BeginDeferWindowPos

The BeginDeferWindowPos function allocates memory for a multiple-window – position structure and returns the handle to the structure.

HDWP BeginDeferWindowPos(
  int nNumWindows   // number of windows
);
 

Parameters

nNumWindows

Specifies the initial number of windows for which to store position information. The DeferWindowPos function increases the size of the structure, if necessary.

Return Values

If the function succeeds, the return value identifies the multiple-window – position structure. If insufficient system resources are available to allocate the structure, the return value is NULL. To get extended error information, call GetLastError.

Remarks

The multiple-window – position structure is an internal structure; an application cannot access it directly.

DeferWindowPos fills the multiple-window – position structure with information about the target position for one or more windows about to be moved. The EndDeferWindowPos function accepts the handle to this structure and repositions the windows by using the information stored in the structure.

If any of the windows in the multiple-window – position structure have the SWP_HIDEWINDOW or SWP_SHOWWINDOW flag set, none of the windows are repositioned.

If the system must increase the size of the multiple-window – position structure beyond the initial size specified by the nNumWindows parameter but cannot allocate enough memory to do so, the system fails the entire window positioning sequence (BeginDeferWindowPos, DeferWindowPos, and EndDeferWindowPos). By specifying the maximum size needed, an application can detect and process failure early in the process.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in winuser.h.
  Import Library: Use user32.lib.

See Also

Windows Overview, Window Functions, DeferWindowPos, EndDeferWindowPos, SetWindowPos