangle
            r.Y += 10
            r.Height -= (10 * 2)
            If (Me.Bounds <> r) Then
                Me.positioningInternal = True
                Me.Bounds = r
                Me.positioningInternal = False
            End If
        End If
    End Sub

    Private cachedParent As Control
    Private positioningInternal As Boolean

End Class

The hard way

The hard way requires native calls. I cannot append a complete solution as this is pretty complex, though doable. The term you're looking for is nonclient area. There are many tutorials on the web, and you should do a search.

The following code is just an example to show you where to start and is not a final solution. For this to work perfect, you'll need to handle Window redraw, Mouse events etc.

Public Class XWizardControl
    Inherits DevExpress.XtraEditors.XtraUserControl

     _
    Private Shared Function GetDCEx(ByVal hWnd As IntPtr, ByVal hrgnClip As IntPtr, ByVal flags As Integer) As IntPtr
    End Function

    Private Sub WmNcCalcSize(ByRef m As Message)
        If (m.WParam.ToInt32() = 0) Then
            Dim ncRect As RECT = DirectCast(m.GetLParam(GetType(RECT)), RECT)
            ncRect.top += 10
            ncRect.bottom -= 10
            Marshal.StructureToPtr(ncRect, m.LParam, False)
            m.Result = IntPtr.Zero
        ElseIf (m.WParam.ToInt32() = 1) Then
            Dim ncParams As NCCALCSIZE_PARAMS = DirectCast(m.GetLParam(GetType(NCCALCSIZE_PARAMS)), NCCALCSIZE_PARAMS)
            ncParams.rectProposed.top += 10
            ncParams.rectProposed.bottom -= 10
            Marshal.StructureToPtr(ncParams, m.LParam, False)
            m.Result = IntPtr.Zero
        Else
            MyBase.WndProc(m)
        End If
    End Sub

    Private Sub WmNcPaint(ByRef m As Message)
        Dim hDC As IntPtr = GetDCEx(m.HWnd, m.WParam, (DCX.WINDOW Or DCX.INTERSECTRGN Or DCX.CACHE Or DCX.CLIPSIBLINGS))
        If (hDC.ToInt32() <> 0) Then
            Using g As Graphics = Graphics.FromHdc(hDC)
                g.Clear(Color.Red)
            End Using
            m.Result = IntPtr.Zero
        Else
            MyBase.WndProc(m)
        End If
    End Sub

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        Select Case m.Msg
            Case WM_NCCALCSIZE : Me.WmNcCalcSize(m) : Exit Select
            Case WM_NCPAINT : Me.WmNcPaint(m) : Exit Select
            Case Else : MyBase.WndProc(m) : Exit Select
        End Select
    End Sub

    Public Const WM_NCCALCSIZE As Integer = 131
    Public Const WM_NCPAINT As Integer = 133

     _
    Private Structure RECT
        Public left As Integer
        Public top As Integer
        Public right As Integer
        Public bottom As Integer
    End Structure

     _
    Private Structure NCCALCSIZE_PARAMS
        Public rectProposed As RECT
        Public rectBeforeMove As RECT
        Public rectClientBeforeMove As RECT
        Public lppos As WINDOWPOS
    End Structure

     _
    Private Structure WINDOWPOS
        Public hwnd As IntPtr
        Public hWndInsertAfter As IntPtr
        Public x As Integer
        Public y As Integer
        Public cx As Integer
        Public cy As Integer
        Public flags As UInteger
    End Structure

    Private Enum DCX As Integer
        CACHE = &H2
        CLIPCHILDREN = &H8
        CLIPSIBLINGS = &H10
        EXCLUDERGN = &H40
        EXCLUDEUPDATE = &H100
        INTERSECTRGN = &H80
        INTERSECTUPDATE = &H200
        LOCKWINDOWUPDATE = &H400
        NORECOMPUTE = &H100000
        NORESETATTRS = &H4
        PARENTCLIP = &H20
        VALIDATE = &H200000
        WINDOW = &H1
    End Enum

End Class