GetUpdateRgn function user32
The GetUpdateRgn function retrieves the update region of a window by copying it into the specified region. The coordinates of the update region are relative to the upper-left corner of the window (that is, they are client coordinates).
int GetUpdateRgn(
HWND hWnd,
HRGN hRgn,
BOOL bErase
);
Implementation
int GetUpdateRgn(int hWnd, int hRgn, int bErase) =>
_GetUpdateRgn(hWnd, hRgn, bErase);