ValidateRgn function (winuser.h)

Article
02/22/2024

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

Syntax

BOOL ValidateRgn(
  [in] HWND hWnd,
  [in] HRGN hRgn
);

Parameters

[in] hWnd

Handle to the window whose update region is to be modified.

[in] hRgn

Handle to a region that defines the area to be removed from the update region. If this parameter is NULL, the entire client area is removed.

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.

Remarks

The specified region must have been created by a region function. The region coordinates are assumed to be client coordinates.

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.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	winuser.h (include Windows.h)
Library	User32.lib
DLL	User32.dll
API set	ext-ms-win-ntuser-draw-l1-1-0 (introduced in Windows 8)