Attribute VB_Name = "ModuleControlAnchor"
Option Explicit
'AnchorModule SeabrookStan 2019
'Place the following one line of code in Form - Sub Form_Resize().
'   Anchor ControlName, AnchorTop, AnchorLeft, AnchorRight, AnchorBottom (as Boolean)

Enum AnchorSide
    AnchorNone
    AnchorLeft
    AnchorTop
    AnchorTopLeft
    AnchorRight
    AnchorLeftRight 'StretchX
    AnchorTopRight 'same as AnchorRight only
    AnchorTopLeftRight 'StretchX
    AnchorBottom
    AnchorBottomLeft
    AnchorTopBottom 'StretchY
    AnchorTopBottomLeft 'StretchY
    AnchorBottomRight
    AnchorBottomLeftRight 'StretchX
    AnchorTopBottomRight 'StretchY
    AnchorTopBottomLeftRight ' StretchXY
End Enum

Type TANCH
    Name As String
    DL As Long
    DT As Long
    DB As Long
    DR As Long
End Type
Dim ctlAnchors() As TANCH

Function IsControlArray(Ctl As Object) As String
    On Error Resume Next
    IsControlArray = Ctl.Index
End Function

Function IsInitialized() As Boolean
    On Error Resume Next
    IsInitialized = IIf(UBound(ctlAnchors) >= 0, True, False)
End Function

Public Sub Anchor(Ctl As Control, Optional acrSide As AnchorSide = AnchorNone)
    Dim ctlExists As Boolean
    Dim strCtlName As String 'name of the form+control+index
    strCtlName = Ctl.Parent.Name & Ctl.Name & IsControlArray(Ctl)
    
    Dim i As Integer

    If Not IsInitialized Then
        i = 0
    Else
        For i = 0 To UBound(ctlAnchors)
            If ctlAnchors(i).Name = strCtlName Then
                ctlExists = True
                Exit For 'save i index
            End If
        Next
    End If
    
    If Not ctlExists Then
        ReDim Preserve ctlAnchors(i)
        ctlAnchors(i).Name = strCtlName
        If (acrSide And AnchorRight) Then ctlAnchors(i).DR = Ctl.container.Width - Ctl.Left - Ctl.Width
        If (acrSide And AnchorBottom) Then ctlAnchors(i).DB = Ctl.container.Height - Ctl.Top - Ctl.Height
        If Not (acrSide And AnchorTop) Then ctlAnchors(i).DT = Ctl.container.Height - Ctl.Top
        If Not (acrSide And AnchorLeft) Then ctlAnchors(i).DL = Ctl.container.Width - Ctl.Left
    End If

    Dim CW As Long, CH As Long

    CW = Ctl.container.Width 'Determine Object Container size
    CH = Ctl.container.Height
  
    If (acrSide And AnchorRight) Then  'Now move the control's sides to follow movement of Form sides
        If (acrSide And AnchorLeft) Then
            'StretchX
            Ctl.Width = IIf(CW - Ctl.Left - ctlAnchors(i).DR > 0, CW - Ctl.Left - ctlAnchors(i).DR, 0)
        Else
            Ctl.Left = Ctl.container.Width - ctlAnchors(i).DL
        End If
    End If

    If (acrSide And AnchorBottom) Then
        If (acrSide And AnchorTop) Then
            'StretchY
            Ctl.Height = IIf(CH - Ctl.Top - ctlAnchors(i).DB > 0, CH - Ctl.Top - ctlAnchors(i).DB, 0)
        Else
            Ctl.Top = Ctl.container.Height - ctlAnchors(i).DT
        End If
    End If

End Sub