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──Microsoft Foundation Classes──────────────────────────────────────────────
 
  void InvalidateRgn( CRgn* pRgn, BOOL bErase = FALSE );
 
  Parameter   Description
 
  <pRgn>      Identifies the region to be added to the update region. The
              region is assumed to have client coordinates.
 
  <bErase>    Specifies whether the background within the update region is
              to be erased.
 
  Remarks
 
  Invalidates the client area within the given region by adding it to the
  current update region of CWnd. The invalidated region, along with all
  other areas in the update region, is marked for painting when the
  ◄WM_PAINT► message is next sent. The invalidated areas accumulate in the
  update region until the region is processed when WM_PAINT is next sent,
  or the region is validated by using the ◄ValidateRect► or ◄ValidateRgn►
  member function.
 
  The <bErase> parameter specifies whether the background within the
  update area is to be erased when the update region is processed. If
  <bErase> is TRUE, the background is erased when the ◄BeginPaint► member
  function is called; if <bErase> is FALSE, the background remains
  unchanged. If <bErase> is TRUE for any part of the update region, the
  background in the entire region is erased, not just in the given part.
 
  Windows sends ◄WM_PAINT► whenever the CWnd update region is not empty
  and there are no other messages in the application queue for that
  window.
 
  The given region must have been previously created by using one of the
  region functions.
 
  See Also
 
  ◄CWnd::BeginPaint►, ◄CWnd::ValidateRect►, ◄CWnd::ValidateRgn►,
  ◄::InvalidateRgn►
 
 
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