GetWindowRgn info  Overview  Group

The GetWindowRgn function obtains a copy of the window region of a window. The window region of a window is set by calling the SetWindowRgn function. The window region determines the area within the window where the operating system permits drawing. The operating system does not display any portion of a window that lies outside of the window region

int GetWindowRgn(

HWND hWnd,	// handle to window whose window region is to be obtained
HRGN hRgn	// handle to region that receives a copy of the window region
);

Parameters

hWnd

Handle to the window whose window region is to be obtained.

hrgn

Handle to a region. This region receives a copy of the window region.

Return Values

The return value specifies the type of the region that the function obtains. It can be one of the following values:

Value	Meaning
NULLREGION	The region is empty.
SIMPLEREGION	The region is a single rectangle.
COMPLEXREGION	The region is more than one rectangle.
ERROR	An error occurred; the region is unaffected.

Comments

The coordinates of a window’s window region are relative to the upper-left corner of the window, not the client area of the window.

To set the window region of a window, call the SetWindowRgn function.

See Also

SetWindowRgn