请大家帮小弟我解释一下这段代码的意思，本人是菜鸟

Public Sub ai()        '窗体的收放
Dim i As Integer
On Error Resume Next
If Controls.Count > 0 Then
    '如果窗体中包括菜单，这时程序将出错
    '解决办法：在代码前加"On Error Resume Next"
    For i = 0 To Controls.Count - 1
      With ap(i)
        .wp = Me.Controls(i).Width / Me.ScaleWidth
        .hp = Me.Controls(i).Height / Me.ScaleHeight
        .lp = Me.Controls(i).Left / Me.ScaleWidth
        .tp = Me.Controls(i).Top / Me.ScaleHeight
      End With
    Next i
End If
End Sub