common file dialog Acces 2010 64-bit

Status
Niet open voor verdere reacties.

VB noob

Gebruiker
Lid geworden
11 feb 2009
Berichten
78
Ik had in een Access 2003 database de functionaliteit om middels een knop een window te openen om de locatie van een foto te selecteren en op te slaan in een veld. Dit met behulp van de code van Ken Getz:
Code:
Option Compare Database

'***************** Code Start **************
'This code was originally written by Ken Getz.
'It is not to be altered or distributed,
'except as part of an application.
'You are free to use it in any application,
'provided the copyright notice is left unchanged.
'
' Code courtesy of:
' Microsoft Access 95 How-To
' Ken Getz and Paul Litwin
' Waite Group Press, 1996

Type tagOPENFILENAME
    lStructSize As Long
    hwndOwner As Long
    hInstance As Long
    strFilter As String
    strCustomFilter As String
    nMaxCustFilter As Long
    nFilterIndex As Long
    strFile As String
    nMaxFile As Long
    strFileTitle As String
    nMaxFileTitle As Long
    strInitialDir As String
    strTitle As String
    Flags As Long
    nFileOffset As Integer
    nFileExtension As Integer
    strDefExt As String
    lCustData As Long
    lpfnHook As Long
    lpTemplateName As String
End Type

Declare PtrSafe Function aht_apiGetOpenFileName Lib "comdlg32.dll" _
    Alias "GetOpenFileNameA" (OFN As tagOPENFILENAME) As Boolean

Declare PtrSafe Function aht_apiGetSaveFileName Lib "comdlg32.dll" _
    Alias "GetSaveFileNameA" (OFN As tagOPENFILENAME) As Boolean
Declare PtrSafe Function CommDlgExtendedError Lib "comdlg32.dll" () As Long

Global Const ahtOFN_READONLY = &H1
Global Const ahtOFN_OVERWRITEPROMPT = &H2
Global Const ahtOFN_HIDEREADONLY = &H4
Global Const ahtOFN_NOCHANGEDIR = &H8
Global Const ahtOFN_SHOWHELP = &H10
' You won't use these.
'Global Const ahtOFN_ENABLEHOOK = &H20
'Global Const ahtOFN_ENABLETEMPLATE = &H40
'Global Const ahtOFN_ENABLETEMPLATEHANDLE = &H80
Global Const ahtOFN_NOVALIDATE = &H100
Global Const ahtOFN_ALLOWMULTISELECT = &H200
Global Const ahtOFN_EXTENSIONDIFFERENT = &H400
Global Const ahtOFN_PATHMUSTEXIST = &H800
Global Const ahtOFN_FILEMUSTEXIST = &H1000
Global Const ahtOFN_CREATEPROMPT = &H2000
Global Const ahtOFN_SHAREAWARE = &H4000
Global Const ahtOFN_NOREADONLYRETURN = &H8000
Global Const ahtOFN_NOTESTFILECREATE = &H10000
Global Const ahtOFN_NONETWORKBUTTON = &H20000
Global Const ahtOFN_NOLONGNAMES = &H40000
' New for Windows 95
Global Const ahtOFN_EXPLORER = &H80000
Global Const ahtOFN_NODEREFERENCELINKS = &H100000
Global Const ahtOFN_LONGNAMES = &H200000

Function TestIt()
    Dim strFilter As String
    Dim lngFlags As Long
    strFilter = ahtAddFilterItem(strFilter, "Access Files (*.mda, *.mdb)", _
                    "*.MDA;*.MDB")
    strFilter = ahtAddFilterItem(strFilter, "dBASE Files (*.dbf)", "*.DBF")
    strFilter = ahtAddFilterItem(strFilter, "Text Files (*.txt)", "*.TXT")
    strFilter = ahtAddFilterItem(strFilter, "All Files (*.*)", "*.*")
    MsgBox "You selected: " & ahtCommonFileOpenSave(InitialDir:="C:\", _
        Filter:=strFilter, FilterIndex:=3, Flags:=lngFlags, _
        DialogTitle:="Hello! Open Me!")
    ' Since you passed in a variable for lngFlags,
    ' the function places the output flags value in the variable.
    Debug.Print Hex(lngFlags)
End Function

Function GetOpenFile(Optional varDirectory As Variant, _
    Optional varTitleForDialog As Variant) As Variant
' Here's an example that gets an Access database name.
Dim strFilter As String
Dim lngFlags As Long
Dim varFileName As Variant
' Specify that the chosen file must already exist,
' don't change directories when you're done
' Also, don't bother displaying
' the read-only box. It'll only confuse people.
    lngFlags = ahtOFN_FILEMUSTEXIST Or _
                ahtOFN_HIDEREADONLY Or ahtOFN_NOCHANGEDIR
    If IsMissing(varDirectory) Then
        varDirectory = ""
    End If
    If IsMissing(varTitleForDialog) Then
        varTitleForDialog = ""
    End If

    ' Define the filter string and allocate space in the "c"
    ' string Duplicate this line with changes as necessary for
    ' more file templates.
    strFilter = ahtAddFilterItem(strFilter, _
                "Access (*.mdb)", "*.MDB;*.MDA")
    ' Now actually call to get the file name.
    varFileName = ahtCommonFileOpenSave( _
                    OpenFile:=True, _
                    InitialDir:=varDirectory, _
                    Filter:=strFilter, _
                    Flags:=lngFlags, _
                    DialogTitle:=varTitleForDialog)
    If Not IsNull(varFileName) Then
        varFileName = TrimNull(varFileName)
    End If
    GetOpenFile = varFileName
End Function

Function ahtCommonFileOpenSave( _
            Optional ByRef Flags As Variant, _
            Optional ByVal InitialDir As Variant, _
            Optional ByVal Filter As Variant, _
            Optional ByVal FilterIndex As Variant, _
            Optional ByVal DefaultExt As Variant, _
            Optional ByVal Filename As Variant, _
            Optional ByVal DialogTitle As Variant, _
            Optional ByVal hwnd As Variant, _
            Optional ByVal OpenFile As Variant) As Variant
' This is the entry point you'll use to call the common
' file open/save dialog. The parameters are listed
' below, and all are optional.
'
' In:
' Flags: one or more of the ahtOFN_* constants, OR'd together.
' InitialDir: the directory in which to first look
' Filter: a set of file filters, set up by calling
' AddFilterItem. See examples.
' FilterIndex: 1-based integer indicating which filter
' set to use, by default (1 if unspecified)
' DefaultExt: Extension to use if the user doesn't enter one.
' Only useful on file saves.
' FileName: Default value for the file name text box.
' DialogTitle: Title for the dialog.
' hWnd: parent window handle
' OpenFile: Boolean(True=Open File/False=Save As)
' Out:
' Return Value: Either Null or the selected filename
Dim OFN As tagOPENFILENAME
Dim strFileName As String
Dim strFileTitle As String
Dim fResult As Boolean
    ' Give the dialog a caption title.
    If IsMissing(InitialDir) Then InitialDir = CurDir
    If IsMissing(Filter) Then Filter = ""
    If IsMissing(FilterIndex) Then FilterIndex = 1
    If IsMissing(Flags) Then Flags = 0&
    If IsMissing(DefaultExt) Then DefaultExt = ""
    If IsMissing(Filename) Then Filename = ""
    If IsMissing(DialogTitle) Then DialogTitle = ""
    If IsMissing(hwnd) Then hwnd = Application.hWndAccessApp
    If IsMissing(OpenFile) Then OpenFile = True
    ' Allocate string space for the returned strings.
    strFileName = Left(Filename & String(256, 0), 256)
    strFileTitle = String(256, 0)
    ' Set up the data structure before you call the function
    With OFN
        .lStructSize = Len(OFN)
        .hwndOwner = hwnd
        .strFilter = Filter
        .nFilterIndex = FilterIndex
        .strFile = strFileName
        .nMaxFile = Len(strFileName)
        .strFileTitle = strFileTitle
        .nMaxFileTitle = Len(strFileTitle)
        .strTitle = DialogTitle
        .Flags = Flags
        .strDefExt = DefaultExt
        .strInitialDir = InitialDir
        ' Didn't think most people would want to deal with
        ' these options.
        .hInstance = 0
        '.strCustomFilter = ""
        '.nMaxCustFilter = 0
        .lpfnHook = 0
        'New for NT 4.0
        .strCustomFilter = String(255, 0)
        .nMaxCustFilter = 255
    End With
    ' This will pass the desired data structure to the
    ' Windows API, which will in turn it uses to display
    ' the Open/Save As Dialog.
    If OpenFile Then
        fResult = aht_apiGetOpenFileName(OFN)
    Else
        fResult = aht_apiGetSaveFileName(OFN)
    End If

    ' The function call filled in the strFileTitle member
    ' of the structure. You'll have to write special code
    ' to retrieve that if you're interested.
    If fResult Then
        ' You might care to check the Flags member of the
        ' structure to get information about the chosen file.
        ' In this example, if you bothered to pass in a
        ' value for Flags, we'll fill it in with the outgoing
        ' Flags value.
        If Not IsMissing(Flags) Then Flags = OFN.Flags
        ahtCommonFileOpenSave = TrimNull(OFN.strFile)
    Else
        ahtCommonFileOpenSave = vbNullString
    End If
End Function

Function ahtAddFilterItem(strFilter As String, _
    strDescription As String, Optional varItem As Variant) As String
' Tack a new chunk onto the file filter.
' That is, take the old value, stick onto it the description,
' (like "Databases"), a null character, the skeleton
' (like "*.mdb;*.mda") and a final null character.

    If IsMissing(varItem) Then varItem = "*.*"
    ahtAddFilterItem = strFilter & _
                strDescription & vbNullChar & _
                varItem & vbNullChar
End Function

Private Function TrimNull(ByVal strItem As String) As String
Dim intPos As Integer
    intPos = InStr(strItem, vbNullChar)
    If intPos > 0 Then
        TrimNull = Left(strItem, intPos - 1)
    Else
        TrimNull = strItem
    End If
End Function
'************** Code End *****************

Echter, nu werk ik met MS Access 2010 met windows 7 64-bit en het werkte niet.
Ik heb eea aangepast met behulp van http://gpgonaccess.blogspot.it/2010/03/work-in-progress-and-64-bit-vba.html maar het werkt nog niet. Er zijn vooral aanpassingen in
Code:
Declare Function
naar
Code:
Private Declare PtrSafe Function
en
Code:
Long
naar
Code:
LongPtr
.

De code die ik nu heb is als volgt:
Code:
Option Compare Database
Option Explicit


'This code was originally written by Ken Getz.
' It is not to be altered or distributed, 'except as part of an application.
' You are free to use it in any application,
' provided the copyright notice is left unchanged.
'
' Code originally courtesy of:
' Microsoft Access 95 How-To
' Ken Getz and Paul Litwin
' Waite Group Press, 1996
' Revised to support multiple files:
' 28 December 2007
' ptrSafe added March, 2010
' LongPtr added March, 2010

Type tagOPENFILENAME
lStructSize As Long
hwndOwner As LongPtr
hInstance As LongPtr
strFilter As String
strCustomFilter As String
nMaxCustFilter As Long
nFilterIndex As Long
strFile As String
nMaxFile As Long
strFileTitle As String
nMaxFileTitle As Long
strInitialDir As String
strTitle As String
Flags As Long
nFileOffset As Integer
nFileExtension As Integer
strDefExt As String
lCustData As Long
lpfnHook As LongPtr
lpTemplateName As String
End Type

Private Declare PtrSafe Function aht_apiGetOpenFileName Lib "comdlg32.dll" _
Alias "aht_apiGetOpenFileNameA" (OFN As tagOPENFILENAME) As Boolean

Private Declare PtrSafe Function aht_apiGetSaveFileName Lib "comdlg32.dll" _
Alias "aht_apiGetSaveFileNameA" (OFN As tagOPENFILENAME) As Boolean


Global Const ahtOFN_READONLY = &H1
Global Const ahtOFN_OVERWRITEPROMPT = &H2
Global Const ahtOFN_HIDEREADONLY = &H4
Global Const ahtOFN_NOCHANGEDIR = &H8
Global Const ahtOFN_SHOWHELP = &H10
' You won't use these.
'Global Const ahtOFN_ENABLEHOOK = &H20
'Global Const ahtOFN_ENABLETEMPLATE = &H40
'Global Const ahtOFN_ENABLETEMPLATEHANDLE = &H80
Global Const ahtOFN_NOVALIDATE = &H100
Global Const ahtOFN_ALLOWMULTISELECT = &H200
Global Const ahtOFN_EXTENSIONDIFFERENT = &H400
Global Const ahtOFN_PATHMUSTEXIST = &H800
Global Const ahtOFN_FILEMUSTEXIST = &H1000
Global Const ahtOFN_CREATEPROMPT = &H2000
Global Const ahtOFN_SHAREAWARE = &H4000
Global Const ahtOFN_NOREADONLYRETURN = &H8000
Global Const ahtOFN_NOTESTFILECREATE = &H10000
Global Const ahtOFN_NONETWORKBUTTON = &H20000
Global Const ahtOFN_NOLONGNAMES = &H40000
' New for Windows 95
Global Const ahtOFN_EXPLORER = &H80000
Global Const ahtOFN_NODEREFERENCELINKS = &H100000
Global Const ahtOFN_LONGNAMES = &H200000

Function TestIt()
    Dim strFilter As String
    Dim lngFlags As Long
    strFilter = ahtAddFilterItem(strFilter, "Access Files (*.mda, *.mdb)", _
                    "*.MDA;*.MDB")
    strFilter = ahtAddFilterItem(strFilter, "dBASE Files (*.dbf)", "*.DBF")
    strFilter = ahtAddFilterItem(strFilter, "Text Files (*.txt)", "*.TXT")
    strFilter = ahtAddFilterItem(strFilter, "All Files (*.*)", "*.*")
    MsgBox "You selected: " & ahtCommonFileOpenSave(InitialDir:="C:\", _
        Filter:=strFilter, FilterIndex:=3, Flags:=lngFlags, _
        DialogTitle:="Hello! Open Me!")
    ' Since you passed in a variable for lngFlags,
    ' the function places the output flags value in the variable.
    Debug.Print Hex(lngFlags)
End Function

Function GetOpenFile(Optional varDirectory As Variant, _
    Optional varTitleForDialog As Variant) As Variant
' Here's an example that gets an Access database name.
Dim strFilter As String
Dim lngFlags As Long
Dim varFileName As Variant
' Specify that the chosen file must already exist,
' don't change directories when you're done
' Also, don't bother displaying
' the read-only box. It'll only confuse people.
    lngFlags = ahtOFN_FILEMUSTEXIST Or _
                ahtOFN_HIDEREADONLY Or ahtOFN_NOCHANGEDIR
    If IsMissing(varDirectory) Then
        varDirectory = ""
    End If
    If IsMissing(varTitleForDialog) Then
        varTitleForDialog = ""
    End If

    ' Define the filter string and allocate space in the "c"
    ' string Duplicate this line with changes as necessary for
    ' more file templates.
    strFilter = ahtAddFilterItem(strFilter, _
                "Access (*.mdb)", "*.MDB;*.MDA")
    ' Now actually call to get the file name.
    varFileName = ahtCommonFileOpenSave( _
                    OpenFile:=True, _
                    InitialDir:=varDirectory, _
                    Filter:=strFilter, _
                    Flags:=lngFlags, _
                    DialogTitle:=varTitleForDialog)
    If Not IsNull(varFileName) Then
        varFileName = TrimNull(varFileName)
    End If
    GetOpenFile = varFileName
End Function

Function ahtCommonFileOpenSave( _
            Optional ByRef Flags As Variant, _
            Optional ByVal InitialDir As Variant, _
            Optional ByVal Filter As Variant, _
            Optional ByVal FilterIndex As Variant, _
            Optional ByVal DefaultExt As Variant, _
            Optional ByVal Filename As Variant, _
            Optional ByVal DialogTitle As Variant, _
            Optional ByVal hwnd As Variant, _
            Optional ByVal OpenFile As Variant) As Variant
' This is the entry point you'll use to call the common
' file open/save dialog. The parameters are listed
' below, and all are optional.
'
' In:
' Flags: one or more of the ahtOFN_* constants, OR'd together.
' InitialDir: the directory in which to first look
' Filter: a set of file filters, set up by calling
' AddFilterItem. See examples.
' FilterIndex: 1-based integer indicating which filter
' set to use, by default (1 if unspecified)
' DefaultExt: Extension to use if the user doesn't enter one.
' Only useful on file saves.
' FileName: Default value for the file name text box.
' DialogTitle: Title for the dialog.
' hWnd: parent window handle
' OpenFile: Boolean(True=Open File/False=Save As)
' Out:
' Return Value: Either Null or the selected filename
Dim OFN As tagOPENFILENAME
Dim strFileName As String
Dim strFileTitle As String
Dim fResult As Boolean
    ' Give the dialog a caption title.
    If IsMissing(InitialDir) Then InitialDir = CurDir
    If IsMissing(Filter) Then Filter = ""
    If IsMissing(FilterIndex) Then FilterIndex = 1
    If IsMissing(Flags) Then Flags = 0&
    If IsMissing(DefaultExt) Then DefaultExt = ""
    If IsMissing(Filename) Then Filename = ""
    If IsMissing(DialogTitle) Then DialogTitle = ""
    If IsMissing(hwnd) Then hwnd = Application.hWndAccessApp
    If IsMissing(OpenFile) Then OpenFile = True
    ' Allocate string space for the returned strings.
    strFileName = Left(Filename & String(256, 0), 256)
    strFileTitle = String(256, 0)
    ' Set up the data structure before you call the function
    With OFN
        .lStructSize = LenB(OFN)
        .hwndOwner = hwnd
        .strFilter = Filter
        .nFilterIndex = FilterIndex
        .strFile = strFileName
        .nMaxFile = Len(strFileName)
        .strFileTitle = strFileTitle
        .nMaxFileTitle = Len(strFileTitle)
        .strTitle = DialogTitle
        .Flags = Flags
        .strDefExt = DefaultExt
        .strInitialDir = InitialDir
        ' Didn't think most people would want to deal with
        ' these options.
        .hInstance = 0
        '.strCustomFilter = ""
        '.nMaxCustFilter = 0
        .lpfnHook = 0
        'New for NT 4.0
        .strCustomFilter = String(255, 0)
        .nMaxCustFilter = 255
    End With
    ' This will pass the desired data structure to the
    ' Windows API, which will in turn it uses to display
    ' the Open/Save As Dialog.
    If OpenFile Then
        fResult = aht_apiGetOpenFileName(OFN)
    Else
        fResult = aht_apiGetSaveFileName(OFN)
    End If

    ' The function call filled in the strFileTitle member
    ' of the structure. You'll have to write special code
    ' to retrieve that if you're interested.
    If fResult Then
        ' You might care to check the Flags member of the
        ' structure to get information about the chosen file.
        ' In this example, if you bothered to pass in a
        ' value for Flags, we'll fill it in with the outgoing
        ' Flags value.
        If Not IsMissing(Flags) Then Flags = OFN.Flags
        ahtCommonFileOpenSave = TrimNull(OFN.strFile)
    Else
        ahtCommonFileOpenSave = vbNullString
    End If
End Function

Function ahtAddFilterItem(strFilter As String, _
    strDescription As String, Optional varItem As Variant) As String
' Tack a new chunk onto the file filter.
' That is, take the old value, stick onto it the description,
' (like "Databases"), a null character, the skeleton
' (like "*.mdb;*.mda") and a final null character.

    If IsMissing(varItem) Then varItem = "*.*"
    ahtAddFilterItem = strFilter & _
                strDescription & vbNullChar & _
                varItem & vbNullChar
End Function

Private Function TrimNull(ByVal strItem As String) As String
Dim intPos As Integer
    intPos = InStr(strItem, vbNullChar)
    If intPos > 0 Then
        TrimNull = Left(strItem, intPos - 1)
    Else
        TrimNull = strItem
    End If
End Function
'************** Code End *****************

Maar ik krijg de volgende foutmelding:
Code:
runtime error '453': Can't find DLL entry point aht_apiGetOpenFileNameA in comdlg32.dll[/quote]

Iemand de me verder kan helpen hiermee? Of een andere manier weet om middels een dialoogvenster een pad naar een foto te selecteren en op te slaan?
 
Ik doe het nog mooier... niet alleen een oplossing voor je probleem, maar een procedure die niet afhankelijk is van een Windows of Office versie, maar gewoon altijd werkt! En met een code die ook nog eens zo'n factor 10 kleiner is, en (daardoor) veel makkelijker te snappen! En het mooiste: hij staat in het voorbeeld :)
 

Bijlagen

Dat ziet er inderdaad perfect uit!

Als ik het goed zie zou ik alleen de code achter de knop 'cmdBestandenSelecteren' en de function 'BestandOpzoeken' nodig moeten hebben.
Bij mij gaat het uitsluitend om plaatjes, dus de overige filters heb ik niet eens nodig. Dit zou dan het pad naar de plaatjes in het veld lstBestanden moeten zetten, wat bij mij wel bound is.

Maar ik krijg het niet gedaan. Als ik de codes van de knop en functie in een lege database inbouw, en ook 'Option Compare Database' lijst toevoeg, dan krijg ik de melding: "User-defined type not defined". Dus schijnbaar gebeurt er meer dan ik doorheb?
 
Je hebt volgens mij alleen de code nodig achter de knop <cmdBestandenSelecteren> en de functie <BestandOpzoeken>. Die maakt wel gebruik van de bibliotheek <Microsoft Shell Controls and Automation> die je dus wel moet laden.
 
Thanks. Heb de bibliotheek toegevoegd.
De filters heb ik in principe niet nodig. Omdat ik alleen maar naar foto's wil zoeken. Ik kan nu wel een veld op het formulier maken met 'chkImage' die als default op '-1' staat en onzichtbaar is, maar liever heb ik gewoon de filter in de code, en dat er niet gezocht wordt naar een veld op het formulier om de filter in te stellen.

Maar er ging meer mis. Zonder het veld 'chkImage' krijg ik de melding: 'Eerst een bestandstype selecteren'. Begrijpelijk, er is immers geen veld waar dat kan gebeuren. Maar voeg ik 'chkImage' toe, en selecteer dat, dan krijg ik de melding:
Code:
 'Run-time error '-2147467259 (80004005)': Method 'FileDialog' of object '_Application' failed
.
Dit heb ik opgelost door de bibliotheek 'Microsoft Office 14.0 Object Library' toe te voegen.

Maar nu krijg ik de foutmelding:
Code:
run-time error '5': Invalid procedure call or argument

En debug verwijst naar de regel
Code:
.Filterindex = 1

Als ik dat stukje code eruit haal gaat het goed, maar werken de filters niet en zie ik alle files.

Enig idee hoe het filtergedeelte eruit kan halen, en terugbrengen tot een filter welke niet geselecteerd hoeft te worden en alleen afbeeldingen laat zien?
 
Als je alleen plaatjes nodig hebt, en niet hoeft te wisselen tussen bestandsformaten, kan er een hoop uit. Ik heb er maar even een nieuwe functie van gemaakt, dan hoef je alleen maar de aanroep vanuit de knop aan te passen. Bovendien kun je dan de andere functie bewaren voor andere doeleinden :)

Code:
Function ImageOpzoeken() As String
Dim tmp As String
Dim bCheck As Boolean

    'Open de Windows bestandenlijst, met als argument het type
    Set dlgPicker = Application.FileDialog(msoFileDialogFilePicker)
    With dlgPicker
        .Title = "Selecteer een bestand." 'De titel voor het venster
        '**************************************************************************
        'Pas dit aan voor map met afbeeldingen
        '**************************************************************************
        .InitialFileName = CurrentProject.Path      'Waar moet het venster beginnen?
        .Filters.Clear
        'Add a filter that includes GIF and JPEG images and make it the second item in the list.
        dlgPicker.Filters.Add "Afbeeldingen", "*.gif; *.jpg; *.jpeg", 1 'Beperk de bestandstypes tot .jpg"
        .FilterIndex = 1
        .AllowMultiSelect = True                   'Slechts één bestand kiezen toegestaan
        .InitialView = msoFileDialogViewList        'Bepaal weergave
        If .Show = -1 Then                          'Bepaal of gebruiker op OK-knop heeft geklikt.
            For Each vrtSelectedItem In .SelectedItems
                strFileName = strFileName & vrtSelectedItem & ";"
                ''strFileName = .SelectedItems.Item(1)    'String wordt gevuld met geselecteerde bestand
            Next
        Else
            MsgBox "Er is op <Cancel> gedrukt..."
        End If
    End With
    
    If Nz(strFileName, "") <> "" Then
        Do While Right(strFileName, 1) = ";"
            strFileName = Left(strFileName, Len(strFileName) - 1)
        Loop
        ImageOpzoeken = strFileName
    End If
    Set dlgPicker = Nothing

End Function
 
Status
Niet open voor verdere reacties.
Terug
Bovenaan Onderaan