## Presentation Device Driver Reference for OS/2

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### GreNotifyClipChange - Syntax

Simulation support:

None. This function is mandatory for all drivers.

Description:

GreNotifyClipChange is called whenever there is any change to the DC region . The call gives the presentation driver an opportunity to optimize clipping by enumerating the clip rectangles and caching them whenever they change.

This function must be supported by the presentation driver. GreNotifyClipChange is called from the graphics engine whenever an application calls a GPI function that modifies the clipping rectangles within the device context. This function can be handled by bit-map simulation.

    #define INCL_GRE_DEVMISC2

    #include <os2.h>

    HDC       hdc;         /*  Device context handle. */

    PRECTL    prclBound;   /*  Pointer to a rectangle that bounds the new clip region in screen coordinates. */

    ULONG     cRect;       /*  Number of rectangles in the new clip region as returned by GetClipRects. */

    ULONG     idClipPath;  /*  Current ClipPath ID. */

    PVOID     pInstance;   /*  Pointer to instance data. */

    ULONG     lFunction;   /*  High-order WORD=flags; low-order WORD=NGreNotifyClipChange. */

    BOOL      rc;          /*  Return Code. */

    rc = GreNotifyClipChange(hdc, prclBound, cRect,

           idClipPath, pInstance, lFunction);