Francesco Geri

Imports System.Collections.Generic

Imports System.Linq

Imports System.Text

Imports System.Windows.Forms

Imports System.Runtime.InteropServices

Public Module MDIUtil

#Region " MDI Activate Child "

    <System.Security.SuppressUnmanagedCodeSecurity>

    <System.Runtime.InteropServices.DllImport("user32.dll", CharSet:=System.Runtime.InteropServices.CharSet.Auto)>

    Public Function SendMessage(hWnd As IntPtr, msg As Integer, wParam As IntPtr, lParam As IntPtr) As IntPtr

    End Function

    Public Const WM_MDINEXT As Integer = &H224

    ''' <summary>

    ''' Attiva la form MDI child specificata eviatando i problemi di flicker/flashing

    ''' che si avrebbero usando semplicemente il metodo <see cref="Form.Activate">Activate</see>.

    ''' Vedi post http://www.codeproject.com/Articles/19524/Workaround-for-flicker-flashing-when-programmatica

    ''' </summary>

    ''' <param name="form">Form MDI partent</param>

    ''' <param name="childToActivate">Form MDI child da attivre</param>

    <System.Runtime.CompilerServices.Extension>

 Public Sub MyActivateMdiChild(form As Form, childToActivate As Form)

        If Not childToActivate Is form.ActiveMdiChild Then

            Dim mdiClient As MdiClient = GetMDIClient(form)

            If mdiClient Is Nothing Then Return

            Dim count As Integer = form.MdiChildren.Length

            Dim childForm As Control = Nothing

            ' next or previous MDIChild form

            Dim pos As Integer = mdiClient.Controls.IndexOf(childToActivate)

            If pos < 0 Then Return 'Throw New InvalidOperationException("MDIChild form not found")

            If mdiClient.Controls.Count <= 1 Then

                ' C'è un solo child, quindi attiva quello in modo classico

                childToActivate.Focus()

                Return

            End If

            If pos = 0 Then

                childForm = mdiClient.Controls(1)

            Else

                ' get next and activate previous

                childForm = mdiClient.Controls(pos - 1)

            End If

            ' get previous and activate next

            ' flag indicating whether to activate previous or next MDIChild

            Dim direction As New IntPtr(If(pos = 0, 1, 0))

            ' bada bing, bada boom

            SendMessage(mdiClient.Handle, WM_MDINEXT, childForm.Handle, direction)

        End If

    End Sub

    Public Function GetMDIClient(form As Form) As MdiClient

        For Each c As Control In form.Controls

            If TypeOf c Is MdiClient Then

                Return DirectCast(c, MdiClient)

            End If

        Next

        Return Nothing 'Throw New InvalidOperationException("No MDIClient")

    End Function

#End Region

End Module

Imports itConsult.josh.joshDesigner.MDIUtil

...

Dim child As Form = getTheFormToActivate()

' La seguente istruzione sostisuice l'istruzione: child.Activate()

Me.MyActivateMdiChild(child)

Imports System.Collections.Generic

Imports System.Linq

Imports System.Text

Imports System.Windows.Forms

Imports System.Runtime.InteropServices

Public Module MDIUtil

#Region " Bordo interno (sunken) "

    <DllImport("user32.dll")> _

    Private Function GetWindowLong(hWnd As IntPtr, nIndex As Integer) As Integer

    End Function

    <DllImport("user32.dll")> _

    Private Function SetWindowLong(hWnd As IntPtr, nIndex As Integer, dwNewLong As Integer) As Integer

    End Function

    <DllImport("user32.dll", ExactSpelling:=True)> _

    Private Function SetWindowPos(hWnd As IntPtr, hWndInsertAfter As IntPtr, X As Integer, Y As Integer, cx As Integer, cy As Integer, _

        uFlags As UInteger) As Integer

    End Function

    Private Const GWL_EXSTYLE As Integer = -20

    Private Const WS_EX_CLIENTEDGE As Integer = &H200

    Private Const SWP_NOSIZE As UInteger = &H1

    Private Const SWP_NOMOVE As UInteger = &H2

    Private Const SWP_NOZORDER As UInteger = &H4

    Private Const SWP_NOREDRAW As UInteger = &H8

    Private Const SWP_NOACTIVATE As UInteger = &H10

    Private Const SWP_FRAMECHANGED As UInteger = &H20

    Private Const SWP_SHOWWINDOW As UInteger = &H40

    Private Const SWP_HIDEWINDOW As UInteger = &H80

    Private Const SWP_NOCOPYBITS As UInteger = &H100

    Private Const SWP_NOOWNERZORDER As UInteger = &H200

    Private Const SWP_NOSENDCHANGING As UInteger = &H400

    ''' <summary>

    ''' Consente di rimuovere il bordo 3D interno della form MDI (sunken).

    ''' Vedi post: http://stackoverflow.com/questions/7752696/how-to-remove-3d-border-sunken-from-mdiclient-component-in-mdi-parent-form

    ''' Oppure articolo: http://www.codeproject.com/Articles/8489/Getting-a-quot-Handle-quot-on-the-MDI-Client#Changing%20the%20Border%20Styles:

    ''' </summary>

    ''' <param name="form"></param>

    ''' <param name="show">False per rimuovere il sunken (3D interno), True per mostrarlo</param>

    ''' <returns></returns>

    <System.Runtime.CompilerServices.Extension>

 Public Function SetBevel(form As Form, show As Boolean) As Boolean

        For Each c As Control In form.Controls

            Dim client As MdiClient = TryCast(c, MdiClient)

            If client IsNot Nothing Then

                Dim windowLong As Integer = GetWindowLong(c.Handle, GWL_EXSTYLE)

                If show Then

                    windowLong = windowLong Or WS_EX_CLIENTEDGE

                Else

                    windowLong = windowLong And Not WS_EX_CLIENTEDGE

                End If

                SetWindowLong(c.Handle, GWL_EXSTYLE, windowLong)

                ' Update the non-client area.

                SetWindowPos(client.Handle, IntPtr.Zero, 0, 0, 0, 0, _

                    SWP_NOACTIVATE Or SWP_NOMOVE Or SWP_NOSIZE Or SWP_NOZORDER Or SWP_NOOWNERZORDER Or SWP_FRAMECHANGED)

                Return True

            End If

        Next

        Return False

    End Function

#End Region

End Module

Imports itConsult.josh.joshDesigner.MDIUtil

Private Sub Form_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    Me.SetBevel(False)

End Sub