Windows API Guide: DefWindowProc Function

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Declare Function EnumChildWindows Lib "user32.dll" (ByVal hWndParent As Long, ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long

Platforms

• Windows 95: Supported.
• Windows 98: Supported.
• Windows NT: Requires Windows NT 3.1 or later.
• Windows 2000: Supported.
• Windows CE: Not Supported.

Description & Usage

EnumChildWindows enumerates and provides handles to all of the child windows of a given window. This function will also enumerate any children of the child windows. Each time a child window is located, the function passes that handle to a program-defined callback function. The function continues doing so until all child windows have been enumerated, or until the process has been aborted.

Return Value

If an error occured, the function returns 0 (use GetLastError to get the error code). If successful, the function returns a non-zero value.

Visual Basic-Specific Issues

None.

Parameters

hWndParent

A handle to the parent window to enumerate the child windows of.

lpEnumFunc

A pointer to the application-defined callback function EnumChildProc.

lParam

An additional value to pass to the application-defined callback function.

Example:

' Display the window title of all children of window MDIForm1.  This ' task is given to the callback function, which will receive each handle individually. ' *** Place this code in a module.  This is the callback function. *** ' This function displays the title bar text of the window identified by hwnd. Public Function EnumChildProc (ByVal hwnd As Long, ByVal lParam As Long) As Long   Dim slength As Long, wintext As String  ' window title text length and buffer   Dim retval As Long  ' return value   Static winnum As Integer  ' counter keeps track of how many windows have been enumerated   winnum = winnum + 1  ' one more window enumerated....   slength = GetWindowTextLength(hwnd) + 1  ' get length of title bar text   buffer = Space(slength)  ' make room in the buffer   retval = GetWindowText(hwnd, buffer, slength)  ' get title bar text   Debug.Print "Window #"; winnum; " : ";  ' display number of enumerated window   Debug.Print Left(buffer, slength - 1)  ' display title bar text of enumerated window   EnumChildProc = 1  ' nonzero return value means continue enumeration End Function ' *** Place this code wherever you want to enumerate the windows. *** Dim retval As Long  ' return value ' Use the above callback function to list all of the enumerated windows.  Note that lParam is ' set to 0 because we don't need to pass any additional information to the function. retval = EnumChildWindows(MDIForm1.hWnd, AddressOf EnumChildProc, 0)

See Also

EnumThreadWindows, EnumWindows

Category

Windows

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Go back to the Reference section index.

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Last Modified: August 15, 1999
This page is copyright © 1999 Paul Kuliniewicz. Copyright Information Revised October 29, 2000
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