SetWindowRgn function (winuser.h)
The SetWindowRgn function sets the window region of a window. The window region determines the area within the window where the system permits drawing. The system does not display any portion of a window that lies outside of the window region
int SetWindowRgn( [in] HWND hWnd, [in] HRGN hRgn, [in] BOOL bRedraw );
A handle to the window whose window region is to be set.
A handle to a region. The function sets the window region of the window to this region.
If hRgn is NULL, the function sets the window region to NULL.
Specifies whether the system redraws the window after setting the window region. If bRedraw is TRUE, the system does so; otherwise, it does not.
Typically, you set bRedraw to TRUE if the window is visible.
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero.
When this function is called, the system sends the WM_WINDOWPOSCHANGING and WM_WINDOWPOSCHANGING messages to the window.
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 obtain the window region of a window, call the GetWindowRgn function.
|Minimum supported client||Windows 2000 Professional [desktop apps only]|
|Minimum supported server||Windows 2000 Server [desktop apps only]|
|Header||winuser.h (include Windows.h)|
|API set||ext-ms-win-ntuser-draw-l1-1-0 (introduced in Windows 8)|
Painting and Drawing Functions