This method obtains a clipped cache presentation space.

#define INCL_WINWINDOWMGR /* Or use INCL_WIN, INCL_PM, Also in COMMON section */
#include <os2.h>

HWND     hwnd;            /*  Handle of window for which the presentation space is required. */
HWND     hwndClipWindow;  /*  Handle of window for clipping. */
ULONG    ulClipflags;     /*  Clipping control flags. */
HPS      hps;             /*  Presentation-space handle that can be used for drawing. */

hps = WinGetClipPS(hwnd, hwndClipWindow, ulClipflags);