Microsoft Access 2010 Bible

Chapter 27: Using the Windows Application Programming Interface

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The window’s handle is passed as an argument, and the function places the window’s class name

in the string lpClassName. The function returns the number of characters copied to the string

buffer if it’s successful, 0 if not.

The DisplayTitle wrapper function (see Listing 27.5) uses GetParent and GetClassNameA

to cycle through the windows and controls of an open Access form until the Access application

form (class Omain) is located. It then captures the text displayed in the title bar, using

GetWindowTextA, and displays the text in a message box.

LISTING 27.5

Returning the Caption Bar Text for a Window

Sub DisplayTitle()

Dim RetVal As Long

Dim Parent As Long

Dim lngRet As Long

Dim Caption As String * 128

Dim CaptionSize As Long

Dim WinHwnd As Long

Dim Class As String * 6

Dim ClassSize As Long

CaptionSize = Len(Caption)

ClassSize = Len(Class)

WinHwnd = Me.hwnd

Do Until Trim(Class) = “OMain”

Parent = apiGetParent(WinHwnd)

lngRet = apiGetClassName(Parent, Class, ClassSize)

WinHwnd = Parent

Loop

RetVal = apiGetWindowText( _

Parent, Caption, CaptionSize)

MsgBox Left$(Caption, RetVal)

End Sub

Notice that the Do...Loop in the middle of DisplayTitle searches for a window with a class

name of OMain. The very first version of Microsoft’s desktop database project was named Omega,

and this very early precursor to Microsoft Access lives on as the class name applied to the Access

main window.

SetWindowTextA

Use SetWindowTextA to change the caption displayed in a window’s title bar.

Declare Function apiSetWindowText _

Lib “User32” _