Centering A Form - Using Available Desktop Space

A variety of ways exist for doing so, but most ignore some aspects of the environment such as the taskbar, the office launchbar, and even the app's own titlebar.

The following function takes all of this into account to center a form perfectly with the client area.

private Declare Function GetSystemMetrics Lib "user32" _
    (byval nIndex as Long) as Long 
private Declare Function GetWindowLong Lib "user32" alias _
    "GetWindowLongA" (byval hwnd as Long, _
    byval nIndex as Long) as Long   

private Const SM_CXFULLSCREEN = 16 
private Const SM_CYFULLSCREEN = 17 
private Const SM_CYCAPTION = 4  

public Sub CenterForm(Frm as Form)  

    Dim Left, Top as Integer  

    Left = Screen.TwipsPerPixelX * _
      GetSystemMetrics(SM_CXFULLSCREEN) / 2 - Frm.Width / 2 
    Top = Screen.TwipsPerPixelY * _
      (GetSystemMetrics(SM_CYFULLSCREEN) + _
       GetSystemMetrics(SM_CYCAPTION)) / 2 - Frm.Height / 2  

    Frm.Move Left, Top

End Sub