ExcludeUpdateRgn

The ExcludeUpdateRgn function prevents drawing within invalid areas of a window by excluding an updated region in the window from a clipping region. 

int ExcludeUpdateRgn(
  HDC hDC,    // handle to device context
  HWND hWnd   // handle to window
);

Parameters

hDC
Handle to the device context associated with the clipping region.
hWnd
Handle to the window to update.

Return Values

The return value specifies the complexity of the excluded region; it can be any one of the following values.

Value Meaning
COMPLEXREGION Region consists of more than one rectangle.
ERROR An error occurred.
NULLREGION Region is empty.
SIMPLEREGION Region is a single rectangle.

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

Painting and Drawing Overview, Painting and Drawing Functions, BeginPaint, GetUpdateRect, GetUpdateRgn, UpdateWindow