## Presentation Device Driver Reference for OS/2

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### GreCombineRegion - Syntax

Simulation support:

This function is simulated by a handling routine in the graphics engine.

Description

GreCombineRegion combines two regions to make a third. The destination region can be the same as one of the source regions. An error is raised when any one of the specified regions is currently selected as the clip region. All source and target regions must be of the same device class.

This function can be hooked by the presentation driver.

    #define INCL_GRE_REGIONS

    #include <os2.h>

    HDC      hdc;        /*  Device context handle. */

    HRGN     hrgnDst;    /*  Destination region handle. */

    HRGN     hrgnSrc1;   /*  First region handle. */

    HRGN     hrgnSrc2;   /*  Second region handle. */

    LONG     cmdMode;    /*  Method of combination. */

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

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

    LONG     rc;

    rc = GreCombineRegion(hdc, hrgnDst, hrgnSrc1,

           hrgnSrc2, cmdMode, pInstance, lFunction);