ValidateRect

The ValidateRect function validates the client area within a rectangle by removing the rectangle from the update region of the specified window.

BOOL ValidateRect(
  HWND hWnd,  // handle of window
  CONST RECT *lpRect
              // address of validation rectangle coordinates
);
 

Parameters

hWnd

Handle to the window whose update region is to be modified. If this parameter is NULL, the system invalidates and redraws all windows and sends the WM_ERASEBKGND and WM_NCPAINT messages to the window procedure before the function returns.

lpRect

Pointer to a RECT structure that contains the client coordinates of the rectangle to be removed from the update region. If this parameter is NULL, the entire client area is removed.

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.

Windows NT: To get extended error information, call GetLastError.

Remarks

The BeginPaint function automatically validates the entire client area. Neither the ValidateRect nor ValidateRgn function should be called if a portion of the update region must be validated before the next WM_PAINT message is generated.

The system continues to generate WM_PAINT messages until the current update region is validated.

Windows CE: Passing in a NULL value for the hWnd parameter is not supported.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Requires version 1.0 or later.
  Header: Declared in winuser.h.
  Import Library: Use user32.lib.

See Also

Painting and Drawing Overview, Painting and Drawing Functions, BeginPaint, InvalidateRect, InvalidateRgn, RECT, ValidateRgn, WM_PAINT