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GetUpdateRgn

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This function retrieves the update region of a window by copying it into the specified region. The coordinates of the update region are relative to the upper-left corner of the window; that is, they are client coordinates.

int GetUpdateRgn( 
  HWND hWnd, 
  HRGN hRgn, 
  BOOL bErase
);

Parameters

  • hWnd
    Handle to the window with an update region that is to be retrieved.
  • hRgn
    Handle to the region to receive the update region.
  • bErase
    Boolean that specifies whether the window background should be erased and whether nonclient areas of child windows should be drawn. If this parameter is FALSE, no drawing is done.

Return Values

The return value indicates the complexity of the resulting region. COMPLEXREGION indicates that the region consists of more than one rectangle. ERROR indicates that an error occurred. NULLREGION indicates that the region is empty. SIMPLEREGION indicates that the region is a single rectangle.

Remarks

The bErase parameter is ignored, the window background is not erased and no drawing is done.

The BeginPaint function automatically validates the update region, so any call to GetUpdateRgn made immediately after the call to BeginPaint retrieves an empty update region.

Requirements

OS Versions: Windows CE 1.0 and later.
Header: Winuser.h.
Link Library: Coredll.lib, Winmgr.lib.

See Also

BeginPaint | GetUpdateRect | UpdateWindow

Last updated on Wednesday, April 13, 2005

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